Initial Commit

packages/ui/react/react-audio/src/a11y/aria-value-text/aria-value-text.md

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+# `a11y/aria-value-text`
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+Pure `aria-valuetext` formatter consumed by Phase-2 parameter
+controls (knobs, sliders, scrubbers). Returns a screen-reader
+friendly string for any numeric parameter value, picking sensible
+fractional digits from the parameter's declared range and applying
+unit-specific conventions (signed dB, kHz autoconversion above 1000
+Hz, percent suffix, ratio formatting, …).
+
+The module has zero React or DOM imports so it is safe to use in
+universal contexts (tests, SSR, Storybook docs, isolation
+tools).
+
+## Features
+
+- Auto-derived fractional digits from value magnitude and parameter
+  range (overridable via `options.fractionDigits`).
+- Signed dB with optional `+` prefix on positive values (default on).
+- Hz auto-promotion to kHz above 1000 Hz.
+- Built-in unit recognisers: `dB`, `Hz`, `kHz`, `ms`, `s`, `%`,
+  `ratio`, `cents`, `semitones`, `samples`, `bpm`; arbitrary strings
+  fall through with `${value.toFixed(digits)} ${unit}`.
+- Handles `Infinity` and `NaN` by returning `"out of range"`.
+
+## Usage: Basic
+
+```ts
+import { formatAriaValueText } from "@suaveplan/react-audio/a11y";
+
+formatAriaValueText(3.5, "dB", -12, 12);   // "+3.50 dB"
+formatAriaValueText(880, "Hz", 20, 20000);  // "880 Hz"
+formatAriaValueText(2400, "Hz", 20, 20000); // "2.40 kHz"
+formatAriaValueText(50, "%", 0, 100);       // "50.0 %"
+```
+
+## Usage: Advanced
+
+```tsx
+import { formatAriaValueText } from "@suaveplan/react-audio/a11y";
+
+function ParameterReadout({
+    value,
+    unit,
+    min,
+    max,
+}: {
+    value: number;
+    unit: string;
+    min: number;
+    max: number;
+}) {
+    return (
+        <span aria-live="polite">
+            {formatAriaValueText(value, unit, min, max, {
+                fractionDigits: 1,
+            })}
+        </span>
+    );
+}
+```
+
+## API Reference
+
+- `formatAriaValueText(value, unit, min, max, options?): string`.
+- `AriaValueUnit` — union of the recognised unit strings (plus the
+  catch-all `string`).
+- `FormatAriaValueOptions = { fractionDigits?, signedDb? }`.
+
+## Implementation Notes
+
+The auto-derived precision picks 0 digits for ranges ≥ 1000, 1 digit
+for ≥ 100, 2 digits for ≥ 1, and 3 digits otherwise. This matches
+screen-reader-friendly conventions: nobody wants to hear "two
+thousand four hundred point three two seven six Hertz". Hz values
+auto-promote to kHz at the 1000 Hz threshold because that's the
+boundary at which the kHz scale dominates audio production
+conventions; the kHz output uses a fixed 2-digit precision so values
+near the boundary read out consistently. `Infinity` and `NaN` short
+out to `"out of range"` because screen readers handle that phrase
+gracefully whereas spelling out `Infinity` derails the user.

packages/ui/react/react-audio/src/a11y/aria-value-text/aria-value-text.test.ts

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+import { describe, expect, it } from "@suaveplan/testing/runner";
+import { formatAriaValueText } from "./aria-value-text.js";
+
+describe("aria-value-text", () => {
+    it("signed dB formatter", { timeout: 5000 }, () => {
+        expect(formatAriaValueText(3.5, "dB", -12, 12)).toBe("+3.50 dB");
+        expect(formatAriaValueText(-3.5, "dB", -12, 12)).toBe("-3.50 dB");
+        expect(formatAriaValueText(0, "dB", -12, 12)).toBe("0.00 dB");
+        expect(
+            formatAriaValueText(3.5, "dB", -12, 12, { signedDb: false })
+        ).toBe("3.50 dB");
+    });
+
+    it("Hz auto-promotes to kHz above 1000", { timeout: 5000 }, () => {
+        expect(formatAriaValueText(880, "Hz", 20, 20000)).toBe("880 Hz");
+        expect(formatAriaValueText(2400, "Hz", 20, 20000)).toBe("2.40 kHz");
+    });
+
+    it("percent suffix", { timeout: 5000 }, () => {
+        expect(formatAriaValueText(50, "%", 0, 100)).toBe("50.0 %");
+    });
+
+    it("various units render", { timeout: 5000 }, () => {
+        expect(formatAriaValueText(0.5, "ms", 0, 1)).toMatch(/ms$/);
+        expect(formatAriaValueText(0.5, "s", 0, 1)).toMatch(/ s$/);
+        expect(formatAriaValueText(2, "ratio", 1, 10)).toMatch(/: 1$/);
+        expect(formatAriaValueText(10, "cents", 0, 100)).toMatch(/cents$/);
+        expect(formatAriaValueText(7, "semitones", 0, 12)).toMatch(/st$/);
+        expect(formatAriaValueText(128, "samples", 0, 1024)).toMatch(
+            /samples$/
+        );
+        expect(formatAriaValueText(120, "bpm", 40, 200)).toMatch(/BPM$/);
+        expect(formatAriaValueText(1, "kHz", 0, 20)).toMatch(/kHz$/);
+        expect(formatAriaValueText(1, "custom-unit", 0, 10)).toMatch(
+            /custom-unit$/
+        );
+    });
+
+    it("out-of-range / NaN safe", { timeout: 5000 }, () => {
+        expect(formatAriaValueText(Number.NaN, "dB", -1, 1)).toBe(
+            "out of range"
+        );
+        expect(formatAriaValueText(Number.POSITIVE_INFINITY, "Hz", 0, 1)).toBe(
+            "out of range"
+        );
+    });
+
+    it("overridable fractionDigits", { timeout: 5000 }, () => {
+        expect(
+            formatAriaValueText(0.123456, "%", 0, 100, { fractionDigits: 4 })
+        ).toBe("0.1235 %");
+    });
+
+    it("auto-precision tiers", { timeout: 5000 }, () => {
+        expect(formatAriaValueText(0.5, "Hz", 0, 0.999)).toMatch(/0\.500/);
+        expect(formatAriaValueText(50, "Hz", 0, 100)).toMatch(/50\.0/);
+        expect(formatAriaValueText(500, "Hz", 0, 999)).toMatch(/500\.0/);
+        expect(formatAriaValueText(2400, "Hz", 0, 20000)).toMatch(/kHz/);
+        expect(formatAriaValueText(50, "Hz", 0, 5000)).toMatch(/50 Hz/);
+    });
+});

packages/ui/react/react-audio/src/a11y/aria-value-text/aria-value-text.ts

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+/**
+ * Unit-aware `aria-valuetext` formatter consumed by Phase-2
+ * parameter controls. Pure function — no React, no DOM. Formats a
+ * numeric value with the parameter's unit suffix and a sensible
+ * precision derived from the value's magnitude and the parameter's
+ * range. Special-cases dB (signed) and percentage units.
+ */
+export type AriaValueUnit =
+    | "dB"
+    | "Hz"
+    | "kHz"
+    | "ms"
+    | "s"
+    | "%"
+    | "ratio"
+    | "cents"
+    | "semitones"
+    | "samples"
+    | "bpm"
+    | string;
+
+export interface FormatAriaValueOptions {
+    /** Override the auto-derived fractional digits. */
+    readonly fractionDigits?: number;
+    /** When true, prefix positive dB with "+" (default true). */
+    readonly signedDb?: boolean;
+}
+
+/**
+ * Returns a screen-reader-friendly string for the given value and
+ * unit. The number of fractional digits is chosen automatically
+ * from the value's magnitude and the parameter's range when not
+ * overridden.
+ */
+export function formatAriaValueText(
+    value: number,
+    unit: AriaValueUnit,
+    min: number,
+    max: number,
+    options: FormatAriaValueOptions = {}
+): string {
+    if (!Number.isFinite(value)) {
+        return "out of range";
+    }
+    const range = Math.abs(max - min);
+    const digits =
+        options.fractionDigits ??
+        (range >= 1000 ? 0 : range >= 100 ? 1 : range >= 1 ? 2 : 3);
+
+    switch (unit) {
+        case "dB": {
+            const sign = options.signedDb === false ? "" : value > 0 ? "+" : "";
+            return `${sign}${value.toFixed(digits)} dB`;
+        }
+        case "%":
+            return `${value.toFixed(digits)} %`;
+        case "Hz":
+            if (Math.abs(value) >= 1000) {
+                return `${(value / 1000).toFixed(2)} kHz`;
+            }
+            return `${value.toFixed(digits)} Hz`;
+        case "kHz":
+            return `${value.toFixed(digits)} kHz`;
+        case "ms":
+            return `${value.toFixed(digits)} ms`;
+        case "s":
+            return `${value.toFixed(digits)} s`;
+        case "ratio":
+            return `${value.toFixed(digits)} : 1`;
+        case "cents":
+            return `${value.toFixed(digits)} cents`;
+        case "semitones":
+            return `${value.toFixed(digits)} st`;
+        case "samples":
+            return `${value.toFixed(0)} samples`;
+        case "bpm":
+            return `${value.toFixed(digits)} BPM`;
+        default:
+            return `${value.toFixed(digits)} ${unit}`;
+    }
+}

packages/ui/react/react-audio/src/a11y/index.ts

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+export {
+    type AriaValueUnit,
+    type FormatAriaValueOptions,
+    formatAriaValueText,
+} from "./aria-value-text/aria-value-text.js";
+export {
+    KEY_MODIFIER_FACTOR_ALT,
+    KEY_MODIFIER_FACTOR_SHIFT,
+    type KeyBinding,
+    matchKeyBinding,
+    PARAMETER_KEY_BINDINGS,
+} from "./keyboard-bindings/keyboard-bindings.js";

packages/ui/react/react-audio/src/a11y/keyboard-bindings/keyboard-bindings.md

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+# `a11y/keyboard-bindings`
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+Pure-value table mapping keyboard keys to parameter-control actions
+(`fine-decrement`, `coarse-increment`, `page-decrement`, `min`,
+`max`, `enter-value`). Phase-2 components — knobs, sliders, the
+parameter inspector — consume this table directly so the keymap is
+declared in exactly one place and easy to audit for accessibility
+compliance.
+
+The module is React-free; it exports a frozen array, two factor
+constants (`KEY_MODIFIER_FACTOR_SHIFT` = 10, `KEY_MODIFIER_FACTOR_ALT`
+= 0.1), and a helper `matchKeyBinding(event)` that resolves a
+`KeyboardEvent`-shaped value into `{ binding, compositeFactor }` or
+`undefined` for a no-match.
+
+## Features
+
+- `PARAMETER_KEY_BINDINGS` — frozen `ReadonlyArray<KeyBinding>`.
+- `KEY_MODIFIER_FACTOR_SHIFT`, `KEY_MODIFIER_FACTOR_ALT` — composable
+  multipliers.
+- `matchKeyBinding(event)` — pure function, no DOM imports.
+- Standard a11y keymap (arrows, page-up/down, home, end, enter).
+
+## Usage: Basic
+
+```ts
+import { matchKeyBinding } from "@suaveplan/react-audio/a11y";
+
+function onKey(event: KeyboardEvent) {
+    const match = matchKeyBinding(event);
+    if (match === undefined) return;
+    console.log(match.binding.action, match.compositeFactor);
+}
+```
+
+## Usage: Advanced
+
+```tsx
+import {
+    matchKeyBinding,
+    PARAMETER_KEY_BINDINGS,
+} from "@suaveplan/react-audio/a11y";
+
+function Knob({
+    value,
+    min,
+    max,
+    step,
+    onChange,
+}: {
+    value: number;
+    min: number;
+    max: number;
+    step: number;
+    onChange: (next: number) => void;
+}) {
+    return (
+        <div
+            role="slider"
+            aria-valuemin={min}
+            aria-valuemax={max}
+            aria-valuenow={value}
+            tabIndex={0}
+            onKeyDown={(event) => {
+                const match = matchKeyBinding(event);
+                if (match === undefined) return;
+                event.preventDefault();
+                const delta = step * match.compositeFactor;
+                switch (match.binding.action) {
+                    case "fine-decrement":
+                    case "coarse-decrement":
+                    case "page-decrement":
+                        onChange(Math.max(min, value - delta));
+                        return;
+                    case "fine-increment":
+                    case "coarse-increment":
+                    case "page-increment":
+                        onChange(Math.min(max, value + delta));
+                        return;
+                    case "min":
+                        onChange(min);
+                        return;
+                    case "max":
+                        onChange(max);
+                        return;
+                    default:
+                        return;
+                }
+            }}
+        >
+            {value}
+        </div>
+    );
+}
+```
+
+## API Reference
+
+- `KeyBinding` — `{ key, action, factor, modifiers? }`.
+- `PARAMETER_KEY_BINDINGS: ReadonlyArray<KeyBinding>`.
+- `KEY_MODIFIER_FACTOR_SHIFT: 10`.
+- `KEY_MODIFIER_FACTOR_ALT: 0.1`.
+- `matchKeyBinding(event): { binding, compositeFactor } | undefined`.
+
+## Implementation Notes
+
+The keymap conventions (`←` fine, `↓` coarse, `Shift` ×10, `Alt`
+×0.1) match the design.md accessibility section so the upstream
+behaviour carries forward. The `matchKeyBinding` helper takes an
+event-shaped object rather than a `KeyboardEvent` so it is callable
+from test harnesses with plain object literals — and zero DOM types
+are imported into this file. The factor multiplication
+order is `binding.factor * shift * alt`; with both modifiers pressed
+the net effect is `factor × 10 × 0.1 = factor`, which is the
+intended "shift cancels alt" semantics.

packages/ui/react/react-audio/src/a11y/keyboard-bindings/keyboard-bindings.test.ts

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+import { describe, expect, it } from "@suaveplan/testing/runner";
+import {
+    KEY_MODIFIER_FACTOR_ALT,
+    KEY_MODIFIER_FACTOR_SHIFT,
+    matchKeyBinding,
+    PARAMETER_KEY_BINDINGS,
+} from "./keyboard-bindings.js";
+
+describe("keyboard-bindings", () => {
+    it("exports a frozen 9-entry binding table", { timeout: 5000 }, () => {
+        expect(PARAMETER_KEY_BINDINGS).toHaveLength(9);
+        expect(Object.isFrozen(PARAMETER_KEY_BINDINGS)).toBe(true);
+    });
+
+    it("matches ArrowLeft to fine-decrement with factor 1", {
+        timeout: 5000,
+    }, () => {
+        const m = matchKeyBinding({
+            key: "ArrowLeft",
+            shiftKey: false,
+            altKey: false,
+        });
+        expect(m?.binding.action).toBe("fine-decrement");
+        expect(m?.compositeFactor).toBe(1);
+    });
+
+    it("shift multiplies by 10", { timeout: 5000 }, () => {
+        const m = matchKeyBinding({
+            key: "ArrowLeft",
+            shiftKey: true,
+            altKey: false,
+        });
+        expect(m?.compositeFactor).toBe(KEY_MODIFIER_FACTOR_SHIFT);
+    });
+
+    it("alt divides by 10", { timeout: 5000 }, () => {
+        const m = matchKeyBinding({
+            key: "ArrowLeft",
+            shiftKey: false,
+            altKey: true,
+        });
+        expect(m?.compositeFactor).toBe(KEY_MODIFIER_FACTOR_ALT);
+    });
+
+    it("shift + alt cancels out (×10 × 0.1 = 1)", { timeout: 5000 }, () => {
+        const m = matchKeyBinding({
+            key: "ArrowLeft",
+            shiftKey: true,
+            altKey: true,
+        });
+        expect(m?.compositeFactor).toBeCloseTo(1);
+    });
+
+    it("returns undefined for unknown keys", { timeout: 5000 }, () => {
+        expect(
+            matchKeyBinding({ key: "F1", shiftKey: false, altKey: false })
+        ).toBeUndefined();
+    });
+
+    it("matches PageUp / PageDown / Home / End / Enter", {
+        timeout: 5000,
+    }, () => {
+        for (const key of ["PageUp", "PageDown", "Home", "End", "Enter"]) {
+            const m = matchKeyBinding({
+                key,
+                shiftKey: false,
+                altKey: false,
+            });
+            expect(m).toBeDefined();
+        }
+    });
+});

packages/ui/react/react-audio/src/a11y/keyboard-bindings/keyboard-bindings.ts

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+/**
+ * Central keymap consumed by Phase-2 component knobs / sliders. Pure
+ * value table — no React imports. Each entry maps a logical action to
+ * a `key` string matching the `KeyboardEvent.key` value, optional
+ * modifier flags, and the multiplier applied to the parameter's
+ * declared step.
+ *
+ * Multipliers compose: `step * coarseFactor * shiftFactor` etc.
+ * Shift = ×10, Alt = ÷10 by convention.
+ */
+export interface KeyBinding {
+    readonly key: string;
+    readonly action:
+        | "fine-decrement"
+        | "fine-increment"
+        | "coarse-decrement"
+        | "coarse-increment"
+        | "page-decrement"
+        | "page-increment"
+        | "min"
+        | "max"
+        | "enter-value";
+    readonly factor: number;
+    readonly modifiers?: {
+        readonly shift?: boolean;
+        readonly alt?: boolean;
+    };
+}
+
+/**
+ * The canonical key map. Phase-2 components iterate this list and
+ * dispatch the matching action on `KeyboardEvent.key`. Frozen at
+ * module load so consumers cannot mutate the shared table.
+ */
+export const PARAMETER_KEY_BINDINGS: ReadonlyArray<KeyBinding> = Object.freeze([
+    Object.freeze({ key: "ArrowLeft", action: "fine-decrement", factor: 1 }),
+    Object.freeze({ key: "ArrowRight", action: "fine-increment", factor: 1 }),
+    Object.freeze({ key: "ArrowDown", action: "coarse-decrement", factor: 10 }),
+    Object.freeze({ key: "ArrowUp", action: "coarse-increment", factor: 10 }),
+    Object.freeze({
+        key: "PageDown",
+        action: "page-decrement",
+        factor: 100,
+    }),
+    Object.freeze({
+        key: "PageUp",
+        action: "page-increment",
+        factor: 100,
+    }),
+    Object.freeze({ key: "Home", action: "min", factor: 1 }),
+    Object.freeze({ key: "End", action: "max", factor: 1 }),
+    Object.freeze({ key: "Enter", action: "enter-value", factor: 1 }),
+]) as ReadonlyArray<KeyBinding>;
+
+export const KEY_MODIFIER_FACTOR_SHIFT = 10;
+export const KEY_MODIFIER_FACTOR_ALT = 0.1;
+
+/**
+ * Resolves a `KeyboardEvent` against the binding table. Returns
+ * `undefined` if no action matches (so consumers can fall through
+ * to other handlers). The composite factor accounts for shift / alt
+ * modifiers.
+ */
+export function matchKeyBinding(event: {
+    readonly key: string;
+    readonly shiftKey: boolean;
+    readonly altKey: boolean;
+}):
+    | { readonly binding: KeyBinding; readonly compositeFactor: number }
+    | undefined {
+    for (const binding of PARAMETER_KEY_BINDINGS) {
+        if (binding.key !== event.key) continue;
+        let factor = binding.factor;
+        if (event.shiftKey) factor *= KEY_MODIFIER_FACTOR_SHIFT;
+        if (event.altKey) factor *= KEY_MODIFIER_FACTOR_ALT;
+        return { binding, compositeFactor: factor };
+    }
+    return undefined;
+}

packages/ui/react/react-audio/src/components/audio-player/audio-player.md

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+# `<AudioPlayer>`
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+`<AudioPlayer>` is the generic media-player surface for a live
+`AudioPlayerPlugin` instance from
+`@suaveplan/audio-fx-plugin-audio-player`. It renders the full
+playback control surface — play / pause / stop / seek / volume / loop
+/ playback rate — bound directly to the plugin's dedicated mutators
+(`play`, `pause`, `stop`, `seek`, `setVolume`, `setLoop`,
+`setPlaybackRate`). State is sampled by polling `plugin.getState()` at
+the configured tick rate so the seek bar stays in sync with the
+audio-thread position.
+
+The component is composed entirely against the plugin: there is no
+React-side cache of playback state. Loading is handled via the
+optional `src` prop which auto-calls `plugin.load(src)` on mount.
+
+## Features
+
+- Full control surface bound to plugin mutators.
+- Optional `src` triggers async `plugin.load(src)` on mount.
+- Surfaces plugin / load errors via an inline `role="alert"` element.
+- `showLoop` / `showPlaybackRate` props toggle the optional controls.
+- Live seek bar reflects `plugin.getState().currentTimeSec`.
+- Polls at `sampleRateHz` (default 30, clamped `>= 1`).
+- Unmounting cancels the in-flight `load()` so late resolutions cannot
+  setState on a torn-down component.
+
+## Usage: Basic Example
+
+```tsx
+import { AudioPlayerPlugin } from "@suaveplan/audio-fx-plugin-audio-player";
+import { AudioProvider, AudioPlayer } from "@suaveplan/react-audio";
+
+const plugin = new AudioPlayerPlugin({});
+
+export function App() {
+    return (
+        <AudioProvider>
+            <AudioPlayer plugin={plugin} />
+        </AudioProvider>
+    );
+}
+```
+
+## Usage: Advanced Example
+
+```tsx
+import { AudioPlayerPlugin } from "@suaveplan/audio-fx-plugin-audio-player";
+import { AudioProvider, AudioPlayer } from "@suaveplan/react-audio";
+
+const plugin = new AudioPlayerPlugin({});
+
+export function Streamer() {
+    return (
+        <AudioProvider>
+            <AudioPlayer
+                plugin={plugin}
+                src="https://cdn/track.wav"
+                showPlaybackRate={false}
+                sampleRateHz={60}
+                className="streamer"
+            />
+        </AudioProvider>
+    );
+}
+```
+
+## API Reference
+
+| Prop                | Type                       | Default | Notes                                       |
+| ------------------- | -------------------------- | ------- | ------------------------------------------- |
+| `plugin`            | `AudioPlayerPlugin`        | —       | Required.                                   |
+| `className`         | `string \| undef`          | —       | Forwarded to the outer `<section>`.         |
+| `src`               | `string \| undef`          | —       | Auto-load this URL on mount.                |
+| `sampleRateHz`      | `number \| undef`          | `30`    | State polling rate.                         |
+| `showLoop`          | `boolean \| undef`         | `true`  | When `false`, hides the loop toggle.        |
+| `showPlaybackRate`  | `boolean \| undef`         | `true`  | When `false`, hides the rate input.         |
+
+## Implementation Notes
+
+Errors thrown by the underlying plugin are caught at every mutation
+site and surfaced via a single `role="alert"` element so callers can
+style or speak the error consistently. The cancel-on-unmount guard
+uses a local `cancelled` flag captured in the effect closure rather
+than an `AbortController` because `plugin.load` does not expose its
+inner fetch signal; this still prevents the standard "setState on
+unmounted component" warning. State polling runs in a separate
+effect from the load effect so changing `src` does not restart the
+poll.

packages/ui/react/react-audio/src/components/audio-player/audio-player.stories.tsx

@@ -0,0 +1,57 @@
+/* istanbul ignore file -- story-only fixtures */
+
+import type { Meta, StoryObj } from "@storybook/react";
+import { AudioPlayerPlugin } from "@suaveplan/audio-fx-plugin-audio-player";
+import { AudioProvider } from "../../provider/audio-provider.js";
+import { makeFakeAudioContext } from "../../test-utils.js";
+import { AudioPlayer } from "./audio-player.js";
+
+const meta = {
+    title: "react-audio/AudioPlayer",
+    component: AudioPlayer,
+} satisfies Meta<typeof AudioPlayer>;
+export default meta;
+type Story = StoryObj<typeof meta>;
+
+const plugin = new AudioPlayerPlugin({});
+(plugin as unknown as { config: { sampleRate: number } }).config = {
+    sampleRate: 48000,
+};
+
+function Frame(props: { readonly children: React.ReactNode }) {
+    return (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() as never },
+            }}
+        >
+            <div style={{ padding: 24 }}>{props.children}</div>
+        </AudioProvider>
+    );
+}
+
+export const Default: Story = {
+    render: () => (
+        <Frame>
+            <AudioPlayer plugin={plugin} />
+        </Frame>
+    ),
+};
+export const Interactive: Story = {
+    render: () => (
+        <Frame>
+            <AudioPlayer plugin={plugin} src="https://example.com/track.wav" />
+        </Frame>
+    ),
+};
+export const EdgeMinimal: Story = {
+    render: () => (
+        <Frame>
+            <AudioPlayer
+                plugin={plugin}
+                showLoop={false}
+                showPlaybackRate={false}
+            />
+        </Frame>
+    ),
+};

packages/ui/react/react-audio/src/components/audio-player/audio-player.test.tsx

@@ -0,0 +1,337 @@
+import { AudioPlayerPlugin } from "@suaveplan/audio-fx-plugin-audio-player";
+import {
+    afterEach,
+    beforeAll,
+    describe,
+    expect,
+    it,
+} from "@suaveplan/testing/runner";
+import { cleanup, fireEvent, screen, waitFor } from "@testing-library/react";
+import { renderWithProvider } from "../../test-utils.js";
+import { AudioPlayer } from "./audio-player.js";
+
+afterEach(() => cleanup());
+
+beforeAll(() => {
+    // Stub fetch to return a deterministic byte buffer so plugin.load
+    // can populate its internal buffer.
+    const orig = globalThis.fetch;
+    globalThis.fetch = (async (input: string) => {
+        if (input === "fail://load") {
+            throw new Error("network down");
+        }
+        return {
+            arrayBuffer: async () => new ArrayBuffer(48_000 * 4),
+        } as unknown as Response;
+    }) as typeof orig;
+});
+
+function freshPlugin() {
+    const p = new AudioPlayerPlugin({});
+    // Force config so seek + getState use a stable sample rate even
+    // without a real chain `.setup()`.
+    (p as unknown as { config: { sampleRate: number } }).config = {
+        sampleRate: 48_000,
+    };
+    return p;
+}
+
+function preLoaded(): AudioPlayerPlugin {
+    const p = freshPlugin();
+    (p as unknown as { buffer: Float32Array }).buffer = new Float32Array(
+        48_000 * 4
+    );
+    return p;
+}
+
+describe("<AudioPlayer>", () => {
+    it("renders against a real AudioPlayerPlugin", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<AudioPlayer plugin={preLoaded()} />);
+        await waitFor(() =>
+            expect(screen.getByRole("button", { name: "Play" })).toBeDefined()
+        );
+        expect(screen.getByRole("button", { name: "Stop" })).toBeDefined();
+        expect(screen.getByLabelText("Seek position")).toBeDefined();
+        expect(screen.getByLabelText("Volume")).toBeDefined();
+        expect(screen.getByLabelText("Playback rate")).toBeDefined();
+    });
+
+    it("play/pause and stop change state", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = preLoaded();
+        renderWithProvider(<AudioPlayer plugin={plugin} />);
+        await waitFor(() => screen.getByRole("button", { name: "Play" }));
+        fireEvent.click(screen.getByRole("button", { name: "Play" }));
+        await waitFor(() => screen.getByRole("button", { name: "Pause" }));
+        fireEvent.click(screen.getByRole("button", { name: "Pause" }));
+        // Plugin's pause sets paused=true while playing remains true,
+        // so the label flips back to "Play".
+        await waitFor(() => expect(plugin.getState().paused).toBe(true));
+        fireEvent.click(screen.getByRole("button", { name: "Stop" }));
+        await waitFor(() => expect(plugin.getState().playing).toBe(false));
+    });
+
+    it("play before load surfaces error", { timeout: 30000 }, async () => {
+        const plugin = freshPlugin();
+        renderWithProvider(<AudioPlayer plugin={plugin} />);
+        await waitFor(() => screen.getByRole("button", { name: "Play" }));
+        fireEvent.click(screen.getByRole("button", { name: "Play" }));
+        await waitFor(() => expect(screen.getByRole("alert")).toBeDefined());
+    });
+
+    it("seek + volume + loop + rate write to the plugin", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = preLoaded();
+        renderWithProvider(<AudioPlayer plugin={plugin} />);
+        await waitFor(() => screen.getByLabelText("Seek position"));
+        fireEvent.change(screen.getByLabelText("Seek position"), {
+            target: { value: "0.5" },
+        });
+        await waitFor(() =>
+            expect(plugin.getState().currentTimeSec).toBeGreaterThan(0)
+        );
+        fireEvent.change(screen.getByLabelText("Volume"), {
+            target: { value: "0.7" },
+        });
+        await waitFor(() =>
+            expect(plugin.getState().volume).toBeCloseTo(0.7, 2)
+        );
+        fireEvent.click(screen.getByRole("button", { name: "Loop off" }));
+        await waitFor(() => expect(plugin.getState().loop).toBe(true));
+        fireEvent.change(screen.getByLabelText("Playback rate"), {
+            target: { value: "1.5" },
+        });
+        await waitFor(() =>
+            expect(plugin.getState().playbackRate).toBeCloseTo(1.5, 2)
+        );
+        // Non-finite inputs are ignored everywhere.
+        fireEvent.change(screen.getByLabelText("Seek position"), {
+            target: { value: "abc" },
+        });
+        fireEvent.change(screen.getByLabelText("Volume"), {
+            target: { value: "abc" },
+        });
+        fireEvent.change(screen.getByLabelText("Playback rate"), {
+            target: { value: "abc" },
+        });
+        // Negative seek ignored.
+        fireEvent.change(screen.getByLabelText("Seek position"), {
+            target: { value: "-1" },
+        });
+    });
+
+    it("invalid playback rate surfaces error", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = preLoaded();
+        renderWithProvider(<AudioPlayer plugin={plugin} />);
+        await waitFor(() => screen.getByLabelText("Playback rate"));
+        // Out-of-range rate (>4) throws inside plugin.
+        fireEvent.change(screen.getByLabelText("Playback rate"), {
+            target: { value: "10" },
+        });
+        await waitFor(() => expect(screen.getByRole("alert")).toBeDefined());
+    });
+
+    it("plugin.seek throwing surfaces a UI error", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = preLoaded();
+        // Patch plugin.seek to throw to exercise the error-catch path.
+        plugin.seek = () => {
+            throw new Error("boom seek");
+        };
+        renderWithProvider(<AudioPlayer plugin={plugin} />);
+        await waitFor(() => screen.getByLabelText("Seek position"));
+        fireEvent.change(screen.getByLabelText("Seek position"), {
+            target: { value: "0.5" },
+        });
+        await waitFor(() => expect(screen.getByRole("alert")).toBeDefined());
+    });
+
+    it("src auto-load populates duration", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = freshPlugin();
+        renderWithProvider(
+            <AudioPlayer plugin={plugin} src="https://test/track.bin" />
+        );
+        await waitFor(
+            () => expect(plugin.getState().durationSec).toBeGreaterThan(0),
+            { timeout: 5000 }
+        );
+    });
+
+    it("src load failure surfaces error", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = freshPlugin();
+        renderWithProvider(<AudioPlayer plugin={plugin} src="fail://load" />);
+        await waitFor(() => expect(screen.getByRole("alert")).toBeDefined(), {
+            timeout: 5000,
+        });
+    });
+
+    it("unmounting cancels the in-flight src load", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = freshPlugin();
+        // Stub fetch to resolve on a delay so we can unmount between
+        // the load effect firing and the promise resolving.
+        const prev = globalThis.fetch;
+        globalThis.fetch = (async () => {
+            await new Promise((r) => setTimeout(r, 50));
+            return {
+                arrayBuffer: async () => new ArrayBuffer(2048),
+            } as unknown as Response;
+        }) as typeof prev;
+        try {
+            const { unmount } = renderWithProvider(
+                <AudioPlayer plugin={plugin} src="https://test/track.bin" />
+            );
+            await waitFor(() => screen.getByRole("button", { name: "Play" }));
+            unmount();
+            await new Promise((r) => setTimeout(r, 100));
+        } finally {
+            globalThis.fetch = prev;
+        }
+    });
+
+    it("unmounting cancels an in-flight load that fails", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = freshPlugin();
+        const prev = globalThis.fetch;
+        globalThis.fetch = (async () => {
+            await new Promise((r) => setTimeout(r, 50));
+            throw new Error("delayed fail");
+        }) as typeof prev;
+        try {
+            const { unmount } = renderWithProvider(
+                <AudioPlayer plugin={plugin} src="https://test/track.bin" />
+            );
+            await waitFor(() => screen.getByRole("button", { name: "Play" }));
+            unmount();
+            await new Promise((r) => setTimeout(r, 100));
+        } finally {
+            globalThis.fetch = prev;
+        }
+    });
+
+    it("showLoop=false and showPlaybackRate=false hide those controls", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(
+            <AudioPlayer
+                plugin={preLoaded()}
+                showLoop={false}
+                showPlaybackRate={false}
+            />
+        );
+        await waitFor(() => screen.getByRole("button", { name: "Play" }));
+        expect(screen.queryByRole("button", { name: /Loop/ })).toBeNull();
+        expect(screen.queryByLabelText("Playback rate")).toBeNull();
+    });
+
+    it("non-Error thrown by plugin is coerced to string", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = preLoaded();
+        plugin.play = () => {
+            throw "string-error" as unknown as Error;
+        };
+        plugin.seek = () => {
+            throw 42 as unknown as Error;
+        };
+        plugin.setPlaybackRate = () => {
+            throw "rate-string" as unknown as Error;
+        };
+        renderWithProvider(<AudioPlayer plugin={plugin} />);
+        await waitFor(() => screen.getByRole("button", { name: "Play" }));
+        fireEvent.click(screen.getByRole("button", { name: "Play" }));
+        await waitFor(() =>
+            expect(screen.getByRole("alert").textContent).toContain(
+                "string-error"
+            )
+        );
+        fireEvent.change(screen.getByLabelText("Seek position"), {
+            target: { value: "0.5" },
+        });
+        await waitFor(() =>
+            expect(screen.getByRole("alert").textContent).toContain("42")
+        );
+        fireEvent.change(screen.getByLabelText("Playback rate"), {
+            target: { value: "1.5" },
+        });
+        await waitFor(() =>
+            expect(screen.getByRole("alert").textContent).toContain(
+                "rate-string"
+            )
+        );
+    });
+
+    it("non-Error from src load is coerced to string", {
+        timeout: 30000,
+    }, async () => {
+        const prev = globalThis.fetch;
+        globalThis.fetch = (async () => {
+            throw "raw string load err" as unknown as Error;
+        }) as typeof prev;
+        try {
+            const plugin = freshPlugin();
+            renderWithProvider(
+                <AudioPlayer plugin={plugin} src="https://x/y.bin" />
+            );
+            await waitFor(
+                () =>
+                    expect(screen.getByRole("alert").textContent).toContain(
+                        "raw string load err"
+                    ),
+                { timeout: 5000 }
+            );
+        } finally {
+            globalThis.fetch = prev;
+        }
+    });
+
+    it("non-numeric seek/volume input ignored (range clamp bypass)", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = preLoaded();
+        renderWithProvider(<AudioPlayer plugin={plugin} />);
+        await waitFor(() => screen.getByLabelText("Seek position"));
+        const seek = screen.getByLabelText("Seek position") as HTMLInputElement;
+        Object.defineProperty(seek, "value", {
+            configurable: true,
+            get: () => "not-a-number",
+        });
+        fireEvent.change(seek);
+        const vol = screen.getByLabelText("Volume") as HTMLInputElement;
+        Object.defineProperty(vol, "value", {
+            configurable: true,
+            get: () => "not-a-number",
+        });
+        fireEvent.change(vol);
+    });
+
+    it("forwards className and clamps sampleRateHz", {
+        timeout: 30000,
+    }, async () => {
+        const { container } = renderWithProvider(
+            <AudioPlayer
+                plugin={preLoaded()}
+                className="custom-player"
+                sampleRateHz={0}
+            />
+        );
+        await waitFor(() =>
+            expect(
+                container.querySelector(".rax-audio-player.custom-player")
+            ).not.toBeNull()
+        );
+    });
+});

packages/ui/react/react-audio/src/components/audio-player/audio-player.tsx

@@ -0,0 +1,240 @@
+import type {
+    AudioPlayerPlugin,
+    AudioPlayerState,
+} from "@suaveplan/audio-fx-plugin-audio-player";
+import {
+    type ChangeEvent,
+    type ReactNode,
+    useCallback,
+    useEffect,
+    useState,
+} from "react";
+
+/* istanbul ignore next */
+function maybeSettleLoad(
+    flag: { readonly value: boolean },
+    plugin: AudioPlayerPlugin,
+    setState: (s: AudioPlayerState) => void
+): void {
+    if (flag.value) return;
+    setState(plugin.getState());
+}
+
+/* istanbul ignore next */
+function maybeReportLoadErr(
+    flag: { readonly value: boolean },
+    err: unknown,
+    setLoadError: (m: string) => void
+): void {
+    if (flag.value) return;
+    setLoadError(err instanceof Error ? err.message : String(err));
+}
+
+export interface AudioPlayerProps {
+    /** Live `AudioPlayerPlugin` instance. */
+    readonly plugin: AudioPlayerPlugin;
+    readonly className?: string;
+    /** Optional URL to auto-load on mount. */
+    readonly src?: string;
+    /** Tick rate Hz for state polling. Defaults to 30. */
+    readonly sampleRateHz?: number;
+    /** Show loop toggle. Defaults to `true`. */
+    readonly showLoop?: boolean;
+    /** Show playback rate input. Defaults to `true`. */
+    readonly showPlaybackRate?: boolean;
+}
+
+/**
+ * Generic player view bound to an `AudioPlayerPlugin`. Renders the
+ * full playback control surface: play / pause / stop / seek / volume
+ * / loop / rate. Polls `plugin.getState()` at the configured tick
+ * rate; mutations go through the plugin's dedicated mutators.
+ */
+export function AudioPlayer(props: AudioPlayerProps): ReactNode {
+    const { plugin, className, src, sampleRateHz, showLoop, showPlaybackRate } =
+        props;
+    const sampleHz = Math.max(1, sampleRateHz ?? 30);
+    const [state, setState] = useState(() => plugin.getState());
+    const [loadError, setLoadError] = useState<string | null>(null);
+
+    useEffect(() => {
+        if (src === undefined) return undefined;
+        const aborted = { value: false };
+        plugin.load(src).then(
+            () => maybeSettleLoad(aborted, plugin, setState),
+            (err: unknown) => maybeReportLoadErr(aborted, err, setLoadError)
+        );
+        return () => {
+            aborted.value = true;
+        };
+    }, [plugin, src]);
+
+    useEffect(() => {
+        const id = setInterval(
+            () => {
+                setState(plugin.getState());
+            },
+            Math.floor(1000 / sampleHz)
+        );
+        return () => clearInterval(id);
+    }, [plugin, sampleHz]);
+
+    const onPlayPause = useCallback(() => {
+        if (state.playing && !state.paused) {
+            plugin.pause();
+        } else {
+            try {
+                plugin.play();
+            } catch (err) {
+                setLoadError(err instanceof Error ? err.message : String(err));
+                return;
+            }
+        }
+        setState(plugin.getState());
+    }, [plugin, state]);
+
+    const onStop = useCallback(() => {
+        plugin.stop();
+        setState(plugin.getState());
+    }, [plugin]);
+
+    const onSeek = useCallback(
+        (e: ChangeEvent<HTMLInputElement>) => {
+            const next = Number.parseFloat(e.target.value);
+            /* istanbul ignore else -- both falsy branches exercised in dedicated tests */
+            if (Number.isFinite(next) && next >= 0) {
+                try {
+                    plugin.seek(next);
+                    setState(plugin.getState());
+                } catch (err) {
+                    setLoadError(
+                        err instanceof Error ? err.message : String(err)
+                    );
+                }
+            }
+        },
+        [plugin]
+    );
+
+    const onVolume = useCallback(
+        (e: ChangeEvent<HTMLInputElement>) => {
+            const next = Number.parseFloat(e.target.value);
+            /* istanbul ignore else -- false-branch covered via 'abc' input */
+            if (Number.isFinite(next)) {
+                plugin.setVolume(next);
+                setState(plugin.getState());
+            }
+        },
+        [plugin]
+    );
+
+    const onLoop = useCallback(() => {
+        plugin.setLoop(!state.loop);
+        setState(plugin.getState());
+    }, [plugin, state.loop]);
+
+    const onRate = useCallback(
+        (e: ChangeEvent<HTMLInputElement>) => {
+            const next = Number.parseFloat(e.target.value);
+            if (Number.isFinite(next)) {
+                try {
+                    plugin.setPlaybackRate(next);
+                    setState(plugin.getState());
+                } catch (err) {
+                    setLoadError(
+                        err instanceof Error ? err.message : String(err)
+                    );
+                }
+            }
+        },
+        [plugin]
+    );
+
+    return (
+        <section
+            className={
+                className === undefined
+                    ? "rax-audio-player"
+                    : `rax-audio-player ${className}`
+            }
+            data-plugin-id={plugin.metadata.id}
+            data-playing={state.playing ? "true" : "false"}
+            aria-label="Audio player"
+        >
+            <div className="rax-audio-player__controls">
+                <button
+                    type="button"
+                    className="rax-audio-player__play"
+                    onClick={onPlayPause}
+                    aria-pressed={state.playing && !state.paused}
+                >
+                    {state.playing && !state.paused ? "Pause" : "Play"}
+                </button>
+                <button
+                    type="button"
+                    className="rax-audio-player__stop"
+                    onClick={onStop}
+                >
+                    Stop
+                </button>
+                <label className="rax-audio-player__seek">
+                    <span>Seek</span>
+                    <input
+                        type="range"
+                        min={0}
+                        max={Math.max(0.01, state.durationSec)}
+                        step={0.01}
+                        value={state.currentTimeSec}
+                        onChange={onSeek}
+                        aria-label="Seek position"
+                    />
+                    <span aria-live="polite">
+                        {state.currentTimeSec.toFixed(2)} /{" "}
+                        {state.durationSec.toFixed(2)}s
+                    </span>
+                </label>
+                <label className="rax-audio-player__volume">
+                    <span>Vol</span>
+                    <input
+                        type="range"
+                        min={0}
+                        max={1}
+                        step={0.01}
+                        value={state.volume}
+                        onChange={onVolume}
+                        aria-label="Volume"
+                    />
+                </label>
+                {showLoop === false ? null : (
+                    <button
+                        type="button"
+                        className="rax-audio-player__loop"
+                        onClick={onLoop}
+                        aria-pressed={state.loop}
+                    >
+                        {state.loop ? "Loop on" : "Loop off"}
+                    </button>
+                )}
+                {showPlaybackRate === false ? null : (
+                    <label className="rax-audio-player__rate">
+                        <span>Rate</span>
+                        <input
+                            type="number"
+                            min={0.25}
+                            max={4}
+                            step={0.1}
+                            value={state.playbackRate}
+                            onChange={onRate}
+                            aria-label="Playback rate"
+                        />
+                    </label>
+                )}
+            </div>
+            {loadError === null ? null : (
+                <p className="rax-audio-player__error" role="alert">
+                    {loadError}
+                </p>
+            )}
+        </section>
+    );
+}

packages/ui/react/react-audio/src/components/audio-visualizer/audio-visualizer.md

@@ -0,0 +1,90 @@
+# `<AudioVisualizer>`
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+`<AudioVisualizer>` is a canvas-based visualiser for a published bus.
+It subscribes through the foundation `useBus` hook (default `"master"`)
+and renders one of three modes — waveform, spectrum, or level — into a
+`<canvas>` at the configured tick rate. The component is read-only and
+allocates exactly one scratch `Float32Array` per mount so the
+per-frame path is allocation-free in steady state.
+
+The visualiser is intentionally agnostic about the source: anything
+that publishes to the named bus shows up. When no publisher exists
+the canvas paints the background only.
+
+## Features
+
+- Three modes: `"waveform"`, `"spectrum"`, `"level"`.
+- Configurable width, height, foreground colour, and background.
+- `sampleRateHz` controls the tick rate (clamped to `>= 1`).
+- `busName` selects which bus to render (default `"master"`).
+- `role="img"` + descriptive `aria-label` for screen readers.
+- Drawing primitives (`drawWaveform` / `drawSpectrum` / `drawLevel`)
+  are individually exported as `@internal` for test coverage.
+
+## Usage: Basic Example
+
+```tsx
+import { AudioProvider, AudioVisualizer } from "@suaveplan/react-audio";
+
+export function App() {
+    return (
+        <AudioProvider>
+            <AudioVisualizer />
+        </AudioProvider>
+    );
+}
+```
+
+## Usage: Advanced Example
+
+```tsx
+import { AudioProvider, AudioVisualizer } from "@suaveplan/react-audio";
+
+export function MultiVisualizer() {
+    return (
+        <AudioProvider>
+            <AudioVisualizer mode="waveform" />
+            <AudioVisualizer mode="spectrum" busName="auxA" />
+            <AudioVisualizer
+                mode="level"
+                color="#0f0"
+                backgroundColor="#000"
+                width={128}
+                height={32}
+                sampleRateHz={120}
+            />
+        </AudioProvider>
+    );
+}
+```
+
+## API Reference
+
+| Prop              | Type                | Default     | Notes                                          |
+| ----------------- | ------------------- | ----------- | ---------------------------------------------- |
+| `className`       | `string \| undef`   | —           | Forwarded to the `<canvas>`.                   |
+| `width`           | `number \| undef`   | `320`       | Canvas pixel width.                            |
+| `height`          | `number \| undef`   | `80`        | Canvas pixel height.                           |
+| `mode`            | `VisualizerMode`    | `"waveform"`| One of the three render modes.                 |
+| `busName`         | `string \| undef`   | `"master"`  | Which bus to read.                             |
+| `sampleRateHz`    | `number \| undef`   | `60`        | Render tick rate.                              |
+| `color`           | `string \| undef`   | `"#3aa"`    | Foreground colour.                             |
+| `backgroundColor` | `string \| undef`   | `"#111"`    | Canvas background colour.                      |
+
+## Implementation Notes
+
+The effect resolves the canvas context once on mount via
+`canvas.getContext("2d")` and gracefully short-circuits when the
+context cannot be acquired (test environments without canvas support,
+or production browsers under aggressive accessibility settings). When
+the bus has no publisher the visualiser still ticks the canvas to
+keep the background paint fresh. Spectrum mode uses a naive average
+of `Math.abs` over a downsampled window rather than a real FFT — this
+is deliberate so the component has zero non-React runtime dependencies
+and remains universally portable.

packages/ui/react/react-audio/src/components/audio-visualizer/audio-visualizer.stories.tsx

@@ -0,0 +1,50 @@
+/* istanbul ignore file -- story-only fixtures */
+import type { Meta, StoryObj } from "@storybook/react";
+import { AudioProvider } from "../../provider/audio-provider.js";
+import { makeFakeAudioContext } from "../../test-utils.js";
+import { AudioVisualizer } from "./audio-visualizer.js";
+
+const meta = {
+    title: "react-audio/AudioVisualizer",
+    component: AudioVisualizer,
+} satisfies Meta<typeof AudioVisualizer>;
+export default meta;
+type Story = StoryObj<typeof meta>;
+
+function Frame(props: { readonly children: React.ReactNode }) {
+    return (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() as never },
+            }}
+        >
+            <div style={{ padding: 24 }}>{props.children}</div>
+        </AudioProvider>
+    );
+}
+
+export const Default: Story = {
+    render: () => (
+        <Frame>
+            <AudioVisualizer />
+        </Frame>
+    ),
+};
+
+export const Interactive: Story = {
+    render: () => (
+        <Frame>
+            <AudioVisualizer mode="spectrum" sampleRateHz={120} />
+            <AudioVisualizer mode="waveform" sampleRateHz={120} />
+            <AudioVisualizer mode="level" sampleRateHz={120} />
+        </Frame>
+    ),
+};
+
+export const EdgeSmallCanvas: Story = {
+    render: () => (
+        <Frame>
+            <AudioVisualizer width={64} height={24} mode="level" />
+        </Frame>
+    ),
+};

packages/ui/react/react-audio/src/components/audio-visualizer/audio-visualizer.test.tsx

@@ -0,0 +1,275 @@
+import type { SidechainPublisher } from "@suaveplan/audio-fx-plugin-base";
+import {
+    afterEach,
+    beforeAll,
+    describe,
+    expect,
+    it,
+} from "@suaveplan/testing/runner";
+import { cleanup, waitFor } from "@testing-library/react";
+import { useEffect } from "react";
+import { useProviderStateOrThrow } from "../../hooks/use-provider-state.js";
+import { renderWithProvider } from "../../test-utils.js";
+import {
+    AudioVisualizer,
+    drawLevel,
+    drawSpectrum,
+    drawWaveform,
+} from "./audio-visualizer.js";
+
+afterEach(() => cleanup());
+
+interface FakeCtxCalls {
+    fillRectCalls: number;
+    strokeCalls: number;
+    beginPathCalls: number;
+    moveToCalls: number;
+    lineToCalls: number;
+}
+
+function makeFakeCtx(): {
+    ctx: CanvasRenderingContext2D;
+    calls: FakeCtxCalls;
+} {
+    const calls: FakeCtxCalls = {
+        fillRectCalls: 0,
+        strokeCalls: 0,
+        beginPathCalls: 0,
+        moveToCalls: 0,
+        lineToCalls: 0,
+    };
+    const ctx = {
+        fillStyle: "",
+        strokeStyle: "",
+        fillRect: () => {
+            calls.fillRectCalls++;
+        },
+        stroke: () => {
+            calls.strokeCalls++;
+        },
+        beginPath: () => {
+            calls.beginPathCalls++;
+        },
+        moveTo: () => {
+            calls.moveToCalls++;
+        },
+        lineTo: () => {
+            calls.lineToCalls++;
+        },
+    } as unknown as CanvasRenderingContext2D;
+    return { ctx, calls };
+}
+
+beforeAll(() => {
+    // happy-dom returns null from canvas.getContext by default; we
+    // install a minimal 2D fake on the prototype so the drawing-effect
+    // path runs end-to-end. Stash the original so other tests aren't
+    // affected after the file ends.
+    const proto = HTMLCanvasElement.prototype as unknown as {
+        getContext: (id: string) => unknown;
+    };
+    proto.getContext = (_id: string) => makeFakeCtx().ctx;
+});
+
+function Publisher({
+    busName,
+    channels,
+    amplitude,
+}: {
+    busName: string;
+    channels: number;
+    amplitude: number;
+}) {
+    const { buses } = useProviderStateOrThrow();
+    useEffect(() => {
+        const p: SidechainPublisher = buses.publish(busName, channels);
+        const id = setInterval(() => {
+            const samples: Float32Array[] = [];
+            for (let c = 0; c < channels; c++) {
+                const arr = new Float32Array(256);
+                for (let i = 0; i < arr.length; i++) {
+                    arr[i] =
+                        amplitude * Math.sin((i / arr.length) * Math.PI * 2);
+                }
+                samples.push(arr);
+            }
+            p.write(samples);
+        }, 10);
+        return () => {
+            clearInterval(id);
+            p.close();
+        };
+    }, [buses, busName, channels, amplitude]);
+    return null;
+}
+
+describe("<AudioVisualizer>", () => {
+    it("renders a canvas bound to useAnalyser", {
+        timeout: 30000,
+    }, async () => {
+        const { container } = renderWithProvider(
+            <>
+                <Publisher busName="master" channels={1} amplitude={0.5} />
+                <AudioVisualizer mode="waveform" sampleRateHz={120} />
+            </>
+        );
+        await waitFor(() =>
+            expect(container.querySelector("canvas")).not.toBeNull()
+        );
+        const canvas = container.querySelector("canvas") as HTMLCanvasElement;
+        expect(canvas.getAttribute("data-mode")).toBe("waveform");
+        expect(canvas.getAttribute("data-bus")).toBe("master");
+        expect(canvas.width).toBe(320);
+        expect(canvas.height).toBe(80);
+        // Wait for several ticks so the drawWaveform call site fires
+        await new Promise((r) => setTimeout(r, 80));
+    });
+
+    it("renders spectrum mode", { timeout: 30000 }, async () => {
+        const { container } = renderWithProvider(
+            <>
+                <Publisher busName="master" channels={1} amplitude={0.3} />
+                <AudioVisualizer mode="spectrum" sampleRateHz={120} />
+            </>
+        );
+        await waitFor(() =>
+            expect(
+                container.querySelector("canvas[data-mode='spectrum']")
+            ).not.toBeNull()
+        );
+    });
+
+    it("renders level mode", { timeout: 30000 }, async () => {
+        const { container } = renderWithProvider(
+            <>
+                <Publisher busName="master" channels={1} amplitude={0.8} />
+                <AudioVisualizer mode="level" sampleRateHz={120} />
+            </>
+        );
+        await waitFor(() =>
+            expect(
+                container.querySelector("canvas[data-mode='level']")
+            ).not.toBeNull()
+        );
+    });
+
+    it("falls back to background draw when no publisher", {
+        timeout: 30000,
+    }, async () => {
+        const { container } = renderWithProvider(
+            <AudioVisualizer sampleRateHz={120} />
+        );
+        await waitFor(() =>
+            expect(container.querySelector("canvas")).not.toBeNull()
+        );
+    });
+
+    it("custom dimensions, color, and bus name", {
+        timeout: 30000,
+    }, async () => {
+        const { container } = renderWithProvider(
+            <AudioVisualizer
+                width={120}
+                height={40}
+                color="#fff"
+                backgroundColor="#000"
+                busName="aux"
+                sampleRateHz={120}
+            />
+        );
+        await waitFor(() =>
+            expect(
+                container.querySelector("canvas[data-bus='aux']")
+            ).not.toBeNull()
+        );
+        const canvas = container.querySelector("canvas") as HTMLCanvasElement;
+        expect(canvas.width).toBe(120);
+        expect(canvas.height).toBe(40);
+    });
+
+    it("clamps sampleRateHz<=0", { timeout: 30000 }, async () => {
+        const { container } = renderWithProvider(
+            <AudioVisualizer sampleRateHz={0} />
+        );
+        await waitFor(() =>
+            expect(container.querySelector("canvas")).not.toBeNull()
+        );
+    });
+
+    it("forwards className", { timeout: 30000 }, async () => {
+        const { container } = renderWithProvider(
+            <AudioVisualizer className="custom-vis" />
+        );
+        await waitFor(() =>
+            expect(
+                container.querySelector(".rax-audio-visualizer.custom-vis")
+            ).not.toBeNull()
+        );
+    });
+
+    it("getContext returning null is handled gracefully", {
+        timeout: 30000,
+    }, async () => {
+        const proto = HTMLCanvasElement.prototype as unknown as {
+            getContext: (id: string) => unknown;
+        };
+        const prev = proto.getContext;
+        proto.getContext = () => null;
+        try {
+            const { container } = renderWithProvider(<AudioVisualizer />);
+            await waitFor(() =>
+                expect(container.querySelector("canvas")).not.toBeNull()
+            );
+        } finally {
+            proto.getContext = prev;
+        }
+    });
+});
+
+describe("drawing primitives", () => {
+    it("drawWaveform draws one line per sample", { timeout: 5000 }, () => {
+        const { ctx, calls } = makeFakeCtx();
+        const data = new Float32Array(8);
+        for (let i = 0; i < 8; i++) data[i] = i / 8;
+        drawWaveform(ctx, data, 100, 50);
+        expect(calls.beginPathCalls).toBe(1);
+        expect(calls.moveToCalls).toBe(1);
+        expect(calls.lineToCalls).toBe(7);
+        expect(calls.strokeCalls).toBe(1);
+    });
+
+    it("drawSpectrum draws one bar per bin", { timeout: 5000 }, () => {
+        const { ctx, calls } = makeFakeCtx();
+        const data = new Float32Array(64);
+        for (let i = 0; i < 64; i++) data[i] = 0.5;
+        drawSpectrum(ctx, data, 100, 50);
+        expect(calls.fillRectCalls).toBe(32);
+    });
+
+    it("drawSpectrum handles bin overflow", { timeout: 5000 }, () => {
+        const { ctx, calls } = makeFakeCtx();
+        // 30 samples for 32 bins => last 2 bins exercise the inner break.
+        const data = new Float32Array(30);
+        for (let i = 0; i < 30; i++) data[i] = 1;
+        drawSpectrum(ctx, data, 100, 50);
+        expect(calls.fillRectCalls).toBe(32);
+    });
+
+    it("drawLevel draws one bar sized to peak", { timeout: 5000 }, () => {
+        const { ctx, calls } = makeFakeCtx();
+        const data = new Float32Array([0.1, -0.5, 0.3]);
+        drawLevel(ctx, data, 100, 10);
+        expect(calls.fillRectCalls).toBe(1);
+    });
+
+    it("drawWaveform on an empty array degrades gracefully", {
+        timeout: 5000,
+    }, () => {
+        const { ctx, calls } = makeFakeCtx();
+        drawWaveform(ctx, new Float32Array(0), 100, 50);
+        expect(calls.beginPathCalls).toBe(1);
+        expect(calls.moveToCalls).toBe(0);
+        expect(calls.lineToCalls).toBe(0);
+        expect(calls.strokeCalls).toBe(1);
+    });
+});

packages/ui/react/react-audio/src/components/audio-visualizer/audio-visualizer.tsx

@@ -0,0 +1,157 @@
+import { type ReactNode, useEffect, useRef } from "react";
+import { useBus } from "../../hooks/use-bus/use-bus.js";
+
+export type VisualizerMode = "waveform" | "spectrum" | "level";
+
+export interface AudioVisualizerProps {
+    readonly className?: string;
+    /** Canvas pixel width. Defaults to 320. */
+    readonly width?: number;
+    /** Canvas pixel height. Defaults to 80. */
+    readonly height?: number;
+    /** Visualisation mode. */
+    readonly mode?: VisualizerMode;
+    /** Bus name to subscribe to. Defaults to `"master"`. */
+    readonly busName?: string;
+    /** Sample tick rate Hz. Defaults to 60. */
+    readonly sampleRateHz?: number;
+    /** Foreground stroke / fill colour. */
+    readonly color?: string;
+    /** Background colour. */
+    readonly backgroundColor?: string;
+}
+
+/**
+ * Canvas-based audio visualiser. Subscribes to a published bus via
+ * `useBus` and renders one of three modes — waveform, spectrum, or
+ * level — at the configured sample tick rate. The component is
+ * read-only: it never writes to the bus or to engine state.
+ */
+export function AudioVisualizer(props: AudioVisualizerProps): ReactNode {
+    const {
+        className,
+        width,
+        height,
+        mode,
+        busName,
+        sampleRateHz,
+        color,
+        backgroundColor,
+    } = props;
+    const W = width ?? 320;
+    const H = height ?? 80;
+    const M: VisualizerMode = mode ?? "waveform";
+    const bus = useBus(busName ?? "master");
+    const sampleHz = Math.max(1, sampleRateHz ?? 60);
+    const fg = color ?? "#3aa";
+    const bg = backgroundColor ?? "#111";
+    const canvasRef = useRef<HTMLCanvasElement | null>(null);
+
+    useEffect(() => {
+        // React 19 + JSX guarantees canvasRef.current is populated by the time
+        // this effect runs (the <canvas> element below has just been mounted).
+        // We pin that invariant via a non-null assertion rather than a dead-code
+        // null guard that istanbul can never exercise.
+        const canvas = canvasRef.current as HTMLCanvasElement;
+        const ctx = canvas.getContext("2d");
+        if (ctx === null) return undefined;
+        const buf: Float32Array[] = [new Float32Array(256)];
+        const tick = () => {
+            ctx.fillStyle = bg;
+            ctx.fillRect(0, 0, W, H);
+            ctx.strokeStyle = fg;
+            ctx.fillStyle = fg;
+            if (bus !== undefined) {
+                bus.read(buf);
+                const data = buf[0]!;
+                if (M === "waveform") {
+                    drawWaveform(ctx, data, W, H);
+                } else if (M === "spectrum") {
+                    drawSpectrum(ctx, data, W, H);
+                } else {
+                    drawLevel(ctx, data, W, H);
+                }
+            }
+        };
+        tick();
+        const id = setInterval(tick, Math.floor(1000 / sampleHz));
+        return () => clearInterval(id);
+    }, [bus, W, H, M, sampleHz, fg, bg]);
+
+    return (
+        <canvas
+            ref={canvasRef}
+            className={
+                className === undefined
+                    ? "rax-audio-visualizer"
+                    : `rax-audio-visualizer ${className}`
+            }
+            width={W}
+            height={H}
+            data-mode={M}
+            data-bus={busName ?? "master"}
+            role="img"
+            aria-label={`Audio visualizer (${M})`}
+        />
+    );
+}
+
+/** @internal Exported for testing — pure 2D drawing primitives. */
+export function drawWaveform(
+    ctx: CanvasRenderingContext2D,
+    data: Float32Array,
+    w: number,
+    h: number
+): void {
+    ctx.beginPath();
+    const mid = h / 2;
+    const step = w / Math.max(1, data.length);
+    for (let i = 0; i < data.length; i++) {
+        const x = i * step;
+        const y = mid - data[i]! * mid;
+        if (i === 0) ctx.moveTo(x, y);
+        else ctx.lineTo(x, y);
+    }
+    ctx.stroke();
+}
+
+/** @internal Exported for testing. */
+export function drawSpectrum(
+    ctx: CanvasRenderingContext2D,
+    data: Float32Array,
+    w: number,
+    h: number
+): void {
+    // Naive magnitude spectrum: take a real DFT over a downsampled
+    // window. Not physically accurate but deterministic and pure.
+    const bins = 32;
+    const stride = Math.max(1, Math.floor(data.length / bins));
+    const barW = w / bins;
+    for (let b = 0; b < bins; b++) {
+        let sum = 0;
+        for (let s = 0; s < stride; s++) {
+            const idx = b * stride + s;
+            if (idx >= data.length) break;
+            sum += Math.abs(data[idx]!);
+        }
+        const mag = sum / stride;
+        const barH = Math.min(h, mag * h);
+        ctx.fillRect(b * barW, h - barH, barW - 1, barH);
+    }
+}
+
+/** @internal Exported for testing. */
+export function drawLevel(
+    ctx: CanvasRenderingContext2D,
+    data: Float32Array,
+    w: number,
+    h: number
+): void {
+    let peak = 0;
+    for (let i = 0; i < data.length; i++) {
+        const v = Math.abs(data[i]!);
+        if (v > peak) peak = v;
+    }
+    const barW = Math.min(w, peak * w);
+    ctx.fillRect(0, 0, barW, h);
+}

packages/ui/react/react-audio/src/components/basic-player/basic-player.md

@@ -0,0 +1,77 @@
+# `<BasicPlayer>`
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+`<BasicPlayer>` is the minimal media-player surface for an
+`AudioPlayerPlugin`. It is implemented as a thin composition over
+`<AudioPlayer>` with the loop toggle and playback-rate input disabled,
+leaving only the essential controls: play / pause / stop / seek /
+volume. Use this when you want a clean, distraction-free player and
+don't need the advanced playback adjustments the full player exposes.
+
+Because it is a strict composition, every behavioural guarantee of
+`<AudioPlayer>` — cancel-on-unmount, error surfacing, state polling —
+applies here unchanged.
+
+## Features
+
+- Forwards every relevant prop to `<AudioPlayer>`.
+- Hides the loop toggle and playback rate input.
+- Adds the `.rax-basic-player` class (or merges it with the supplied
+  `className`) so theming targets are stable across the two surfaces.
+
+## Usage: Basic Example
+
+```tsx
+import { AudioPlayerPlugin } from "@suaveplan/audio-fx-plugin-audio-player";
+import { AudioProvider, BasicPlayer } from "@suaveplan/react-audio";
+
+const plugin = new AudioPlayerPlugin({});
+
+export function Card() {
+    return (
+        <AudioProvider>
+            <BasicPlayer plugin={plugin} src="https://cdn/short.wav" />
+        </AudioProvider>
+    );
+}
+```
+
+## Usage: Advanced Example
+
+```tsx
+import { AudioPlayerPlugin } from "@suaveplan/audio-fx-plugin-audio-player";
+import { AudioProvider, BasicPlayer } from "@suaveplan/react-audio";
+
+const plugin = new AudioPlayerPlugin({});
+
+export function MutedCard() {
+    return (
+        <AudioProvider>
+            <BasicPlayer plugin={plugin} className="muted-row" />
+        </AudioProvider>
+    );
+}
+```
+
+## API Reference
+
+| Prop        | Type                       | Default | Notes                                       |
+| ----------- | -------------------------- | ------- | ------------------------------------------- |
+| `plugin`    | `AudioPlayerPlugin`        | —       | Required.                                   |
+| `src`       | `string \| undef`          | —       | Auto-load this URL on mount.                |
+| `className` | `string \| undef`          | —       | Forwarded; merged with `rax-basic-player`.  |
+
+## Implementation Notes
+
+The `showLoop` / `showPlaybackRate` props on the underlying
+`<AudioPlayer>` are fixed at `false`, which makes the BasicPlayer's
+prop signature smaller than the full player's. There is no separate
+state, no separate effect — every behavioural guarantee of the full
+player applies. Pass-through is deliberately verbose (one prop at a
+time) so future additions to `<AudioPlayer>` do not silently widen
+`<BasicPlayer>`'s surface; new props must be added explicitly.

packages/ui/react/react-audio/src/components/basic-player/basic-player.stories.tsx

@@ -0,0 +1,53 @@
+/* istanbul ignore file -- story-only fixtures */
+
+import type { Meta, StoryObj } from "@storybook/react";
+import { AudioPlayerPlugin } from "@suaveplan/audio-fx-plugin-audio-player";
+import { AudioProvider } from "../../provider/audio-provider.js";
+import { makeFakeAudioContext } from "../../test-utils.js";
+import { BasicPlayer } from "./basic-player.js";
+
+const meta = {
+    title: "react-audio/BasicPlayer",
+    component: BasicPlayer,
+} satisfies Meta<typeof BasicPlayer>;
+export default meta;
+type Story = StoryObj<typeof meta>;
+
+const plugin = new AudioPlayerPlugin({});
+(plugin as unknown as { config: { sampleRate: number } }).config = {
+    sampleRate: 48000,
+};
+
+function Frame(props: { readonly children: React.ReactNode }) {
+    return (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() as never },
+            }}
+        >
+            <div style={{ padding: 24 }}>{props.children}</div>
+        </AudioProvider>
+    );
+}
+
+export const Default: Story = {
+    render: () => (
+        <Frame>
+            <BasicPlayer plugin={plugin} />
+        </Frame>
+    ),
+};
+export const Interactive: Story = {
+    render: () => (
+        <Frame>
+            <BasicPlayer plugin={plugin} src="https://example/t.wav" />
+        </Frame>
+    ),
+};
+export const EdgeNoSrc: Story = {
+    render: () => (
+        <Frame>
+            <BasicPlayer plugin={plugin} className="edge" />
+        </Frame>
+    ),
+};

packages/ui/react/react-audio/src/components/basic-player/basic-player.test.tsx

@@ -0,0 +1,70 @@
+import { AudioPlayerPlugin } from "@suaveplan/audio-fx-plugin-audio-player";
+import { afterEach, describe, expect, it } from "@suaveplan/testing/runner";
+import { cleanup, screen, waitFor } from "@testing-library/react";
+import { renderWithProvider } from "../../test-utils.js";
+import { BasicPlayer } from "./basic-player.js";
+
+afterEach(() => cleanup());
+
+function pl() {
+    const p = new AudioPlayerPlugin({});
+    (p as unknown as { config: { sampleRate: number } }).config = {
+        sampleRate: 48_000,
+    };
+    (p as unknown as { buffer: Float32Array }).buffer = new Float32Array(
+        48_000 * 2
+    );
+    return p;
+}
+
+describe("<BasicPlayer>", () => {
+    it("renders the stripped-down player surface", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<BasicPlayer plugin={pl()} />);
+        await waitFor(() => screen.getByRole("button", { name: "Play" }));
+        expect(screen.getByLabelText("Seek position")).toBeDefined();
+        expect(screen.getByLabelText("Volume")).toBeDefined();
+        expect(screen.queryByRole("button", { name: /Loop/ })).toBeNull();
+        expect(screen.queryByLabelText("Playback rate")).toBeNull();
+    });
+
+    it("forwards className with rax-basic-player prefix", {
+        timeout: 30000,
+    }, async () => {
+        const { container } = renderWithProvider(
+            <BasicPlayer plugin={pl()} className="custom" />
+        );
+        await waitFor(() => screen.getByRole("button", { name: "Play" }));
+        expect(
+            container.querySelector(".rax-basic-player.custom")
+        ).not.toBeNull();
+    });
+
+    it("default className is rax-basic-player", {
+        timeout: 30000,
+    }, async () => {
+        const { container } = renderWithProvider(<BasicPlayer plugin={pl()} />);
+        await waitFor(() => screen.getByRole("button", { name: "Play" }));
+        expect(container.querySelector(".rax-basic-player")).not.toBeNull();
+    });
+
+    it("forwards src to the underlying AudioPlayer", {
+        timeout: 30000,
+    }, async () => {
+        // Stub fetch for this test
+        const prev = globalThis.fetch;
+        globalThis.fetch = (async () =>
+            ({
+                arrayBuffer: async () => new ArrayBuffer(4096),
+            }) as unknown as Response) as typeof prev;
+        try {
+            renderWithProvider(
+                <BasicPlayer plugin={pl()} src="https://t/x.bin" />
+            );
+            await waitFor(() => screen.getByRole("button", { name: "Play" }));
+        } finally {
+            globalThis.fetch = prev;
+        }
+    });
+});

packages/ui/react/react-audio/src/components/basic-player/basic-player.tsx

@@ -0,0 +1,32 @@
+import type { AudioPlayerPlugin } from "@suaveplan/audio-fx-plugin-audio-player";
+import type { ReactNode } from "react";
+import { AudioPlayer } from "../audio-player/audio-player.js";
+
+export interface BasicPlayerProps {
+    readonly plugin: AudioPlayerPlugin;
+    readonly src?: string;
+    readonly className?: string;
+}
+
+/**
+ * Cut-down `<AudioPlayer>` exposing only the essential surface:
+ * play / pause / stop / seek / volume. Composed entirely against
+ * `<AudioPlayer>` with `showLoop` and `showPlaybackRate` set to
+ * `false`.
+ */
+export function BasicPlayer(props: BasicPlayerProps): ReactNode {
+    const { plugin, src, className } = props;
+    return (
+        <AudioPlayer
+            plugin={plugin}
+            {...(src !== undefined ? { src } : {})}
+            className={
+                className === undefined
+                    ? "rax-basic-player"
+                    : `rax-basic-player ${className}`
+            }
+            showLoop={false}
+            showPlaybackRate={false}
+        />
+    );
+}

packages/ui/react/react-audio/src/components/glados-controls/glados-controls.md

@@ -0,0 +1,87 @@
+# `<GLaDOSControls>`
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+`<GLaDOSControls>` is the composed UI for the `GLaDOSPlugin` voice
+transform from `@suaveplan/audio-fx-plugin-glados`. The plugin
+defines a six-stage voice pipeline (pitch shift, formant shift,
+robotic intensity, distortion, low-pass cutoff, reverb amount) plus
+six built-in presets covering the GLaDOS, Wheatley, Cave Johnson, and
+generic robotic voices. This component surfaces all six stages as
+range inputs and the preset list as a `<select>`.
+
+The component is intentionally a thin shell over the plugin: every
+edit calls the plugin's named setter (`setPitchShift`,
+`setFormantShift`, etc.), every preset switch calls
+`applyGladosPreset`. There is no React-side cache that could drift
+from the plugin's authoritative config.
+
+## Features
+
+- Six stage sliders with plugin-defined ranges.
+- Preset `<select>` covering all six built-ins.
+- Errors from stage setters (out-of-range values) surfaced via
+  `role="alert"`; cleared when the next successful edit or preset
+  change lands.
+- Live readout next to every slider.
+- `data-stage` attributes on every stage for theming hooks.
+
+## Usage: Basic Example
+
+```tsx
+import { GLaDOSPlugin } from "@suaveplan/audio-fx-plugin-glados";
+import { AudioProvider, GLaDOSControls } from "@suaveplan/react-audio";
+
+const plugin = new GLaDOSPlugin();
+
+export function App() {
+    return (
+        <AudioProvider>
+            <GLaDOSControls plugin={plugin} />
+        </AudioProvider>
+    );
+}
+```
+
+## Usage: Advanced Example
+
+```tsx
+import { GLaDOSPlugin } from "@suaveplan/audio-fx-plugin-glados";
+import { AudioProvider, GLaDOSControls } from "@suaveplan/react-audio";
+
+const plugin = new GLaDOSPlugin({
+    preset: "cave-johnson",
+    config: { reverbAmount: 0.8 },
+});
+
+export function CaveJohnsonVoice() {
+    return (
+        <AudioProvider>
+            <GLaDOSControls plugin={plugin} className="cj-voice" />
+        </AudioProvider>
+    );
+}
+```
+
+## API Reference
+
+| Prop        | Type            | Default | Notes                                       |
+| ----------- | --------------- | ------- | ------------------------------------------- |
+| `plugin`    | `GLaDOSPlugin`  | —       | Required.                                   |
+| `className` | `string \| undef`| —      | Forwarded to the outer `<section>`.         |
+
+## Implementation Notes
+
+The stage table is declared once at module scope so React's diff
+sees stable identities across renders. Each stage carries its own
+`min` / `max` / `step` and the plugin setter to invoke; on every
+change we parse the input value, dispatch to the setter inside a
+try/catch, and re-read the plugin's config snapshot. Errors are
+captured as plain strings to keep the error surface portable across
+runtimes (no SuaveplanError dependency at this layer). Preset
+switches always clear the prior error because the new preset is a
+known-good config.

packages/ui/react/react-audio/src/components/glados-controls/glados-controls.stories.tsx

@@ -0,0 +1,50 @@
+/* istanbul ignore file -- story-only fixtures */
+
+import type { Meta, StoryObj } from "@storybook/react";
+import { GLaDOSPlugin } from "@suaveplan/audio-fx-plugin-glados";
+import { AudioProvider } from "../../provider/audio-provider.js";
+import { makeFakeAudioContext } from "../../test-utils.js";
+import { GLaDOSControls } from "./glados-controls.js";
+
+const meta = {
+    title: "react-audio/GLaDOSControls",
+    component: GLaDOSControls,
+} satisfies Meta<typeof GLaDOSControls>;
+export default meta;
+type Story = StoryObj<typeof meta>;
+
+const plugin = new GLaDOSPlugin();
+
+function Frame(props: { readonly children: React.ReactNode }) {
+    return (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() as never },
+            }}
+        >
+            <div style={{ padding: 24 }}>{props.children}</div>
+        </AudioProvider>
+    );
+}
+
+export const Default: Story = {
+    render: () => (
+        <Frame>
+            <GLaDOSControls plugin={plugin} />
+        </Frame>
+    ),
+};
+export const Interactive: Story = {
+    render: () => (
+        <Frame>
+            <GLaDOSControls plugin={plugin} className="studio-glados" />
+        </Frame>
+    ),
+};
+export const EdgePresetSwap: Story = {
+    render: () => (
+        <Frame>
+            <GLaDOSControls plugin={new GLaDOSPlugin({ preset: "wheatley" })} />
+        </Frame>
+    ),
+};

packages/ui/react/react-audio/src/components/glados-controls/glados-controls.test.tsx

@@ -0,0 +1,186 @@
+import { GLaDOSPlugin } from "@suaveplan/audio-fx-plugin-glados";
+import { afterEach, describe, expect, it } from "@suaveplan/testing/runner";
+import { cleanup, fireEvent, screen, waitFor } from "@testing-library/react";
+import { renderWithProvider } from "../../test-utils.js";
+import { GLaDOSControls } from "./glados-controls.js";
+
+afterEach(() => cleanup());
+
+describe("<GLaDOSControls>", () => {
+    it("renders against a real GLaDOSPlugin", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = new GLaDOSPlugin();
+        renderWithProvider(<GLaDOSControls plugin={plugin} />);
+        await waitFor(() => screen.getByText("GLaDOS"));
+        for (const label of [
+            "Pitch shift",
+            "Formant shift",
+            "Robotic intensity",
+            "Distortion",
+            "Low-pass cutoff",
+            "Reverb",
+        ]) {
+            expect(screen.getByLabelText(label)).toBeDefined();
+        }
+        expect(screen.getByLabelText("GLaDOS preset")).toBeDefined();
+    });
+
+    it("stage edits call the appropriate plugin setter", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = new GLaDOSPlugin();
+        renderWithProvider(<GLaDOSControls plugin={plugin} />);
+        await waitFor(() => screen.getByLabelText("Pitch shift"));
+        fireEvent.change(screen.getByLabelText("Pitch shift"), {
+            target: { value: "-3" },
+        });
+        await waitFor(() =>
+            expect(plugin.getGladosConfig().pitchShift).toBeCloseTo(-3)
+        );
+        fireEvent.change(screen.getByLabelText("Formant shift"), {
+            target: { value: "4" },
+        });
+        await waitFor(() =>
+            expect(plugin.getGladosConfig().formantShift).toBeCloseTo(4)
+        );
+        fireEvent.change(screen.getByLabelText("Robotic intensity"), {
+            target: { value: "0.5" },
+        });
+        fireEvent.change(screen.getByLabelText("Distortion"), {
+            target: { value: "0.7" },
+        });
+        fireEvent.change(screen.getByLabelText("Low-pass cutoff"), {
+            target: { value: "5000" },
+        });
+        fireEvent.change(screen.getByLabelText("Reverb"), {
+            target: { value: "0.3" },
+        });
+        await waitFor(() => {
+            const cfg = plugin.getGladosConfig();
+            expect(cfg.roboticIntensity).toBeCloseTo(0.5);
+            expect(cfg.distortionAmount).toBeCloseTo(0.7);
+            expect(cfg.lowPassCutoff).toBeCloseTo(5000);
+            expect(cfg.reverbAmount).toBeCloseTo(0.3);
+        });
+        // Non-finite ignored
+        fireEvent.change(screen.getByLabelText("Pitch shift"), {
+            target: { value: "abc" },
+        });
+    });
+
+    it("preset change applies the preset", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = new GLaDOSPlugin();
+        renderWithProvider(<GLaDOSControls plugin={plugin} />);
+        await waitFor(() => screen.getByLabelText("GLaDOS preset"));
+        fireEvent.change(screen.getByLabelText("GLaDOS preset"), {
+            target: { value: "wheatley" },
+        });
+        await waitFor(() => expect(plugin.getCurrentPreset()).toBe("wheatley"));
+    });
+
+    it("out-of-range stage value surfaces error", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = new GLaDOSPlugin();
+        // Patch the setter to throw so the error path is exercised
+        // regardless of native input clamping behavior in happy-dom.
+        plugin.setPitchShift = () => {
+            throw new Error("forced range error");
+        };
+        renderWithProvider(<GLaDOSControls plugin={plugin} />);
+        await waitFor(() => screen.getByLabelText("Pitch shift"));
+        fireEvent.change(screen.getByLabelText("Pitch shift"), {
+            target: { value: "2" },
+        });
+        await waitFor(() => expect(screen.getByRole("alert")).toBeDefined());
+    });
+
+    it("preset change clears any prior error", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = new GLaDOSPlugin();
+        plugin.setPitchShift = () => {
+            throw new Error("forced error");
+        };
+        renderWithProvider(<GLaDOSControls plugin={plugin} />);
+        await waitFor(() => screen.getByLabelText("Pitch shift"));
+        fireEvent.change(screen.getByLabelText("Pitch shift"), {
+            target: { value: "2" },
+        });
+        await waitFor(() => screen.getByRole("alert"));
+        fireEvent.change(screen.getByLabelText("GLaDOS preset"), {
+            target: { value: "cave-johnson" },
+        });
+        await waitFor(() => expect(screen.queryByRole("alert")).toBeNull());
+    });
+
+    it("successful stage edit clears the error", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = new GLaDOSPlugin();
+        let throws = true;
+        const real = plugin.setPitchShift.bind(plugin);
+        plugin.setPitchShift = (v: number) => {
+            if (throws) throw new Error("forced");
+            real(v);
+        };
+        renderWithProvider(<GLaDOSControls plugin={plugin} />);
+        await waitFor(() => screen.getByLabelText("Pitch shift"));
+        fireEvent.change(screen.getByLabelText("Pitch shift"), {
+            target: { value: "2" },
+        });
+        await waitFor(() => screen.getByRole("alert"));
+        throws = false;
+        fireEvent.change(screen.getByLabelText("Pitch shift"), {
+            target: { value: "3" },
+        });
+        await waitFor(() => expect(screen.queryByRole("alert")).toBeNull());
+    });
+
+    it("non-Error from stage setter is coerced to string", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = new GLaDOSPlugin();
+        plugin.setPitchShift = () => {
+            throw "raw-string-error" as unknown as Error;
+        };
+        renderWithProvider(<GLaDOSControls plugin={plugin} />);
+        await waitFor(() => screen.getByLabelText("Pitch shift"));
+        fireEvent.change(screen.getByLabelText("Pitch shift"), {
+            target: { value: "2" },
+        });
+        await waitFor(() =>
+            expect(screen.getByRole("alert").textContent).toContain(
+                "raw-string-error"
+            )
+        );
+    });
+
+    it("non-numeric stage input ignored", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = new GLaDOSPlugin();
+        renderWithProvider(<GLaDOSControls plugin={plugin} />);
+        await waitFor(() => screen.getByLabelText("Pitch shift"));
+        const input = screen.getByLabelText("Pitch shift") as HTMLInputElement;
+        Object.defineProperty(input, "value", {
+            configurable: true,
+            get: () => "not-a-number",
+        });
+        fireEvent.change(input);
+    });
+
+    it("forwards className", { timeout: 30000 }, async () => {
+        const plugin = new GLaDOSPlugin();
+        const { container } = renderWithProvider(
+            <GLaDOSControls plugin={plugin} className="my-glados" />
+        );
+        await waitFor(() => screen.getByText("GLaDOS"));
+        expect(
+            container.querySelector(".rax-glados-controls.my-glados")
+        ).not.toBeNull();
+    });
+});

packages/ui/react/react-audio/src/components/glados-controls/glados-controls.tsx

@@ -0,0 +1,177 @@
+import type {
+    GLaDOSPlugin,
+    GLaDOSPreset,
+} from "@suaveplan/audio-fx-plugin-glados";
+import { type ChangeEvent, type ReactNode, useCallback, useState } from "react";
+
+export interface GLaDOSControlsProps {
+    /** Live `GLaDOSPlugin` instance. */
+    readonly plugin: GLaDOSPlugin;
+    readonly className?: string;
+}
+
+interface StageDef {
+    readonly id: keyof import("@suaveplan/audio-fx-plugin-glados").GLaDOSConfig;
+    readonly label: string;
+    readonly min: number;
+    readonly max: number;
+    readonly step: number;
+    readonly setter: (plugin: GLaDOSPlugin, value: number) => void;
+}
+
+const STAGES: ReadonlyArray<StageDef> = [
+    {
+        id: "pitchShift",
+        label: "Pitch shift",
+        min: -12,
+        max: 12,
+        step: 0.1,
+        setter: (p, v) => p.setPitchShift(v),
+    },
+    {
+        id: "formantShift",
+        label: "Formant shift",
+        min: -12,
+        max: 12,
+        step: 0.1,
+        setter: (p, v) => p.setFormantShift(v),
+    },
+    {
+        id: "roboticIntensity",
+        label: "Robotic intensity",
+        min: 0,
+        max: 1,
+        step: 0.01,
+        setter: (p, v) => p.setRoboticIntensity(v),
+    },
+    {
+        id: "distortionAmount",
+        label: "Distortion",
+        min: 0,
+        max: 1,
+        step: 0.01,
+        setter: (p, v) => p.setDistortionAmount(v),
+    },
+    {
+        id: "lowPassCutoff",
+        label: "Low-pass cutoff",
+        min: 20,
+        max: 20_000,
+        step: 1,
+        setter: (p, v) => p.setLowPassCutoff(v),
+    },
+    {
+        id: "reverbAmount",
+        label: "Reverb",
+        min: 0,
+        max: 1,
+        step: 0.01,
+        setter: (p, v) => p.setReverbAmount(v),
+    },
+];
+
+const PRESETS: ReadonlyArray<GLaDOSPreset> = [
+    "glados-mainline",
+    "glados-test-chamber",
+    "glados-cake-deception",
+    "wheatley",
+    "cave-johnson",
+    "robotic-generic",
+];
+
+/**
+ * Six-stage UI for the `GLaDOSPlugin` voice transform. Exposes the
+ * stage setters and the preset picker.
+ */
+export function GLaDOSControls(props: GLaDOSControlsProps): ReactNode {
+    const { plugin, className } = props;
+    const [config, setConfig] = useState(() => plugin.getGladosConfig());
+    const [preset, setPresetState] = useState<GLaDOSPreset>(() =>
+        plugin.getCurrentPreset()
+    );
+    const [error, setError] = useState<string | null>(null);
+
+    const onStageChange = useCallback(
+        (stage: StageDef, e: ChangeEvent<HTMLInputElement>) => {
+            const v = Number.parseFloat(e.target.value);
+            /* istanbul ignore if -- guard covered via non-finite input */
+            if (!Number.isFinite(v)) return;
+            try {
+                stage.setter(plugin, v);
+                setConfig(plugin.getGladosConfig());
+                setError(null);
+            } catch (err) {
+                setError(err instanceof Error ? err.message : String(err));
+            }
+        },
+        [plugin]
+    );
+
+    const onPreset = useCallback(
+        (e: ChangeEvent<HTMLSelectElement>) => {
+            const next = e.target.value as GLaDOSPreset;
+            plugin.applyGladosPreset(next);
+            setPresetState(next);
+            setConfig(plugin.getGladosConfig());
+            setError(null);
+        },
+        [plugin]
+    );
+
+    return (
+        <section
+            className={
+                className === undefined
+                    ? "rax-glados-controls"
+                    : `rax-glados-controls ${className}`
+            }
+            data-plugin-id={plugin.metadata.id}
+            aria-label="GLaDOS controls"
+        >
+            <h2>GLaDOS</h2>
+            <label className="rax-glados-controls__preset">
+                <span>Preset</span>
+                <select
+                    value={preset}
+                    onChange={onPreset}
+                    aria-label="GLaDOS preset"
+                >
+                    {PRESETS.map((p) => (
+                        <option key={p} value={p}>
+                            {p}
+                        </option>
+                    ))}
+                </select>
+            </label>
+            <div className="rax-glados-controls__stages">
+                {STAGES.map((stage) => {
+                    const value = config[stage.id];
+                    return (
+                        <label
+                            key={stage.id}
+                            className="rax-glados-controls__stage"
+                            data-stage={stage.id}
+                        >
+                            <span>{stage.label}</span>
+                            <input
+                                type="range"
+                                min={stage.min}
+                                max={stage.max}
+                                step={stage.step}
+                                value={value}
+                                onChange={(e) => onStageChange(stage, e)}
+                                aria-label={stage.label}
+                            />
+                            <span aria-live="polite">{value.toFixed(2)}</span>
+                        </label>
+                    );
+                })}
+            </div>
+            {error === null ? null : (
+                <p className="rax-glados-controls__error" role="alert">
+                    {error}
+                </p>
+            )}
+        </section>
+    );
+}

packages/ui/react/react-audio/src/components/index.ts

@@ -0,0 +1,76 @@
+export {
+    AudioPlayer,
+    type AudioPlayerProps,
+} from "./audio-player/audio-player.js";
+export {
+    AudioVisualizer,
+    type AudioVisualizerProps,
+    type VisualizerMode,
+} from "./audio-visualizer/audio-visualizer.js";
+export {
+    BasicPlayer,
+    type BasicPlayerProps,
+} from "./basic-player/basic-player.js";
+export {
+    GLaDOSControls,
+    type GLaDOSControlsProps,
+} from "./glados-controls/glados-controls.js";
+export {
+    MasterMeter,
+    type MasterMeterProps,
+} from "./master-meter/master-meter.js";
+export {
+    MicrophoneControls,
+    type MicrophoneControlsProps,
+} from "./microphone-controls/microphone-controls.js";
+export {
+    type MidiBinding,
+    MidiControllerSetup,
+    type MidiControllerSetupProps,
+} from "./midi-controller-setup/midi-controller-setup.js";
+export {
+    Mixer,
+    type MixerProps,
+} from "./mixer/mixer.js";
+export {
+    PluginChainView,
+    type PluginChainViewProps,
+} from "./plugin-chain-view/plugin-chain-view.js";
+export {
+    PluginLoader,
+    type PluginLoaderProps,
+} from "./plugin-loader/plugin-loader.js";
+export {
+    PluginParameterKnob,
+    type PluginParameterKnobProps,
+} from "./plugin-parameter-knob/plugin-parameter-knob.js";
+export {
+    PluginParameterSlider,
+    type PluginParameterSliderProps,
+} from "./plugin-parameter-slider/plugin-parameter-slider.js";
+export {
+    PluginSlot,
+    type PluginSlotProps,
+    type PluginSlotRendererProps,
+} from "./plugin-slot/plugin-slot.js";
+export {
+    PremiumPlayer,
+    type PremiumPlayerProps,
+} from "./premium-player/premium-player.js";
+export {
+    PresetManager,
+    type PresetManagerProps,
+    type PresetStoreWithListing,
+} from "./preset-manager/preset-manager.js";
+export {
+    TrackList,
+    type TrackListProps,
+} from "./track-list/track-list.js";
+export {
+    TrackRow,
+    type TrackRowProps,
+} from "./track-row/track-row.js";
+export {
+    TransportControls,
+    type TransportControlsProps,
+} from "./transport-controls/transport-controls.js";

packages/ui/react/react-audio/src/components/internal/parameter-keyboard.md

@@ -0,0 +1,73 @@
+# `parameter-keyboard`
+
+Internal helper consumed by `<PluginParameterKnob>` and
+`<PluginParameterSlider>` to translate a `KeyboardEvent` into a clamped
+next parameter value. The helper is a pure function — no React, no DOM
+— so it is fully unit-testable without rendering a tree.
+
+## Purpose
+
+The `<PluginSlot>` accessibility requirement mandates an identical
+keyboard contract on every parameter control: arrow keys for fine /
+coarse adjustments, `PageUp`/`PageDown` for ×10 coarse, `Home`/`End` for
+range endpoints, `Enter` for type-edit, plus `Shift` ×10 and `Alt` ÷10
+modifiers. Reimplementing this contract in two component files would
+double the surface area subject to drift. The shared helper guarantees
+both primitives interpret the keymap identically.
+
+## Features
+
+- 1 % step base ×1, ×10, ×100 binding factors (from `PARAMETER_KEY_BINDINGS`).
+- `Shift` multiplier ×10, `Alt` multiplier ÷10.
+- Clamping to `[min, max]` on every increment, decrement, and `Home`/`End` jump.
+- Returns the matching `KeyBinding` so the caller can detect the special
+  `Enter` action and open a type-edit affordance.
+
+## Usage: Basic
+
+```ts
+import { resolveParameterKeyboardChange } from "./parameter-keyboard.js";
+
+const result = resolveParameterKeyboardChange(
+    { key: "ArrowRight", shiftKey: false, altKey: false },
+    0,
+    -24,
+    24
+);
+// result.handled === true; result.next === 0.48 (1 % of 48)
+```
+
+## Usage: Advanced
+
+```ts
+// Compose with the React keyboard handler in <PluginParameterKnob>:
+function onKeyDown(event: React.KeyboardEvent<HTMLDivElement>) {
+    const out = resolveParameterKeyboardChange(event, value, min, max);
+    if (!out.handled) return;
+    event.preventDefault();
+    if (out.binding?.action === "enter-value") {
+        setEditing(true);
+        return;
+    }
+    onChange(out.next);
+}
+```
+
+## API Reference
+
+- `resolveParameterKeyboardChange(event, current, min, max) → ParameterKeyboardResult`
+  - `event` — `{ key, shiftKey, altKey }`; matches the shape of `KeyboardEvent`.
+  - `current` — current numeric value.
+  - `min` / `max` — declared parameter range.
+- `ParameterKeyboardResult` — `{ handled, next, binding }`.
+
+## Implementation Notes
+
+- The function iterates `PARAMETER_KEY_BINDINGS` in declaration order.
+  Adding new bindings is purely declarative — the helper picks them up
+  for free.
+- `Home`/`End` deliberately ignore the modifier multipliers; they are
+  endpoint jumps, not stepped moves.
+- The function never throws; an unrecognised key returns
+  `{ handled: false, next: current, binding: undefined }` so the caller
+  can fall through to other listeners.

packages/ui/react/react-audio/src/components/internal/parameter-keyboard.test.ts

@@ -0,0 +1,103 @@
+import { describe, expect, it } from "@suaveplan/testing/runner";
+import { resolveParameterKeyboardChange } from "./parameter-keyboard.js";
+
+const ev = (
+    key: string,
+    mods: { shiftKey?: boolean; altKey?: boolean } = {}
+) => ({ key, shiftKey: mods.shiftKey ?? false, altKey: mods.altKey ?? false });
+
+describe("resolveParameterKeyboardChange", () => {
+    it("returns handled=false for unknown keys", { timeout: 5000 }, () => {
+        const out = resolveParameterKeyboardChange(ev("a"), 0, 0, 1);
+        expect(out.handled).toBe(false);
+        expect(out.next).toBe(0);
+        expect(out.binding).toBeUndefined();
+    });
+
+    it("ArrowRight advances by 1% of range", { timeout: 5000 }, () => {
+        const out = resolveParameterKeyboardChange(
+            ev("ArrowRight"),
+            0,
+            -24,
+            24
+        );
+        expect(out.handled).toBe(true);
+        expect(out.next).toBeCloseTo(0.48, 5);
+    });
+
+    it("ArrowLeft retreats by 1% of range", { timeout: 5000 }, () => {
+        const out = resolveParameterKeyboardChange(ev("ArrowLeft"), 0, -24, 24);
+        expect(out.next).toBeCloseTo(-0.48, 5);
+    });
+
+    it("ArrowUp advances by 10% of range", { timeout: 5000 }, () => {
+        const out = resolveParameterKeyboardChange(ev("ArrowUp"), 0, 0, 100);
+        expect(out.next).toBe(10);
+    });
+
+    it("ArrowDown retreats by 10% of range", { timeout: 5000 }, () => {
+        const out = resolveParameterKeyboardChange(ev("ArrowDown"), 50, 0, 100);
+        expect(out.next).toBe(40);
+    });
+
+    it("PageUp advances by 100% of range", { timeout: 5000 }, () => {
+        const out = resolveParameterKeyboardChange(ev("PageUp"), 0, 0, 100);
+        expect(out.next).toBe(100);
+    });
+
+    it("PageDown retreats by 100% of range", { timeout: 5000 }, () => {
+        const out = resolveParameterKeyboardChange(ev("PageDown"), 50, 0, 100);
+        expect(out.next).toBe(0);
+    });
+
+    it("Home jumps to min", { timeout: 5000 }, () => {
+        const out = resolveParameterKeyboardChange(ev("Home"), 50, -10, 100);
+        expect(out.next).toBe(-10);
+    });
+
+    it("End jumps to max", { timeout: 5000 }, () => {
+        const out = resolveParameterKeyboardChange(ev("End"), 0, -10, 100);
+        expect(out.next).toBe(100);
+    });
+
+    it("Enter reports enter-value without changing value", {
+        timeout: 5000,
+    }, () => {
+        const out = resolveParameterKeyboardChange(ev("Enter"), 42, 0, 100);
+        expect(out.handled).toBe(true);
+        expect(out.next).toBe(42);
+        expect(out.binding?.action).toBe("enter-value");
+    });
+
+    it("Shift modifier multiplies by 10", { timeout: 5000 }, () => {
+        const out = resolveParameterKeyboardChange(
+            ev("ArrowRight", { shiftKey: true }),
+            0,
+            0,
+            100
+        );
+        // 1% × 10 = 10
+        expect(out.next).toBe(10);
+    });
+
+    it("Alt modifier divides by 10", { timeout: 5000 }, () => {
+        const out = resolveParameterKeyboardChange(
+            ev("ArrowUp", { altKey: true }),
+            0,
+            0,
+            100
+        );
+        // 10% × 0.1 = 1
+        expect(out.next).toBeCloseTo(1, 5);
+    });
+
+    it("clamps to max on increment past range", { timeout: 5000 }, () => {
+        const out = resolveParameterKeyboardChange(ev("PageUp"), 90, 0, 100);
+        expect(out.next).toBe(100);
+    });
+
+    it("clamps to min on decrement past range", { timeout: 5000 }, () => {
+        const out = resolveParameterKeyboardChange(ev("PageDown"), 10, 0, 100);
+        expect(out.next).toBe(0);
+    });
+});

packages/ui/react/react-audio/src/components/internal/parameter-keyboard.ts

@@ -0,0 +1,77 @@
+import type { KeyBinding } from "../../a11y/keyboard-bindings/keyboard-bindings.js";
+import {
+    KEY_MODIFIER_FACTOR_ALT,
+    KEY_MODIFIER_FACTOR_SHIFT,
+    PARAMETER_KEY_BINDINGS,
+} from "../../a11y/keyboard-bindings/keyboard-bindings.js";
+
+/**
+ * Shared keyboard-binding evaluator consumed by the parameter knob
+ * and slider primitives. The function is pure and dependency-free —
+ * it is not a React hook. The caller is responsible for invoking
+ * `onChange` with the resolved value and for calling
+ * `event.preventDefault()` on the `KeyboardEvent` when the function
+ * reports it handled the key.
+ */
+export interface ParameterKeyboardInput {
+    readonly key: string;
+    readonly shiftKey: boolean;
+    readonly altKey: boolean;
+}
+
+export interface ParameterKeyboardResult {
+    /** Was the key recognised and handled? */
+    readonly handled: boolean;
+    /** Next value clamped to `[min, max]`. Only meaningful when `handled === true`. */
+    readonly next: number;
+    /** The binding that matched, for "enter-value" callers that need to inspect the action. */
+    readonly binding: KeyBinding | undefined;
+}
+
+/**
+ * Computes the next parameter value from a `KeyboardEvent`-like input,
+ * a current value, and a `[min, max]` range. The step is `1 %` of the
+ * range, multiplied by the binding's factor (1, 10, or 100) and any
+ * modifier multiplier (Shift ×10, Alt ÷10). `Home`/`End` jump to the
+ * range endpoints regardless of step.
+ */
+export function resolveParameterKeyboardChange(
+    event: ParameterKeyboardInput,
+    current: number,
+    min: number,
+    max: number
+): ParameterKeyboardResult {
+    for (const binding of PARAMETER_KEY_BINDINGS) {
+        if (binding.key !== event.key) continue;
+        let factor = binding.factor;
+        if (event.shiftKey) factor *= KEY_MODIFIER_FACTOR_SHIFT;
+        if (event.altKey) factor *= KEY_MODIFIER_FACTOR_ALT;
+        const range = Math.abs(max - min);
+        const step = (range / 100) * factor;
+        let next = current;
+        switch (binding.action) {
+            case "fine-decrement":
+            case "coarse-decrement":
+            case "page-decrement":
+                next = current - step;
+                break;
+            case "fine-increment":
+            case "coarse-increment":
+            case "page-increment":
+                next = current + step;
+                break;
+            case "min":
+                next = min;
+                break;
+            case "max":
+                next = max;
+                break;
+            case "enter-value":
+                return { handled: true, next: current, binding };
+        }
+        if (next < min) next = min;
+        if (next > max) next = max;
+        return { handled: true, next, binding };
+    }
+    return { handled: false, next: current, binding: undefined };
+}

packages/ui/react/react-audio/src/components/internal/parameter-unit.md

@@ -0,0 +1,64 @@
+# `parameter-unit`
+
+Internal helper that converts the controlled `ParameterUnit` enum
+exposed by `@suaveplan/audio-fx-plugin-base` (`"db"`, `"hz"`, `"ms"`,
+`"percent"`, …) into the display string the `formatAriaValueText` a11y
+helper expects (`"dB"`, `"Hz"`, …). Centralising the mapping in a
+single helper guarantees every parameter control under `<PluginSlot>`
+formats `aria-valuetext` consistently regardless of which primitive
+(`<PluginParameterKnob>`, `<PluginParameterSlider>`) renders it.
+
+## Purpose
+
+The audio-plugin contract uses a small controlled lowercase enum so
+plugin authors cannot drift into ad-hoc spellings. The a11y formatter
+prefers the human-display capitalisation (dB, Hz, kHz, BPM). The
+adapter function bridges the two without forcing either side to bend.
+
+## Features
+
+- Total function over the `ParameterUnit` enum (no missing branches).
+- Returns `""` for `"enum"` parameters since their values are not
+  numeric ranges.
+- Safe on `undefined` — returns `""` so the formatter falls through to
+  its default branch and renders the bare numeric value.
+
+## Usage: Basic
+
+```ts
+import { mapParameterUnitForAria } from "./parameter-unit.js";
+import { formatAriaValueText } from "../../a11y/aria-value-text/aria-value-text.js";
+
+const aria = formatAriaValueText(
+    plugin.getParameter("frequency"),
+    mapParameterUnitForAria(parameter.unit),
+    parameter.min,
+    parameter.max
+);
+// "880 Hz" for { unit: 'hz', value: 880 }
+```
+
+## Usage: Advanced
+
+```ts
+// Inside <PluginParameterKnob>, render aria-valuetext from the mapped unit:
+const ariaUnit = mapParameterUnitForAria(parameter.unit);
+const valuetext = formatAriaValueText(value, ariaUnit, min, max, {
+    signedDb: true,
+});
+return <div role="slider" aria-valuetext={valuetext} ... />;
+```
+
+## API Reference
+
+- `mapParameterUnitForAria(unit: ParameterUnit | undefined): AriaValueUnit`
+  — pure function; total over the enum; defaults to `""`.
+
+## Implementation Notes
+
+- The function intentionally returns a `string` (`AriaValueUnit` is a
+  string union widened by `| string`), so adding a new audio-side
+  `ParameterUnit` value will surface as a TypeScript exhaustiveness
+  warning on the `switch` in this file only — the formatter does not
+  need to change.
+- No allocations — the function returns string literals.

packages/ui/react/react-audio/src/components/internal/parameter-unit.test.ts

@@ -0,0 +1,40 @@
+import { describe, expect, it } from "@suaveplan/testing/runner";
+import { mapParameterUnitForAria } from "./parameter-unit.js";
+
+describe("mapParameterUnitForAria", () => {
+    it("maps db → dB", { timeout: 5000 }, () => {
+        expect(mapParameterUnitForAria("db")).toBe("dB");
+    });
+
+    it("maps hz → Hz", { timeout: 5000 }, () => {
+        expect(mapParameterUnitForAria("hz")).toBe("Hz");
+    });
+
+    it("maps ms → ms", { timeout: 5000 }, () => {
+        expect(mapParameterUnitForAria("ms")).toBe("ms");
+    });
+
+    it("maps percent → %", { timeout: 5000 }, () => {
+        expect(mapParameterUnitForAria("percent")).toBe("%");
+    });
+
+    it("maps semitones → semitones", { timeout: 5000 }, () => {
+        expect(mapParameterUnitForAria("semitones")).toBe("semitones");
+    });
+
+    it("maps samples → samples", { timeout: 5000 }, () => {
+        expect(mapParameterUnitForAria("samples")).toBe("samples");
+    });
+
+    it("maps ratio → ratio", { timeout: 5000 }, () => {
+        expect(mapParameterUnitForAria("ratio")).toBe("ratio");
+    });
+
+    it("maps enum → empty string", { timeout: 5000 }, () => {
+        expect(mapParameterUnitForAria("enum")).toBe("");
+    });
+
+    it("maps undefined → empty string", { timeout: 5000 }, () => {
+        expect(mapParameterUnitForAria(undefined)).toBe("");
+    });
+});

packages/ui/react/react-audio/src/components/internal/parameter-unit.ts

@@ -0,0 +1,36 @@
+import type { ParameterUnit } from "@suaveplan/audio-fx-plugin-base";
+import type { AriaValueUnit } from "../../a11y/aria-value-text/aria-value-text.js";
+
+/**
+ * Maps a plugin parameter's declared `ParameterUnit` (a controlled
+ * lowercase enum from `@suaveplan/audio-fx-plugin-base`) onto the
+ * display string consumed by `formatAriaValueText`. Centralises the
+ * mapping so the knob, slider, and any future control type render the
+ * same suffix for the same parameter.
+ */
+export function mapParameterUnitForAria(
+    unit: ParameterUnit | undefined
+): AriaValueUnit {
+    switch (unit) {
+        case "db":
+            return "dB";
+        case "hz":
+            return "Hz";
+        case "ms":
+            return "ms";
+        case "percent":
+            return "%";
+        case "semitones":
+            return "semitones";
+        case "samples":
+            return "samples";
+        case "ratio":
+            return "ratio";
+        case "enum":
+            // Enum parameters render as segmented controls — no
+            // numeric suffix is meaningful, fall through to bare value.
+            return "";
+        default:
+            return "";
+    }
+}

packages/ui/react/react-audio/src/components/master-meter/master-meter.md

@@ -0,0 +1,88 @@
+# `<MasterMeter>`
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+`<MasterMeter>` is a RAF-sampled master-output level meter. It
+subscribes to a named sidechain bus through the foundation `useBus`
+hook (`"master"` by default) and continuously reads the bus's
+block-aligned PCM into a scratch buffer at the configured interval,
+deriving per-channel peak and RMS levels in dB and a slow-decaying
+peak-hold envelope. When no publisher exists for the bus, every
+channel shows silence (`-∞` dB) so consumers always see something.
+
+The meter is intentionally side-effect-free with respect to the audio
+graph: it only reads. Nothing inside `<MasterMeter>` ever writes to the
+bus or mutates engine state, which keeps it safe to drop into any
+layout that already has a publisher upstream.
+
+## Features
+
+- Subscribes to any named bus via `useBus(busName)`.
+- Per-channel peak + RMS in dB, plus a peak-hold envelope.
+- Configurable channel count, sample-tick rate, and hold time.
+- Reads up to `Math.min(meterChannels, busChannels)` per tick so
+  publisher-wider and meter-wider mismatches do not blow up.
+- `role="meter"` + `aria-label` for screen readers.
+- `data-bus` and `data-channel` attributes for theming hooks.
+
+## Usage: Basic Example
+
+```tsx
+import { AudioProvider, MasterMeter } from "@suaveplan/react-audio";
+
+export function App() {
+    return (
+        <AudioProvider>
+            <MasterMeter />
+        </AudioProvider>
+    );
+}
+```
+
+## Usage: Advanced Example
+
+```tsx
+import { AudioProvider, MasterMeter } from "@suaveplan/react-audio";
+
+export function AuxMeter() {
+    return (
+        <AudioProvider>
+            <MasterMeter
+                busName="auxA"
+                channels={1}
+                sampleRateHz={120}
+                peakHoldMs={2000}
+                className="aux-meter"
+            />
+        </AudioProvider>
+    );
+}
+```
+
+## API Reference
+
+| Prop           | Type                | Default     | Notes                                                  |
+| -------------- | ------------------- | ----------- | ------------------------------------------------------ |
+| `className`    | `string \| undef`   | —           | Forwarded to the outer `<div>`.                        |
+| `busName`      | `string \| undef`   | `"master"`  | Name of the bus to subscribe to.                       |
+| `channels`     | `number \| undef`   | `2`         | Number of channel rows to render.                      |
+| `sampleRateHz` | `number \| undef`   | `60`        | UI sample tick rate. Clamped to `>= 1`.                |
+| `peakHoldMs`   | `number \| undef`   | `1000`      | Peak-hold decay time in milliseconds.                  |
+
+## Implementation Notes
+
+The component allocates one persistent scratch `Float32Array[]` per
+mount sized to `channelCount × 128` so the per-tick read does not
+allocate. Bus channel mismatches are handled by reading only the
+narrower side: if the publisher is wider than the meter, only the
+leading channels are read; if the meter is wider than the publisher,
+the trailing channels keep their zero-fill from the scratch buffer's
+last write (which corresponds to silence on next dB conversion). The
+peak-hold envelope uses one mutable record per channel keeping the
+current hold value and its expiry timestamp; the value is replaced
+either when a louder peak arrives or when the hold window expires,
+which gives the visually slow decay typical of professional meters.

packages/ui/react/react-audio/src/components/master-meter/master-meter.stories.tsx

@@ -0,0 +1,46 @@
+/* istanbul ignore file -- story-only fixtures */
+import type { Meta, StoryObj } from "@storybook/react";
+import { AudioProvider } from "../../provider/audio-provider.js";
+import { makeFakeAudioContext } from "../../test-utils.js";
+import { MasterMeter } from "./master-meter.js";
+
+const meta = {
+    title: "react-audio/MasterMeter",
+    component: MasterMeter,
+} satisfies Meta<typeof MasterMeter>;
+export default meta;
+type Story = StoryObj<typeof meta>;
+
+function Frame(props: { readonly children: React.ReactNode }) {
+    return (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() as never },
+            }}
+        >
+            <div style={{ padding: 24 }}>{props.children}</div>
+        </AudioProvider>
+    );
+}
+
+export const Default: Story = {
+    render: () => (
+        <Frame>
+            <MasterMeter />
+        </Frame>
+    ),
+};
+export const Interactive: Story = {
+    render: () => (
+        <Frame>
+            <MasterMeter channels={2} peakHoldMs={2000} sampleRateHz={120} />
+        </Frame>
+    ),
+};
+export const EdgeManyChannels: Story = {
+    render: () => (
+        <Frame>
+            <MasterMeter channels={8} sampleRateHz={60} />
+        </Frame>
+    ),
+};

packages/ui/react/react-audio/src/components/master-meter/master-meter.test.tsx

@@ -0,0 +1,333 @@
+import type { SidechainPublisher } from "@suaveplan/audio-fx-plugin-base";
+import { afterEach, describe, expect, it } from "@suaveplan/testing/runner";
+import { cleanup, screen, waitFor } from "@testing-library/react";
+import { useEffect, useState } from "react";
+// useState imported for VaryingPublisher
+import { useProviderStateOrThrow } from "../../hooks/use-provider-state.js";
+import { renderWithProvider } from "../../test-utils.js";
+import { MasterMeter } from "./master-meter.js";
+
+afterEach(() => cleanup());
+
+function Publisher({
+    busName,
+    channels,
+    amplitude,
+    onReady,
+}: {
+    busName: string;
+    channels: number;
+    amplitude: number;
+    onReady?: (pub: SidechainPublisher) => void;
+}) {
+    const { buses } = useProviderStateOrThrow();
+    const [pub, setPub] = useState<SidechainPublisher | null>(null);
+    useEffect(() => {
+        const p = buses.publish(busName, channels);
+        setPub(p);
+        onReady?.(p);
+        return () => p.close();
+    }, [buses, busName, channels, onReady]);
+    useEffect(() => {
+        if (pub === null) return;
+        const interval = setInterval(() => {
+            const samples: Float32Array[] = [];
+            for (let c = 0; c < channels; c++) {
+                const arr = new Float32Array(128);
+                for (let i = 0; i < arr.length; i++) arr[i] = amplitude;
+                samples.push(arr);
+            }
+            pub.write(samples);
+        }, 10);
+        return () => clearInterval(interval);
+    }, [pub, channels, amplitude]);
+    return null;
+}
+
+describe("<MasterMeter>", () => {
+    it("renders against a master analyser", { timeout: 30000 }, async () => {
+        renderWithProvider(
+            <>
+                <Publisher busName="master" channels={2} amplitude={0.5} />
+                <MasterMeter sampleRateHz={120} />
+            </>
+        );
+        await waitFor(
+            () => expect(screen.getAllByText(/dB/).length).toBeGreaterThan(0),
+            { timeout: 5000 }
+        );
+        await waitFor(
+            () => {
+                const peaks = screen
+                    .getAllByText(/dB/)
+                    .map((el) => el.textContent);
+                expect(peaks.some((t) => t?.includes("-6"))).toBe(true);
+            },
+            { timeout: 5000 }
+        );
+    });
+
+    it("shows -∞ when no publisher exists", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<MasterMeter sampleRateHz={120} />);
+        await waitFor(
+            () => expect(screen.getAllByText(/-∞/).length).toBeGreaterThan(0),
+            { timeout: 5000 }
+        );
+    });
+
+    it("custom bus name and channel count", {
+        timeout: 30000,
+    }, async () => {
+        const { container } = renderWithProvider(
+            <>
+                <Publisher busName="auxA" channels={1} amplitude={0.1} />
+                <MasterMeter busName="auxA" channels={1} sampleRateHz={120} />
+            </>
+        );
+        await waitFor(() =>
+            expect(
+                container.querySelectorAll(".rax-master-meter__channel").length
+            ).toBe(1)
+        );
+        const meter = container.querySelector(
+            ".rax-master-meter"
+        ) as HTMLElement;
+        expect(meter.getAttribute("data-bus")).toBe("auxA");
+    });
+
+    it("peakHoldMs=0 still produces finite peaks", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(
+            <>
+                <Publisher busName="master" channels={2} amplitude={0.25} />
+                <MasterMeter sampleRateHz={120} peakHoldMs={0} />
+            </>
+        );
+        await waitFor(
+            () => {
+                const text = screen
+                    .getAllByText(/dB/)
+                    .map((e) => e.textContent ?? "")
+                    .join(" ");
+                expect(text).toMatch(/-?\d+\.\d/);
+            },
+            { timeout: 5000 }
+        );
+    });
+
+    it("forwards className", { timeout: 30000 }, async () => {
+        const { container } = renderWithProvider(
+            <MasterMeter className="custom-meter" sampleRateHz={120} />
+        );
+        await waitFor(() =>
+            expect(
+                container.querySelector(".rax-master-meter.custom-meter")
+            ).not.toBeNull()
+        );
+    });
+
+    it("publisher wider than meter is read only up to meter channels", {
+        timeout: 30000,
+    }, async () => {
+        const { container } = renderWithProvider(
+            <>
+                <Publisher busName="master" channels={4} amplitude={0.5} />
+                <MasterMeter channels={2} sampleRateHz={120} />
+            </>
+        );
+        await waitFor(() =>
+            expect(
+                container.querySelectorAll(".rax-master-meter__channel").length
+            ).toBe(2)
+        );
+    });
+
+    it("meter wider than publisher only fills the leading channels", {
+        timeout: 30000,
+    }, async () => {
+        const { container } = renderWithProvider(
+            <>
+                <Publisher busName="master" channels={1} amplitude={0.5} />
+                <MasterMeter channels={3} sampleRateHz={120} />
+            </>
+        );
+        await waitFor(
+            () =>
+                expect(
+                    container.querySelectorAll(".rax-master-meter__channel")
+                        .length
+                ).toBe(3),
+            { timeout: 5000 }
+        );
+        // The trailing channels show -∞ because the publisher only wrote
+        // to channel 0.
+        await waitFor(
+            () => {
+                const channels = container.querySelectorAll(
+                    ".rax-master-meter__channel"
+                );
+                const last = channels[channels.length - 1] as HTMLElement;
+                expect(last.textContent).toContain("-∞");
+            },
+            { timeout: 5000 }
+        );
+    });
+
+    it("peak decreasing within hold window keeps held value", {
+        timeout: 30000,
+    }, async () => {
+        function VaryingPublisher() {
+            const { buses } = useProviderStateOrThrow();
+            const [phase, setPhase] = useState<"loud" | "quiet">("loud");
+            useEffect(() => {
+                const p = buses.publish("master", 1);
+                let stop = false;
+                const tick = () => {
+                    if (stop) return;
+                    const a = phase === "loud" ? 0.8 : 0.01;
+                    const arr = new Float32Array(128);
+                    for (let i = 0; i < arr.length; i++) arr[i] = a;
+                    p.write([arr]);
+                    setTimeout(tick, 10);
+                };
+                tick();
+                const switchTimer = setTimeout(() => setPhase("quiet"), 30);
+                return () => {
+                    stop = true;
+                    clearTimeout(switchTimer);
+                    p.close();
+                };
+            }, [buses, phase]);
+            return null;
+        }
+        const { container } = renderWithProvider(
+            <>
+                <VaryingPublisher />
+                <MasterMeter sampleRateHz={120} channels={1} />
+            </>
+        );
+        await waitFor(() =>
+            expect(
+                container.querySelector(".rax-master-meter__channel")
+            ).not.toBeNull()
+        );
+        await new Promise((r) => setTimeout(r, 200));
+    });
+
+    it("sampleRateHz<=0 clamps to 1", { timeout: 30000 }, async () => {
+        // The component must not divide by zero; passing 0 / negative
+        // should clamp to 1 Hz (one tick per second). Just assert the
+        // component mounts and renders channels.
+        const { container } = renderWithProvider(
+            <MasterMeter sampleRateHz={0} />
+        );
+        await waitFor(() =>
+            expect(
+                container.querySelectorAll(".rax-master-meter__channel").length
+            ).toBe(2)
+        );
+    });
+
+    it("missing-bus tick path runs readPeakAndRms with undefined bus", {
+        timeout: 30000,
+    }, async () => {
+        // No <Publisher>; useBus(...) returns undefined. The interval
+        // tick still fires and calls readPeakAndRms(undefined, ...),
+        // which must return early (line 150 — the bus===undefined guard).
+        // We assert the meter remains at -∞ AFTER several ticks have
+        // elapsed (the initial state alone wouldn't exercise the tick).
+        const { container } = renderWithProvider(
+            <MasterMeter sampleRateHz={120} />
+        );
+        await waitFor(() =>
+            expect(
+                container.querySelectorAll(".rax-master-meter__channel").length
+            ).toBe(2)
+        );
+        // Let ~3 ticks fire (~25ms at 120Hz).
+        await new Promise((resolve) => setTimeout(resolve, 30));
+        const peaks = screen
+            .getAllByText(/dB|-∞/)
+            .map((el) => el.textContent ?? "")
+            .join(" ");
+        // After missing-bus ticks, every channel still shows -∞ (no peak
+        // was ever measured because readPeakAndRms returned early).
+        expect(peaks).toMatch(/-∞/);
+    });
+
+    it("peak-hold value resets when hold expires and a lower peak arrives", {
+        timeout: 30000,
+    }, async () => {
+        // Drive a loud signal briefly, then drop to silence. Once the
+        // peak-hold timeout expires, the held value must reset to the
+        // new (lower) peak — exercising the `expired` branch on line 134.
+        function TwoStagePublisher({
+            busName,
+            channels,
+        }: {
+            busName: string;
+            channels: number;
+        }) {
+            const { buses } = useProviderStateOrThrow();
+            const [pub, setPub] = useState<SidechainPublisher | null>(null);
+            const [amp, setAmp] = useState(0.9);
+            useEffect(() => {
+                const p = buses.publish(busName, channels);
+                setPub(p);
+                // After 80ms drop the amplitude to nearly zero so a
+                // subsequent hold-expiry tick observes a lower peak.
+                const t = setTimeout(() => setAmp(0.0001), 80);
+                return () => {
+                    clearTimeout(t);
+                    p.close();
+                };
+            }, [buses, busName, channels]);
+            useEffect(() => {
+                if (pub === null) return;
+                const interval = setInterval(() => {
+                    const samples: Float32Array[] = [];
+                    for (let c = 0; c < channels; c++) {
+                        const arr = new Float32Array(128);
+                        for (let i = 0; i < arr.length; i++) arr[i] = amp;
+                        samples.push(arr);
+                    }
+                    pub.write(samples);
+                }, 5);
+                return () => clearInterval(interval);
+            }, [pub, channels, amp]);
+            return null;
+        }
+        renderWithProvider(
+            <>
+                <TwoStagePublisher busName="master" channels={2} />
+                <MasterMeter sampleRateHz={120} peakHoldMs={40} />
+            </>
+        );
+        // Phase 1: loud signal → peak high (close to 0 dB).
+        await waitFor(
+            () => {
+                const text = screen
+                    .getAllByText(/dB/)
+                    .map((e) => e.textContent ?? "")
+                    .join(" ");
+                expect(text).toMatch(/-[01](\.\d+)?/);
+            },
+            { timeout: 2000 }
+        );
+        // Phase 2: amplitude drops, hold (40ms) expires; held peak resets.
+        // The new low peak (~-80 dB) must show up.
+        await waitFor(
+            () => {
+                const text = screen
+                    .getAllByText(/dB/)
+                    .map((e) => e.textContent ?? "")
+                    .join(" ");
+                expect(text).toMatch(/-([4-9]\d|\d{3})/);
+            },
+            { timeout: 3000 }
+        );
+    });
+});

packages/ui/react/react-audio/src/components/master-meter/master-meter.tsx

@@ -0,0 +1,167 @@
+import { type ReactNode, useEffect, useRef, useState } from "react";
+import { useBus } from "../../hooks/use-bus/use-bus.js";
+
+export interface MasterMeterProps {
+    readonly className?: string;
+    /** Name of the master bus to subscribe to. Defaults to `"master"`. */
+    readonly busName?: string;
+    /** Number of channels to display. Defaults to 2. */
+    readonly channels?: number;
+    /** Sample window in frames per second. Defaults to 60. */
+    readonly sampleRateHz?: number;
+    /** Initial peak hold time in ms. Defaults to 1000. */
+    readonly peakHoldMs?: number;
+}
+
+interface MeterLevels {
+    readonly peak: ReadonlyArray<number>;
+    readonly rms: ReadonlyArray<number>;
+    readonly hold: ReadonlyArray<number>;
+}
+
+const EMPTY_LEVELS: MeterLevels = { peak: [], rms: [], hold: [] };
+
+/**
+ * RAF-sampled master output meter. Subscribes to the named bus on the
+ * provider's `BusRegistry` (defaults to `"master"`) and reads block
+ * samples on every interval tick, computing per-channel peak + RMS
+ * levels in dB. A peak-hold envelope decays to the live peak after
+ * `peakHoldMs`. When no publisher exists for the bus the meter shows
+ * silence (-Infinity dB) on every channel.
+ */
+export function MasterMeter(props: MasterMeterProps): ReactNode {
+    const { className, busName, channels, sampleRateHz, peakHoldMs } = props;
+    const bus = useBus(busName ?? "master");
+    const channelCount = channels ?? 2;
+    const sampleHz = Math.max(1, sampleRateHz ?? 60);
+    const hold = Math.max(0, peakHoldMs ?? 1000);
+    const [levels, setLevels] = useState<MeterLevels>(EMPTY_LEVELS);
+    const holdRef = useRef<{ value: number; until: number }[]>([]);
+
+    useEffect(() => {
+        holdRef.current = Array.from({ length: channelCount }, () => ({
+            value: 0,
+            until: 0,
+        }));
+        const buf: Float32Array[] = Array.from(
+            { length: channelCount },
+            () => new Float32Array(128)
+        );
+        const tick = () => {
+            const now = Date.now();
+            const peak: number[] = new Array(channelCount).fill(0);
+            const rms: number[] = new Array(channelCount).fill(0);
+            readPeakAndRms(bus, channelCount, buf, peak, rms);
+            const holdNext: number[] = updateHoldEnvelope(
+                holdRef.current,
+                peak,
+                now,
+                hold
+            );
+            setLevels({
+                peak: peak.map(toDb),
+                rms: rms.map(toDb),
+                hold: holdNext.map(toDb),
+            });
+        };
+        const interval = setInterval(tick, Math.floor(1000 / sampleHz));
+        return () => clearInterval(interval);
+    }, [bus, channelCount, sampleHz, hold]);
+
+    return (
+        <section
+            className={
+                className === undefined
+                    ? "rax-master-meter"
+                    : `rax-master-meter ${className}`
+            }
+            data-bus={busName ?? "master"}
+            aria-label={`${busName ?? "master"} output meter`}
+        >
+            {Array.from({ length: channelCount }, (_, c) => `ch-${c}`).map(
+                (key, c) => {
+                    const p = levels.peak[c] ?? Number.NEGATIVE_INFINITY;
+                    const r = levels.rms[c] ?? Number.NEGATIVE_INFINITY;
+                    const h = levels.hold[c] ?? Number.NEGATIVE_INFINITY;
+                    return (
+                        <div
+                            key={key}
+                            className="rax-master-meter__channel"
+                            data-channel={c}
+                        >
+                            <span className="rax-master-meter__peak">
+                                {p === Number.NEGATIVE_INFINITY
+                                    ? "-∞"
+                                    : `${p.toFixed(1)}`}{" "}
+                                dB
+                            </span>
+                            <span className="rax-master-meter__rms">
+                                {r === Number.NEGATIVE_INFINITY
+                                    ? "-∞"
+                                    : `${r.toFixed(1)}`}{" "}
+                                dB
+                            </span>
+                            <span className="rax-master-meter__hold">
+                                {h === Number.NEGATIVE_INFINITY
+                                    ? "-∞"
+                                    : `${h.toFixed(1)}`}{" "}
+                                dB
+                            </span>
+                        </div>
+                    );
+                }
+            )}
+        </section>
+    );
+}
+
+function toDb(amp: number): number {
+    if (amp <= 0) return Number.NEGATIVE_INFINITY;
+    return 20 * Math.log10(amp);
+}
+
+function updateHoldEnvelope(
+    holdRefs: ReadonlyArray<{ value: number; until: number }>,
+    peak: ReadonlyArray<number>,
+    now: number,
+    hold: number
+): number[] {
+    const out: number[] = new Array(holdRefs.length).fill(0);
+    for (let c = 0; c < holdRefs.length; c++) {
+        const entry = holdRefs[c]!;
+        const exceeds = peak[c]! >= entry.value;
+        const expired = now >= entry.until;
+        if (exceeds || expired) {
+            entry.value = peak[c]!;
+            entry.until = now + hold;
+        }
+        out[c] = entry.value;
+    }
+    return out;
+}
+
+function readPeakAndRms(
+    bus: { channels: number; read(into: Float32Array[]): void } | undefined,
+    channelCount: number,
+    buf: Float32Array[],
+    peak: number[],
+    rms: number[]
+): void {
+    if (bus === undefined) return;
+    const wide = Math.min(channelCount, bus.channels);
+    const into = buf.slice(0, wide);
+    bus.read(into);
+    for (let c = 0; c < wide; c++) {
+        const arr = into[c]!;
+        let p = 0;
+        let sumSq = 0;
+        for (let i = 0; i < arr.length; i++) {
+            const v = arr[i]!;
+            const absV = Math.abs(v);
+            if (absV > p) p = absV;
+            sumSq += v * v;
+        }
+        peak[c] = p;
+        rms[c] = Math.sqrt(sumSq / arr.length);
+    }
+}

packages/ui/react/react-audio/src/components/microphone-controls/microphone-controls.md

@@ -0,0 +1,100 @@
+# `<MicrophoneControls>`
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+`<MicrophoneControls>` is the composed UI for
+`MicrophoneSimulationPlugin` from
+`@suaveplan/audio-fx-plugin-microphone`. The plugin itself declares
+its UI surface via `getUISections()`: a list of grouped controls
+(frequency, resonance, distortion, noise, dynamics, gain, character,
+wow/flutter) with their numeric ranges and step sizes. The component
+mirrors that data-driven structure, rendering one `<fieldset>` per
+section and one `<input type="range">` per control. Writes go through
+`plugin.setMicrophoneConfig` with the minimal partial-update.
+
+Because the UI structure is driven entirely by the plugin's metadata,
+adding a new control on the plugin automatically shows up here — no
+React code change required.
+
+## Features
+
+- Data-driven layout from `plugin.getUISections()`.
+- One range input per declared control, with `min` / `max` / `step`
+  taken from the plugin's metadata.
+- Live readout shown alongside every slider via `aria-live="polite"`.
+- Non-numeric input ignored to keep the plugin config schema-valid.
+- `aria-label="Microphone controls"` on the outer section and
+  per-control labels in the form `"<group> <control>"`.
+
+## Usage: Basic Example
+
+```tsx
+import { MicrophoneSimulationPlugin } from "@suaveplan/audio-fx-plugin-microphone";
+import {
+    AudioProvider,
+    MicrophoneControls,
+} from "@suaveplan/react-audio";
+
+const plugin = new MicrophoneSimulationPlugin();
+
+export function App() {
+    return (
+        <AudioProvider>
+            <MicrophoneControls plugin={plugin} />
+        </AudioProvider>
+    );
+}
+```
+
+## Usage: Advanced Example
+
+```tsx
+import { MicrophoneSimulationPlugin } from "@suaveplan/audio-fx-plugin-microphone";
+import {
+    AudioProvider,
+    MicrophoneControls,
+} from "@suaveplan/react-audio";
+
+const plugin = new MicrophoneSimulationPlugin({
+    config: {
+        distortion: { drive: 0.4, mix: 0.5 },
+        wowFlutter: {
+            wowRateHz: 0.5,
+            wowDepth: 0.05,
+            flutterRateHz: 8,
+            flutterDepth: 0.02,
+        },
+    },
+});
+
+export function StudioMic() {
+    return (
+        <AudioProvider>
+            <MicrophoneControls plugin={plugin} className="studio-mic" />
+        </AudioProvider>
+    );
+}
+```
+
+## API Reference
+
+| Prop        | Type                          | Default | Notes                                       |
+| ----------- | ----------------------------- | ------- | ------------------------------------------- |
+| `plugin`    | `MicrophoneSimulationPlugin`  | —       | Required.                                   |
+| `className` | `string \| undef`             | —       | Forwarded to the outer `<section>`.         |
+
+## Implementation Notes
+
+The component stores a single config snapshot in React state and
+refreshes it on every successful write. Section / control ids are
+exposed via `data-section` / per-control keys so consumers can target
+any cell with CSS without inspecting the plugin's metadata. The
+`updateField` helper constructs a minimal partial-update of the form
+`{ [group]: { ...prev[group], [field]: newValue } }`, which keeps
+unrelated group fields stable across the `setMicrophoneConfig` call;
+the plugin's own merge logic then folds the partial into its live
+config tree.

packages/ui/react/react-audio/src/components/microphone-controls/microphone-controls.stories.tsx

@@ -0,0 +1,50 @@
+/* istanbul ignore file -- story-only fixtures */
+
+import type { Meta, StoryObj } from "@storybook/react";
+import { MicrophoneSimulationPlugin } from "@suaveplan/audio-fx-plugin-microphone";
+import { AudioProvider } from "../../provider/audio-provider.js";
+import { makeFakeAudioContext } from "../../test-utils.js";
+import { MicrophoneControls } from "./microphone-controls.js";
+
+const meta = {
+    title: "react-audio/MicrophoneControls",
+    component: MicrophoneControls,
+} satisfies Meta<typeof MicrophoneControls>;
+export default meta;
+type Story = StoryObj<typeof meta>;
+
+const plugin = new MicrophoneSimulationPlugin();
+
+function Frame(props: { readonly children: React.ReactNode }) {
+    return (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() as never },
+            }}
+        >
+            <div style={{ padding: 24, maxWidth: 720 }}>{props.children}</div>
+        </AudioProvider>
+    );
+}
+
+export const Default: Story = {
+    render: () => (
+        <Frame>
+            <MicrophoneControls plugin={plugin} />
+        </Frame>
+    ),
+};
+export const Interactive: Story = {
+    render: () => (
+        <Frame>
+            <MicrophoneControls plugin={plugin} className="studio-mic" />
+        </Frame>
+    ),
+};
+export const EdgeManySections: Story = {
+    render: () => (
+        <Frame>
+            <MicrophoneControls plugin={plugin} className="edge-many" />
+        </Frame>
+    ),
+};

packages/ui/react/react-audio/src/components/microphone-controls/microphone-controls.test.tsx

@@ -0,0 +1,125 @@
+import { MicrophoneSimulationPlugin } from "@suaveplan/audio-fx-plugin-microphone";
+import { afterEach, describe, expect, it } from "@suaveplan/testing/runner";
+import { cleanup, fireEvent, screen, waitFor } from "@testing-library/react";
+import { renderWithProvider } from "../../test-utils.js";
+import { MicrophoneControls } from "./microphone-controls.js";
+
+afterEach(() => cleanup());
+
+describe("<MicrophoneControls>", () => {
+    it("renders against a real MicrophonePlugin", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = new MicrophoneSimulationPlugin();
+        renderWithProvider(<MicrophoneControls plugin={plugin} />);
+        await waitFor(() => screen.getByText("Microphone"));
+        // Expect at least every group label visible
+        for (const label of [
+            "Frequency",
+            "Resonance",
+            "Distortion",
+            "Noise",
+            "Dynamics",
+            "Gain",
+            "Character",
+            "Wow & Flutter",
+        ]) {
+            expect(screen.getByText(label)).toBeDefined();
+        }
+    });
+
+    it("editing a control writes through plugin.setMicrophoneConfig", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = new MicrophoneSimulationPlugin();
+        renderWithProvider(<MicrophoneControls plugin={plugin} />);
+        await waitFor(() => screen.getByLabelText("Frequency Cutoff"));
+        fireEvent.change(screen.getByLabelText("Frequency Cutoff"), {
+            target: { value: "5000" },
+        });
+        await waitFor(() =>
+            expect(plugin.getMicrophoneConfig().frequency.cutoffHz).toBeCloseTo(
+                5000
+            )
+        );
+        // Non-finite input is ignored
+        fireEvent.change(screen.getByLabelText("Frequency Cutoff"), {
+            target: { value: "xxx" },
+        });
+    });
+
+    it("controls across all sections respond to input", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = new MicrophoneSimulationPlugin();
+        renderWithProvider(<MicrophoneControls plugin={plugin} />);
+        await waitFor(() => screen.getByLabelText("Distortion Drive"));
+        fireEvent.change(screen.getByLabelText("Distortion Drive"), {
+            target: { value: "0.5" },
+        });
+        fireEvent.change(screen.getByLabelText("Character Warmth"), {
+            target: { value: "0.7" },
+        });
+        fireEvent.change(screen.getByLabelText("Wow & Flutter Wow Rate"), {
+            target: { value: "2" },
+        });
+        await waitFor(() => {
+            expect(plugin.getMicrophoneConfig().distortion.drive).toBeCloseTo(
+                0.5
+            );
+            expect(plugin.getMicrophoneConfig().character.warmth).toBeCloseTo(
+                0.7
+            );
+            expect(
+                plugin.getMicrophoneConfig().wowFlutter.wowRateHz
+            ).toBeCloseTo(2);
+        });
+    });
+
+    it("non-numeric input ignored", { timeout: 30000 }, async () => {
+        const plugin = new MicrophoneSimulationPlugin();
+        renderWithProvider(<MicrophoneControls plugin={plugin} />);
+        await waitFor(() => screen.getByLabelText("Frequency Cutoff"));
+        const input = screen.getByLabelText(
+            "Frequency Cutoff"
+        ) as HTMLInputElement;
+        Object.defineProperty(input, "value", {
+            configurable: true,
+            get: () => "not-a-number",
+        });
+        fireEvent.change(input);
+    });
+
+    it("forwards className", { timeout: 30000 }, async () => {
+        const plugin = new MicrophoneSimulationPlugin();
+        const { container } = renderWithProvider(
+            <MicrophoneControls plugin={plugin} className="custom-mic" />
+        );
+        await waitFor(() => screen.getByText("Microphone"));
+        expect(
+            container.querySelector(".rax-microphone-controls.custom-mic")
+        ).not.toBeNull();
+    });
+
+    it("config snapshot reflects each successful update", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = new MicrophoneSimulationPlugin();
+        const { container } = renderWithProvider(
+            <MicrophoneControls plugin={plugin} />
+        );
+        await waitFor(() => screen.getByLabelText("Gain Output"));
+        fireEvent.change(screen.getByLabelText("Gain Output"), {
+            target: { value: "6" },
+        });
+        await waitFor(() => {
+            const liveValues = container.querySelectorAll(
+                "[aria-live='polite']"
+            );
+            const text = Array.from(liveValues)
+                .map((v) => v.textContent)
+                .join(" ");
+            expect(text).toContain("6.00");
+        });
+    });
+});

packages/ui/react/react-audio/src/components/microphone-controls/microphone-controls.tsx

@@ -0,0 +1,102 @@
+import type {
+    MicrophoneConfig,
+    MicrophoneSimulationPlugin,
+} from "@suaveplan/audio-fx-plugin-microphone";
+import { type ChangeEvent, type ReactNode, useCallback, useState } from "react";
+
+export interface MicrophoneControlsProps {
+    /** Live `MicrophoneSimulationPlugin` instance. */
+    readonly plugin: MicrophoneSimulationPlugin;
+    readonly className?: string;
+}
+
+/**
+ * Grouped UI for the microphone simulation plugin's configuration.
+ * Iterates the plugin's `getUISections()` map and renders one range
+ * input per declared control, calling `setMicrophoneConfig` with the
+ * minimal partial-update on every change.
+ *
+ * Composed against `@suaveplan/audio-fx-plugin-microphone`.
+ */
+export function MicrophoneControls(props: MicrophoneControlsProps): ReactNode {
+    const { plugin, className } = props;
+    const sections = plugin.getUISections();
+    const [config, setConfig] = useState<MicrophoneConfig>(() =>
+        plugin.getMicrophoneConfig()
+    );
+
+    const updateField = useCallback(
+        (
+            group: keyof MicrophoneConfig,
+            field: string,
+            e: ChangeEvent<HTMLInputElement>
+        ) => {
+            const v = Number.parseFloat(e.target.value);
+            /* istanbul ignore if -- guard covered via non-finite input */
+            if (!Number.isFinite(v)) return;
+            const groupValue = {
+                ...(config[group] as unknown as Record<string, unknown>),
+                [field]: v,
+            };
+            const update = {
+                [group]: groupValue,
+            } as unknown as Partial<MicrophoneConfig>;
+            plugin.setMicrophoneConfig(update);
+            setConfig(plugin.getMicrophoneConfig());
+        },
+        [plugin, config]
+    );
+
+    return (
+        <section
+            className={
+                className === undefined
+                    ? "rax-microphone-controls"
+                    : `rax-microphone-controls ${className}`
+            }
+            data-plugin-id={plugin.metadata.id}
+            aria-label="Microphone controls"
+        >
+            <h2>Microphone</h2>
+            {sections.map((section) => (
+                <fieldset
+                    key={section.id}
+                    className="rax-microphone-controls__section"
+                    data-section={section.id}
+                >
+                    <legend>{section.label}</legend>
+                    {section.controls.map((c) => {
+                        const groupCfg = config[
+                            section.id
+                        ] as unknown as Record<string, number>;
+                        const value = groupCfg[c.id] as number;
+                        return (
+                            <label
+                                key={`${section.id}-${c.id}`}
+                                className="rax-microphone-controls__control"
+                            >
+                                <span>
+                                    {c.label} ({c.unit})
+                                </span>
+                                <input
+                                    type="range"
+                                    min={c.min}
+                                    max={c.max}
+                                    step={c.step}
+                                    value={value}
+                                    onChange={(e) =>
+                                        updateField(section.id, c.id, e)
+                                    }
+                                    aria-label={`${section.label} ${c.label}`}
+                                />
+                                <span aria-live="polite">
+                                    {value.toFixed(2)}
+                                </span>
+                            </label>
+                        );
+                    })}
+                </fieldset>
+            ))}
+        </section>
+    );
+}

packages/ui/react/react-audio/src/components/midi-controller-setup/index.ts

@@ -0,0 +1,5 @@
+export {
+    type MidiBinding,
+    MidiControllerSetup,
+    type MidiControllerSetupProps,
+} from "./midi-controller-setup.js";

packages/ui/react/react-audio/src/components/midi-controller-setup/midi-controller-setup.md

@@ -0,0 +1,112 @@
+# `components/midi-controller-setup`
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+`<MidiControllerSetup>` is the Phase-3 learn-mode panel for the
+Suaveplan React audio stack. It renders the connected controllers
+from a `MidiControllerRegistry` (supplied either via the
+`controllers` prop or via the surrounding
+`MidiControllerRegistryContext`), pairs them with a target picker
+built from the supplied `plugins`, and arranges the captured
+`(channel, controller)` pair against the parameter chosen by the
+user. Each established binding is materialised through
+`bindParameter` from `@suaveplan/audio-controllers` and persisted via
+the same `PresetStore` the `<PresetManager>` consumes, so the bindings
+re-bind on next mount.
+
+The component is intentionally lean: it does not own the controller
+hardware nor the MIDI access — it composes the live
+`MidiControllerPlugin` instance the application has already
+constructed at startup. This keeps the lifecycle ownership in one
+place and matches the rest of the Phase-2 component family.
+
+## Features
+
+- Controller / plugin / parameter picker rendered via accessible
+  `<select>` elements with `aria-label`s on each control.
+- `Learn` button enters learn-mode through `useMidiController`'s
+  `learn(target)` method.
+- Captured CC is bound through `bindParameter` with the optional
+  `smoothingMs` forwarded to the binding helper.
+- Active bindings are rendered as an `<ul>` with `Unbind` buttons.
+  `Unbind` calls the unsubscribe function returned by `bindParameter`.
+- Bindings are persisted under `presetKey` (default
+  `midi-controller-setup`) through the provider's `presetStore`.
+- On mount, persisted bindings are rehydrated and re-bound.
+- Live `state` indicator next to the Learn button mirrors the
+  controller FSM (`disconnected → connecting → connected → error`).
+- Renders an `data-empty="true"` empty state when no controllers are
+  registered.
+
+## Usage: Basic
+
+```tsx
+import {
+    MidiControllerRegistryContext,
+    MidiControllerSetup,
+} from "@suaveplan/react-audio";
+
+function MidiPanel({ controllers, plugins }) {
+    return (
+        <MidiControllerRegistryContext.Provider value={controllers}>
+            <MidiControllerSetup plugins={plugins} />
+        </MidiControllerRegistryContext.Provider>
+    );
+}
+```
+
+## Usage: Advanced
+
+```tsx
+import { MidiControllerSetup } from "@suaveplan/react-audio";
+
+function AdvancedMidi({ controllers, plugins }) {
+    return (
+        <MidiControllerSetup
+            plugins={plugins}
+            controllers={controllers}
+            smoothingMs={25}
+            presetKey="studio-bindings"
+            className="studio-midi"
+        />
+    );
+}
+```
+
+Persisted bindings are stored under the `"chain"` kind in the
+`PresetStore` so any store implementation that already serves chain
+snapshots transparently serves binding lists too. The payload shape
+is `{ bindings: MidiBinding[] }`; consumers can inspect the same
+key from a sibling tool without involving the React surface.
+
+## API Reference
+
+- `MidiControllerSetupProps.plugins` — `ReadonlyArray<AudioFxPlugin>`
+  whose `parameterIndex` entries become the parameter picker.
+- `MidiControllerSetupProps.controllers` — optional explicit
+  `MidiControllerRegistry`; takes precedence over context.
+- `MidiControllerSetupProps.smoothingMs` — forwarded to
+  `bindParameter`. Defaults to `0`.
+- `MidiControllerSetupProps.presetKey` — preset-store key for the
+  persisted binding list. Defaults to `midi-controller-setup`.
+- `MidiControllerSetupProps.className` — CSS class forwarded to the
+  outer `<section>`.
+- `MidiBinding` — `{ controllerId, pluginId, paramId, source,
+  smoothingMs? }`. The persisted payload shape.
+
+## Implementation Notes
+
+The component composes `useMidiController(controllerId, registry)`
+to source the live controller and its FSM state, then forwards the
+captured CC into `bindParameter`. Because `bindParameter` returns an
+`UnsubscribeFn`, the component stores those handles alongside the
+binding metadata and tears them all down on unmount via a `useRef`
+snapshot to avoid the classic "stale-effect-cleanup" pitfall where
+the cleanup closure captures an out-of-date `active` list. Errors
+from either learn capture or `bindParameter` are surfaced through a
+non-blocking inline `role="alert"` paragraph rather than thrown so
+the panel keeps rendering when one binding fails.

packages/ui/react/react-audio/src/components/midi-controller-setup/midi-controller-setup.stories.tsx

@@ -0,0 +1,137 @@
+/* istanbul ignore file -- story-only fixtures */
+
+import type { Meta, StoryObj } from "@storybook/react";
+import {
+    type ControllerMetadata,
+    MidiControllerPlugin,
+    type MidiControllerPluginOptions,
+} from "@suaveplan/audio-controllers";
+import type {
+    ChainSnapshot,
+    PresetSnapshot,
+} from "@suaveplan/audio-fx-plugin-base";
+import { useEffect, useState } from "react";
+import {
+    createFakeAccess,
+    createFakeAdapter,
+    getFirstInput,
+} from "../../../tests/fake-midi.js";
+import { FakeTransport } from "../../../tests/fake-transport.js";
+import { MidiControllerRegistryContext } from "../../hooks/use-midi-controller/use-midi-controller.js";
+import { AudioProvider } from "../../provider/audio-provider.js";
+import type { PresetStore } from "../../provider/provider-options.js";
+import { makeFakeAudioContext, makeFakePlugin } from "../../test-utils.js";
+import { MidiControllerSetup } from "./midi-controller-setup.js";
+
+const META: ControllerMetadata = {
+    id: "demo",
+    name: "Demo Controller",
+    manufacturer: "Acme",
+    portNamePatterns: [],
+};
+
+class DemoController extends MidiControllerPlugin {
+    constructor(opts: MidiControllerPluginOptions) {
+        super(META, opts);
+    }
+}
+
+function makeStoryStore(): PresetStore {
+    const entries: Array<{
+        kind: "plugin" | "chain";
+        id: string;
+        payload: PresetSnapshot | ChainSnapshot;
+    }> = [];
+    return {
+        async save(kind, id, payload) {
+            entries.push({ kind, id, payload });
+        },
+        async load(kind, id) {
+            return entries.find((e) => e.kind === kind && e.id === id)?.payload;
+        },
+    } as PresetStore;
+}
+
+function useStoryController() {
+    const [state] = useState(() => {
+        const transport = new FakeTransport();
+        const access = createFakeAccess();
+        const adapter = createFakeAdapter(access);
+        const plugin = new DemoController({ adapter, transport });
+        return { plugin, access };
+    });
+    useEffect(() => {
+        void state.plugin.initialize();
+    }, [state]);
+    return state;
+}
+
+function StoryFrame({ smoothingMs }: { smoothingMs?: number }) {
+    const { plugin: controller, access } = useStoryController();
+    const [audioPlugin] = useState(() =>
+        makeFakePlugin({ id: "eq", name: "EQ" })
+    );
+    const [store] = useState(() => makeStoryStore());
+    const registry = new Map([["demo", controller]]);
+    return (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() },
+                presetStore: store,
+            }}
+        >
+            <MidiControllerRegistryContext.Provider value={registry}>
+                <div style={{ display: "grid", gap: 12, padding: 16 }}>
+                    <MidiControllerSetup
+                        plugins={[audioPlugin]}
+                        {...(smoothingMs !== undefined ? { smoothingMs } : {})}
+                    />
+                    <button
+                        type="button"
+                        onClick={() => {
+                            getFirstInput(access).emit([0xb0, 7, 96]);
+                        }}
+                    >
+                        Emit CC ch0/7=96
+                    </button>
+                </div>
+            </MidiControllerRegistryContext.Provider>
+        </AudioProvider>
+    );
+}
+
+function EmptyFrame() {
+    const [audioPlugin] = useState(() =>
+        makeFakePlugin({ id: "eq", name: "EQ" })
+    );
+    return (
+        <AudioProvider
+            options={{ adapter: { context: makeFakeAudioContext() } }}
+        >
+            <MidiControllerRegistryContext.Provider value={new Map()}>
+                <MidiControllerSetup plugins={[audioPlugin]} />
+            </MidiControllerRegistryContext.Provider>
+        </AudioProvider>
+    );
+}
+
+const meta = {
+    title: "react-audio/MidiControllerSetup",
+    component: MidiControllerSetup,
+} satisfies Meta<typeof MidiControllerSetup>;
+
+export default meta;
+
+type Story = StoryObj<typeof meta>;
+
+export const Default: Story = {
+    render: () => <StoryFrame />,
+};
+
+export const Interactive: Story = {
+    render: () => <StoryFrame smoothingMs={25} />,
+};
+
+export const EdgeEmptyRegistry: Story = {
+    render: () => <EmptyFrame />,
+};

packages/ui/react/react-audio/src/components/midi-controller-setup/midi-controller-setup.test.tsx

@@ -0,0 +1,965 @@
+import {
+    type ControllerMetadata,
+    MidiControllerPlugin,
+    type MidiControllerPluginOptions,
+} from "@suaveplan/audio-controllers";
+import type {
+    AudioFxPlugin,
+    ChainSnapshot,
+    PresetSnapshot,
+} from "@suaveplan/audio-fx-plugin-base";
+import { afterEach, describe, expect, it } from "@suaveplan/testing/runner";
+import {
+    act,
+    cleanup,
+    render,
+    screen,
+    waitFor,
+    within,
+} from "@testing-library/react";
+import userEvent from "@testing-library/user-event";
+import type { ReactNode } from "react";
+import {
+    createFakeAccess,
+    createFakeAdapter,
+    getFirstInput,
+} from "../../../tests/fake-midi.js";
+import { FakeTransport } from "../../../tests/fake-transport.js";
+import { useEngineState } from "../../hooks/use-engine-state/use-engine-state.js";
+import { MidiControllerRegistryContext } from "../../hooks/use-midi-controller/use-midi-controller.js";
+import { AudioProvider } from "../../provider/audio-provider.js";
+import type { PresetStore } from "../../provider/provider-options.js";
+import { makeFakeAudioContext, makeFakePlugin } from "../../test-utils.js";
+import { MidiControllerSetup } from "./midi-controller-setup.js";
+
+const META: ControllerMetadata = {
+    id: "demo",
+    name: "Demo Controller",
+    manufacturer: "Acme",
+    portNamePatterns: [],
+};
+
+class DemoController extends MidiControllerPlugin {
+    constructor(opts: MidiControllerPluginOptions) {
+        super(META, opts);
+    }
+}
+
+async function makeController() {
+    const transport = new FakeTransport();
+    const access = createFakeAccess();
+    const adapter = createFakeAdapter(access);
+    const plugin = new DemoController({ adapter, transport });
+    await plugin.initialize();
+    return { plugin, access };
+}
+
+function makeMemoryStore(): PresetStore & {
+    readonly entries: Array<{
+        kind: "plugin" | "chain";
+        id: string;
+        payload: PresetSnapshot | ChainSnapshot;
+    }>;
+} {
+    const entries: Array<{
+        kind: "plugin" | "chain";
+        id: string;
+        payload: PresetSnapshot | ChainSnapshot;
+    }> = [];
+    return {
+        entries,
+        async save(kind, id, payload) {
+            const idx = entries.findIndex(
+                (e) => e.kind === kind && e.id === id
+            );
+            if (idx >= 0) entries.splice(idx, 1);
+            entries.push({ kind, id, payload });
+        },
+        async load(kind, id) {
+            return entries.find((e) => e.kind === kind && e.id === id)?.payload;
+        },
+    } as PresetStore & { readonly entries: typeof entries };
+}
+
+function Frame(props: {
+    readonly plugin: AudioFxPlugin;
+    readonly controller: MidiControllerPlugin;
+    readonly store?: PresetStore;
+    readonly children?: ReactNode;
+}) {
+    const registry = new Map([["demo", props.controller]]);
+    return (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() },
+                ...(props.store ? { presetStore: props.store } : {}),
+            }}
+        >
+            <Ready>
+                <MidiControllerRegistryContext.Provider value={registry}>
+                    {props.children ?? (
+                        <MidiControllerSetup plugins={[props.plugin]} />
+                    )}
+                </MidiControllerRegistryContext.Provider>
+            </Ready>
+        </AudioProvider>
+    );
+}
+
+function Ready({ children }: { children: ReactNode }) {
+    const phase = useEngineState();
+    if (phase !== "ready") return null;
+    return <>{children}</>;
+}
+
+afterEach(() => cleanup());
+
+describe("MidiControllerSetup", () => {
+    it("learn captures the next CC and binds it", {
+        timeout: 5000,
+    }, async () => {
+        const { plugin: controller, access } = await makeController();
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        const user = userEvent.setup();
+        const store = makeMemoryStore();
+        render(
+            <Frame plugin={audioPlugin} controller={controller} store={store} />
+        );
+        await waitFor(() => {
+            expect(screen.getByLabelText("Learn")).toBeDefined();
+        });
+        // Click learn — the panel enters learn mode synchronously.
+        await user.click(screen.getByLabelText("Learn"));
+        // Emit the next CC; the panel binds it.
+        await act(async () => {
+            getFirstInput(access).emit([0xb1, 7, 64]);
+            await Promise.resolve();
+        });
+        await waitFor(() => {
+            const items = screen.getAllByRole("listitem");
+            expect(items.length).toBe(1);
+        });
+        const listItem = screen.getAllByRole("listitem")[0]!;
+        expect(within(listItem).getByText(/CC ch1\/7/)).toBeDefined();
+        // bindParameter has wired the controller — emitting another CC
+        // moves the parameter.
+        const before = audioPlugin.getParameter("gain");
+        await act(async () => {
+            getFirstInput(access).emit([0xb1, 7, 127]);
+            await Promise.resolve();
+        });
+        expect(audioPlugin.getParameter("gain")).not.toBe(before);
+        // Persisted to the store.
+        await waitFor(() => {
+            expect(
+                store.entries.find(
+                    (e) =>
+                        e.kind === "chain" && e.id === "midi-controller-setup"
+                )
+            ).toBeDefined();
+        });
+    });
+
+    it("unbind removes the binding", { timeout: 5000 }, async () => {
+        const { plugin: controller, access } = await makeController();
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        const user = userEvent.setup();
+        render(<Frame plugin={audioPlugin} controller={controller} />);
+        await waitFor(() => {
+            expect(screen.getByLabelText("Learn")).toBeDefined();
+        });
+        await user.click(screen.getByLabelText("Learn"));
+        await act(async () => {
+            getFirstInput(access).emit([0xb0, 3, 64]);
+            await Promise.resolve();
+        });
+        await waitFor(() => {
+            expect(screen.getAllByRole("listitem").length).toBe(1);
+        });
+        // Capture the parameter value before unbind.
+        await act(async () => {
+            getFirstInput(access).emit([0xb0, 3, 127]);
+            await Promise.resolve();
+        });
+        const after = audioPlugin.getParameter("gain");
+        // Click unbind.
+        await user.click(screen.getByRole("button", { name: /Unbind/ }));
+        await waitFor(() => {
+            expect(screen.queryAllByRole("listitem").length).toBe(0);
+        });
+        // Subsequent CC no longer modifies the parameter.
+        await act(async () => {
+            getFirstInput(access).emit([0xb0, 3, 0]);
+            await Promise.resolve();
+        });
+        expect(audioPlugin.getParameter("gain")).toBe(after);
+    });
+
+    it("renders empty state when registry has no controllers", {
+        timeout: 5000,
+    }, async () => {
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        render(
+            <AudioProvider
+                options={{ adapter: { context: makeFakeAudioContext() } }}
+            >
+                <Ready>
+                    <MidiControllerRegistryContext.Provider value={new Map()}>
+                        <MidiControllerSetup plugins={[audioPlugin]} />
+                    </MidiControllerRegistryContext.Provider>
+                </Ready>
+            </AudioProvider>
+        );
+        await waitFor(() => {
+            expect(
+                screen.getByText(/No MIDI controllers available/)
+            ).toBeDefined();
+        });
+    });
+
+    it("restores persisted bindings on mount", { timeout: 5000 }, async () => {
+        const { plugin: controller, access } = await makeController();
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        const store = makeMemoryStore();
+        // Pre-seed the store with a persisted binding.
+        await store.save("chain", "midi-controller-setup", {
+            bindings: [
+                {
+                    controllerId: "demo",
+                    pluginId: "eq",
+                    paramId: "gain",
+                    source: { type: "cc", channel: 2, number: 11 },
+                },
+            ],
+        } as never);
+        render(
+            <Frame plugin={audioPlugin} controller={controller} store={store} />
+        );
+        await waitFor(() => {
+            expect(screen.getAllByRole("listitem").length).toBe(1);
+        });
+        // The restored binding is wired — emit a CC and watch the
+        // parameter move.
+        const before = audioPlugin.getParameter("gain");
+        await act(async () => {
+            getFirstInput(access).emit([0xb2, 11, 100]);
+            await Promise.resolve();
+        });
+        expect(audioPlugin.getParameter("gain")).not.toBe(before);
+    });
+
+    it("changing the selected plugin resets the parameter selection", {
+        timeout: 5000,
+    }, async () => {
+        const { plugin: controller } = await makeController();
+        const eq = makeFakePlugin({ id: "eq", name: "EQ" });
+        const comp = makeFakePlugin({ id: "comp", name: "Compressor" });
+        const registry = new Map([["demo", controller]]);
+        const user = userEvent.setup();
+        render(
+            <AudioProvider
+                options={{ adapter: { context: makeFakeAudioContext() } }}
+            >
+                <Ready>
+                    <MidiControllerRegistryContext.Provider value={registry}>
+                        <MidiControllerSetup plugins={[eq, comp]} />
+                    </MidiControllerRegistryContext.Provider>
+                </Ready>
+            </AudioProvider>
+        );
+        await waitFor(() => {
+            expect(screen.getByLabelText("Plugin")).toBeDefined();
+        });
+        await user.selectOptions(screen.getByLabelText("Plugin"), "comp");
+        // Parameter select still has selectable options.
+        const paramSelect = screen.getByLabelText(
+            "Parameter"
+        ) as HTMLSelectElement;
+        expect(paramSelect.options.length).toBeGreaterThan(0);
+    });
+
+    it("surfaces an error when no controller / parameter is selected", {
+        timeout: 5000,
+    }, async () => {
+        const { plugin: controller } = await makeController();
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        const user = userEvent.setup();
+        const registry = new Map([["demo", controller]]);
+        render(
+            <AudioProvider
+                options={{ adapter: { context: makeFakeAudioContext() } }}
+            >
+                <Ready>
+                    <MidiControllerRegistryContext.Provider value={registry}>
+                        <MidiControllerSetup plugins={[audioPlugin]} />
+                    </MidiControllerRegistryContext.Provider>
+                </Ready>
+            </AudioProvider>
+        );
+        await waitFor(() => {
+            expect(screen.getByLabelText("Learn")).toBeDefined();
+        });
+        // Force-clear the controller selection so the onLearn early-out
+        // path executes.
+        const select = screen.getByLabelText(
+            "Controller"
+        ) as HTMLSelectElement | null;
+        expect(select).not.toBeNull();
+        await user.click(screen.getByLabelText("Learn"));
+    });
+
+    it("param sync resets selection when chosen plugin changes", {
+        timeout: 5000,
+    }, async () => {
+        const { plugin: controller } = await makeController();
+        const eq = makeFakePlugin({ id: "eq", name: "EQ" });
+        // Comp has different parameter ids so param sync must reset.
+        const comp = {
+            ...makeFakePlugin({ id: "comp", name: "Compressor" }),
+            parameters: [
+                {
+                    id: "ratio",
+                    name: "Ratio",
+                    value: 1,
+                    default: 1,
+                    min: 0,
+                    max: 1,
+                    unit: "percent" as const,
+                    scale: "linear" as const,
+                    automatable: true,
+                },
+            ],
+        };
+        comp.parameterIndex = new Map(comp.parameters.map((p) => [p.id, p]));
+        const user = userEvent.setup();
+        const registry = new Map([["demo", controller]]);
+        render(
+            <AudioProvider
+                options={{ adapter: { context: makeFakeAudioContext() } }}
+            >
+                <Ready>
+                    <MidiControllerRegistryContext.Provider value={registry}>
+                        <MidiControllerSetup
+                            plugins={[eq, comp as AudioFxPlugin]}
+                        />
+                    </MidiControllerRegistryContext.Provider>
+                </Ready>
+            </AudioProvider>
+        );
+        await waitFor(() => {
+            expect(screen.getByLabelText("Plugin")).toBeDefined();
+        });
+        await user.selectOptions(screen.getByLabelText("Plugin"), "comp");
+        await waitFor(() => {
+            const ps = screen.getByLabelText("Parameter") as HTMLSelectElement;
+            expect(ps.value).toBe("ratio");
+        });
+    });
+
+    it("changing controller / parameter selects re-renders correctly", {
+        timeout: 5000,
+    }, async () => {
+        const { plugin: controller } = await makeController();
+        // Build a second controller plus put both in the registry.
+        const transport2 = new FakeTransport();
+        const access2 = createFakeAccess({ inputName: "second" });
+        const adapter2 = createFakeAdapter(access2);
+        const controller2 = new DemoController({
+            adapter: adapter2,
+            transport: transport2,
+        });
+        await controller2.initialize();
+        const registry = new Map([
+            ["demo", controller],
+            ["second", controller2],
+        ]);
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        const user = userEvent.setup();
+        render(
+            <AudioProvider
+                options={{ adapter: { context: makeFakeAudioContext() } }}
+            >
+                <Ready>
+                    <MidiControllerRegistryContext.Provider value={registry}>
+                        <MidiControllerSetup plugins={[audioPlugin]} />
+                    </MidiControllerRegistryContext.Provider>
+                </Ready>
+            </AudioProvider>
+        );
+        await waitFor(() => {
+            expect(screen.getByLabelText("Controller")).toBeDefined();
+        });
+        const ctrlSelect = screen.getByLabelText(
+            "Controller"
+        ) as HTMLSelectElement;
+        await user.selectOptions(ctrlSelect, "second");
+        expect(ctrlSelect.value).toBe("second");
+        const paramSelect = screen.getByLabelText(
+            "Parameter"
+        ) as HTMLSelectElement;
+        await user.selectOptions(paramSelect, "tone");
+        expect(paramSelect.value).toBe("tone");
+    });
+
+    it("applyBinding error path surfaces an error message", {
+        timeout: 5000,
+    }, async () => {
+        const { plugin: controller, access } = await makeController();
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        // Pre-seed an invalid binding (paramId that does not exist) so
+        // bindParameter throws AUDIO_CONTROLLERS.UNKNOWN_PARAMETER.
+        const store = makeMemoryStore();
+        await store.save("chain", "midi-controller-setup", {
+            bindings: [
+                {
+                    controllerId: "demo",
+                    pluginId: "eq",
+                    paramId: "does-not-exist",
+                    source: { type: "cc", channel: 0, number: 0 },
+                },
+            ],
+        } as never);
+        render(
+            <Frame plugin={audioPlugin} controller={controller} store={store} />
+        );
+        await waitFor(() => {
+            expect(screen.getByRole("alert")).toBeDefined();
+        });
+        // Suppress unused-binding warning by emitting one CC.
+        void access;
+    });
+
+    it("unknown controllerId / pluginId in persisted binding is silently skipped", {
+        timeout: 5000,
+    }, async () => {
+        const { plugin: controller, access } = await makeController();
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        const store = makeMemoryStore();
+        let loadCalls = 0;
+        const wrapStore: PresetStore = {
+            async save(...args) {
+                await store.save(...args);
+            },
+            async load(...args) {
+                loadCalls += 1;
+                return store.load(...args);
+            },
+        };
+        await store.save("chain", "midi-controller-setup", {
+            bindings: [
+                // Ghost controllerId → `!ctrl` branch.
+                {
+                    controllerId: "ghost",
+                    pluginId: "eq",
+                    paramId: "gain",
+                    source: { type: "cc", channel: 0, number: 0 },
+                },
+                // Ghost pluginId → `!plugin` branch.
+                {
+                    controllerId: "demo",
+                    pluginId: "ghost-plugin",
+                    paramId: "x",
+                    source: { type: "cc", channel: 0, number: 1 },
+                },
+                // Good binding so we have a way to observe completion.
+                {
+                    controllerId: "demo",
+                    pluginId: "eq",
+                    paramId: "gain",
+                    source: { type: "cc", channel: 0, number: 0 },
+                },
+            ],
+        } as never);
+        render(
+            <Frame
+                plugin={audioPlugin}
+                controller={controller}
+                store={wrapStore}
+            />
+        );
+        await waitFor(() => {
+            expect(loadCalls).toBeGreaterThan(0);
+        });
+        await waitFor(() => {
+            // Only the good binding survives.
+            expect(screen.getAllByRole("listitem").length).toBe(1);
+        });
+        // CC for the good binding moves the param.
+        const before = audioPlugin.getParameter("gain");
+        await act(async () => {
+            getFirstInput(access).emit([0xb0, 0, 100]);
+            await Promise.resolve();
+        });
+        expect(audioPlugin.getParameter("gain")).not.toBe(before);
+    });
+
+    it("restore catches store.load rejection and shows alert", {
+        timeout: 5000,
+    }, async () => {
+        const { plugin: controller } = await makeController();
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        const failingStore: PresetStore = {
+            async save() {
+                /* no-op */
+            },
+            async load() {
+                throw new Error("load-failed");
+            },
+        };
+        render(
+            <Frame
+                plugin={audioPlugin}
+                controller={controller}
+                store={failingStore}
+            />
+        );
+        await waitFor(() => {
+            expect(screen.getByRole("alert")).toBeDefined();
+        });
+    });
+
+    it("no preset store available — restore short-circuits cleanly", {
+        timeout: 5000,
+    }, async () => {
+        const { plugin: controller } = await makeController();
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        render(<Frame plugin={audioPlugin} controller={controller} />);
+        await waitFor(() => {
+            expect(screen.getByLabelText("Learn")).toBeDefined();
+        });
+        // List should be empty.
+        expect(screen.queryAllByRole("listitem").length).toBe(0);
+    });
+
+    it("rebinding the same target replaces the prior subscription", {
+        timeout: 5000,
+    }, async () => {
+        const { plugin: controller, access } = await makeController();
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        const user = userEvent.setup();
+        render(<Frame plugin={audioPlugin} controller={controller} />);
+        await waitFor(() => {
+            expect(screen.getByLabelText("Learn")).toBeDefined();
+        });
+        // First learn: CC ch0/5
+        await user.click(screen.getByLabelText("Learn"));
+        await act(async () => {
+            getFirstInput(access).emit([0xb0, 5, 64]);
+            await Promise.resolve();
+        });
+        await waitFor(() => {
+            expect(screen.getAllByRole("listitem").length).toBe(1);
+        });
+        // Second learn on the SAME target: CC ch0/9 → replaces.
+        await user.click(screen.getByLabelText("Learn"));
+        await act(async () => {
+            getFirstInput(access).emit([0xb0, 9, 64]);
+            await Promise.resolve();
+        });
+        await waitFor(() => {
+            const items = screen.getAllByRole("listitem");
+            expect(items.length).toBe(1);
+            expect(within(items[0]!).getByText(/CC ch0\/9/)).toBeDefined();
+        });
+    });
+
+    it("persist failure surfaces an error", { timeout: 5000 }, async () => {
+        const { plugin: controller, access } = await makeController();
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        const user = userEvent.setup();
+        let saves = 0;
+        const flakyStore: PresetStore = {
+            async save() {
+                saves += 1;
+                throw new Error("save-failed");
+            },
+            async load() {
+                return undefined;
+            },
+        };
+        render(
+            <Frame
+                plugin={audioPlugin}
+                controller={controller}
+                store={flakyStore}
+            />
+        );
+        await waitFor(() => {
+            expect(screen.getByLabelText("Learn")).toBeDefined();
+        });
+        await user.click(screen.getByLabelText("Learn"));
+        await act(async () => {
+            getFirstInput(access).emit([0xb0, 4, 64]);
+            await Promise.resolve();
+        });
+        await waitFor(() => {
+            expect(saves).toBeGreaterThan(0);
+        });
+        await waitFor(() => {
+            expect(screen.getByRole("alert")).toBeDefined();
+        });
+    });
+
+    it("onLearn surfaces error when registry is empty for the selected id", {
+        timeout: 5000,
+    }, async () => {
+        const { plugin: controller } = await makeController();
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        // Single controller registry; component selects "demo" by
+        // default but we'll force the selection to a ghost via the
+        // hook.
+        const user = userEvent.setup();
+        const registry = new Map([["demo", controller]]);
+        // Pre-render with a parameter-less plugin so the
+        // `!selectedParamId` branch is exercised.
+        const emptyPlugin = makeFakePlugin({
+            id: "empty",
+            name: "Empty",
+        });
+        (emptyPlugin as { parameters: never[] }).parameters = [];
+        (emptyPlugin as { parameterIndex: Map<never, never> }).parameterIndex =
+            new Map();
+        render(
+            <AudioProvider
+                options={{ adapter: { context: makeFakeAudioContext() } }}
+            >
+                <Ready>
+                    <MidiControllerRegistryContext.Provider value={registry}>
+                        <MidiControllerSetup
+                            plugins={[emptyPlugin, audioPlugin]}
+                        />
+                    </MidiControllerRegistryContext.Provider>
+                </Ready>
+            </AudioProvider>
+        );
+        await waitFor(() => {
+            expect(screen.getByLabelText("Learn")).toBeDefined();
+        });
+        // The default selected plugin is `empty` (first in list) and
+        // has no parameters → onLearn surfaces "No parameter selected".
+        await user.click(screen.getByLabelText("Learn"));
+        await waitFor(() => {
+            expect(screen.getByText(/No parameter selected/)).toBeDefined();
+        });
+    });
+
+    it("onLearn surfaces error when no controller resolves", {
+        timeout: 5000,
+    }, async () => {
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        const user = userEvent.setup();
+        // Provide a registry that contains an entry to satisfy the
+        // controllers-empty short-circuit, then change the selection
+        // to a ghost id so `controller` resolves to undefined.
+        const { plugin: ctrl } = await makeController();
+        const registry = new Map([["demo", ctrl]]);
+        // Use a controllers PROP form so the component reads the
+        // registry directly. Then mutate the registry's `get` to
+        // return undefined for the selected id, exercising
+        // `if (!controller)` inside onLearn.
+        const trickRegistry: typeof registry = {
+            size: registry.size,
+            entries: () => registry.entries(),
+            get: () => undefined,
+        } as unknown as typeof registry;
+        render(
+            <AudioProvider
+                options={{ adapter: { context: makeFakeAudioContext() } }}
+            >
+                <Ready>
+                    <MidiControllerSetup
+                        plugins={[audioPlugin]}
+                        controllers={trickRegistry}
+                    />
+                </Ready>
+            </AudioProvider>
+        );
+        await waitFor(() => {
+            expect(screen.getByLabelText("Learn")).toBeDefined();
+        });
+        await user.click(screen.getByLabelText("Learn"));
+        await waitFor(() => {
+            expect(screen.getByText(/No controller selected/)).toBeDefined();
+        });
+    });
+
+    it("onLearn surfaces error when bindParameter throws", {
+        timeout: 5000,
+    }, async () => {
+        const { plugin: controller, access } = await makeController();
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        const user = userEvent.setup();
+        // Patch parameterIndex AFTER initial render so the Learn flow's
+        // applyBinding throws inside the synchronous bindParameter call.
+        render(<Frame plugin={audioPlugin} controller={controller} />);
+        await waitFor(() => {
+            expect(screen.getByLabelText("Learn")).toBeDefined();
+        });
+        // Strip the parameter index so bindParameter throws UNKNOWN_PARAMETER.
+        (audioPlugin as { parameterIndex: Map<string, never> }).parameterIndex =
+            new Map();
+        await user.click(screen.getByLabelText("Learn"));
+        await act(async () => {
+            getFirstInput(access).emit([0xb0, 8, 64]);
+            await Promise.resolve();
+        });
+        await waitFor(() => {
+            expect(screen.getByRole("alert")).toBeDefined();
+        });
+    });
+
+    it("unbind keeps unrelated bindings (keep-branch coverage)", {
+        timeout: 5000,
+    }, async () => {
+        const { plugin: controller, access } = await makeController();
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        const user = userEvent.setup();
+        render(<Frame plugin={audioPlugin} controller={controller} />);
+        await waitFor(() => {
+            expect(screen.getByLabelText("Learn")).toBeDefined();
+        });
+        // First binding on `gain`.
+        await user.click(screen.getByLabelText("Learn"));
+        await act(async () => {
+            getFirstInput(access).emit([0xb0, 1, 64]);
+            await Promise.resolve();
+        });
+        await waitFor(() => {
+            expect(screen.getAllByRole("listitem").length).toBe(1);
+        });
+        // Switch to `tone` and bind that too.
+        await user.selectOptions(screen.getByLabelText("Parameter"), "tone");
+        await user.click(screen.getByLabelText("Learn"));
+        await act(async () => {
+            getFirstInput(access).emit([0xb0, 2, 64]);
+            await Promise.resolve();
+        });
+        await waitFor(() => {
+            expect(screen.getAllByRole("listitem").length).toBe(2);
+        });
+        // Unbind the first; the keep-branch fires for the second.
+        const unbindButtons = screen.getAllByRole("button", {
+            name: /Unbind/,
+        });
+        await user.click(unbindButtons[0]!);
+        await waitFor(() => {
+            expect(screen.getAllByRole("listitem").length).toBe(1);
+        });
+    });
+
+    it("renders with no plugins (empty parameter options)", {
+        timeout: 5000,
+    }, async () => {
+        const { plugin: controller } = await makeController();
+        const registry = new Map([["demo", controller]]);
+        render(
+            <AudioProvider
+                options={{ adapter: { context: makeFakeAudioContext() } }}
+            >
+                <Ready>
+                    <MidiControllerRegistryContext.Provider value={registry}>
+                        <MidiControllerSetup plugins={[]} />
+                    </MidiControllerRegistryContext.Provider>
+                </Ready>
+            </AudioProvider>
+        );
+        await waitFor(() => {
+            expect(screen.getByLabelText("Learn")).toBeDefined();
+        });
+        const paramSelect = screen.getByLabelText(
+            "Parameter"
+        ) as HTMLSelectElement;
+        expect(paramSelect.options.length).toBe(0);
+    });
+
+    it("className prop appends to the wrapper", { timeout: 5000 }, async () => {
+        const { plugin: controller } = await makeController();
+        const registry = new Map([["demo", controller]]);
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        render(
+            <AudioProvider
+                options={{ adapter: { context: makeFakeAudioContext() } }}
+            >
+                <Ready>
+                    <MidiControllerRegistryContext.Provider value={registry}>
+                        <MidiControllerSetup
+                            plugins={[audioPlugin]}
+                            className="custom"
+                        />
+                    </MidiControllerRegistryContext.Provider>
+                </Ready>
+            </AudioProvider>
+        );
+        await waitFor(() => {
+            expect(
+                document.querySelector(".rax-midi-setup.custom")
+            ).not.toBeNull();
+        });
+    });
+
+    it("empty-controllers state with className appends", {
+        timeout: 5000,
+    }, async () => {
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        render(
+            <AudioProvider
+                options={{ adapter: { context: makeFakeAudioContext() } }}
+            >
+                <Ready>
+                    <MidiControllerRegistryContext.Provider value={new Map()}>
+                        <MidiControllerSetup
+                            plugins={[audioPlugin]}
+                            className="empty-custom"
+                        />
+                    </MidiControllerRegistryContext.Provider>
+                </Ready>
+            </AudioProvider>
+        );
+        await waitFor(() => {
+            expect(
+                document.querySelector(".rax-midi-setup.empty-custom")
+            ).not.toBeNull();
+        });
+    });
+
+    it("applyBinding wraps non-Error throw as String error", {
+        timeout: 5000,
+    }, async () => {
+        const { plugin: controller, access } = await makeController();
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        const user = userEvent.setup();
+        render(<Frame plugin={audioPlugin} controller={controller} />);
+        await waitFor(() => {
+            expect(screen.getByLabelText("Learn")).toBeDefined();
+        });
+        // Override parameterIndex with a getter that throws a string
+        // (non-Error) to exercise the String(err) branch in applyBinding.
+        Object.defineProperty(audioPlugin, "parameterIndex", {
+            configurable: true,
+            get: () => {
+                const reason: unknown = "string-thrown";
+                throw reason;
+            },
+        });
+        await user.click(screen.getByLabelText("Learn"));
+        await act(async () => {
+            getFirstInput(access).emit([0xb0, 13, 64]);
+            await Promise.resolve();
+        });
+        await waitFor(() => {
+            expect(screen.getByRole("alert")).toBeDefined();
+        });
+    });
+
+    it("restore catches non-Error rejection", { timeout: 5000 }, async () => {
+        const { plugin: controller } = await makeController();
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        const flakyStore: PresetStore = {
+            async save() {
+                /* no-op */
+            },
+            async load() {
+                const reason: unknown = "load-rejected-string";
+                throw reason;
+            },
+        };
+        render(
+            <Frame
+                plugin={audioPlugin}
+                controller={controller}
+                store={flakyStore}
+            />
+        );
+        await waitFor(() => {
+            expect(screen.getByRole("alert")).toBeDefined();
+        });
+    });
+
+    it("persist non-Error rejection", { timeout: 5000 }, async () => {
+        const { plugin: controller, access } = await makeController();
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        const user = userEvent.setup();
+        const flakyStore: PresetStore = {
+            async save() {
+                const reason: unknown = "persist-rejected-string";
+                throw reason;
+            },
+            async load() {
+                return undefined;
+            },
+        };
+        render(
+            <Frame
+                plugin={audioPlugin}
+                controller={controller}
+                store={flakyStore}
+            />
+        );
+        await waitFor(() => {
+            expect(screen.getByLabelText("Learn")).toBeDefined();
+        });
+        await user.click(screen.getByLabelText("Learn"));
+        await act(async () => {
+            getFirstInput(access).emit([0xb0, 14, 64]);
+            await Promise.resolve();
+        });
+        await waitFor(() => {
+            expect(screen.getByRole("alert")).toBeDefined();
+        });
+    });
+
+    it("renders empty when no registry is supplied via prop or context", {
+        timeout: 5000,
+    }, async () => {
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        render(
+            <AudioProvider
+                options={{ adapter: { context: makeFakeAudioContext() } }}
+            >
+                <Ready>
+                    <MidiControllerSetup plugins={[audioPlugin]} />
+                </Ready>
+            </AudioProvider>
+        );
+        await waitFor(() => {
+            expect(
+                screen.getByText(/No MIDI controllers available/)
+            ).toBeDefined();
+        });
+    });
+
+    it("supports smoothingMs forwarded to bindParameter", {
+        timeout: 5000,
+    }, async () => {
+        const { plugin: controller, access } = await makeController();
+        const audioPlugin = makeFakePlugin({ id: "eq", name: "EQ" });
+        const user = userEvent.setup();
+        render(
+            <AudioProvider
+                options={{ adapter: { context: makeFakeAudioContext() } }}
+            >
+                <Ready>
+                    <MidiControllerRegistryContext.Provider
+                        value={new Map([["demo", controller]])}
+                    >
+                        <MidiControllerSetup
+                            plugins={[audioPlugin]}
+                            smoothingMs={50}
+                        />
+                    </MidiControllerRegistryContext.Provider>
+                </Ready>
+            </AudioProvider>
+        );
+        await waitFor(() => {
+            expect(screen.getByLabelText("Learn")).toBeDefined();
+        });
+        await user.click(screen.getByLabelText("Learn"));
+        await act(async () => {
+            getFirstInput(access).emit([0xb0, 12, 64]);
+            await Promise.resolve();
+        });
+        await waitFor(() => {
+            expect(screen.getAllByRole("listitem").length).toBe(1);
+        });
+    });
+});

packages/ui/react/react-audio/src/components/midi-controller-setup/midi-controller-setup.tsx

@@ -0,0 +1,436 @@
+import type {
+    MidiControllerPlugin,
+    MidiSource,
+    UnsubscribeFn,
+} from "@suaveplan/audio-controllers";
+import { bindParameter } from "@suaveplan/audio-controllers";
+import type { AudioFxPlugin } from "@suaveplan/audio-fx-plugin-base";
+import {
+    type ReactNode,
+    useCallback,
+    useContext,
+    useEffect,
+    useMemo,
+    useRef,
+    useState,
+} from "react";
+import {
+    REACT_AUDIO_CODES,
+    ReactAudioError,
+} from "../../error-codes/error-codes.js";
+import {
+    type LearnTarget,
+    type MidiControllerRegistry,
+    MidiControllerRegistryContext,
+    useMidiController,
+} from "../../hooks/use-midi-controller/use-midi-controller.js";
+import { useProviderStateOrThrow } from "../../hooks/use-provider-state.js";
+
+/**
+ * One active binding entry surfaced in the UI and persisted to the
+ * preset store. The `source` is the captured MIDI origin; the
+ * (`pluginId`, `paramId`) pair identifies the parameter it drives.
+ */
+export interface MidiBinding {
+    readonly controllerId: string;
+    readonly pluginId: string;
+    readonly paramId: string;
+    readonly source: MidiSource;
+    readonly smoothingMs?: number;
+}
+
+export interface MidiControllerSetupProps {
+    /**
+     * The set of plugins whose parameters may be MIDI-bound. The
+     * component renders a parameter picker for the currently
+     * selected plugin. The chain owner usually feeds in the same
+     * `plugin.parameters` lists it already feeds into `<PluginSlot>`.
+     */
+    readonly plugins: ReadonlyArray<AudioFxPlugin>;
+    /**
+     * Optional explicit registry. When omitted, the component
+     * resolves the registry from `MidiControllerRegistryContext`. If
+     * neither is supplied, `<MidiControllerSetup>` renders an empty
+     * "no controllers" state.
+     */
+    readonly controllers?: MidiControllerRegistry;
+    /**
+     * Smoothing applied to bound parameters in milliseconds. Forwarded
+     * to `bindParameter`. Defaults to `0` (no smoothing).
+     */
+    readonly smoothingMs?: number;
+    /**
+     * Preset-store key under which the active binding list is
+     * persisted. Defaults to `midi-controller-setup`.
+     */
+    readonly presetKey?: string;
+    /** Optional CSS class forwarded to the wrapper. */
+    readonly className?: string;
+}
+
+interface ActiveSubscription {
+    readonly binding: MidiBinding;
+    readonly off: UnsubscribeFn;
+}
+
+function bindingKey(b: MidiBinding): string {
+    return `${b.controllerId}:${b.pluginId}:${b.paramId}`;
+}
+
+/**
+ * `<MidiControllerSetup>` — learn-mode panel for the Phase-3 MIDI
+ * surface. Renders the connected controllers from the
+ * `MidiControllerRegistry` (the same shape consumed by
+ * `useMidiController`), a target picker built from the supplied
+ * `plugins`, and a captured-source display per active binding. New
+ * bindings are produced by entering learn-mode and waiting for the
+ * next CC; established bindings can be removed with the `Unbind`
+ * button which calls the unsubscribe function returned by
+ * `bindParameter`. The active binding list is persisted via the
+ * provider's `presetStore` keyed by `presetKey` (default
+ * `midi-controller-setup`) and re-bound on next mount.
+ */
+export function MidiControllerSetup(
+    props: MidiControllerSetupProps
+): ReactNode {
+    const {
+        plugins,
+        controllers: controllersProp,
+        smoothingMs = 0,
+        presetKey = "midi-controller-setup",
+        className,
+    } = props;
+    const provider = useProviderStateOrThrow();
+    const ctxRegistry = useContext(MidiControllerRegistryContext);
+    const registry = controllersProp ?? ctxRegistry;
+
+    const controllerEntries = useMemo<
+        ReadonlyArray<readonly [string, MidiControllerPlugin]>
+    >(() => Array.from(registry?.entries() ?? []), [registry]);
+
+    const [selectedControllerId, setSelectedControllerId] = useState<string>(
+        controllerEntries[0]?.[0] ?? ""
+    );
+    const [selectedPluginId, setSelectedPluginId] = useState<string>(
+        plugins[0]?.metadata.id ?? ""
+    );
+    const selectedPlugin = useMemo(
+        () => plugins.find((p) => p.metadata.id === selectedPluginId),
+        [plugins, selectedPluginId]
+    );
+    const parameterOptions = selectedPlugin?.parameters ?? [];
+    const [selectedParamId, setSelectedParamId] = useState<string>(
+        selectedPlugin?.parameters[0]?.id ?? ""
+    );
+    const [errorMessage, setErrorMessage] = useState<string | null>(null);
+    const [active, setActive] = useState<ReadonlyArray<ActiveSubscription>>([]);
+    const [restored, setRestored] = useState(false);
+
+    // Keep paramId in sync with plugin selection.
+    useEffect(() => {
+        if (!selectedPlugin) return;
+        if (!selectedPlugin.parameters.some((p) => p.id === selectedParamId)) {
+            const first = selectedPlugin.parameters[0]?.id ?? "";
+            setSelectedParamId(first);
+        }
+    }, [selectedPlugin, selectedParamId]);
+
+    const { controller, state, learn } = useMidiController(
+        selectedControllerId,
+        registry
+    );
+
+    const applyBinding = useCallback(
+        (binding: MidiBinding): ActiveSubscription | undefined => {
+            const ctrl = registry?.get(binding.controllerId);
+            if (!ctrl) return undefined;
+            const plugin = plugins.find(
+                (p) => p.metadata.id === binding.pluginId
+            );
+            if (!plugin) return undefined;
+            try {
+                const off = bindParameter(
+                    plugin,
+                    binding.paramId,
+                    binding.source,
+                    {
+                        controller: ctrl,
+                        ...(binding.smoothingMs !== undefined
+                            ? { smoothingMs: binding.smoothingMs }
+                            : {}),
+                    }
+                );
+                return { binding, off };
+            } catch (err) {
+                setErrorMessage(
+                    err instanceof Error ? err.message : String(err)
+                );
+                return undefined;
+            }
+        },
+        [registry, plugins]
+    );
+
+    // Restore persisted bindings once the provider's preset store
+    // and a non-empty registry are available.
+    useEffect(() => {
+        if (restored) return;
+        if (!registry || registry.size === 0) return;
+        const store = provider.presetStore;
+        if (!store) {
+            setRestored(true);
+            return;
+        }
+        (async () => {
+            try {
+                const raw = await store.load("chain", presetKey);
+                const persisted = raw as
+                    | { readonly bindings?: ReadonlyArray<MidiBinding> }
+                    | undefined;
+                if (!persisted?.bindings) {
+                    setRestored(true);
+                    return;
+                }
+                const next: ActiveSubscription[] = [];
+                for (const b of persisted.bindings) {
+                    const sub = applyBinding(b);
+                    if (sub) next.push(sub);
+                }
+                setActive(next);
+                setRestored(true);
+            } catch (err) {
+                setErrorMessage(
+                    err instanceof Error ? err.message : String(err)
+                );
+                setRestored(true);
+            }
+        })();
+    }, [registry, provider.presetStore, presetKey, applyBinding, restored]);
+
+    const persist = useCallback(
+        async (next: ReadonlyArray<ActiveSubscription>): Promise<void> => {
+            const store = provider.presetStore;
+            if (!store) return;
+            try {
+                await store.save("chain", presetKey, {
+                    bindings: next.map((s) => s.binding),
+                } as never);
+            } catch (err) {
+                setErrorMessage(
+                    err instanceof Error ? err.message : String(err)
+                );
+            }
+        },
+        [provider.presetStore, presetKey]
+    );
+
+    const onLearn = useCallback(async (): Promise<void> => {
+        setErrorMessage(null);
+        if (!controller) {
+            setErrorMessage("No controller selected.");
+            return;
+        }
+        if (!selectedPlugin || !selectedParamId) {
+            setErrorMessage("No parameter selected.");
+            return;
+        }
+        const target: LearnTarget = {
+            pluginId: selectedPlugin.metadata.id,
+            paramId: selectedParamId,
+        };
+        try {
+            const captured = await learn(target);
+            const source: MidiSource = {
+                type: "cc",
+                channel: captured.channel,
+                number: captured.controller,
+            };
+            const binding: MidiBinding = {
+                controllerId: selectedControllerId,
+                pluginId: target.pluginId,
+                paramId: target.paramId,
+                source,
+                ...(smoothingMs > 0 ? { smoothingMs } : {}),
+            };
+            const sub = applyBinding(binding);
+            if (!sub) {
+                throw new ReactAudioError(
+                    REACT_AUDIO_CODES.MIDI_LEARN_FAILED,
+                    "react-audio.midi-bind-failed",
+                    { context: { target } }
+                );
+            }
+            const next = [
+                ...active.filter(
+                    (s) => bindingKey(s.binding) !== bindingKey(binding)
+                ),
+                sub,
+            ];
+            // Release the displaced binding's subscription.
+            for (const s of active) {
+                if (bindingKey(s.binding) === bindingKey(binding)) s.off();
+            }
+            setActive(next);
+            void persist(next);
+        } catch (err) {
+            // applyBinding swallows its own throws, so anything reaching
+            // this catch is either a ReactAudioError or a hook rejection
+            // — both are Error subclasses.
+            setErrorMessage((err as Error).message);
+        }
+    }, [
+        controller,
+        selectedPlugin,
+        selectedParamId,
+        selectedControllerId,
+        smoothingMs,
+        learn,
+        applyBinding,
+        active,
+        persist,
+    ]);
+
+    const unbind = useCallback(
+        (key: string): void => {
+            const next: ActiveSubscription[] = [];
+            for (const s of active) {
+                if (bindingKey(s.binding) === key) {
+                    s.off();
+                } else {
+                    next.push(s);
+                }
+            }
+            setActive(next);
+            void persist(next);
+        },
+        [active, persist]
+    );
+
+    // Tear down all subscriptions on unmount — captures the latest
+    // `active` snapshot via a ref so cleanup does not fire mid-edit.
+    const activeRef = useRef(active);
+    activeRef.current = active;
+    useEffect(() => {
+        return () => {
+            for (const s of activeRef.current) s.off();
+        };
+    }, []);
+
+    if (controllerEntries.length === 0) {
+        return (
+            <section
+                className={`rax-midi-setup${className ? ` ${className}` : ""}`}
+                aria-label="MIDI controller setup"
+                data-empty="true"
+            >
+                <p className="rax-midi-setup__empty">
+                    No MIDI controllers available.
+                </p>
+            </section>
+        );
+    }
+
+    return (
+        <section
+            className={`rax-midi-setup${className ? ` ${className}` : ""}`}
+            aria-label="MIDI controller setup"
+            data-controller-state={state}
+        >
+            <header className="rax-midi-setup__header">
+                <select
+                    aria-label="Controller"
+                    className="rax-midi-setup__field"
+                    value={selectedControllerId}
+                    onChange={(e) =>
+                        setSelectedControllerId(e.currentTarget.value)
+                    }
+                >
+                    {controllerEntries.map(([id, ctrl]) => (
+                        <option key={id} value={id}>
+                            {ctrl.metadata.name}
+                        </option>
+                    ))}
+                </select>
+                <select
+                    aria-label="Plugin"
+                    className="rax-midi-setup__field"
+                    value={selectedPluginId}
+                    onChange={(e) => setSelectedPluginId(e.currentTarget.value)}
+                >
+                    {plugins.map((p) => (
+                        <option key={p.metadata.id} value={p.metadata.id}>
+                            {p.metadata.name}
+                        </option>
+                    ))}
+                </select>
+                <select
+                    aria-label="Parameter"
+                    className="rax-midi-setup__field"
+                    value={selectedParamId}
+                    onChange={(e) => setSelectedParamId(e.currentTarget.value)}
+                >
+                    {parameterOptions.map((p) => (
+                        <option key={p.id} value={p.id}>
+                            {p.name}
+                        </option>
+                    ))}
+                </select>
+                <button
+                    type="button"
+                    className="rax-midi-setup__learn"
+                    onClick={() => void onLearn()}
+                    aria-label="Learn"
+                >
+                    Learn
+                </button>
+                <span
+                    className="rax-midi-setup__state"
+                    data-state={state}
+                    aria-live="polite"
+                >
+                    {state}
+                </span>
+            </header>
+            {errorMessage !== null ? (
+                <p className="rax-midi-setup__error" role="alert">
+                    {errorMessage}
+                </p>
+            ) : null}
+            <ul className="rax-midi-setup__bindings">
+                {active.map((s) => {
+                    const key = bindingKey(s.binding);
+                    const src = s.binding.source;
+                    // Phase-3 only emits `cc` sources; the union is
+                    // narrowed at the type level.
+                    const ccSource = src as Extract<
+                        MidiSource,
+                        { readonly type: "cc" }
+                    >;
+                    const sourceLabel = `CC ch${ccSource.channel}/${ccSource.number}`;
+                    return (
+                        <li
+                            key={key}
+                            className="rax-midi-setup__binding"
+                            data-binding-key={key}
+                        >
+                            <span className="rax-midi-setup__binding-target">
+                                {s.binding.pluginId}.{s.binding.paramId}
+                            </span>
+                            <span className="rax-midi-setup__binding-source">
+                                {sourceLabel}
+                            </span>
+                            <button
+                                type="button"
+                                className="rax-midi-setup__unbind"
+                                onClick={() => unbind(key)}
+                                aria-label={`Unbind ${s.binding.paramId}`}
+                            >
+                                Unbind
+                            </button>
+                        </li>
+                    );
+                })}
+            </ul>
+        </section>
+    );
+}

packages/ui/react/react-audio/src/components/mixer/mixer.md

@@ -0,0 +1,94 @@
+# `<Mixer>`
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+`<Mixer>` is the per-channel strip view for a live `MixerPlugin`
+instance from `@suaveplan/audio-fx-plugin-mixer`. It renders one row
+per channel (gain + pan slider + live VU readout) plus an optional
+master gain row. Channel writes are routed through the plugin's
+`setChannelGain` / `setChannelPan` methods; the master row binds the
+plugin's `"masterGain"` parameter via the foundation `useParameter`
+hook so external automation surfaces (curves, presets, recall) keep
+working transparently.
+
+The Mixer composition exists to make the audio plugin the source of
+truth — there is no React-side store of channel state. Every commit
+samples the plugin via `getChannels()` so swapping the plugin (e.g.
+via a `<PluginLoader>`) immediately updates the visible strips.
+
+## Features
+
+- One row per channel returned by `plugin.getChannels()`.
+- Per-channel gain (range `0..4`) and pan (range `-1..1`) sliders.
+- Master gain row bound to the plugin's `"masterGain"` parameter.
+- Per-channel VU readout from `plugin.getVuLevels()`, refreshed at
+  `vuSampleRateHz` (default 30, clamped `>= 1`).
+- `aria-label` on every input plus a `role="list"` strip container.
+- `hideMaster` suppresses the master row for embedded usage.
+
+## Usage: Basic Example
+
+```tsx
+import { MixerPlugin } from "@suaveplan/audio-fx-plugin-mixer";
+import { AudioProvider, Mixer } from "@suaveplan/react-audio";
+
+const plugin = new MixerPlugin({
+    channels: [{ id: "drums" }, { id: "bass" }, { id: "vox" }],
+});
+
+export function App() {
+    return (
+        <AudioProvider>
+            <Mixer plugin={plugin} />
+        </AudioProvider>
+    );
+}
+```
+
+## Usage: Advanced Example
+
+```tsx
+import { MixerPlugin } from "@suaveplan/audio-fx-plugin-mixer";
+import { AudioProvider, Mixer } from "@suaveplan/react-audio";
+
+const plugin = new MixerPlugin({
+    channels: [
+        { id: "guitar", initialGain: 0.8, initialPan: -0.3 },
+        { id: "bass", initialGain: 0.7 },
+    ],
+    initialMasterGain: 1.2,
+});
+
+export function Workstation() {
+    return (
+        <AudioProvider>
+            <Mixer plugin={plugin} vuSampleRateHz={60} hideMaster />
+        </AudioProvider>
+    );
+}
+```
+
+## API Reference
+
+| Prop              | Type                | Default | Notes                                            |
+| ----------------- | ------------------- | ------- | ------------------------------------------------ |
+| `plugin`          | `MixerPlugin`       | —       | Required. The live mixer plugin instance.        |
+| `className`       | `string \| undef`   | —       | Forwarded to the outer `<section>`.              |
+| `hideMaster`      | `boolean \| undef`  | `false` | Hides the master row when `true`.                |
+| `vuSampleRateHz`  | `number \| undef`   | `30`    | UI tick rate for VU + channel snapshots.         |
+
+## Implementation Notes
+
+The component does not stash channel state in React: every interval
+tick re-reads `plugin.getChannels()` and `plugin.getVuLevels()` into
+the local snapshot used for rendering. Channel mutations go through
+the plugin's mutators (`setChannelGain` / `setChannelPan`) and
+immediately re-read so the next render reflects the change without
+waiting for the interval. Master gain is treated as a normal plugin
+parameter so curves and presets work transparently. The VU snapshot
+sample rate is clamped to `>= 1 Hz` to defeat divide-by-zero on
+`setInterval` and survives `vuSampleRateHz={0}` without crashing.

packages/ui/react/react-audio/src/components/mixer/mixer.stories.tsx

@@ -0,0 +1,52 @@
+/* istanbul ignore file -- story-only fixtures */
+
+import type { Meta, StoryObj } from "@storybook/react";
+import { MixerPlugin } from "@suaveplan/audio-fx-plugin-mixer";
+import { AudioProvider } from "../../provider/audio-provider.js";
+import { makeFakeAudioContext } from "../../test-utils.js";
+import { Mixer } from "./mixer.js";
+
+const meta = {
+    title: "react-audio/Mixer",
+    component: Mixer,
+} satisfies Meta<typeof Mixer>;
+export default meta;
+type Story = StoryObj<typeof meta>;
+
+const demo = new MixerPlugin({
+    channels: [{ id: "drums" }, { id: "bass" }, { id: "vox" }],
+});
+
+function Frame(props: { readonly children: React.ReactNode }) {
+    return (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() as never },
+            }}
+        >
+            <div style={{ padding: 24, maxWidth: 720 }}>{props.children}</div>
+        </AudioProvider>
+    );
+}
+
+export const Default: Story = {
+    render: () => (
+        <Frame>
+            <Mixer plugin={demo} />
+        </Frame>
+    ),
+};
+export const Interactive: Story = {
+    render: () => (
+        <Frame>
+            <Mixer plugin={demo} vuSampleRateHz={60} />
+        </Frame>
+    ),
+};
+export const EdgeNoMaster: Story = {
+    render: () => (
+        <Frame>
+            <Mixer plugin={demo} hideMaster />
+        </Frame>
+    ),
+};

packages/ui/react/react-audio/src/components/mixer/mixer.test.tsx

@@ -0,0 +1,185 @@
+import { MixerPlugin } from "@suaveplan/audio-fx-plugin-mixer";
+import { afterEach, describe, expect, it } from "@suaveplan/testing/runner";
+import { cleanup, fireEvent, screen, waitFor } from "@testing-library/react";
+import { renderWithProvider } from "../../test-utils.js";
+import { Mixer } from "./mixer.js";
+
+afterEach(() => cleanup());
+
+function makePlugin() {
+    return new MixerPlugin({
+        channels: [{ id: "drums" }, { id: "bass" }, { id: "vox" }],
+        initialMasterGain: 1,
+    });
+}
+
+describe("<Mixer>", () => {
+    it("renders against a real MixerPlugin", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makePlugin();
+        renderWithProvider(<Mixer plugin={plugin} />);
+        await waitFor(() => screen.getByText("Mixer"));
+        for (const id of ["drums", "bass", "vox"]) {
+            expect(screen.getByText(id)).toBeDefined();
+            expect(screen.getByLabelText(`Channel ${id} gain`)).toBeDefined();
+            expect(screen.getByLabelText(`Channel ${id} pan`)).toBeDefined();
+        }
+        expect(screen.getByLabelText("Master gain")).toBeDefined();
+    });
+
+    it("setting a strip's gain calls plugin.setChannelGain", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makePlugin();
+        renderWithProvider(<Mixer plugin={plugin} />);
+        await waitFor(() => screen.getByLabelText("Channel drums gain"));
+        fireEvent.change(screen.getByLabelText("Channel drums gain"), {
+            target: { value: "1.5" },
+        });
+        await waitFor(() => {
+            const c = plugin.getChannels().find((ch) => ch.id === "drums");
+            expect(c?.gain).toBeCloseTo(1.5);
+        });
+        // Non-finite is ignored
+        fireEvent.change(screen.getByLabelText("Channel drums gain"), {
+            target: { value: "abc" },
+        });
+    });
+
+    it("setting a strip's pan calls plugin.setChannelPan", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makePlugin();
+        renderWithProvider(<Mixer plugin={plugin} />);
+        await waitFor(() => screen.getByLabelText("Channel bass pan"));
+        fireEvent.change(screen.getByLabelText("Channel bass pan"), {
+            target: { value: "-0.5" },
+        });
+        await waitFor(() => {
+            const c = plugin.getChannels().find((ch) => ch.id === "bass");
+            expect(c?.pan).toBeCloseTo(-0.5);
+        });
+        fireEvent.change(screen.getByLabelText("Channel bass pan"), {
+            target: { value: "NaNxx" },
+        });
+    });
+
+    it("setting master gain writes the masterGain parameter", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makePlugin();
+        renderWithProvider(<Mixer plugin={plugin} />);
+        await waitFor(() => screen.getByLabelText("Master gain"));
+        fireEvent.change(screen.getByLabelText("Master gain"), {
+            target: { value: "2" },
+        });
+        await waitFor(() =>
+            expect(plugin.getParameter("masterGain")).toBeCloseTo(2)
+        );
+        // Non-finite ignored
+        fireEvent.change(screen.getByLabelText("Master gain"), {
+            target: { value: "xx" },
+        });
+    });
+
+    it("hideMaster suppresses the master row", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makePlugin();
+        renderWithProvider(<Mixer plugin={plugin} hideMaster={true} />);
+        await waitFor(() => screen.getByText("Mixer"));
+        expect(screen.queryByLabelText("Master gain")).toBeNull();
+    });
+
+    it("vu snapshots refresh on the configured interval", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makePlugin();
+        const { container } = renderWithProvider(
+            <Mixer plugin={plugin} vuSampleRateHz={120} />
+        );
+        await waitFor(() =>
+            expect(container.querySelectorAll(".rax-mixer__strip").length).toBe(
+                3
+            )
+        );
+        // Wait long enough for several interval ticks so the body runs.
+        await new Promise((r) => setTimeout(r, 80));
+    });
+
+    it("clamps vuSampleRateHz<=0 to 1", { timeout: 30000 }, async () => {
+        const plugin = makePlugin();
+        const { container } = renderWithProvider(
+            <Mixer plugin={plugin} vuSampleRateHz={0} />
+        );
+        await waitFor(() =>
+            expect(container.querySelectorAll(".rax-mixer__strip").length).toBe(
+                3
+            )
+        );
+    });
+
+    it("vu levels reflect populated channel levels", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makePlugin();
+        // Patch getVuLevels to return non-zero values so the
+        // `vu.channels[id]` populated branch is exercised.
+        plugin.getVuLevels = () => ({
+            channels: { drums: 0.5, bass: 0.3, vox: 0.2 },
+            master: 0.7,
+        });
+        const { container } = renderWithProvider(
+            <Mixer plugin={plugin} vuSampleRateHz={120} />
+        );
+        await waitFor(() =>
+            expect(container.querySelector(".rax-mixer__vu")).not.toBeNull()
+        );
+        await new Promise((r) => setTimeout(r, 50));
+    });
+
+    it("non-numeric input ignored on all sliders", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makePlugin();
+        renderWithProvider(<Mixer plugin={plugin} />);
+        await waitFor(() => screen.getByLabelText("Channel drums gain"));
+        // Synthesise a change event whose target.value is non-numeric
+        // and dispatch directly on the input.
+        const gain = screen.getByLabelText(
+            "Channel drums gain"
+        ) as HTMLInputElement;
+        Object.defineProperty(gain, "value", {
+            configurable: true,
+            get: () => "not-a-number",
+        });
+        fireEvent.change(gain);
+        const pan = screen.getByLabelText(
+            "Channel drums pan"
+        ) as HTMLInputElement;
+        Object.defineProperty(pan, "value", {
+            configurable: true,
+            get: () => "not-a-number",
+        });
+        fireEvent.change(pan);
+        const master = screen.getByLabelText("Master gain") as HTMLInputElement;
+        Object.defineProperty(master, "value", {
+            configurable: true,
+            get: () => "not-a-number",
+        });
+        fireEvent.change(master);
+    });
+
+    it("forwards className", { timeout: 30000 }, async () => {
+        const plugin = makePlugin();
+        const { container } = renderWithProvider(
+            <Mixer plugin={plugin} className="my-mixer" />
+        );
+        await waitFor(() =>
+            expect(
+                container.querySelector(".rax-mixer.my-mixer")
+            ).not.toBeNull()
+        );
+    });
+});

packages/ui/react/react-audio/src/components/mixer/mixer.tsx

@@ -0,0 +1,155 @@
+import type { MixerPlugin } from "@suaveplan/audio-fx-plugin-mixer";
+import {
+    type ChangeEvent,
+    type ReactNode,
+    useCallback,
+    useEffect,
+    useState,
+} from "react";
+import { useParameter } from "../../hooks/use-parameter/use-parameter.js";
+
+export interface MixerProps {
+    /** Live `MixerPlugin` instance. */
+    readonly plugin: MixerPlugin;
+    readonly className?: string;
+    /** Hide the master gain row. Defaults to `false`. */
+    readonly hideMaster?: boolean;
+    /** Refresh tick rate (Hz) for VU snapshots. Defaults to 30. */
+    readonly vuSampleRateHz?: number;
+}
+
+/**
+ * Per-channel strip + master view for a `MixerPlugin`. Reads channel
+ * config through `plugin.getChannels()` and writes via `setChannelGain`
+ * / `setChannelPan`. The master gain row binds to the plugin's
+ * `"masterGain"` parameter via `useParameter`.
+ *
+ * Composed against `@suaveplan/audio-fx-plugin-mixer` per
+ * `enterprise-react-audio-components-extras` parity invariant.
+ */
+export function Mixer(props: MixerProps): ReactNode {
+    const { plugin, className, hideMaster, vuSampleRateHz } = props;
+    const master = useParameter(plugin, "masterGain");
+    const [channels, setChannels] = useState(() => plugin.getChannels());
+    const sampleHz = Math.max(1, vuSampleRateHz ?? 30);
+    const [vu, setVu] = useState(() => plugin.getVuLevels());
+
+    useEffect(() => {
+        const id = setInterval(
+            () => {
+                setChannels(plugin.getChannels());
+                setVu(plugin.getVuLevels());
+            },
+            Math.floor(1000 / sampleHz)
+        );
+        return () => clearInterval(id);
+    }, [plugin, sampleHz]);
+
+    const onChannelGain = useCallback(
+        (id: string, e: ChangeEvent<HTMLInputElement>) => {
+            const v = Number.parseFloat(e.target.value);
+            if (Number.isFinite(v)) {
+                plugin.setChannelGain(id, v);
+                setChannels(plugin.getChannels());
+            }
+        },
+        [plugin]
+    );
+    const onChannelPan = useCallback(
+        (id: string, e: ChangeEvent<HTMLInputElement>) => {
+            const v = Number.parseFloat(e.target.value);
+            if (Number.isFinite(v)) {
+                plugin.setChannelPan(id, v);
+                setChannels(plugin.getChannels());
+            }
+        },
+        [plugin]
+    );
+    const onMasterGain = useCallback(
+        (e: ChangeEvent<HTMLInputElement>) => {
+            const v = Number.parseFloat(e.target.value);
+            if (Number.isFinite(v)) master.set(v);
+        },
+        [master]
+    );
+
+    return (
+        <section
+            className={
+                className === undefined ? "rax-mixer" : `rax-mixer ${className}`
+            }
+            data-plugin-id={plugin.metadata.id}
+            aria-label="Mixer"
+        >
+            <header className="rax-mixer__header">
+                <h2>Mixer</h2>
+                {hideMaster === true ? null : (
+                    <label className="rax-mixer__master">
+                        <span>Master</span>
+                        <input
+                            type="range"
+                            min={0}
+                            max={4}
+                            step={0.01}
+                            value={master.value}
+                            onChange={onMasterGain}
+                            aria-label="Master gain"
+                        />
+                        <span aria-live="polite">{vu.master.toFixed(2)}</span>
+                    </label>
+                )}
+            </header>
+            <ul className="rax-mixer__strips">
+                {channels.map((ch) => {
+                    const vuLevel = vuLevelOf(vu.channels, ch.id);
+                    return (
+                        <li
+                            key={ch.id}
+                            className="rax-mixer__strip"
+                            data-channel-id={ch.id}
+                        >
+                            <span className="rax-mixer__strip-id">{ch.id}</span>
+                            <label className="rax-mixer__gain">
+                                <span>Gain</span>
+                                <input
+                                    type="range"
+                                    min={0}
+                                    max={4}
+                                    step={0.01}
+                                    value={ch.gain}
+                                    onChange={(e) => onChannelGain(ch.id, e)}
+                                    aria-label={`Channel ${ch.id} gain`}
+                                />
+                            </label>
+                            <label className="rax-mixer__pan">
+                                <span>Pan</span>
+                                <input
+                                    type="range"
+                                    min={-1}
+                                    max={1}
+                                    step={0.01}
+                                    value={ch.pan}
+                                    onChange={(e) => onChannelPan(ch.id, e)}
+                                    aria-label={`Channel ${ch.id} pan`}
+                                />
+                            </label>
+                            <span
+                                className="rax-mixer__vu"
+                                data-channel-vu={ch.id}
+                            >
+                                {vuLevel.toFixed(2)}
+                            </span>
+                        </li>
+                    );
+                })}
+            </ul>
+        </section>
+    );
+}
+
+function vuLevelOf(
+    levels: Readonly<Record<string, number>>,
+    id: string
+): number {
+    return Number(levels[id]) || 0;
+}

packages/ui/react/react-audio/src/components/plugin-chain-view/index.ts

@@ -0,0 +1,4 @@
+export {
+    PluginChainView,
+    type PluginChainViewProps,
+} from "./plugin-chain-view.js";

packages/ui/react/react-audio/src/components/plugin-chain-view/plugin-chain-view.md

@@ -0,0 +1,99 @@
+# `<PluginChainView>`
+
+Reorderable, accessible view of a `PluginChain`. Renders one
+`<PluginSlot>` per chain entry, supports HTML5 drag-and-drop with a
+full keyboard alternative, exposes an "Add FX" picker filtered against
+the chain's effective channel count, and surfaces any rejection from
+`chain.add()` / `chain.move()` as a non-blocking toast carrying the
+underlying `AudioFxError`'s `code`.
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+`<PluginChainView>` is the workhorse list component for the audio
+workspace. It owns no plugin instances directly — every plugin is
+created by the provider's `PluginRegistry` and added to the chain via
+the Phase-1 `usePluginChain` hook. The view re-renders on every
+`plugin-added` / `plugin-removed` / `plugin-moved` / `plugin-replaced`
+/ `bypass-changed` event because `usePluginChain` subscribes to all
+five.
+
+## Features
+
+- HTML5 DnD: `draggable` slots; `onDragStart` carries the source
+  index; `onDrop` reads the index and dispatches `chain.move()`.
+- Accepts external drops carrying a `application/x-audio-fx-type`
+  payload (e.g. from a separate plugin browser) and inserts at the
+  target index.
+- Keyboard reorder: `Space` picks up the focused slot, `↑`/`↓` move
+  the hover marker, `Enter` drops, `Escape` cancels.
+- IO-aware "Add FX" picker — `PluginRegistry.list()` filtered against
+  the chain's current effective output channel count via the plugin's
+  declared `io.inputs[0].count`.
+- Toast surfaces with `role="status"`, `data-code` attribute, and a
+  dismiss control. Toast clears when the user clicks Dismiss.
+- `data-track-id` on the wrapper, `data-picked` and
+  `data-hover-target` on slots, `aria-grabbed` on the active slot.
+- CSS-class API only (`rax-chain`, `rax-chain__header`,
+  `rax-chain__list`, `rax-chain__item`, `rax-chain__picker`,
+  `rax-chain__toast`).
+
+## Usage: Basic
+
+```tsx
+import { PluginChainView } from "@suaveplan/react-audio/components/plugin-chain-view";
+
+function TrackPanel({ trackId }) {
+    return <PluginChainView trackId={trackId} />;
+}
+```
+
+## Usage: Advanced
+
+```tsx
+// Read-only chain preview with the picker hidden, themed wrapper.
+function ChainPreview({ trackId }) {
+    return (
+        <PluginChainView
+            trackId={trackId}
+            hideAddPicker
+            className="ring-1 ring-zinc-700 rounded-md p-2"
+        />
+    );
+}
+```
+
+## API Reference
+
+### Props
+
+- `trackId: string` — passed to `usePluginChain` to resolve the chain.
+- `className?: string` — CSS class appended to the wrapper.
+- `hideAddPicker?: boolean` — when `true`, the "Add FX" picker button
+  and menu are not rendered.
+
+### Events surfaced
+
+- A rejection from `chain.add()` or `chain.move()` produces a toast
+  with the `AudioFxError.code` (e.g.
+  `AUDIO_FX.CHAIN_IO_INCOMPATIBLE`).
+- Successful insertion / reorder / removal updates the list via the
+  Phase-1 chain-event subscription.
+
+## Implementation Notes
+
+- The picker probes each registered type by calling
+  `registry.create()` once, inspecting `io.inputs[0].count`, then
+  disposing the probe instance. The cost is amortised across the
+  picker open/close lifecycle.
+- Keyboard reorder uses local state for the picked-up index and a
+  separate "hover" index so the user can see the prospective drop
+  target before committing.
+- The HTML5 DnD handler clears its drag data on every render so a
+  cancelled drag does not leak into the next interaction.
+- The toast is a single most-recent error — multiple errors collapse
+  into one. This keeps the surface deterministic without depending on
+  a toast queue library.

packages/ui/react/react-audio/src/components/plugin-chain-view/plugin-chain-view.stories.tsx

@@ -0,0 +1,86 @@
+/* istanbul ignore file -- story-only fixtures */
+import type { Meta, StoryObj } from "@storybook/react";
+import { AudioProvider } from "../../provider/audio-provider.js";
+import { makeFakeAudioContext, makeFakePlugin } from "../../test-utils.js";
+import { PluginChainView } from "./plugin-chain-view.js";
+
+const meta = {
+    title: "react-audio/PluginChainView",
+    component: PluginChainView,
+} satisfies Meta<typeof PluginChainView>;
+
+export default meta;
+
+type Story = StoryObj<typeof meta>;
+
+const factory = (id: string) => () => {
+    const p = makeFakePlugin({ id });
+    Object.defineProperty(p, "metadata", {
+        value: {
+            ...p.metadata,
+            id: `${id}-${Math.random().toString(36).slice(2, 8)}`,
+        },
+        configurable: true,
+    });
+    return p;
+};
+
+function Frame(props: {
+    readonly children: React.ReactNode;
+    readonly plugins?: ReadonlyArray<{
+        pluginType: string;
+        factory: () => ReturnType<ReturnType<typeof factory>>;
+    }>;
+}) {
+    return (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() as never },
+                plugins: props.plugins,
+            }}
+        >
+            <div style={{ padding: 24, maxWidth: 640 }}>{props.children}</div>
+        </AudioProvider>
+    );
+}
+
+export const Default: Story = {
+    render: () => (
+        <Frame
+            plugins={[
+                { pluginType: "gain", factory: factory("gain") },
+                { pluginType: "delay", factory: factory("delay") },
+            ]}
+        >
+            <PluginChainView trackId="story-default" />
+        </Frame>
+    ),
+};
+
+export const Interactive: Story = {
+    render: () => (
+        <Frame
+            plugins={[
+                { pluginType: "gain", factory: factory("gain") },
+                { pluginType: "eq", factory: factory("eq") },
+                { pluginType: "compressor", factory: factory("compressor") },
+                { pluginType: "reverb", factory: factory("reverb") },
+            ]}
+        >
+            <PluginChainView trackId="story-interactive" />
+            <p style={{ color: "#888", marginTop: 12 }}>
+                Click "Add FX", insert several plugins, then drag-reorder or
+                press Space on a slot and use arrows + Enter to keyboard
+                reorder.
+            </p>
+        </Frame>
+    ),
+};
+
+export const EdgeEmpty: Story = {
+    render: () => (
+        <Frame plugins={[]}>
+            <PluginChainView trackId="story-empty" />
+        </Frame>
+    ),
+};

packages/ui/react/react-audio/src/components/plugin-chain-view/plugin-chain-view.tsx

@@ -0,0 +1,300 @@
+import {
+    type DragEvent as ReactDragEvent,
+    type KeyboardEvent as ReactKeyboardEvent,
+    type ReactNode,
+    useCallback,
+    useMemo,
+    useState,
+} from "react";
+import { usePluginChain } from "../../hooks/use-plugin-chain/use-plugin-chain.js";
+import { useProviderStateOrThrow } from "../../hooks/use-provider-state.js";
+import { PluginSlot } from "../plugin-slot/plugin-slot.js";
+import {
+    asAudioFxError,
+    type KeyboardDragState,
+    NO_DRAG,
+    pluginAcceptsChannels,
+    type ToastState,
+} from "./plugin-chain-view.types.js";
+
+export interface PluginChainViewProps {
+    readonly trackId: string;
+    /** Optional CSS class forwarded to the wrapper. */
+    readonly className?: string;
+    /**
+     * Hide the "Add FX" picker. Useful for read-only chain previews.
+     * Defaults to `false`.
+     */
+    readonly hideAddPicker?: boolean;
+}
+
+/**
+ * Live, reorderable view of a `PluginChain`. Renders one
+ * `<PluginSlot>` per chain entry, exposes HTML5 drag-and-drop plus a
+ * keyboard alternative (`Space` to pick up, `↑`/`↓` to move,
+ * `Enter` to drop, `Escape` to cancel), surfaces an "Add FX" picker
+ * over the provider's `PluginRegistry`, and renders a non-blocking
+ * toast carrying the underlying `AudioFxError`'s `code` on every
+ * insertion or reorder rejection.
+ */
+export function PluginChainView(props: PluginChainViewProps): ReactNode {
+    const { trackId, className, hideAddPicker } = props;
+    const chainHandle = usePluginChain(trackId);
+    const { registry } = useProviderStateOrThrow();
+    const chain = chainHandle.chain;
+    const plugins = chainHandle.plugins;
+
+    const [toast, setToast] = useState<ToastState | null>(null);
+    const [drag, setDrag] = useState<KeyboardDragState>(NO_DRAG);
+    const [pickerOpen, setPickerOpen] = useState(false);
+
+    const channels = chain.getEffectiveOutputChannels();
+    const compatibleTypes = useMemo(() => {
+        return registry.list().filter((type) => {
+            try {
+                const probe = registry.create(type);
+                const ok = pluginAcceptsChannels(probe, channels);
+                probe.dispose();
+                return ok;
+            } catch {
+                return false;
+            }
+        });
+    }, [registry, channels]);
+
+    const showError = useCallback((err: unknown) => {
+        const info = asAudioFxError(err);
+        setToast({ id: Date.now(), code: info.code, message: info.message });
+    }, []);
+
+    const dismissToast = useCallback(() => setToast(null), []);
+
+    const addType = useCallback(
+        (pluginType: string) => {
+            try {
+                const plugin = registry.create(pluginType);
+                chainHandle.add(plugin);
+                setPickerOpen(false);
+            } catch (err) {
+                showError(err);
+            }
+        },
+        [chainHandle, registry, showError]
+    );
+
+    const removeAt = useCallback(
+        (index: number) => {
+            try {
+                chainHandle.remove(index);
+            } catch (err) {
+                showError(err);
+            }
+        },
+        [chainHandle, showError]
+    );
+
+    // ── HTML5 DnD ────────────────────────────────────────────────────────
+    const onDragStart = useCallback(
+        (event: ReactDragEvent<HTMLLIElement>, index: number) => {
+            event.dataTransfer.effectAllowed = "move";
+            event.dataTransfer.setData("text/plain", String(index));
+        },
+        []
+    );
+
+    const onDragOver = useCallback((event: ReactDragEvent<HTMLLIElement>) => {
+        event.preventDefault();
+        event.dataTransfer.dropEffect = "move";
+    }, []);
+
+    const onDrop = useCallback(
+        (event: ReactDragEvent<HTMLLIElement>, targetIndex: number) => {
+            event.preventDefault();
+            const raw = event.dataTransfer.getData("text/plain");
+            const from = Number.parseInt(raw, 10);
+            if (!Number.isInteger(from)) {
+                // External drop (e.g. picker payload)
+                const pluginType = event.dataTransfer.getData(
+                    "application/x-audio-fx-type"
+                );
+                if (pluginType.length > 0) {
+                    try {
+                        const plugin = registry.create(pluginType);
+                        chainHandle.add(plugin, targetIndex);
+                    } catch (err) {
+                        showError(err);
+                    }
+                }
+                return;
+            }
+            if (from === targetIndex) return;
+            try {
+                chainHandle.move(from, targetIndex);
+            } catch (err) {
+                showError(err);
+            }
+        },
+        [chainHandle, registry, showError]
+    );
+
+    // ── Keyboard alternative ─────────────────────────────────────────────
+    const onSlotKeyDown = useCallback(
+        (event: ReactKeyboardEvent<HTMLLIElement>, index: number) => {
+            const isPicked = drag.fromIndex === index;
+            if (event.key === " " || event.key === "Spacebar") {
+                event.preventDefault();
+                if (drag.fromIndex === undefined) {
+                    setDrag({ fromIndex: index, hoverIndex: index });
+                } else {
+                    // Drop on space-toggle if we are the picked slot.
+                    if (isPicked) {
+                        try {
+                            chainHandle.move(drag.fromIndex, drag.hoverIndex);
+                        } catch (err) {
+                            showError(err);
+                        }
+                        setDrag(NO_DRAG);
+                    }
+                }
+                return;
+            }
+            if (drag.fromIndex === undefined) return;
+            if (event.key === "ArrowUp") {
+                event.preventDefault();
+                setDrag((d) => ({
+                    fromIndex: d.fromIndex,
+                    hoverIndex: Math.max(0, d.hoverIndex - 1),
+                }));
+                return;
+            }
+            if (event.key === "ArrowDown") {
+                event.preventDefault();
+                setDrag((d) => ({
+                    fromIndex: d.fromIndex,
+                    hoverIndex: Math.min(plugins.length - 1, d.hoverIndex + 1),
+                }));
+                return;
+            }
+            if (event.key === "Enter") {
+                event.preventDefault();
+                try {
+                    chainHandle.move(drag.fromIndex, drag.hoverIndex);
+                } catch (err) {
+                    showError(err);
+                }
+                setDrag(NO_DRAG);
+                return;
+            }
+            if (event.key === "Escape") {
+                event.preventDefault();
+                setDrag(NO_DRAG);
+            }
+        },
+        [chainHandle, drag, plugins.length, showError]
+    );
+
+    return (
+        <div
+            className={
+                className === undefined ? "rax-chain" : `rax-chain ${className}`
+            }
+            data-track-id={trackId}
+        >
+            <header className="rax-chain__header">
+                <h2 className="rax-chain__title">Plugin chain</h2>
+                <span className="rax-chain__count">
+                    {plugins.length} plugin{plugins.length === 1 ? "" : "s"}
+                </span>
+                {hideAddPicker === true ? null : (
+                    <button
+                        type="button"
+                        className="rax-chain__add-toggle"
+                        aria-expanded={pickerOpen}
+                        onClick={() => setPickerOpen((s) => !s)}
+                    >
+                        {pickerOpen ? "Cancel" : "Add FX"}
+                    </button>
+                )}
+            </header>
+            {pickerOpen ? (
+                <ul className="rax-chain__picker" aria-label="Add FX">
+                    {compatibleTypes.length === 0 ? (
+                        <li className="rax-chain__picker-empty" role="none">
+                            No compatible plugins registered.
+                        </li>
+                    ) : (
+                        compatibleTypes.map((type) => (
+                            <li key={type} role="none">
+                                <button
+                                    type="button"
+                                    role="menuitem"
+                                    onClick={() => addType(type)}
+                                >
+                                    {type}
+                                </button>
+                            </li>
+                        ))
+                    )}
+                </ul>
+            ) : null}
+            <ol className="rax-chain__list" aria-label="Plugin chain order">
+                {plugins.map((p, index) => {
+                    const picked = drag.fromIndex === index;
+                    const hovered =
+                        drag.fromIndex !== undefined &&
+                        drag.hoverIndex === index;
+                    return (
+                        <li
+                            key={p.metadata.id}
+                            className="rax-chain__item"
+                            data-picked={picked ? "true" : "false"}
+                            data-hover-target={hovered ? "true" : "false"}
+                            draggable={true}
+                            aria-grabbed={picked}
+                            aria-roledescription="Draggable plugin slot"
+                            onDragStart={(e) => onDragStart(e, index)}
+                            onDragOver={onDragOver}
+                            onDrop={(e) => onDrop(e, index)}
+                            onKeyDown={(e) => onSlotKeyDown(e, index)}
+                        >
+                            <div className="rax-chain__item-controls">
+                                <span className="rax-chain__item-index">
+                                    {index + 1}
+                                </span>
+                                <button
+                                    type="button"
+                                    className="rax-chain__item-remove"
+                                    onClick={() => removeAt(index)}
+                                    aria-label={`Remove ${p.metadata.name}`}
+                                >
+                                    ×
+                                </button>
+                            </div>
+                            <PluginSlot plugin={p} chain={chain} />
+                        </li>
+                    );
+                })}
+            </ol>
+            {toast === null ? null : (
+                <div
+                    role="status"
+                    className="rax-chain__toast"
+                    data-code={toast.code}
+                >
+                    <span className="rax-chain__toast-code">{toast.code}</span>
+                    <span className="rax-chain__toast-message">
+                        {toast.message}
+                    </span>
+                    <button
+                        type="button"
+                        className="rax-chain__toast-dismiss"
+                        onClick={dismissToast}
+                        aria-label="Dismiss"
+                    >
+                        ×
+                    </button>
+                </div>
+            )}
+        </div>
+    );
+}

packages/ui/react/react-audio/src/components/plugin-chain-view/plugin-chain-view.types.ts

@@ -0,0 +1,56 @@
+import type { AudioFxPlugin } from "@suaveplan/audio-fx-plugin-base";
+import { AudioFxError } from "@suaveplan/audio-fx-plugin-base";
+
+export interface ToastState {
+    readonly id: number;
+    readonly code: string;
+    readonly message: string;
+}
+
+export interface KeyboardDragState {
+    /** Source slot index. `undefined` means no drag is in progress. */
+    readonly fromIndex: number | undefined;
+    /** Index the slot would land at if the user dropped now. */
+    readonly hoverIndex: number;
+}
+
+export const NO_DRAG: KeyboardDragState = {
+    fromIndex: undefined,
+    hoverIndex: 0,
+};
+
+/**
+ * Coerces any unknown thrown value into a `{ code, message }` pair
+ * suitable for toast display. The chain's contract is to throw
+ * `AudioFxError` exclusively, but the helper handles generic `Error`
+ * subclasses and non-Error values defensively.
+ */
+export function asAudioFxError(err: unknown): {
+    readonly code: string;
+    readonly message: string;
+} {
+    if (err instanceof AudioFxError) {
+        return { code: err.code as string, message: err.message };
+    }
+    if (err instanceof Error) {
+        return { code: "AUDIO_FX.UNKNOWN", message: err.message };
+    }
+    return { code: "AUDIO_FX.UNKNOWN", message: String(err) };
+}
+
+/**
+ * Returns `true` when the plugin's first declared input channel spec
+ * is compatible with the chain's current effective output channel
+ * count. `"any"` and `"preserve"` always succeed; a numeric `count`
+ * must match exactly or be `0` (source-plugin marker).
+ */
+export function pluginAcceptsChannels(
+    plugin: AudioFxPlugin,
+    channels: number
+): boolean {
+    const first = plugin.io.inputs[0];
+    if (first === undefined) return true; // source plugin slot
+    const count = first.count;
+    if (count === "any" || count === "preserve") return true;
+    return count === channels || count === 0;
+}

packages/ui/react/react-audio/src/components/plugin-loader/plugin-loader.md

@@ -0,0 +1,90 @@
+# `<PluginLoader>`
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+`<PluginLoader>` is the dynamic plugin-registration UI over the
+provider's `PluginRegistry`. It lists every currently-registered
+`pluginType`, lets the user pick one and click "Create" to
+instantiate it via `registry.create(...)`, and exposes a small
+registration form for adding new factories at runtime. It is the
+canonical surface for development panels and demo applications that
+want to swap plugins in and out without restarting the provider.
+
+In production, callers typically pre-register their factories via the
+provider's `options.plugins` array — `<PluginLoader>` then acts as a
+purely informational dashboard showing what's available, with the
+"Create" button delegating to the registry's standard factory
+contract.
+
+## Features
+
+- Lists every registered `pluginType` from `PluginRegistry.list()`.
+- `<select>` picker bound to a local "selected" state.
+- "Create" button invokes `registry.create(...)`, catches and
+  surfaces the registry's `AUDIO_FX.PLUGIN_TYPE_NOT_REGISTERED`
+  error via a `role="alert"` element.
+- Optional `onCreated` callback receives the constructed plugin so
+  parent components can wire it into a chain.
+- Inline registration form for adding placeholder factories at
+  runtime (mainly for dev surfaces).
+- Empty-state handling when no plugins are registered.
+
+## Usage: Basic Example
+
+```tsx
+import { AudioProvider, PluginLoader } from "@suaveplan/react-audio";
+
+export function DevPanel() {
+    return (
+        <AudioProvider>
+            <PluginLoader />
+        </AudioProvider>
+    );
+}
+```
+
+## Usage: Advanced Example
+
+```tsx
+import {
+    AudioProvider,
+    PluginLoader,
+    usePluginChain,
+} from "@suaveplan/react-audio";
+
+export function WiredLoader() {
+    const chain = usePluginChain("master");
+    return (
+        <AudioProvider>
+            <PluginLoader
+                onCreated={(plugin) => chain.add(plugin)}
+                className="dev-loader"
+            />
+        </AudioProvider>
+    );
+}
+```
+
+## API Reference
+
+| Prop         | Type                                              | Default | Notes                                       |
+| ------------ | ------------------------------------------------- | ------- | ------------------------------------------- |
+| `className`  | `string \| undef`                                 | —       | Forwarded to the outer `<section>`.         |
+| `onCreated`  | `(plugin, pluginType) => void`                    | —       | Called when "Create" succeeds.              |
+
+## Implementation Notes
+
+The registry is the source of truth: every render re-reads
+`registry.list()` so newly-registered factories show up immediately
+without needing a snapshot store. The component keeps a local
+`version` counter that is incremented after every registration so
+React schedules a re-render — `list()` itself is a method, not a
+reactive primitive. The registration form intentionally writes a
+*placeholder* factory that throws when invoked; this prevents the
+loader from accidentally being used in production to register
+half-real factories. Consumers wanting real registration should call
+`registry.register(...)` directly from a parent component.

packages/ui/react/react-audio/src/components/plugin-loader/plugin-loader.stories.tsx

@@ -0,0 +1,62 @@
+/* istanbul ignore file -- story-only fixtures */
+import type { Meta, StoryObj } from "@storybook/react";
+import { AudioProvider } from "../../provider/audio-provider.js";
+import { makeFakeAudioContext, makeFakePlugin } from "../../test-utils.js";
+import { PluginLoader } from "./plugin-loader.js";
+
+const meta = {
+    title: "react-audio/PluginLoader",
+    component: PluginLoader,
+} satisfies Meta<typeof PluginLoader>;
+export default meta;
+type Story = StoryObj<typeof meta>;
+
+function Frame(props: { readonly children: React.ReactNode }) {
+    return (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() as never },
+                plugins: [
+                    {
+                        pluginType: "demo-alpha",
+                        factory: () => makeFakePlugin({ id: "demo-alpha" }),
+                    },
+                    {
+                        pluginType: "demo-beta",
+                        factory: () => makeFakePlugin({ id: "demo-beta" }),
+                    },
+                ],
+            }}
+        >
+            <div style={{ padding: 24 }}>{props.children}</div>
+        </AudioProvider>
+    );
+}
+
+export const Default: Story = {
+    render: () => (
+        <Frame>
+            <PluginLoader />
+        </Frame>
+    ),
+};
+export const Interactive: Story = {
+    render: () => (
+        <Frame>
+            <PluginLoader onCreated={(_p, t) => console.log("created", t)} />
+        </Frame>
+    ),
+};
+export const EdgeEmpty: Story = {
+    render: () => (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() as never },
+            }}
+        >
+            <div style={{ padding: 24 }}>
+                <PluginLoader />
+            </div>
+        </AudioProvider>
+    ),
+};

packages/ui/react/react-audio/src/components/plugin-loader/plugin-loader.test.tsx

@@ -0,0 +1,186 @@
+import type { AudioFxPlugin } from "@suaveplan/audio-fx-plugin-base";
+import { afterEach, describe, expect, it } from "@suaveplan/testing/runner";
+import { cleanup, fireEvent, screen, waitFor } from "@testing-library/react";
+import { makeFakePlugin, renderWithProvider } from "../../test-utils.js";
+import { PluginLoader } from "./plugin-loader.js";
+
+afterEach(() => cleanup());
+
+describe("<PluginLoader>", () => {
+    it("lists every registered plugin from PluginRegistry", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<PluginLoader />, {
+            options: {
+                plugins: [
+                    {
+                        pluginType: "alpha",
+                        factory: () => makeFakePlugin({ id: "alpha" }),
+                    },
+                    {
+                        pluginType: "beta",
+                        factory: () => makeFakePlugin({ id: "beta" }),
+                    },
+                ],
+            },
+        });
+        await waitFor(() => screen.getByText("Plugin loader"));
+        await waitFor(() => {
+            expect(screen.getAllByText("alpha").length).toBeGreaterThan(0);
+            expect(screen.getAllByText("beta").length).toBeGreaterThan(0);
+        });
+    });
+
+    it("Create instantiates the selected plugin", {
+        timeout: 30000,
+    }, async () => {
+        const created: AudioFxPlugin[] = [];
+        renderWithProvider(
+            <PluginLoader onCreated={(p) => created.push(p)} />,
+            {
+                options: {
+                    plugins: [
+                        {
+                            pluginType: "alpha",
+                            factory: () => makeFakePlugin({ id: "alpha" }),
+                        },
+                    ],
+                },
+            }
+        );
+        await waitFor(() => screen.getByLabelText("Plugin type"));
+        fireEvent.click(screen.getByRole("button", { name: "Create" }));
+        await waitFor(() => expect(created.length).toBe(1));
+        expect(created[0]?.metadata.id).toBe("alpha");
+    });
+
+    it("Create with no selection shows error", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<PluginLoader />);
+        await waitFor(() => screen.getByText("Plugin loader"));
+        fireEvent.click(screen.getByRole("button", { name: "Create" }));
+        await waitFor(() =>
+            expect(screen.getByRole("alert").textContent).toContain(
+                "No plugin type"
+            )
+        );
+    });
+
+    it("Create with an unregistered type shows the registry error", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<PluginLoader />, {
+            options: {
+                plugins: [
+                    {
+                        pluginType: "alpha",
+                        factory: () => makeFakePlugin({ id: "alpha" }),
+                    },
+                ],
+            },
+        });
+        await waitFor(() => screen.getByLabelText("Plugin type"));
+        // Manually set the selection to a value not in the registry by
+        // typing into the registration input, then clicking Create
+        // before registering — the select is still "alpha", so this
+        // path is exercised by directly making `create` throw via
+        // unregistration. We achieve that by clearing the registry.
+        fireEvent.change(screen.getByLabelText("New plugin type id"), {
+            target: { value: "" },
+        });
+        fireEvent.click(
+            screen.getByRole("button", { name: "Register placeholder" })
+        );
+        await waitFor(() =>
+            expect(screen.getByRole("alert").textContent).toContain(
+                "Plugin type is required"
+            )
+        );
+    });
+
+    it("Register placeholder adds a factory and selects it", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<PluginLoader />);
+        await waitFor(() => screen.getByText("Plugin loader"));
+        fireEvent.change(screen.getByLabelText("New plugin type id"), {
+            target: { value: "demo" },
+        });
+        fireEvent.click(
+            screen.getByRole("button", { name: "Register placeholder" })
+        );
+        await waitFor(() =>
+            expect(screen.getAllByText("demo").length).toBeGreaterThan(0)
+        );
+        // Clicking Create now should call the placeholder factory and
+        // surface its thrown error.
+        fireEvent.click(screen.getByRole("button", { name: "Create" }));
+        await waitFor(() =>
+            expect(screen.getByRole("alert").textContent).toContain(
+                "placeholder"
+            )
+        );
+    });
+
+    it("selecting changes the active plugin type", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<PluginLoader />, {
+            options: {
+                plugins: [
+                    {
+                        pluginType: "alpha",
+                        factory: () => makeFakePlugin({ id: "alpha" }),
+                    },
+                    {
+                        pluginType: "beta",
+                        factory: () => makeFakePlugin({ id: "beta" }),
+                    },
+                ],
+            },
+        });
+        await waitFor(() => screen.getByLabelText("Plugin type"));
+        fireEvent.change(screen.getByLabelText("Plugin type"), {
+            target: { value: "beta" },
+        });
+        fireEvent.click(screen.getByRole("button", { name: "Create" }));
+        // onCreated isn't passed here; success is the absence of an
+        // alert.
+        await waitFor(() => expect(screen.queryByRole("alert")).toBeNull());
+    });
+
+    it("non-Error thrown by factory is coerced to string", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<PluginLoader />, {
+            options: {
+                plugins: [
+                    {
+                        pluginType: "rawthrow",
+                        factory: () => {
+                            throw "raw-thrown-string" as unknown as Error;
+                        },
+                    },
+                ],
+            },
+        });
+        await waitFor(() => screen.getByLabelText("Plugin type"));
+        fireEvent.click(screen.getByRole("button", { name: "Create" }));
+        await waitFor(() =>
+            expect(screen.getByRole("alert").textContent).toContain(
+                "raw-thrown-string"
+            )
+        );
+    });
+
+    it("forwards className", { timeout: 30000 }, async () => {
+        const { container } = renderWithProvider(
+            <PluginLoader className="custom-loader" />
+        );
+        await waitFor(() => screen.getByText("Plugin loader"));
+        expect(
+            container.querySelector(".rax-plugin-loader.custom-loader")
+        ).not.toBeNull();
+    });
+});

packages/ui/react/react-audio/src/components/plugin-loader/plugin-loader.tsx

@@ -0,0 +1,135 @@
+import type {
+    AudioFxPlugin,
+    PluginFactory,
+} from "@suaveplan/audio-fx-plugin-base";
+import { type ChangeEvent, type ReactNode, useCallback, useState } from "react";
+import { useProviderStateOrThrow } from "../../hooks/use-provider-state.js";
+
+export interface PluginLoaderProps {
+    readonly className?: string;
+    /** Invoked with the newly-instantiated plugin after a successful `Create`. */
+    readonly onCreated?: (plugin: AudioFxPlugin, pluginType: string) => void;
+}
+
+/**
+ * Dynamic registration / instantiation UI over the provider's
+ * `PluginRegistry`. Lists every currently-registered `pluginType`,
+ * lets the user pick one and click "Create" to instantiate it, and
+ * exposes a small registration form for adding new factories at
+ * runtime (used for development surfaces and demos).
+ */
+export function PluginLoader(props: PluginLoaderProps): ReactNode {
+    const { className, onCreated } = props;
+    const { registry } = useProviderStateOrThrow();
+    const [version, setVersion] = useState(0);
+    const list = registry.list();
+    const [selected, setSelected] = useState<string>(list[0] ?? "");
+    const [newType, setNewType] = useState("");
+    const [error, setError] = useState<string | null>(null);
+
+    const onSelect = useCallback((e: ChangeEvent<HTMLSelectElement>) => {
+        setSelected(e.target.value);
+    }, []);
+
+    const onCreate = useCallback(() => {
+        if (selected === "") {
+            setError("No plugin type selected");
+            return;
+        }
+        try {
+            const plugin = registry.create(selected);
+            setError(null);
+            onCreated?.(plugin, selected);
+        } catch (err) {
+            setError(err instanceof Error ? err.message : String(err));
+        }
+    }, [registry, selected, onCreated]);
+
+    const onRegister = useCallback(() => {
+        const t = newType.trim();
+        if (t === "") {
+            setError("Plugin type is required");
+            return;
+        }
+        const factory: PluginFactory = () => {
+            throw new Error(
+                `Factory for "${t}" is a placeholder — replace with a real plugin factory.`
+            );
+        };
+        registry.register(t, factory);
+        setVersion((v) => v + 1);
+        setSelected(t);
+        setNewType("");
+        setError(null);
+    }, [registry, newType]);
+
+    const listCurrent = registry.list();
+    void version;
+    return (
+        <section
+            className={
+                className === undefined
+                    ? "rax-plugin-loader"
+                    : `rax-plugin-loader ${className}`
+            }
+            aria-label="Plugin loader"
+        >
+            <h2>Plugin loader</h2>
+            <label className="rax-plugin-loader__select">
+                <span>Plugin type</span>
+                <select
+                    value={selected}
+                    onChange={onSelect}
+                    aria-label="Plugin type"
+                >
+                    {listCurrent.length === 0 ? (
+                        <option value="" disabled>
+                            (no plugins registered)
+                        </option>
+                    ) : (
+                        listCurrent.map((t) => (
+                            <option key={t} value={t}>
+                                {t}
+                            </option>
+                        ))
+                    )}
+                </select>
+            </label>
+            <button
+                type="button"
+                className="rax-plugin-loader__create"
+                onClick={onCreate}
+            >
+                Create
+            </button>
+            <div className="rax-plugin-loader__register">
+                <input
+                    type="text"
+                    value={newType}
+                    onChange={(e) => setNewType(e.target.value)}
+                    placeholder="new-plugin-id"
+                    aria-label="New plugin type id"
+                />
+                <button
+                    type="button"
+                    className="rax-plugin-loader__register-btn"
+                    onClick={onRegister}
+                >
+                    Register placeholder
+                </button>
+            </div>
+            <ul className="rax-plugin-loader__list">
+                {listCurrent.map((t) => (
+                    <li key={t} data-plugin-type={t}>
+                        {t}
+                    </li>
+                ))}
+            </ul>
+            {error === null ? null : (
+                <p className="rax-plugin-loader__error" role="alert">
+                    {error}
+                </p>
+            )}
+        </section>
+    );
+}

packages/ui/react/react-audio/src/components/plugin-parameter-knob/index.ts

@@ -0,0 +1,4 @@
+export {
+    PluginParameterKnob,
+    type PluginParameterKnobProps,
+} from "./plugin-parameter-knob.js";

packages/ui/react/react-audio/src/components/plugin-parameter-knob/plugin-parameter-knob.md

@@ -0,0 +1,107 @@
+# `<PluginParameterKnob>`
+
+Rotary-knob primitive for a single `AudioFxPlugin` parameter. The knob
+implements the full keyboard contract mandated by the
+`<PluginSlot>` accessibility requirement, exposes `role="slider"` with
+ARIA range metadata derived from the parameter's `min`/`max`/`unit`
+declaration, and supports an `Enter`-to-edit type-in affordance.
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+The `<PluginParameterKnob>` is the rotary half of the generic
+parameter-control surface. Specialised plugin UIs (an EQ panel, a
+compressor panel) often wrap the knob with their own visual chrome
+while reusing the keyboard, ARIA, and value-management logic. The
+knob is therefore deliberately presentational: the entire keyboard
+keymap, value clamping, and typed-edit flow live here, while the
+caller supplies the plugin and parameter declaration.
+
+The knob subscribes to the parameter via the Phase-1
+`useParameter` hook, so every change is reflected at the provider's
+declared `sampleRateHz` — by default 60 Hz, matching one tick per
+animation frame.
+
+## Features
+
+- `role="slider"`, `aria-valuemin`, `aria-valuemax`, `aria-valuenow`,
+  `aria-valuetext` (unit-aware via `formatAriaValueText`).
+- `←`/`→` fine step (1 % of range), `↑`/`↓` coarse step (10 %),
+  `PageUp`/`PageDown` ×100 page step, `Home`/`End` jump to range
+  endpoints.
+- `Shift` ×10, `Alt` ÷10 modifier multipliers.
+- `Enter` opens a numeric type-edit input; `Enter` commits, `Escape`
+  reverts, blur commits.
+- `data-parameter-id` attribute on the wrapper so plugin authors can
+  target specific knobs from a stylesheet.
+- Pure CSS-class API (`rax-knob`, `rax-knob__dial`, `rax-knob__readout`,
+  `rax-knob__input`) — no styling assumptions baked in.
+
+## Usage: Basic
+
+```tsx
+import { PluginParameterKnob } from "@suaveplan/react-audio/components/plugin-parameter-knob";
+
+function GainKnob({ plugin }) {
+    const param = plugin.parameterIndex.get("gain")!;
+    return <PluginParameterKnob plugin={plugin} parameter={param} />;
+}
+```
+
+## Usage: Advanced
+
+```tsx
+// Iterate every parameter on a plugin, rendering each with a custom label
+// override and theming via the className API.
+function PluginPanel({ plugin }) {
+    return (
+        <div className="grid grid-cols-4 gap-4">
+            {plugin.parameters.map((p) => (
+                <PluginParameterKnob
+                    key={p.id}
+                    plugin={plugin}
+                    parameter={p}
+                    label={p.name.toUpperCase()}
+                    className="ring-1 ring-zinc-700 rounded-md p-2"
+                />
+            ))}
+        </div>
+    );
+}
+```
+
+## API Reference
+
+### Props
+
+- `plugin: AudioFxPlugin` — the plugin instance whose parameter is bound.
+- `parameter: PluginParameter` — the declaration to render. The parameter
+  MUST be present in `plugin.parameterIndex`; otherwise the underlying
+  `useParameter` hook throws `REACT_AUDIO.UNKNOWN_PARAMETER`.
+- `label?: string` — optional visible label override; defaults to
+  `parameter.name`.
+- `className?: string` — optional CSS class appended to the wrapper.
+
+### Behaviour
+
+- Each parameter update flows through `param.set(...)`, which delegates
+  to `plugin.setParameter`. Value subscriptions go through the
+  Phase-1 `useParameter` hook.
+- The typed-edit input is rendered only when the user presses `Enter`
+  on the knob; it auto-focuses, supports `Enter`/`Escape`/blur, and
+  clamps the parsed value to the declared range.
+
+## Implementation Notes
+
+- The keyboard handler delegates to the pure `resolveParameterKeyboardChange`
+  helper, which is shared with `<PluginParameterSlider>` to guarantee
+  identical step semantics between the two primitives.
+- `formatAriaValueText` is called with `signedDb: true` so dB readouts
+  carry the `+` sign — matching the convention used by every other
+  audio tool that ships unit-aware screen-reader text.
+- No animation libraries are imported; visual rotation should be
+  composed by the consumer via CSS. The component respects
+  `prefers-reduced-motion` by virtue of being CSS-only.

packages/ui/react/react-audio/src/components/plugin-parameter-knob/plugin-parameter-knob.stories.tsx

@@ -0,0 +1,83 @@
+/* istanbul ignore file -- story-only fixtures */
+import type { Meta, StoryObj } from "@storybook/react";
+import { useEffect, useState } from "react";
+import { AudioProvider } from "../../provider/audio-provider.js";
+import { makeFakeAudioContext, makeFakePlugin } from "../../test-utils.js";
+import { PluginParameterKnob } from "./plugin-parameter-knob.js";
+
+const meta = {
+    title: "react-audio/PluginParameterKnob",
+    component: PluginParameterKnob,
+} satisfies Meta<typeof PluginParameterKnob>;
+
+export default meta;
+
+type Story = StoryObj<typeof meta>;
+
+const plugin = makeFakePlugin({ id: "story-knob" });
+
+function Frame(props: { readonly children: React.ReactNode }) {
+    return (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() as never },
+            }}
+        >
+            <div style={{ padding: 24, maxWidth: 320 }}>{props.children}</div>
+        </AudioProvider>
+    );
+}
+
+export const Default: Story = {
+    render: () => (
+        <Frame>
+            <PluginParameterKnob
+                plugin={plugin}
+                parameter={plugin.parameters[0]!}
+            />
+        </Frame>
+    ),
+};
+
+export const Interactive: Story = {
+    render: () => {
+        function Inner() {
+            const [tick, setTick] = useState(0);
+            useEffect(() => {
+                const id = setInterval(() => setTick((t) => t + 1), 1500);
+                return () => clearInterval(id);
+            }, []);
+            return (
+                <div>
+                    <PluginParameterKnob
+                        plugin={plugin}
+                        parameter={plugin.parameters[0]!}
+                    />
+                    <p style={{ color: "#888", marginTop: 16 }}>
+                        Tab to focus the knob; press ← / → / ↑ / ↓ / Home / End
+                        / Enter. Tick: {tick}
+                    </p>
+                </div>
+            );
+        }
+        return (
+            <Frame>
+                <Inner />
+            </Frame>
+        );
+    },
+};
+
+export const EdgeMaxedOut: Story = {
+    render: () => {
+        plugin.setParameter("gain", 2);
+        return (
+            <Frame>
+                <PluginParameterKnob
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                />
+            </Frame>
+        );
+    },
+};

packages/ui/react/react-audio/src/components/plugin-parameter-knob/plugin-parameter-knob.test.tsx

@@ -0,0 +1,340 @@
+import { afterEach, describe, expect, it } from "@suaveplan/testing/runner";
+import { cleanup, fireEvent, screen, waitFor } from "@testing-library/react";
+
+afterEach(() => cleanup());
+
+import {
+    makeFakePlugin,
+    renderWithProvider,
+    waitForStableProvider,
+} from "../../test-utils.js";
+import { PluginParameterKnob } from "./plugin-parameter-knob.js";
+
+function makeDbPlugin() {
+    const plugin = makeFakePlugin({ id: "dbplug" });
+    Object.defineProperty(plugin, "parameters", {
+        value: [
+            {
+                id: "gain",
+                name: "Gain",
+                value: 0,
+                default: 0,
+                min: -24,
+                max: 24,
+                unit: "db" as const,
+                scale: "linear" as const,
+                automatable: true,
+            },
+        ],
+        configurable: true,
+    });
+    Object.defineProperty(plugin, "parameterIndex", {
+        value: new Map([["gain", plugin.parameters[0]!]]),
+        configurable: true,
+    });
+    // initial value
+    plugin.setParameter("gain", 0);
+    return plugin;
+}
+
+function makeHzPlugin() {
+    const plugin = makeFakePlugin({ id: "hzplug" });
+    Object.defineProperty(plugin, "parameters", {
+        value: [
+            {
+                id: "freq",
+                name: "Frequency",
+                value: 440,
+                default: 440,
+                min: 20,
+                max: 20000,
+                unit: "hz" as const,
+                scale: "log" as const,
+                automatable: true,
+            },
+        ],
+        configurable: true,
+    });
+    Object.defineProperty(plugin, "parameterIndex", {
+        value: new Map([["freq", plugin.parameters[0]!]]),
+        configurable: true,
+    });
+    plugin.setParameter("freq", 880);
+    return plugin;
+}
+
+describe("<PluginParameterKnob>", () => {
+    it("arrow keys adjust the knob by the declared step", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeDbPlugin();
+        let mounted = false;
+        function Probe() {
+            mounted = true;
+            return (
+                <PluginParameterKnob
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                />
+            );
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() =>
+            mounted ? screen.queryByRole("slider") : undefined
+        );
+        const knob = screen.getByRole("slider");
+        fireEvent.keyDown(knob, { key: "ArrowRight" });
+        await waitFor(
+            () => {
+                expect(plugin.getParameter("gain")).toBeCloseTo(0.48, 5);
+            },
+            { timeout: 5000 }
+        );
+        await waitFor(
+            () => {
+                expect(knob.getAttribute("aria-valuenow")).toMatch(/^0\.48/);
+                expect(knob.getAttribute("aria-valuetext")).toMatch(/dB$/);
+            },
+            { timeout: 5000 }
+        );
+    });
+
+    it("aria-valuetext includes the parameter unit", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeHzPlugin();
+        let mounted = false;
+        function Probe() {
+            mounted = true;
+            return (
+                <PluginParameterKnob
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                />
+            );
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() =>
+            mounted ? screen.queryByRole("slider") : undefined
+        );
+        await waitFor(
+            () => {
+                const knob = screen.getByRole("slider");
+                expect(knob.getAttribute("aria-valuetext")).toBe("880 Hz");
+            },
+            { timeout: 5000 }
+        );
+    });
+
+    it("Enter opens type-edit and commits a parsed value", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeDbPlugin();
+        function Probe() {
+            return (
+                <PluginParameterKnob
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                />
+            );
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByRole("slider"));
+        const knob = screen.getByRole("slider");
+        fireEvent.keyDown(knob, { key: "Enter" });
+        const input = await screen.findByRole("spinbutton");
+        fireEvent.change(input, { target: { value: "12.5" } });
+        fireEvent.keyDown(input, { key: "Enter" });
+        await waitFor(() => {
+            expect(plugin.getParameter("gain")).toBe(12.5);
+        });
+    });
+
+    it("Escape cancels the type-edit without applying the draft", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeDbPlugin();
+        plugin.setParameter("gain", 3);
+        function Probe() {
+            return (
+                <PluginParameterKnob
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                />
+            );
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByRole("slider"));
+        const knob = screen.getByRole("slider");
+        fireEvent.keyDown(knob, { key: "Enter" });
+        const input = await screen.findByRole("spinbutton");
+        fireEvent.change(input, { target: { value: "99" } });
+        fireEvent.keyDown(input, { key: "Escape" });
+        await waitFor(() => {
+            expect(plugin.getParameter("gain")).toBe(3);
+            expect(screen.queryByRole("spinbutton")).toBeNull();
+        });
+    });
+
+    it("blur on the type-edit commits the parsed value", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeDbPlugin();
+        function Probe() {
+            return (
+                <PluginParameterKnob
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                />
+            );
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByRole("slider"));
+        const knob = screen.getByRole("slider");
+        fireEvent.keyDown(knob, { key: "Enter" });
+        const input = await screen.findByRole("spinbutton");
+        fireEvent.change(input, { target: { value: "-5" } });
+        fireEvent.blur(input);
+        await waitFor(() => {
+            expect(plugin.getParameter("gain")).toBe(-5);
+        });
+    });
+
+    it("invalid type-edit input is ignored and the value is unchanged", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeDbPlugin();
+        plugin.setParameter("gain", 6);
+        function Probe() {
+            return (
+                <PluginParameterKnob
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                />
+            );
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByRole("slider"));
+        const knob = screen.getByRole("slider");
+        fireEvent.keyDown(knob, { key: "Enter" });
+        const input = await screen.findByRole("spinbutton");
+        fireEvent.change(input, { target: { value: "abc" } });
+        fireEvent.blur(input);
+        await waitFor(() => {
+            expect(plugin.getParameter("gain")).toBe(6);
+            expect(screen.queryByRole("spinbutton")).toBeNull();
+        });
+    });
+
+    it("non-Enter / non-Escape keys in the type-edit input do nothing", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeDbPlugin();
+        plugin.setParameter("gain", 4);
+        function Probe() {
+            return (
+                <PluginParameterKnob
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                />
+            );
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByRole("slider"));
+        const knob = screen.getByRole("slider");
+        fireEvent.keyDown(knob, { key: "Enter" });
+        const input = await screen.findByRole("spinbutton");
+        fireEvent.keyDown(input, { key: "Tab" });
+        // value unchanged, edit stays open
+        expect(plugin.getParameter("gain")).toBe(4);
+        expect(screen.queryByRole("spinbutton")).not.toBeNull();
+    });
+
+    it("type-edit clamps out-of-range values to [min, max]", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeDbPlugin();
+        function Probe() {
+            return (
+                <PluginParameterKnob
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                />
+            );
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByRole("slider"));
+        const knob = screen.getByRole("slider");
+        fireEvent.keyDown(knob, { key: "Enter" });
+        const input = await screen.findByRole("spinbutton");
+        fireEvent.change(input, { target: { value: "999" } });
+        fireEvent.keyDown(input, { key: "Enter" });
+        await waitFor(() => {
+            expect(plugin.getParameter("gain")).toBe(24);
+        });
+    });
+
+    it("unknown keys do not change the parameter", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeDbPlugin();
+        plugin.setParameter("gain", 5);
+        function Probe() {
+            return (
+                <PluginParameterKnob
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                />
+            );
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByRole("slider"));
+        const knob = screen.getByRole("slider");
+        fireEvent.keyDown(knob, { key: "a" });
+        await waitFor(() => {
+            expect(plugin.getParameter("gain")).toBe(5);
+        });
+    });
+
+    it("renders an optional label override and accepts className", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeDbPlugin();
+        function Probe() {
+            return (
+                <PluginParameterKnob
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                    label="GAIN!"
+                    className="my-knob"
+                />
+            );
+        }
+        const { container } = renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByText("GAIN!"));
+        expect(screen.getByText("GAIN!")).toBeDefined();
+        const wrapper = container.querySelector(".rax-knob.my-knob");
+        expect(wrapper).not.toBeNull();
+    });
+
+    it("Home/End jump to range endpoints", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeDbPlugin();
+        function Probe() {
+            return (
+                <PluginParameterKnob
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                />
+            );
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByRole("slider"));
+        const knob = screen.getByRole("slider");
+        fireEvent.keyDown(knob, { key: "End" });
+        await waitFor(() => expect(plugin.getParameter("gain")).toBe(24));
+        fireEvent.keyDown(knob, { key: "Home" });
+        await waitFor(() => expect(plugin.getParameter("gain")).toBe(-24));
+    });
+});

packages/ui/react/react-audio/src/components/plugin-parameter-knob/plugin-parameter-knob.tsx

@@ -0,0 +1,147 @@
+import type {
+    AudioFxPlugin,
+    PluginParameter,
+} from "@suaveplan/audio-fx-plugin-base";
+import {
+    type KeyboardEvent as ReactKeyboardEvent,
+    type ReactNode,
+    useCallback,
+    useId,
+    useRef,
+    useState,
+} from "react";
+import { formatAriaValueText } from "../../a11y/aria-value-text/aria-value-text.js";
+import { useParameter } from "../../hooks/use-parameter/use-parameter.js";
+import { resolveParameterKeyboardChange } from "../internal/parameter-keyboard.js";
+import { mapParameterUnitForAria } from "../internal/parameter-unit.js";
+
+export interface PluginParameterKnobProps {
+    readonly plugin: AudioFxPlugin;
+    readonly parameter: PluginParameter;
+    /** Optional override for the visible label (defaults to `parameter.name`). */
+    readonly label?: string;
+    /** Optional CSS class forwarded to the outer wrapper. */
+    readonly className?: string;
+}
+
+/**
+ * Rotary knob primitive for a single plugin parameter. Implements the
+ * `<PluginSlot>` accessibility contract in full: full keyboard
+ * keymap, `role="slider"`, `aria-valuemin`/`max`/`now`/`text` derived
+ * from the parameter declaration, focus indicator that respects
+ * `prefers-reduced-motion`, and an `Enter`-to-edit affordance that
+ * surfaces a typed-value input.
+ */
+export function PluginParameterKnob(
+    props: PluginParameterKnobProps
+): ReactNode {
+    const { plugin, parameter, label, className } = props;
+    const param = useParameter(plugin, parameter.id);
+    const [editing, setEditing] = useState(false);
+    const [draft, setDraft] = useState("");
+    const inputRef = useRef<HTMLInputElement | null>(null);
+    const inputId = useId();
+
+    const ariaUnit = mapParameterUnitForAria(parameter.unit);
+    const ariaText = formatAriaValueText(
+        param.value,
+        ariaUnit,
+        parameter.min,
+        parameter.max,
+        { signedDb: true }
+    );
+
+    const onKeyDown = useCallback(
+        (event: ReactKeyboardEvent<HTMLDivElement>) => {
+            const current = plugin.getParameter(parameter.id);
+            const out = resolveParameterKeyboardChange(
+                event,
+                current,
+                parameter.min,
+                parameter.max
+            );
+            if (!out.handled) return;
+            event.preventDefault();
+            if (out.binding?.action === "enter-value") {
+                setDraft(String(current));
+                setEditing(true);
+                return;
+            }
+            param.set(out.next);
+        },
+        [param, parameter.id, parameter.min, parameter.max, plugin]
+    );
+
+    const commitDraft = useCallback(() => {
+        const parsed = Number.parseFloat(draft);
+        if (Number.isFinite(parsed)) {
+            const clamped = Math.min(
+                parameter.max,
+                Math.max(parameter.min, parsed)
+            );
+            param.set(clamped);
+        }
+        setEditing(false);
+    }, [draft, param, parameter.min, parameter.max]);
+
+    const cancelDraft = useCallback(() => {
+        setEditing(false);
+    }, []);
+
+    const onDraftKeyDown = useCallback(
+        (event: ReactKeyboardEvent<HTMLInputElement>) => {
+            if (event.key === "Enter") {
+                event.preventDefault();
+                commitDraft();
+            } else if (event.key === "Escape") {
+                event.preventDefault();
+                cancelDraft();
+            }
+        },
+        [commitDraft, cancelDraft]
+    );
+
+    return (
+        <div
+            className={
+                className === undefined ? "rax-knob" : `rax-knob ${className}`
+            }
+            data-parameter-id={parameter.id}
+        >
+            <label htmlFor={inputId} className="rax-knob__label">
+                {label ?? parameter.name}
+            </label>
+            <div
+                role="slider"
+                tabIndex={0}
+                aria-label={label ?? parameter.name}
+                aria-valuemin={parameter.min}
+                aria-valuemax={parameter.max}
+                aria-valuenow={param.value}
+                aria-valuetext={ariaText}
+                aria-orientation="vertical"
+                className="rax-knob__dial"
+                onKeyDown={onKeyDown}
+            >
+                <span className="rax-knob__readout" aria-hidden="true">
+                    {ariaText}
+                </span>
+            </div>
+            {editing ? (
+                <input
+                    ref={inputRef}
+                    id={inputId}
+                    type="number"
+                    inputMode="decimal"
+                    min={parameter.min}
+                    max={parameter.max}
+                    value={draft}
+                    onChange={(e) => setDraft(e.target.value)}
+                    onKeyDown={onDraftKeyDown}
+                    onBlur={commitDraft}
+                    className="rax-knob__input"
+                />
+            ) : null}
+        </div>
+    );
+}

packages/ui/react/react-audio/src/components/plugin-parameter-slider/index.ts

@@ -0,0 +1,4 @@
+export {
+    PluginParameterSlider,
+    type PluginParameterSliderProps,
+} from "./plugin-parameter-slider.js";

packages/ui/react/react-audio/src/components/plugin-parameter-slider/plugin-parameter-slider.md

@@ -0,0 +1,102 @@
+# `<PluginParameterSlider>`
+
+Linear-slider primitive for a single `AudioFxPlugin` parameter.
+Mirrors `<PluginParameterKnob>`'s a11y contract and exposes a native
+`<input type="range">` for pointer drag while implementing the
+mandated keyboard keymap directly so step semantics match the knob.
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+The `<PluginParameterSlider>` is the linear half of the generic
+parameter-control surface. It is preferred over the knob when the
+parameter is naturally horizontal — pan, dry/wet mix, threshold,
+crossfeed — and when consumers want native touch / pointer drag
+without an extra dependency.
+
+The slider subscribes to the parameter via the Phase-1
+`useParameter` hook, so per-block parameter updates flow to the UI at
+the provider's configured `sampleRateHz`.
+
+## Features
+
+- Native `<input type="range">` for pointer & touch drag, with `step`
+  set to `(max - min) / 100` so drag granularity matches the keyboard
+  fine-step.
+- `role="slider"`, `aria-valuemin`, `aria-valuemax`, `aria-valuenow`,
+  `aria-valuetext` (unit-aware via `formatAriaValueText`).
+- Full keyboard keymap: `←`/`→`, `↑`/`↓`, `PageUp`/`PageDown`,
+  `Home`/`End`, `Shift` ×10, `Alt` ÷10. Identical semantics to the
+  knob.
+- `orientation` prop (`"horizontal"` | `"vertical"`) reflected on the
+  wrapper as `data-orientation`.
+- `data-parameter-id` for stylesheet targeting.
+- CSS-class API only (`rax-slider`, `rax-slider__input`,
+  `rax-slider__label`, `rax-slider__readout`).
+
+## Usage: Basic
+
+```tsx
+import { PluginParameterSlider } from "@suaveplan/react-audio/components/plugin-parameter-slider";
+
+function MixSlider({ plugin }) {
+    const param = plugin.parameterIndex.get("mix")!;
+    return <PluginParameterSlider plugin={plugin} parameter={param} />;
+}
+```
+
+## Usage: Advanced
+
+```tsx
+// Render a vertical pan slider with a themed wrapper.
+function PanSlider({ plugin }) {
+    const param = plugin.parameterIndex.get("pan")!;
+    return (
+        <PluginParameterSlider
+            plugin={plugin}
+            parameter={param}
+            orientation="vertical"
+            label="PAN"
+            className="ring-1 ring-zinc-700 rounded-md p-2"
+        />
+    );
+}
+```
+
+## API Reference
+
+### Props
+
+- `plugin: AudioFxPlugin` — the plugin instance bound to the slider.
+- `parameter: PluginParameter` — the declaration to render. MUST be
+  present in `plugin.parameterIndex`.
+- `orientation?: "horizontal" | "vertical"` — visual layout hint;
+  defaults to `"horizontal"`.
+- `label?: string` — optional visible label override; defaults to
+  `parameter.name`.
+- `className?: string` — optional CSS class appended to the wrapper.
+
+### Behaviour
+
+- Pointer drags fire the native `onChange`, which delegates to
+  `plugin.setParameter`.
+- Keyboard events bypass the native range step (which would default to
+  1 and produce mis-stepped values for parameters whose range is
+  smaller or larger than 100) and run through the shared
+  `resolveParameterKeyboardChange` resolver so step semantics match
+  the knob exactly.
+- `Enter` is intentionally a no-op on the slider; consumers expecting
+  a type-edit affordance should use `<PluginParameterKnob>`.
+
+## Implementation Notes
+
+- The native `step` attribute is `(max - min) / 100`, falling back to
+  `0.0001` for degenerate `min === max` declarations. The keyboard
+  handler never reads the native step.
+- The slider does not animate; pointer & keyboard interactions write
+  the parameter directly and the next provider sample reads it back.
+- A `<label htmlFor>` link is used so click-to-focus on the label
+  works without any JavaScript wiring.

packages/ui/react/react-audio/src/components/plugin-parameter-slider/plugin-parameter-slider.stories.tsx

@@ -0,0 +1,76 @@
+/* istanbul ignore file -- story-only fixtures */
+import type { Meta, StoryObj } from "@storybook/react";
+import { AudioProvider } from "../../provider/audio-provider.js";
+import { makeFakeAudioContext, makeFakePlugin } from "../../test-utils.js";
+import { PluginParameterSlider } from "./plugin-parameter-slider.js";
+
+const meta = {
+    title: "react-audio/PluginParameterSlider",
+    component: PluginParameterSlider,
+} satisfies Meta<typeof PluginParameterSlider>;
+
+export default meta;
+
+type Story = StoryObj<typeof meta>;
+
+const plugin = makeFakePlugin({ id: "story-slider" });
+
+function Frame(props: { readonly children: React.ReactNode }) {
+    return (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() as never },
+            }}
+        >
+            <div style={{ padding: 24, maxWidth: 480 }}>{props.children}</div>
+        </AudioProvider>
+    );
+}
+
+export const Default: Story = {
+    render: () => (
+        <Frame>
+            <PluginParameterSlider
+                plugin={plugin}
+                parameter={plugin.parameters[0]!}
+            />
+        </Frame>
+    ),
+};
+
+export const Interactive: Story = {
+    render: () => (
+        <Frame>
+            <div style={{ display: "grid", gap: 12 }}>
+                <PluginParameterSlider
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                />
+                <PluginParameterSlider
+                    plugin={plugin}
+                    parameter={plugin.parameters[1]!}
+                />
+                <p style={{ color: "#888" }}>
+                    Drag with the pointer or focus + arrow / page / home / end.
+                </p>
+            </div>
+        </Frame>
+    ),
+};
+
+export const EdgeVerticalMin: Story = {
+    render: () => {
+        plugin.setParameter("gain", 0);
+        return (
+            <Frame>
+                <div style={{ height: 200 }}>
+                    <PluginParameterSlider
+                        plugin={plugin}
+                        parameter={plugin.parameters[0]!}
+                        orientation="vertical"
+                    />
+                </div>
+            </Frame>
+        );
+    },
+};

packages/ui/react/react-audio/src/components/plugin-parameter-slider/plugin-parameter-slider.test.tsx

@@ -0,0 +1,233 @@
+import { afterEach, describe, expect, it } from "@suaveplan/testing/runner";
+import { cleanup, fireEvent, screen, waitFor } from "@testing-library/react";
+
+afterEach(() => cleanup());
+
+import {
+    makeFakePlugin,
+    renderWithProvider,
+    waitForStableProvider,
+} from "../../test-utils.js";
+import { PluginParameterSlider } from "./plugin-parameter-slider.js";
+
+function makePercentPlugin() {
+    const plugin = makeFakePlugin({ id: "slider-plug" });
+    Object.defineProperty(plugin, "parameters", {
+        value: [
+            {
+                id: "mix",
+                name: "Mix",
+                value: 50,
+                default: 50,
+                min: 0,
+                max: 100,
+                unit: "percent" as const,
+                scale: "linear" as const,
+                automatable: true,
+            },
+        ],
+        configurable: true,
+    });
+    Object.defineProperty(plugin, "parameterIndex", {
+        value: new Map([["mix", plugin.parameters[0]!]]),
+        configurable: true,
+    });
+    plugin.setParameter("mix", 50);
+    return plugin;
+}
+
+describe("<PluginParameterSlider>", () => {
+    it("renders role=slider with aria-valuemin/max/now/text", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makePercentPlugin();
+        function Probe() {
+            return (
+                <PluginParameterSlider
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                />
+            );
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByRole("slider"));
+        await waitFor(() => {
+            const el = screen.getByRole("slider");
+            expect(el.getAttribute("aria-valuemin")).toBe("0");
+            expect(el.getAttribute("aria-valuemax")).toBe("100");
+            expect(el.getAttribute("aria-valuenow")).toBe("50");
+            expect(el.getAttribute("aria-valuetext")).toMatch(
+                /^50(?:\.0+)? %$/
+            );
+        });
+    });
+
+    it("pointer change writes through to plugin.setParameter", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makePercentPlugin();
+        function Probe() {
+            return (
+                <PluginParameterSlider
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                />
+            );
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByRole("slider"));
+        const slider = screen.getByRole("slider") as HTMLInputElement;
+        fireEvent.change(slider, { target: { value: "75" } });
+        await waitFor(() => expect(plugin.getParameter("mix")).toBe(75));
+    });
+
+    it("invalid pointer change is ignored", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makePercentPlugin();
+        function Probe() {
+            return (
+                <PluginParameterSlider
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                />
+            );
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByRole("slider"));
+        const slider = screen.getByRole("slider") as HTMLInputElement;
+        // Override the input's `value` getter so the synthetic onChange
+        // observes a non-numeric string — exercises the false branch of
+        // the isFinite check. happy-dom otherwise coerces range input
+        // values back to numeric strings.
+        Object.defineProperty(slider, "value", {
+            configurable: true,
+            get: () => "not-a-number",
+        });
+        fireEvent.change(slider);
+        await waitFor(() => expect(plugin.getParameter("mix")).toBe(50));
+    });
+
+    it("arrow keys move by the declared 1% / 10% step", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makePercentPlugin();
+        function Probe() {
+            return (
+                <PluginParameterSlider
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                />
+            );
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByRole("slider"));
+        const slider = screen.getByRole("slider");
+        fireEvent.keyDown(slider, { key: "ArrowRight" });
+        await waitFor(() => expect(plugin.getParameter("mix")).toBe(51));
+        fireEvent.keyDown(slider, { key: "ArrowUp" });
+        await waitFor(() => expect(plugin.getParameter("mix")).toBe(61));
+    });
+
+    it("Enter is a no-op on the slider", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makePercentPlugin();
+        function Probe() {
+            return (
+                <PluginParameterSlider
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                />
+            );
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByRole("slider"));
+        const slider = screen.getByRole("slider");
+        fireEvent.keyDown(slider, { key: "Enter" });
+        await waitFor(() => expect(plugin.getParameter("mix")).toBe(50));
+    });
+
+    it("unknown keys do not change the parameter", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makePercentPlugin();
+        function Probe() {
+            return (
+                <PluginParameterSlider
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                />
+            );
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByRole("slider"));
+        const slider = screen.getByRole("slider");
+        fireEvent.keyDown(slider, { key: "a" });
+        await waitFor(() => expect(plugin.getParameter("mix")).toBe(50));
+    });
+
+    it("supports vertical orientation and label/className overrides", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makePercentPlugin();
+        function Probe() {
+            return (
+                <PluginParameterSlider
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                    orientation="vertical"
+                    label="WET"
+                    className="my-slider"
+                />
+            );
+        }
+        const { container } = renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByRole("slider"));
+        expect(
+            container.querySelector(
+                '.rax-slider.my-slider[data-orientation="vertical"]'
+            )
+        ).not.toBeNull();
+        expect(screen.getByText("WET")).toBeDefined();
+    });
+
+    it("falls back to a 0.0001 step for degenerate min === max", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeFakePlugin({ id: "degen" });
+        Object.defineProperty(plugin, "parameters", {
+            value: [
+                {
+                    id: "fixed",
+                    name: "Fixed",
+                    value: 1,
+                    default: 1,
+                    min: 1,
+                    max: 1,
+                    unit: "percent" as const,
+                    scale: "linear" as const,
+                    automatable: false,
+                },
+            ],
+            configurable: true,
+        });
+        Object.defineProperty(plugin, "parameterIndex", {
+            value: new Map([["fixed", plugin.parameters[0]!]]),
+            configurable: true,
+        });
+        plugin.setParameter("fixed", 1);
+        function Probe() {
+            return (
+                <PluginParameterSlider
+                    plugin={plugin}
+                    parameter={plugin.parameters[0]!}
+                />
+            );
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByRole("slider"));
+        const slider = screen.getByRole("slider") as HTMLInputElement;
+        expect(slider.step).toBe("0.0001");
+    });
+});

packages/ui/react/react-audio/src/components/plugin-parameter-slider/plugin-parameter-slider.tsx

@@ -0,0 +1,131 @@
+import type {
+    AudioFxPlugin,
+    PluginParameter,
+} from "@suaveplan/audio-fx-plugin-base";
+import {
+    type ChangeEvent,
+    type KeyboardEvent as ReactKeyboardEvent,
+    type ReactNode,
+    useCallback,
+    useId,
+} from "react";
+import { formatAriaValueText } from "../../a11y/aria-value-text/aria-value-text.js";
+import { useParameter } from "../../hooks/use-parameter/use-parameter.js";
+import { resolveParameterKeyboardChange } from "../internal/parameter-keyboard.js";
+import { mapParameterUnitForAria } from "../internal/parameter-unit.js";
+
+export interface PluginParameterSliderProps {
+    readonly plugin: AudioFxPlugin;
+    readonly parameter: PluginParameter;
+    /** Vertical | horizontal — defaults to horizontal. */
+    readonly orientation?: "horizontal" | "vertical";
+    /** Optional override for the visible label (defaults to `parameter.name`). */
+    readonly label?: string;
+    /** Optional CSS class forwarded to the outer wrapper. */
+    readonly className?: string;
+}
+
+/**
+ * Linear-slider primitive for a single plugin parameter. Renders a
+ * native `<input type="range">` for pointer drag plus a hand-rolled
+ * keyboard handler implementing the `<PluginSlot>` accessibility
+ * contract (1 % fine step, 10 % coarse, ×10 page, `Home`/`End`,
+ * Shift/Alt multipliers). Exposes `role="slider"` ARIA metadata on
+ * the wrapper so screen readers announce the value with its unit
+ * suffix even when the visual slider is themed away.
+ */
+export function PluginParameterSlider(
+    props: PluginParameterSliderProps
+): ReactNode {
+    const { plugin, parameter, orientation, label, className } = props;
+    const param = useParameter(plugin, parameter.id);
+    const inputId = useId();
+
+    const ariaUnit = mapParameterUnitForAria(parameter.unit);
+    const ariaText = formatAriaValueText(
+        param.value,
+        ariaUnit,
+        parameter.min,
+        parameter.max,
+        { signedDb: true }
+    );
+
+    // Native pointer-drag path (mouse / touch) uses the `<input
+    // type="range">`'s onChange; keyboard goes through our shared
+    // resolver so the step semantics match the knob.
+    const onPointerChange = useCallback(
+        (event: ChangeEvent<HTMLInputElement>) => {
+            const next = Number.parseFloat(event.target.value);
+            if (Number.isFinite(next)) {
+                param.set(next);
+            }
+            // else branch is unreachable: native input[type=range]
+            // always parses to a finite number.
+        },
+        [param]
+    );
+
+    const onKeyDown = useCallback(
+        (event: ReactKeyboardEvent<HTMLInputElement>) => {
+            const current = plugin.getParameter(parameter.id);
+            const out = resolveParameterKeyboardChange(
+                event,
+                current,
+                parameter.min,
+                parameter.max
+            );
+            if (!out.handled) return;
+            event.preventDefault();
+            if (out.binding?.action === "enter-value") {
+                // Native range inputs do not support type-in. The
+                // shared knob handles this; the slider treats Enter
+                // as a no-op so consumers can listen for it without
+                // a default value change.
+                return;
+            }
+            param.set(out.next);
+        },
+        [param, parameter.id, parameter.min, parameter.max, plugin]
+    );
+
+    // Native range needs a numeric `step`; pick `(max - min) / 100`
+    // so pointer drags follow the same 1 % granularity as the
+    // keyboard fine-step.
+    const nativeStep = (parameter.max - parameter.min) / 100;
+
+    return (
+        <div
+            className={
+                className === undefined
+                    ? "rax-slider"
+                    : `rax-slider ${className}`
+            }
+            data-parameter-id={parameter.id}
+            data-orientation={orientation ?? "horizontal"}
+        >
+            <label htmlFor={inputId} className="rax-slider__label">
+                {label ?? parameter.name}
+            </label>
+            <input
+                id={inputId}
+                type="range"
+                aria-label={label ?? parameter.name}
+                aria-valuemin={parameter.min}
+                aria-valuemax={parameter.max}
+                aria-valuenow={param.value}
+                aria-valuetext={ariaText}
+                aria-orientation={orientation ?? "horizontal"}
+                min={parameter.min}
+                max={parameter.max}
+                step={nativeStep > 0 ? nativeStep : 0.0001}
+                value={param.value}
+                onChange={onPointerChange}
+                onKeyDown={onKeyDown}
+                className="rax-slider__input"
+            />
+            <span className="rax-slider__readout" aria-hidden="true">
+                {ariaText}
+            </span>
+        </div>
+    );
+}

packages/ui/react/react-audio/src/components/plugin-slot/index.ts

@@ -0,0 +1,5 @@
+export {
+    PluginSlot,
+    type PluginSlotProps,
+    type PluginSlotRendererProps,
+} from "./plugin-slot.js";

packages/ui/react/react-audio/src/components/plugin-slot/plugin-slot.md

@@ -0,0 +1,99 @@
+# `<PluginSlot>`
+
+Generic renderer for any `AudioFxPlugin`. Reads the plugin's
+declarative `parameters` array and renders each one through the
+primitive picked by the parameter's unit declaration. A specialised
+renderer registered through the provider's `slotRenderers` option
+supersedes the generic slot for the matching plugin id.
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+`<PluginSlot>` is the per-plugin face of `<PluginChainView>`. It
+turns a plugin's static declaration (metadata + parameter list + IO
+shape) into a reactive form without the consumer having to wire up
+each control by hand. The component is intentionally
+presentational — bypass, advanced-toggle, and parameter writes go
+through the same hooks any caller would use, so an EQ panel that
+wants its own visual chrome can replace the slot through the
+`slotRenderers` map without losing the keyboard / ARIA contract.
+
+## Features
+
+- Renders `plugin.metadata.name`, `version`, and `category` in the slot header.
+- Iterates `plugin.parameters` in declaration order.
+- Picks a knob for `unit: "db"` / `unit: "hz"` and a slider for every
+  other unit (including `"percent"`, `"ms"`, `"semitones"`).
+- Exposes a bypass toggle wired to `chain.bypass(plugin.metadata.id, …)`
+  when a `chain` prop is supplied; the toggle reflects the live
+  bypass state via a `bypass-changed` subscription.
+- Filters parameters whose `category === "advanced"` behind a toggle
+  that defaults to hidden.
+- Forwards a CSS-class API (`rax-slot`, `rax-slot__header`,
+  `rax-slot__params`, `rax-slot__bypass`, `rax-slot__advanced-toggle`)
+  and `data-plugin-id` / `data-plugin-category` / `data-bypassed`
+  attributes for stylesheet targeting.
+
+## Usage: Basic
+
+```tsx
+import { PluginSlot } from "@suaveplan/react-audio/components/plugin-slot";
+
+function ChainItem({ plugin, chain }) {
+    return <PluginSlot plugin={plugin} chain={chain} />;
+}
+```
+
+## Usage: Advanced
+
+```tsx
+// Provide a specialised EQ panel through provider options; the slot
+// will render <EQPanel/> instead of the generic form for the eq plugin.
+function App() {
+    return (
+        <AudioProvider
+            options={{
+                slotRenderers: {
+                    eq: EQPanel,
+                },
+            }}
+        >
+            <PluginSlot plugin={eqPlugin} chain={chain} />
+        </AudioProvider>
+    );
+}
+```
+
+## API Reference
+
+### Props
+
+- `plugin: AudioFxPlugin` — the plugin to render.
+- `chain?: PluginChain` — when supplied, the bypass toggle is rendered
+  and writes via `chain.bypass()`; without a chain there is no
+  bypass surface to talk to.
+- `className?: string` — CSS class appended to the wrapper.
+- `hideAdvancedToggle?: boolean` — hide the advanced toggle even when
+  advanced parameters are present.
+
+### Provider integration
+
+- `slotRenderers: Record<string, ComponentType<PluginSlotRendererProps>>`
+  on `AudioProviderOptions` maps a plugin id to a specialised
+  renderer. The generic slot consults the map first and bails to the
+  registered component when present.
+
+## Implementation Notes
+
+- The bypass toggle subscribes via `chain.on("bypass-changed", …)` so
+  toggles initiated elsewhere (preset apply, another panel, MIDI in
+  Phase 3) propagate without a polling tick.
+- The advanced toggle is local state on the slot; it does not survive
+  unmount. Persisting it would require an addition to the provider's
+  UI store, which is deferred to extras.
+- The unit→control table (`db` / `hz` → knob, else slider) is
+  intentionally minimal. Specialised renderers cover any remaining
+  cases (segmented control for `enum`, log-curve knob, …).

packages/ui/react/react-audio/src/components/plugin-slot/plugin-slot.stories.tsx

@@ -0,0 +1,69 @@
+/* istanbul ignore file -- story-only fixtures */
+import type { Meta, StoryObj } from "@storybook/react";
+import { AudioProvider } from "../../provider/audio-provider.js";
+import { makeFakeAudioContext, makeFakePlugin } from "../../test-utils.js";
+import { PluginSlot } from "./plugin-slot.js";
+
+const meta = {
+    title: "react-audio/PluginSlot",
+    component: PluginSlot,
+} satisfies Meta<typeof PluginSlot>;
+
+export default meta;
+
+type Story = StoryObj<typeof meta>;
+
+const plugin = makeFakePlugin({ id: "story-slot", name: "Demo Plugin" });
+
+function Frame(props: { readonly children: React.ReactNode }) {
+    return (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() as never },
+            }}
+        >
+            <div style={{ padding: 24, maxWidth: 520 }}>{props.children}</div>
+        </AudioProvider>
+    );
+}
+
+export const Default: Story = {
+    render: () => (
+        <Frame>
+            <PluginSlot plugin={plugin} />
+        </Frame>
+    ),
+};
+
+export const Interactive: Story = {
+    render: () => (
+        <Frame>
+            <div>
+                <PluginSlot plugin={plugin} />
+                <p style={{ color: "#888", marginTop: 8 }}>
+                    Each control is keyboard-driven; tab to focus, arrows / page
+                    / home / end to nudge.
+                </p>
+            </div>
+        </Frame>
+    ),
+};
+
+export const EdgeNoParameters: Story = {
+    render: () => {
+        const empty = makeFakePlugin({ id: "empty" });
+        Object.defineProperty(empty, "parameters", {
+            value: [],
+            configurable: true,
+        });
+        Object.defineProperty(empty, "parameterIndex", {
+            value: new Map(),
+            configurable: true,
+        });
+        return (
+            <Frame>
+                <PluginSlot plugin={empty} />
+            </Frame>
+        );
+    },
+};

packages/ui/react/react-audio/src/components/plugin-slot/plugin-slot.test.tsx

@@ -0,0 +1,324 @@
+import type { PluginChain } from "@suaveplan/audio-fx-plugin-base";
+import { afterEach, describe, expect, it } from "@suaveplan/testing/runner";
+import { cleanup, fireEvent, screen, waitFor } from "@testing-library/react";
+
+afterEach(() => cleanup());
+
+import { useEffect, useState } from "react";
+import { useProviderStateOrThrow } from "../../hooks/use-provider-state.js";
+import {
+    makeFakePlugin,
+    renderWithProvider,
+    waitForStableProvider,
+} from "../../test-utils.js";
+import { PluginSlot, type PluginSlotRendererProps } from "./plugin-slot.js";
+
+function makeEqPlugin() {
+    const plugin = makeFakePlugin({ id: "eq", name: "Equaliser" });
+    const params = [
+        {
+            id: "low",
+            name: "Low",
+            value: 0,
+            default: 0,
+            min: -24,
+            max: 24,
+            unit: "db" as const,
+            scale: "linear" as const,
+            automatable: true,
+        },
+        {
+            id: "mid",
+            name: "Mid",
+            value: 0,
+            default: 0,
+            min: -24,
+            max: 24,
+            unit: "db" as const,
+            scale: "linear" as const,
+            automatable: true,
+        },
+        {
+            id: "high",
+            name: "High",
+            value: 0,
+            default: 0,
+            min: -24,
+            max: 24,
+            unit: "db" as const,
+            scale: "linear" as const,
+            automatable: true,
+        },
+        {
+            id: "freq",
+            name: "Frequency",
+            value: 1000,
+            default: 1000,
+            min: 20,
+            max: 20000,
+            unit: "hz" as const,
+            scale: "log" as const,
+            automatable: true,
+        },
+        {
+            id: "q",
+            name: "Q",
+            value: 1,
+            default: 1,
+            min: 0.1,
+            max: 18,
+            unit: "ratio" as const,
+            scale: "linear" as const,
+            automatable: true,
+        },
+    ];
+    Object.defineProperty(plugin, "parameters", {
+        value: params,
+        configurable: true,
+    });
+    Object.defineProperty(plugin, "parameterIndex", {
+        value: new Map(params.map((p) => [p.id, p])),
+        configurable: true,
+    });
+    for (const p of params) plugin.setParameter(p.id, p.default);
+    return plugin;
+}
+
+function _ChainProbe({
+    trackId,
+    onReady,
+    children,
+}: {
+    trackId: string;
+    onReady: (chain: PluginChain) => void;
+    children: (chain: PluginChain) => React.ReactNode;
+}) {
+    const { chains } = useProviderStateOrThrow();
+    const [chain] = useState(() => chains.getOrCreate(trackId));
+    useEffect(() => {
+        onReady(chain);
+    }, [chain, onReady]);
+    return <>{children(chain)}</>;
+}
+
+describe("<PluginSlot>", () => {
+    it("renders one control per parameter with correct role and label", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeEqPlugin();
+        function Probe() {
+            return <PluginSlot plugin={plugin} />;
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByText("Equaliser"));
+        await waitFor(() => {
+            const sliders = screen.getAllByRole("slider");
+            expect(sliders.length).toBe(5);
+        });
+        for (const name of ["Low", "Mid", "High", "Frequency", "Q"]) {
+            expect(screen.getAllByText(name).length).toBeGreaterThan(0);
+        }
+    });
+
+    it("registered specialised renderer supersedes the generic slot", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeEqPlugin();
+        function EQPanel(props: PluginSlotRendererProps) {
+            const p = props.plugin as typeof plugin;
+            return <div data-testid="eq-panel">EQ-PANEL:{p.metadata.id}</div>;
+        }
+        function Probe() {
+            return <PluginSlot plugin={plugin} />;
+        }
+        renderWithProvider(<Probe />, {
+            options: { slotRenderers: { eq: EQPanel } },
+        });
+        await waitForStableProvider(() => screen.queryByTestId("eq-panel"));
+        expect(screen.getByTestId("eq-panel").textContent).toBe("EQ-PANEL:eq");
+        expect(screen.queryByText("Equaliser")).toBeNull();
+    });
+
+    it("renders metadata name / version / category in the header", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeEqPlugin();
+        function Probe() {
+            return <PluginSlot plugin={plugin} />;
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByText("Equaliser"));
+        expect(screen.getByText("Equaliser")).toBeDefined();
+        expect(screen.getByText("v0.1.0")).toBeDefined();
+        expect(screen.getByText("utility")).toBeDefined();
+    });
+
+    it("bypass toggle writes through to chain.bypass and reflects state", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeEqPlugin();
+        let captured: PluginChain | undefined;
+        function Setup() {
+            const { chains } = useProviderStateOrThrow();
+            const [chain] = useState(() => {
+                const c = chains.getOrCreate("bp-track");
+                if (c.findById(plugin.metadata.id) === undefined) {
+                    c.add(plugin);
+                }
+                return c;
+            });
+            useEffect(() => {
+                captured = chain;
+            }, [chain]);
+            return <PluginSlot plugin={plugin} chain={chain} />;
+        }
+        renderWithProvider(<Setup />);
+        await waitForStableProvider(() => captured);
+        await waitFor(() => screen.getByRole("button", { name: "Active" }));
+        fireEvent.click(screen.getByRole("button", { name: "Active" }));
+        await waitFor(() => {
+            expect(
+                screen.getByRole("button", { name: "Bypassed" })
+            ).toBeDefined();
+        });
+    });
+
+    it("omits the bypass button when no chain is supplied", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeEqPlugin();
+        function Probe() {
+            return <PluginSlot plugin={plugin} />;
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByText("Equaliser"));
+        expect(screen.queryByRole("button", { name: "Active" })).toBeNull();
+        expect(screen.queryByRole("button", { name: "Bypassed" })).toBeNull();
+    });
+
+    it("advanced toggle hides advanced parameters by default and reveals them on click", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeEqPlugin();
+        // Inject an "advanced" parameter
+        Object.defineProperty(plugin, "parameters", {
+            value: [
+                ...plugin.parameters,
+                {
+                    id: "oversample",
+                    name: "Oversample",
+                    value: 1,
+                    default: 1,
+                    min: 1,
+                    max: 8,
+                    unit: "ratio" as const,
+                    scale: "linear" as const,
+                    automatable: false,
+                    category: "advanced",
+                } as never,
+            ],
+            configurable: true,
+        });
+        Object.defineProperty(plugin, "parameterIndex", {
+            value: new Map(plugin.parameters.map((p) => [p.id, p])),
+            configurable: true,
+        });
+        plugin.setParameter("oversample", 1);
+        function Probe() {
+            return <PluginSlot plugin={plugin} />;
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByText("Equaliser"));
+        expect(screen.queryByText("Oversample")).toBeNull();
+        fireEvent.click(screen.getByRole("button", { name: "Show advanced" }));
+        await waitFor(() =>
+            expect(screen.getByText("Oversample")).toBeDefined()
+        );
+        fireEvent.click(screen.getByRole("button", { name: "Hide advanced" }));
+        await waitFor(() =>
+            expect(screen.queryByText("Oversample")).toBeNull()
+        );
+    });
+
+    it("hideAdvancedToggle suppresses the advanced button entirely", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeEqPlugin();
+        function Probe() {
+            return <PluginSlot plugin={plugin} hideAdvancedToggle={true} />;
+        }
+        renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByText("Equaliser"));
+        expect(screen.queryByRole("button", { name: /advanced/i })).toBeNull();
+    });
+
+    it("bypass-changed event for a different plugin id is ignored", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeEqPlugin();
+        const other = makeFakePlugin({ id: "other" });
+        let captured: PluginChain | undefined;
+        function Setup() {
+            const { chains } = useProviderStateOrThrow();
+            const [chain] = useState(() => {
+                const c = chains.getOrCreate("two-track");
+                if (c.findById(plugin.metadata.id) === undefined) {
+                    c.add(plugin);
+                }
+                if (c.findById(other.metadata.id) === undefined) {
+                    c.add(other);
+                }
+                return c;
+            });
+            useEffect(() => {
+                captured = chain;
+            }, [chain]);
+            return <PluginSlot plugin={plugin} chain={chain} />;
+        }
+        renderWithProvider(<Setup />);
+        await waitForStableProvider(() => captured);
+        await waitFor(() => screen.getByRole("button", { name: "Active" }));
+        // Toggle bypass on the OTHER plugin directly via the chain —
+        // exercises the id-mismatch guard in the bypass listener.
+        captured!.bypass(other.metadata.id, true);
+        // EQ slot button should still say "Active"
+        await new Promise((r) => setTimeout(r, 10));
+        expect(screen.getByRole("button", { name: "Active" })).toBeDefined();
+    });
+
+    it("specialised renderer receives the chain prop when supplied", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeEqPlugin();
+        function ChainAware(props: PluginSlotRendererProps) {
+            const chainId = (props.chain as { id?: string } | undefined)?.id;
+            return (
+                <div data-testid="chain-aware">chain:{chainId ?? "none"}</div>
+            );
+        }
+        function Setup() {
+            const { chains } = useProviderStateOrThrow();
+            const [chain] = useState(() => chains.getOrCreate("aware-track"));
+            return <PluginSlot plugin={plugin} chain={chain} />;
+        }
+        renderWithProvider(<Setup />, {
+            options: { slotRenderers: { eq: ChainAware } },
+        });
+        await waitForStableProvider(() => screen.queryByTestId("chain-aware"));
+        expect(screen.getByTestId("chain-aware").textContent).toBe(
+            "chain:aware-track"
+        );
+    });
+
+    it("forwards className to the wrapper", {
+        timeout: 30000,
+    }, async () => {
+        const plugin = makeEqPlugin();
+        function Probe() {
+            return <PluginSlot plugin={plugin} className="my-slot" />;
+        }
+        const { container } = renderWithProvider(<Probe />);
+        await waitForStableProvider(() => screen.queryByText("Equaliser"));
+        expect(container.querySelector(".rax-slot.my-slot")).not.toBeNull();
+    });
+});

packages/ui/react/react-audio/src/components/plugin-slot/plugin-slot.tsx

@@ -0,0 +1,205 @@
+import type {
+    AudioFxPlugin,
+    PluginChain,
+    PluginParameter,
+} from "@suaveplan/audio-fx-plugin-base";
+import {
+    type ComponentType,
+    type ReactNode,
+    useCallback,
+    useEffect,
+    useMemo,
+    useState,
+} from "react";
+import { useProviderStateOrThrow } from "../../hooks/use-provider-state.js";
+import { PluginParameterKnob } from "../plugin-parameter-knob/plugin-parameter-knob.js";
+import { PluginParameterSlider } from "../plugin-parameter-slider/plugin-parameter-slider.js";
+
+export interface PluginSlotProps {
+    readonly plugin: AudioFxPlugin;
+    /**
+     * Optional chain handle. When supplied the slot's bypass toggle
+     * delegates to `chain.bypass(plugin.metadata.id, ...)`; otherwise
+     * the toggle is hidden because there is no chain-level bypass
+     * surface to talk to.
+     */
+    readonly chain?: PluginChain;
+    /** Optional CSS class appended to the wrapper. */
+    readonly className?: string;
+    /** Hide the "advanced" toggle even if advanced parameters exist. */
+    readonly hideAdvancedToggle?: boolean;
+}
+
+/**
+ * Props accepted by a specialised renderer registered via the
+ * provider's `slotRenderers` option. The specialised renderer
+ * supersedes the generic slot when its key matches the plugin's
+ * `metadata.id`.
+ */
+export interface PluginSlotRendererProps {
+    readonly plugin: AudioFxPlugin;
+    readonly chain?: PluginChain;
+}
+
+interface PluginParameterCategory {
+    readonly category?: string;
+}
+
+function isAdvancedParameter(
+    parameter: PluginParameter & PluginParameterCategory
+): boolean {
+    return parameter.category === "advanced";
+}
+
+function pickControl(parameter: PluginParameter): "knob" | "slider" {
+    if (parameter.unit === "hz") return "knob";
+    if (parameter.unit === "db") return "knob";
+    return "slider";
+}
+
+/**
+ * Generic renderer for any `AudioFxPlugin`. Iterates the plugin's
+ * `parameters` array in declaration order and renders each via the
+ * primitive chosen by the parameter's unit. A specialised renderer
+ * registered through the provider's `slotRenderers` option
+ * supersedes the generic slot for the matching plugin id.
+ */
+export function PluginSlot(props: PluginSlotProps): ReactNode {
+    const { plugin, chain, className, hideAdvancedToggle } = props;
+    const provider = useProviderStateOrThrow();
+
+    const SpecialisedRenderer = provider.slotRenderers[plugin.metadata.id] as
+        | ComponentType<PluginSlotRendererProps>
+        | undefined;
+    if (SpecialisedRenderer !== undefined) {
+        return (
+            <SpecialisedRenderer
+                plugin={plugin}
+                {...(chain !== undefined ? { chain } : {})}
+            />
+        );
+    }
+
+    return (
+        <GenericPluginSlot
+            plugin={plugin}
+            {...(chain !== undefined ? { chain } : {})}
+            {...(className !== undefined ? { className } : {})}
+            {...(hideAdvancedToggle !== undefined
+                ? { hideAdvancedToggle }
+                : {})}
+        />
+    );
+}
+
+function GenericPluginSlot(props: PluginSlotProps): ReactNode {
+    const { plugin, chain, className, hideAdvancedToggle } = props;
+    const [showAdvanced, setShowAdvanced] = useState(false);
+
+    const params = plugin.parameters;
+    const advanced = useMemo(
+        () =>
+            params.filter((p) =>
+                isAdvancedParameter(
+                    p as PluginParameter & PluginParameterCategory
+                )
+            ),
+        [params]
+    );
+    const visibleParams = useMemo(
+        () =>
+            showAdvanced
+                ? params
+                : params.filter(
+                      (p) =>
+                          !isAdvancedParameter(
+                              p as PluginParameter & PluginParameterCategory
+                          )
+                  ),
+        [params, showAdvanced]
+    );
+
+    const [bypassed, setBypassed] = useState(false);
+    useEffect(() => {
+        if (chain === undefined) return undefined;
+        const off = chain.on("bypass-changed", (payload) => {
+            if (payload.plugin.metadata.id === plugin.metadata.id) {
+                setBypassed(payload.bypassed);
+            }
+        });
+        return () => off();
+    }, [chain, plugin.metadata.id]);
+
+    const onToggleBypass = useCallback(() => {
+        // chain is guaranteed defined when this callback fires —
+        // the bypass button is only rendered when `chain !==
+        // undefined` (see the guarded JSX below). The non-null
+        // assertion avoids an unreachable branch.
+        chain!.bypass(plugin.metadata.id, !bypassed);
+    }, [chain, plugin.metadata.id, bypassed]);
+
+    return (
+        <section
+            className={
+                className === undefined ? "rax-slot" : `rax-slot ${className}`
+            }
+            data-plugin-id={plugin.metadata.id}
+            data-plugin-category={plugin.metadata.category}
+            data-bypassed={bypassed ? "true" : "false"}
+        >
+            <header className="rax-slot__header">
+                <h3 className="rax-slot__name">{plugin.metadata.name}</h3>
+                <span className="rax-slot__version">
+                    v{plugin.metadata.version}
+                </span>
+                <span
+                    className="rax-slot__category"
+                    data-category={plugin.metadata.category}
+                >
+                    {plugin.metadata.category}
+                </span>
+                {chain === undefined ? null : (
+                    <button
+                        type="button"
+                        className="rax-slot__bypass"
+                        aria-pressed={bypassed}
+                        onClick={onToggleBypass}
+                    >
+                        {bypassed ? "Bypassed" : "Active"}
+                    </button>
+                )}
+            </header>
+            <div className="rax-slot__params">
+                {visibleParams.map((p) => {
+                    const control = pickControl(p);
+                    if (control === "knob") {
+                        return (
+                            <PluginParameterKnob
+                                key={p.id}
+                                plugin={plugin}
+                                parameter={p}
+                            />
+                        );
+                    }
+                    return (
+                        <PluginParameterSlider
+                            key={p.id}
+                            plugin={plugin}
+                            parameter={p}
+                        />
+                    );
+                })}
+            </div>
+            {hideAdvancedToggle === true || advanced.length === 0 ? null : (
+                <button
+                    type="button"
+                    className="rax-slot__advanced-toggle"
+                    aria-pressed={showAdvanced}
+                    onClick={() => setShowAdvanced((s) => !s)}
+                >
+                    {showAdvanced ? "Hide advanced" : "Show advanced"}
+                </button>
+            )}
+        </section>
+    );
+}

packages/ui/react/react-audio/src/components/premium-player/premium-player.md

@@ -0,0 +1,88 @@
+# `<PremiumPlayer>`
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+`<PremiumPlayer>` is the full-featured media-player surface — a
+composition of `<AudioPlayer>`, `<AudioVisualizer>`, and
+`<MasterMeter>` arranged as a single instrument panel. It is intended
+for hero player surfaces (landing pages, profile pages, demo apps)
+that want the whole monitoring suite without forcing consumers to
+wire three components by hand.
+
+Every behavioural guarantee of the underlying components applies:
+the player polls plugin state, the visualiser reads block samples
+from the named bus, and the meter computes peak / RMS / hold envelope
+on every UI tick. None of the three sub-components share state; they
+compose by sitting in the same DOM section.
+
+## Features
+
+- Bundles `<AudioPlayer>` + `<AudioVisualizer>` + `<MasterMeter>`.
+- Routes a single `busName` to both the visualiser and the meter so
+  they show the same source.
+- Forwards `src` to the player for auto-load on mount.
+- Adds the `.rax-premium-player` class for theming.
+
+## Usage: Basic Example
+
+```tsx
+import { AudioPlayerPlugin } from "@suaveplan/audio-fx-plugin-audio-player";
+import { AudioProvider, PremiumPlayer } from "@suaveplan/react-audio";
+
+const plugin = new AudioPlayerPlugin({});
+
+export function Hero() {
+    return (
+        <AudioProvider>
+            <PremiumPlayer plugin={plugin} src="https://cdn/hero.wav" />
+        </AudioProvider>
+    );
+}
+```
+
+## Usage: Advanced Example
+
+```tsx
+import { AudioPlayerPlugin } from "@suaveplan/audio-fx-plugin-audio-player";
+import { AudioProvider, PremiumPlayer } from "@suaveplan/react-audio";
+
+const plugin = new AudioPlayerPlugin({});
+
+export function AuxBusPlayer() {
+    return (
+        <AudioProvider>
+            <PremiumPlayer
+                plugin={plugin}
+                src="https://cdn/aux.wav"
+                busName="auxA"
+                className="aux-hero"
+            />
+        </AudioProvider>
+    );
+}
+```
+
+## API Reference
+
+| Prop        | Type                | Default     | Notes                                              |
+| ----------- | ------------------- | ----------- | -------------------------------------------------- |
+| `plugin`    | `AudioPlayerPlugin` | —           | Required.                                          |
+| `src`       | `string \| undef`   | —           | Forwarded to `<AudioPlayer>` for auto-load.        |
+| `busName`   | `string \| undef`   | `"master"`  | Routed to the visualiser and meter.                |
+| `className` | `string \| undef`   | —           | Forwarded; merged with `rax-premium-player`.       |
+
+## Implementation Notes
+
+The composition only forwards the `busName` to the visualiser + meter
+when one is supplied — otherwise the sub-components fall back to
+their own `"master"` defaults, which keeps the API surface honest
+about what we are choosing for the user. The player sub-component
+also receives the `src` only when it is defined, so the auto-load
+effect inside `<AudioPlayer>` doesn't run with `undefined` and trip a
+guard. There is no separate state in this component; it is pure
+composition. New monitoring sub-components (e.g. spectrum analysers,
+oscilloscope) can be added inline without changing the prop signature.

packages/ui/react/react-audio/src/components/premium-player/premium-player.stories.tsx

@@ -0,0 +1,55 @@
+/* istanbul ignore file -- story-only fixtures */
+
+import type { Meta, StoryObj } from "@storybook/react";
+import { AudioPlayerPlugin } from "@suaveplan/audio-fx-plugin-audio-player";
+import { AudioProvider } from "../../provider/audio-provider.js";
+import { makeFakeAudioContext } from "../../test-utils.js";
+import { PremiumPlayer } from "./premium-player.js";
+
+const meta = {
+    title: "react-audio/PremiumPlayer",
+    component: PremiumPlayer,
+} satisfies Meta<typeof PremiumPlayer>;
+export default meta;
+type Story = StoryObj<typeof meta>;
+
+const plugin = new AudioPlayerPlugin({});
+(plugin as unknown as { config: { sampleRate: number } }).config = {
+    sampleRate: 48000,
+};
+
+function Frame(props: { readonly children: React.ReactNode }) {
+    return (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() as never },
+            }}
+        >
+            <div style={{ padding: 24 }}>{props.children}</div>
+        </AudioProvider>
+    );
+}
+
+export const Default: Story = {
+    render: () => (
+        <Frame>
+            <PremiumPlayer plugin={plugin} />
+        </Frame>
+    ),
+};
+export const Interactive: Story = {
+    render: () => (
+        <Frame>
+            <PremiumPlayer plugin={plugin} busName="auxA" />
+        </Frame>
+    ),
+};
+export const EdgeWideLayout: Story = {
+    render: () => (
+        <Frame>
+            <div style={{ width: 800 }}>
+                <PremiumPlayer plugin={plugin} className="wide" />
+            </div>
+        </Frame>
+    ),
+};

packages/ui/react/react-audio/src/components/premium-player/premium-player.test.tsx

@@ -0,0 +1,105 @@
+import { AudioPlayerPlugin } from "@suaveplan/audio-fx-plugin-audio-player";
+import {
+    afterEach,
+    beforeAll,
+    describe,
+    expect,
+    it,
+} from "@suaveplan/testing/runner";
+import { cleanup, screen, waitFor } from "@testing-library/react";
+import { renderWithProvider } from "../../test-utils.js";
+import { PremiumPlayer } from "./premium-player.js";
+
+afterEach(() => cleanup());
+
+beforeAll(() => {
+    // happy-dom has no canvas; install a minimal 2D fake.
+    const proto = HTMLCanvasElement.prototype as unknown as {
+        getContext: (id: string) => unknown;
+    };
+    proto.getContext = () =>
+        ({
+            fillStyle: "",
+            strokeStyle: "",
+            fillRect: () => undefined,
+            stroke: () => undefined,
+            beginPath: () => undefined,
+            moveTo: () => undefined,
+            lineTo: () => undefined,
+        }) as unknown as CanvasRenderingContext2D;
+});
+
+function pl() {
+    const p = new AudioPlayerPlugin({});
+    (p as unknown as { config: { sampleRate: number } }).config = {
+        sampleRate: 48_000,
+    };
+    (p as unknown as { buffer: Float32Array }).buffer = new Float32Array(
+        48_000 * 2
+    );
+    return p;
+}
+
+describe("<PremiumPlayer>", () => {
+    it("renders player + visualizer + meter", {
+        timeout: 30000,
+    }, async () => {
+        const { container } = renderWithProvider(
+            <PremiumPlayer plugin={pl()} />
+        );
+        await waitFor(() => screen.getByRole("button", { name: "Play" }));
+        expect(container.querySelector("canvas")).not.toBeNull();
+        expect(container.querySelector(".rax-master-meter")).not.toBeNull();
+    });
+
+    it("forwards custom bus name to the visualiser + meter", {
+        timeout: 30000,
+    }, async () => {
+        const { container } = renderWithProvider(
+            <PremiumPlayer plugin={pl()} busName="auxA" />
+        );
+        await waitFor(() => screen.getByRole("button", { name: "Play" }));
+        expect(
+            container.querySelector("canvas[data-bus='auxA']")
+        ).not.toBeNull();
+        expect(
+            container.querySelector(".rax-master-meter[data-bus='auxA']")
+        ).not.toBeNull();
+    });
+
+    it("forwards className", { timeout: 30000 }, async () => {
+        const { container } = renderWithProvider(
+            <PremiumPlayer plugin={pl()} className="hero-player" />
+        );
+        await waitFor(() => screen.getByRole("button", { name: "Play" }));
+        expect(
+            container.querySelector(".rax-premium-player.hero-player")
+        ).not.toBeNull();
+    });
+
+    it("default className is rax-premium-player", {
+        timeout: 30000,
+    }, async () => {
+        const { container } = renderWithProvider(
+            <PremiumPlayer plugin={pl()} />
+        );
+        await waitFor(() => screen.getByRole("button", { name: "Play" }));
+        expect(container.querySelector(".rax-premium-player")).not.toBeNull();
+    });
+
+    it("accepts a src prop", { timeout: 30000 }, async () => {
+        const prev = globalThis.fetch;
+        globalThis.fetch = (async () =>
+            ({
+                arrayBuffer: async () => new ArrayBuffer(4096),
+            }) as unknown as Response) as typeof prev;
+        try {
+            renderWithProvider(
+                <PremiumPlayer plugin={pl()} src="https://x/y.bin" />
+            );
+            await waitFor(() => screen.getByRole("button", { name: "Play" }));
+        } finally {
+            globalThis.fetch = prev;
+        }
+    });
+});

packages/ui/react/react-audio/src/components/premium-player/premium-player.tsx

@@ -0,0 +1,43 @@
+import type { AudioPlayerPlugin } from "@suaveplan/audio-fx-plugin-audio-player";
+import type { ReactNode } from "react";
+import { AudioPlayer } from "../audio-player/audio-player.js";
+import { AudioVisualizer } from "../audio-visualizer/audio-visualizer.js";
+import { MasterMeter } from "../master-meter/master-meter.js";
+
+export interface PremiumPlayerProps {
+    readonly plugin: AudioPlayerPlugin;
+    readonly src?: string;
+    readonly className?: string;
+    /** Bus to read for the visualiser + meter. Defaults to `"master"`. */
+    readonly busName?: string;
+}
+
+/**
+ * Full-featured player composing `<AudioPlayer>` with a visualiser
+ * and a master meter for VU monitoring. Suitable for media-player
+ * style surfaces that want the whole instrument panel without manual
+ * wiring.
+ */
+export function PremiumPlayer(props: PremiumPlayerProps): ReactNode {
+    const { plugin, src, className, busName } = props;
+    const cls =
+        className === undefined
+            ? "rax-premium-player"
+            : `rax-premium-player ${className}`;
+    return (
+        <section className={cls} aria-label="Premium player">
+            <AudioPlayer
+                plugin={plugin}
+                {...(src !== undefined ? { src } : {})}
+            />
+            <AudioVisualizer
+                {...(busName !== undefined ? { busName } : {})}
+                mode="waveform"
+            />
+            <MasterMeter
+                {...(busName !== undefined ? { busName } : {})}
+                channels={2}
+            />
+        </section>
+    );
+}

packages/ui/react/react-audio/src/components/preset-manager/index.ts

@@ -0,0 +1,5 @@
+export {
+    PresetManager,
+    type PresetManagerProps,
+    type PresetStoreWithListing,
+} from "./preset-manager.js";

packages/ui/react/react-audio/src/components/preset-manager/preset-manager.md

@@ -0,0 +1,103 @@
+# `<PresetManager>`
+
+`ChainSnapshot` save / load / delete UI layered over the provider's
+preset store. The save path persists the snapshot through
+`useChainSnapshot(chain).save(id)`, which validates against the
+`ChainSnapshotSchema` re-exported from
+`@suaveplan/audio-fx-plugin-base` and hands the serialised payload
+to the store. The load path calls `chain.restore()` through the
+hook; the delete path calls the optional `store.delete()` extension.
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+Plugin chains have a non-trivial state shape (per-slot plugin id,
+parameter values, bypass flags) and survive only as long as the
+provider stays mounted. The `<PresetManager>` gives an end-user a
+direct affordance to capture that state, name it, restore it later,
+and surface store / restore errors without crashing the surrounding
+UI. The component is intentionally chain-scoped — the same
+`<PresetManager chain={c}>` instance can sit beside any
+`<PluginChainView>` for the same chain.
+
+## Features
+
+- `Save` button — disabled until the name input is non-empty;
+  invokes `snapshot.save(name)`, optimistically updates the local
+  saved-id list, bumps an internal `version` counter so subscribed
+  views re-render.
+- `Load` button — invokes `snapshot.load(id)`, which restores the
+  chain order, parameters, and bypass states.
+- `Delete` button — invokes `store.delete("chain", id)` when the
+  store supports the optional extension.
+- Saved-id list is fetched from `store.list("chain")` if the store
+  supports it; otherwise the list reflects only the saves issued by
+  the live component instance.
+- Toast surfaces every rejection with `role="status"`, the
+  `AudioFxError` code (e.g.
+  `AUDIO_FX.CHAIN_SLOT_NOT_FOUND`), and a dismiss button.
+- Renders an explanatory empty state when no preset store is
+  configured on the provider.
+
+## Usage: Basic
+
+```tsx
+import { PresetManager } from "@suaveplan/react-audio/components/preset-manager";
+
+function ChainSidebar({ chain }) {
+    return <PresetManager chain={chain} />;
+}
+```
+
+## Usage: Advanced
+
+```tsx
+// Wire a custom IndexedDB-backed preset store on the provider so
+// PresetManager can render a fully reactive saved-id list.
+function App() {
+    const store = useMemo(() => createIndexedDbPresetStore(), []);
+    return (
+        <AudioProvider options={{ presetStore: store }}>
+            <PresetManager chain={chain} className="rounded-md p-4" />
+        </AudioProvider>
+    );
+}
+```
+
+## API Reference
+
+### Props
+
+- `chain: PluginChain` — the chain whose snapshot is persisted.
+- `className?: string` — CSS class appended to the wrapper.
+
+### Optional store extension
+
+```ts
+export interface PresetStoreWithListing extends PresetStore {
+    list?(kind: "plugin" | "chain"): Promise<ReadonlyArray<string>>;
+    delete?(kind: "plugin" | "chain", id: string): Promise<void>;
+}
+```
+
+When the configured `presetStore` implements `list`, the saved-id
+list is fetched on mount and after every save / delete; when it
+implements `delete`, the Delete button is functional.
+
+## Implementation Notes
+
+- The save path runs `snapshot.save(id)` which itself wraps store
+  rejections in `REACT_AUDIO.PRESET_STORE_FAILED`; the component
+  re-surfaces the rejection in the toast.
+- The load path goes through `chain.restore(snapshot, registry)`,
+  which is where `AUDIO_FX.CHAIN_SLOT_NOT_FOUND` is thrown for
+  missing plugin types — exactly the error the spec scenario asserts
+  the toast carries.
+- The version counter exists so any external `useChainSnapshot(chain)`
+  consumer that calls `snapshot.load(...)` after a delete re-runs
+  through React's effect graph rather than caching stale ids.
+- The component does not attempt to round-trip the preset on save;
+  the chain's own `chain.snapshot()` is the source of truth.

packages/ui/react/react-audio/src/components/preset-manager/preset-manager.stories.tsx

@@ -0,0 +1,112 @@
+/* istanbul ignore file -- story-only fixtures */
+
+import type { Meta, StoryObj } from "@storybook/react";
+import type {
+    ChainSnapshot,
+    PluginChain,
+    PresetSnapshot,
+} from "@suaveplan/audio-fx-plugin-base";
+import { useEffect, useState } from "react";
+import { useProviderStateOrThrow } from "../../hooks/use-provider-state.js";
+import { AudioProvider } from "../../provider/audio-provider.js";
+import type { PresetStore } from "../../provider/provider-options.js";
+import { makeFakeAudioContext } from "../../test-utils.js";
+import { PresetManager } from "./preset-manager.js";
+
+const meta = {
+    title: "react-audio/PresetManager",
+    component: PresetManager,
+} satisfies Meta<typeof PresetManager>;
+
+export default meta;
+
+type Story = StoryObj<typeof meta>;
+
+function makeStoryStore() {
+    const entries: {
+        kind: "plugin" | "chain";
+        id: string;
+        payload: PresetSnapshot | ChainSnapshot;
+    }[] = [];
+    return {
+        entries,
+        async save(kind: "plugin" | "chain", id: string, payload: never) {
+            entries.push({ kind, id, payload });
+        },
+        async load(kind: "plugin" | "chain", id: string) {
+            return entries.find((e) => e.kind === kind && e.id === id)?.payload;
+        },
+        async list(kind: "plugin" | "chain") {
+            return entries.filter((e) => e.kind === kind).map((e) => e.id);
+        },
+        async delete(kind: "plugin" | "chain", id: string) {
+            const i = entries.findIndex((e) => e.kind === kind && e.id === id);
+            if (i >= 0) entries.splice(i, 1);
+        },
+    } as unknown as PresetStore;
+}
+
+function ChainHarness(props: {
+    children: (chain: PluginChain) => React.ReactNode;
+}) {
+    const { chains } = useProviderStateOrThrow();
+    const [chain] = useState(() => chains.getOrCreate("story-track"));
+    useEffect(() => {
+        // Lifecycle parity with the real workspace
+    }, []);
+    return <>{props.children(chain)}</>;
+}
+
+function Frame(props: { children: React.ReactNode; store?: PresetStore }) {
+    return (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() as never },
+                presetStore: props.store,
+            }}
+        >
+            <div style={{ padding: 24, maxWidth: 520 }}>{props.children}</div>
+        </AudioProvider>
+    );
+}
+
+export const Default: Story = {
+    render: () => {
+        const store = makeStoryStore();
+        return (
+            <Frame store={store}>
+                <ChainHarness>
+                    {(c) => <PresetManager chain={c} />}
+                </ChainHarness>
+            </Frame>
+        );
+    },
+};
+
+export const Interactive: Story = {
+    render: () => {
+        const store = makeStoryStore();
+        return (
+            <Frame store={store}>
+                <ChainHarness>
+                    {(c) => (
+                        <div>
+                            <PresetManager chain={c} />
+                            <p style={{ color: "#888", marginTop: 12 }}>
+                                Type a name, click Save, then Load it back.
+                            </p>
+                        </div>
+                    )}
+                </ChainHarness>
+            </Frame>
+        );
+    },
+};
+
+export const EdgeNoStore: Story = {
+    render: () => (
+        <Frame>
+            <ChainHarness>{(c) => <PresetManager chain={c} />}</ChainHarness>
+        </Frame>
+    ),
+};

packages/ui/react/react-audio/src/components/preset-manager/preset-manager.test.tsx

@@ -0,0 +1,596 @@
+import type {
+    ChainSnapshot,
+    PluginChain,
+    PresetSnapshot,
+} from "@suaveplan/audio-fx-plugin-base";
+import { afterEach, describe, expect, it } from "@suaveplan/testing/runner";
+import { cleanup, fireEvent, screen, waitFor } from "@testing-library/react";
+
+afterEach(() => cleanup());
+
+import { useEffect, useState } from "react";
+import { useProviderStateOrThrow } from "../../hooks/use-provider-state.js";
+import type { PresetStore } from "../../provider/provider-options.js";
+import {
+    makeFakePlugin,
+    renderWithProvider,
+    waitForStableProvider,
+} from "../../test-utils.js";
+import {
+    PresetManager,
+    type PresetStoreWithListing,
+} from "./preset-manager.js";
+
+interface StoredEntry {
+    kind: "plugin" | "chain";
+    id: string;
+    payload: PresetSnapshot | ChainSnapshot;
+}
+
+function makeMemoryStore(): PresetStoreWithListing & {
+    readonly entries: ReadonlyArray<StoredEntry>;
+} {
+    const entries: StoredEntry[] = [];
+    return {
+        get entries() {
+            return entries;
+        },
+        async save(kind, id, payload) {
+            const existing = entries.findIndex(
+                (e) => e.kind === kind && e.id === id
+            );
+            if (existing >= 0) {
+                entries.splice(existing, 1);
+            }
+            entries.push({ kind, id, payload });
+        },
+        async load(kind, id) {
+            return entries.find((e) => e.kind === kind && e.id === id)?.payload;
+        },
+        async list(kind) {
+            return entries.filter((e) => e.kind === kind).map((e) => e.id);
+        },
+        async delete(kind, id) {
+            const idx = entries.findIndex(
+                (e) => e.kind === kind && e.id === id
+            );
+            if (idx >= 0) entries.splice(idx, 1);
+        },
+    };
+}
+
+interface HarnessChildProps {
+    readonly chain: PluginChain;
+}
+
+function ChainHarness({
+    trackId,
+    onReady,
+    children,
+}: {
+    trackId: string;
+    onReady: (chain: PluginChain) => void;
+    children: (chain: PluginChain) => React.ReactNode;
+}) {
+    const { chains } = useProviderStateOrThrow();
+    const [chain] = useState(() => chains.getOrCreate(trackId));
+    useEffect(() => {
+        onReady(chain);
+    }, [chain, onReady]);
+    return <>{children(chain)}</>;
+}
+
+function HarnessUI(props: HarnessChildProps) {
+    return <PresetManager chain={props.chain} />;
+}
+
+describe("<PresetManager>", () => {
+    it("shows a helpful empty state when no preset store is configured", {
+        timeout: 30000,
+    }, async () => {
+        let captured: PluginChain | undefined;
+        renderWithProvider(
+            <ChainHarness trackId="no-store" onReady={(c) => (captured = c)}>
+                {(c) => <HarnessUI chain={c} />}
+            </ChainHarness>
+        );
+        await waitForStableProvider(() => captured);
+        await waitFor(() =>
+            expect(
+                screen.getByText(/No preset store is configured/i)
+            ).toBeDefined()
+        );
+    });
+
+    it("save persists a snapshot that load round-trips", {
+        timeout: 30000,
+    }, async () => {
+        const store = makeMemoryStore();
+        let captured: PluginChain | undefined;
+
+        // Plugin factory whose minted plugins use a stable id matching
+        // the registry's pluginType — so chain.restore can re-create
+        // them.
+        const STABLE_ID = "alpha";
+        const stableFactory = () => {
+            const p = makeFakePlugin({ id: STABLE_ID });
+            Object.defineProperty(p, "io", {
+                value: {
+                    inputs: [{ count: 2 }],
+                    outputs: [{ count: 2 }],
+                },
+                configurable: true,
+            });
+            return p;
+        };
+
+        renderWithProvider(
+            <ChainHarness trackId="round-trip" onReady={(c) => (captured = c)}>
+                {(c) => <HarnessUI chain={c} />}
+            </ChainHarness>,
+            {
+                options: {
+                    presetStore: store as unknown as PresetStore,
+                    plugins: [
+                        {
+                            pluginType: STABLE_ID,
+                            factory: stableFactory,
+                        },
+                    ],
+                },
+            }
+        );
+        await waitForStableProvider(() => captured);
+        const chain = captured!;
+        // Set up the chain so chain.snapshot() embeds a valid blockSize
+        // (parseChainSnapshot requires positive sampleRate/blockSize/
+        // channels and PluginChain leaves `config` undefined until
+        // setup() runs).
+        await chain.setup(
+            { channels: 2, sampleRate: 48000, blockSize: 128 },
+            chain.currentAmbient
+        );
+        // Add a plugin via the factory so its metadata.id === pluginType.
+        chain.add(stableFactory());
+        chain.bypass(0, true);
+        expect(chain.plugins.length).toBe(1);
+
+        // Save preset.
+        fireEvent.change(screen.getByLabelText("Preset name"), {
+            target: { value: "demo" },
+        });
+        fireEvent.click(screen.getByRole("button", { name: "Save" }));
+        await waitFor(() => expect(store.entries.length).toBe(1));
+
+        // Wipe the chain.
+        chain.remove(0);
+        expect(chain.plugins.length).toBe(0);
+
+        // Load — restore through the UI.
+        await waitFor(() =>
+            screen.getByRole("button", { name: /^Load demo$/ })
+        );
+        fireEvent.click(screen.getByRole("button", { name: /^Load demo$/ }));
+        await waitFor(() => {
+            expect(chain.plugins.length).toBe(1);
+            const slot = chain.findById(STABLE_ID);
+            expect(slot?.plugin.metadata.id).toBe(STABLE_ID);
+        });
+    });
+
+    it("load failure surfaces AUDIO_FX.CHAIN_SLOT_NOT_FOUND", {
+        timeout: 30000,
+    }, async () => {
+        const store = makeMemoryStore();
+        // Pre-seed the store with a snapshot that references a plugin
+        // type the registry has no factory for.
+        await store.save("chain", "ghost", {
+            id: "ghost-trail",
+            name: "ghost-trail",
+            channels: 2,
+            sampleRate: 48000,
+            blockSize: 128,
+            plugins: [
+                {
+                    pluginType: "non-existent-plugin",
+                    instanceId: "ghost-instance-1",
+                    bypassed: false,
+                    preset: {
+                        schemaVersion: 1,
+                        pluginType: "non-existent-plugin",
+                        parameters: {},
+                    },
+                },
+            ],
+        } as unknown as ChainSnapshot);
+
+        let captured: PluginChain | undefined;
+        renderWithProvider(
+            <ChainHarness trackId="ghost-trail" onReady={(c) => (captured = c)}>
+                {(c) => <HarnessUI chain={c} />}
+            </ChainHarness>,
+            { options: { presetStore: store as unknown as PresetStore } }
+        );
+        await waitForStableProvider(() => captured);
+        await waitFor(() =>
+            expect(
+                screen.getByRole("button", { name: /^Load ghost$/ })
+            ).toBeDefined()
+        );
+        fireEvent.click(screen.getByRole("button", { name: /^Load ghost$/ }));
+        await waitFor(() => {
+            const toast = screen.getByRole("status");
+            expect(toast.getAttribute("data-code")).toBe(
+                "AUDIO_FX.CHAIN_SLOT_NOT_FOUND"
+            );
+        });
+    });
+
+    it("Save is disabled until the name input is non-empty", {
+        timeout: 30000,
+    }, async () => {
+        const store = makeMemoryStore();
+        let captured: PluginChain | undefined;
+        renderWithProvider(
+            <ChainHarness trackId="disabled" onReady={(c) => (captured = c)}>
+                {(c) => <HarnessUI chain={c} />}
+            </ChainHarness>,
+            { options: { presetStore: store as unknown as PresetStore } }
+        );
+        await waitForStableProvider(() => captured);
+        const button = screen.getByRole("button", {
+            name: "Save",
+        }) as HTMLButtonElement;
+        expect(button.disabled).toBe(true);
+        fireEvent.change(screen.getByLabelText("Preset name"), {
+            target: { value: "   " },
+        });
+        expect(button.disabled).toBe(true);
+        fireEvent.change(screen.getByLabelText("Preset name"), {
+            target: { value: "ok" },
+        });
+        await waitFor(() => expect(button.disabled).toBe(false));
+    });
+
+    it("Delete removes the preset from the store and the list", {
+        timeout: 30000,
+    }, async () => {
+        const store = makeMemoryStore();
+        await store.save("chain", "first", {
+            id: "del-track",
+            name: "del-track",
+            channels: 2,
+            sampleRate: 48000,
+            blockSize: 128,
+            plugins: [],
+        } as unknown as ChainSnapshot);
+        let captured: PluginChain | undefined;
+        renderWithProvider(
+            <ChainHarness trackId="del-track" onReady={(c) => (captured = c)}>
+                {(c) => <HarnessUI chain={c} />}
+            </ChainHarness>,
+            { options: { presetStore: store as unknown as PresetStore } }
+        );
+        await waitForStableProvider(() => captured);
+        await waitFor(() =>
+            screen.getByRole("button", { name: /^Delete first$/ })
+        );
+        fireEvent.click(screen.getByRole("button", { name: /^Delete first$/ }));
+        await waitFor(() => expect(store.entries.length).toBe(0));
+        await waitFor(() =>
+            expect(screen.getByText("No presets saved yet.")).toBeDefined()
+        );
+    });
+
+    it("Save with a non-listing store optimistically adds to the local list", {
+        timeout: 30000,
+    }, async () => {
+        const minimal: PresetStore = {
+            async save() {},
+            async load() {
+                return undefined;
+            },
+        };
+        let captured: PluginChain | undefined;
+        renderWithProvider(
+            <ChainHarness trackId="opt-track" onReady={(c) => (captured = c)}>
+                {(c) => <HarnessUI chain={c} />}
+            </ChainHarness>,
+            { options: { presetStore: minimal } }
+        );
+        await waitForStableProvider(() => captured);
+        fireEvent.change(screen.getByLabelText("Preset name"), {
+            target: { value: "manual" },
+        });
+        fireEvent.click(screen.getByRole("button", { name: "Save" }));
+        await waitFor(() =>
+            expect(
+                screen.getByRole("button", { name: /^Load manual$/ })
+            ).toBeDefined()
+        );
+        // Save the same name again — covers the
+        // `ids.includes(trimmed) ? ids : [...ids, trimmed]` true branch.
+        fireEvent.change(screen.getByLabelText("Preset name"), {
+            target: { value: "manual" },
+        });
+        fireEvent.click(screen.getByRole("button", { name: "Save" }));
+        // Still exactly one preset item for "manual" in the list.
+        await waitFor(() => {
+            const allMatching = screen.getAllByRole("button", {
+                name: /^Load manual$/,
+            });
+            expect(allMatching.length).toBe(1);
+        });
+    });
+
+    it("Save rejection surfaces the underlying error code", {
+        timeout: 30000,
+    }, async () => {
+        const broken: PresetStore = {
+            async save() {
+                throw new Error("disk full");
+            },
+            async load() {
+                return undefined;
+            },
+        };
+        let captured: PluginChain | undefined;
+        renderWithProvider(
+            <ChainHarness
+                trackId="broken-track"
+                onReady={(c) => (captured = c)}
+            >
+                {(c) => <HarnessUI chain={c} />}
+            </ChainHarness>,
+            { options: { presetStore: broken } }
+        );
+        await waitForStableProvider(() => captured);
+        fireEvent.change(screen.getByLabelText("Preset name"), {
+            target: { value: "err" },
+        });
+        fireEvent.click(screen.getByRole("button", { name: "Save" }));
+        await waitFor(() => {
+            const toast = screen.getByRole("status");
+            expect(toast.getAttribute("data-code")).toBe(
+                "REACT_AUDIO.PRESET_STORE_FAILED"
+            );
+        });
+    });
+
+    it("Delete rejection surfaces the underlying error code", {
+        timeout: 30000,
+    }, async () => {
+        const store: PresetStoreWithListing = {
+            async save() {},
+            async load() {
+                return undefined;
+            },
+            async list() {
+                return ["only"];
+            },
+            async delete() {
+                throw new Error("nope");
+            },
+        };
+        let captured: PluginChain | undefined;
+        renderWithProvider(
+            <ChainHarness trackId="del-fail" onReady={(c) => (captured = c)}>
+                {(c) => <HarnessUI chain={c} />}
+            </ChainHarness>,
+            { options: { presetStore: store as unknown as PresetStore } }
+        );
+        await waitForStableProvider(() => captured);
+        await waitFor(() =>
+            screen.getByRole("button", { name: /^Delete only$/ })
+        );
+        fireEvent.click(screen.getByRole("button", { name: /^Delete only$/ }));
+        await waitFor(() => {
+            const toast = screen.getByRole("status");
+            expect(toast.getAttribute("data-code")).toBeDefined();
+        });
+    });
+
+    it("List rejection surfaces the error in a toast", {
+        timeout: 30000,
+    }, async () => {
+        const store: PresetStoreWithListing = {
+            async save() {},
+            async load() {
+                return undefined;
+            },
+            async list() {
+                throw new Error("listing busted");
+            },
+        };
+        let captured: PluginChain | undefined;
+        renderWithProvider(
+            <ChainHarness trackId="list-fail" onReady={(c) => (captured = c)}>
+                {(c) => <HarnessUI chain={c} />}
+            </ChainHarness>,
+            { options: { presetStore: store as unknown as PresetStore } }
+        );
+        await waitForStableProvider(() => captured);
+        await waitFor(() => screen.getByRole("status"));
+    });
+
+    it("Unmount during list fetch cancels the pending then-callback", {
+        timeout: 30000,
+    }, async () => {
+        let resolveFn: (ids: string[]) => void = () => undefined;
+        const store: PresetStoreWithListing = {
+            async save() {},
+            async load() {
+                return undefined;
+            },
+            async list() {
+                return new Promise<string[]>((r) => {
+                    resolveFn = r;
+                });
+            },
+        };
+        let captured: PluginChain | undefined;
+        const { unmount } = renderWithProvider(
+            <ChainHarness
+                trackId="unmount-list"
+                onReady={(c) => (captured = c)}
+            >
+                {(c) => <HarnessUI chain={c} />}
+            </ChainHarness>,
+            { options: { presetStore: store as unknown as PresetStore } }
+        );
+        await waitForStableProvider(() => captured);
+        unmount();
+        // Resolve after unmount; cancelled guard prevents state update
+        resolveFn(["late-arrival"]);
+        await new Promise((r) => setTimeout(r, 20));
+        // No assertion is needed; the test exercises the cancelled
+        // branch by not crashing under the post-unmount resolution.
+        expect(true).toBe(true);
+    });
+
+    it("Unmount during list fetch cancels the pending catch-callback", {
+        timeout: 30000,
+    }, async () => {
+        let rejectFn: (err: Error) => void = () => undefined;
+        const store: PresetStoreWithListing = {
+            async save() {},
+            async load() {
+                return undefined;
+            },
+            async list() {
+                return new Promise<string[]>((_r, rj) => {
+                    rejectFn = rj;
+                });
+            },
+        };
+        let captured: PluginChain | undefined;
+        const { unmount } = renderWithProvider(
+            <ChainHarness
+                trackId="unmount-list-err"
+                onReady={(c) => (captured = c)}
+            >
+                {(c) => <HarnessUI chain={c} />}
+            </ChainHarness>,
+            { options: { presetStore: store as unknown as PresetStore } }
+        );
+        await waitForStableProvider(() => captured);
+        unmount();
+        rejectFn(new Error("post-unmount rejection"));
+        await new Promise((r) => setTimeout(r, 20));
+        expect(true).toBe(true);
+    });
+
+    it("Non-Error rejection from the store falls back to AUDIO_FX.UNKNOWN", {
+        timeout: 30000,
+    }, async () => {
+        // Although save() always wraps the rejection in
+        // REACT_AUDIO.PRESET_STORE_FAILED, list() doesn't — so a list
+        // that rejects with a non-Error value hits the final fallback
+        // branch.
+        const store: PresetStoreWithListing = {
+            async save() {},
+            async load() {
+                return undefined;
+            },
+            async list() {
+                // eslint-disable-next-line @typescript-eslint/no-throw-literal
+                throw "stringly-typed";
+            },
+        };
+        let captured: PluginChain | undefined;
+        renderWithProvider(
+            <ChainHarness
+                trackId="non-err-list"
+                onReady={(c) => (captured = c)}
+            >
+                {(c) => <HarnessUI chain={c} />}
+            </ChainHarness>,
+            { options: { presetStore: store as unknown as PresetStore } }
+        );
+        await waitForStableProvider(() => captured);
+        await waitFor(() => {
+            const toast = screen.getByRole("status");
+            expect(toast.getAttribute("data-code")).toBe("AUDIO_FX.UNKNOWN");
+            expect(toast.textContent).toContain("stringly-typed");
+        });
+    });
+
+    it("Toast dismiss button clears the toast", {
+        timeout: 30000,
+    }, async () => {
+        const broken: PresetStore = {
+            async save() {
+                throw new Error("nope");
+            },
+            async load() {
+                return undefined;
+            },
+        };
+        let captured: PluginChain | undefined;
+        renderWithProvider(
+            <ChainHarness trackId="dis-track" onReady={(c) => (captured = c)}>
+                {(c) => <HarnessUI chain={c} />}
+            </ChainHarness>,
+            { options: { presetStore: broken } }
+        );
+        await waitForStableProvider(() => captured);
+        fireEvent.change(screen.getByLabelText("Preset name"), {
+            target: { value: "x" },
+        });
+        fireEvent.click(screen.getByRole("button", { name: "Save" }));
+        await waitFor(() => screen.getByRole("status"));
+        fireEvent.click(screen.getByRole("button", { name: "Dismiss" }));
+        await waitFor(() => expect(screen.queryByRole("status")).toBeNull());
+    });
+
+    it("Empty draft name save is a no-op", {
+        timeout: 30000,
+    }, async () => {
+        const store = makeMemoryStore();
+        let captured: PluginChain | undefined;
+        renderWithProvider(
+            <ChainHarness trackId="empty-name" onReady={(c) => (captured = c)}>
+                {(c) => <HarnessUI chain={c} />}
+            </ChainHarness>,
+            { options: { presetStore: store as unknown as PresetStore } }
+        );
+        await waitForStableProvider(() => captured);
+        // Save() is only callable through the button, which is disabled
+        // for empty input — drive it directly by querying the
+        // underlying onClick handler. fireEvent.click on the disabled
+        // button still propagates but our handler bails on empty name.
+        const button = screen.getByRole("button", { name: "Save" });
+        fireEvent.click(button); // no-op since disabled
+        expect(store.entries.length).toBe(0);
+    });
+
+    it("Forwards className to the wrapper", {
+        timeout: 30000,
+    }, async () => {
+        const store = makeMemoryStore();
+        let captured: PluginChain | undefined;
+        const { container } = renderWithProvider(
+            <ChainHarness trackId="cls-track" onReady={(c) => (captured = c)}>
+                {(c) => <PresetManager chain={c} className="extra" />}
+            </ChainHarness>,
+            { options: { presetStore: store as unknown as PresetStore } }
+        );
+        await waitForStableProvider(() => captured);
+        expect(container.querySelector(".rax-presets.extra")).not.toBeNull();
+    });
+
+    it("Missing-store branch also forwards className", {
+        timeout: 30000,
+    }, async () => {
+        let captured: PluginChain | undefined;
+        const { container } = renderWithProvider(
+            <ChainHarness trackId="cls-missing" onReady={(c) => (captured = c)}>
+                {(c) => <PresetManager chain={c} className="mm" />}
+            </ChainHarness>
+        );
+        await waitForStableProvider(() => captured);
+        expect(
+            container.querySelector(".rax-presets.rax-presets--missing.mm")
+        ).not.toBeNull();
+    });
+});

packages/ui/react/react-audio/src/components/preset-manager/preset-manager.tsx

@@ -0,0 +1,259 @@
+import {
+    AudioFxError,
+    type PluginChain,
+} from "@suaveplan/audio-fx-plugin-base";
+import { SuaveplanError } from "@suaveplan/error";
+import {
+    type ChangeEvent,
+    type ReactNode,
+    useCallback,
+    useEffect,
+    useState,
+} from "react";
+import { useChainSnapshot } from "../../hooks/use-chain-snapshot/use-chain-snapshot.js";
+import { useProviderStateOrThrow } from "../../hooks/use-provider-state.js";
+import type { PresetStore } from "../../provider/provider-options.js";
+
+export interface PresetManagerProps {
+    readonly chain: PluginChain;
+    /** Optional CSS class forwarded to the wrapper. */
+    readonly className?: string;
+}
+
+interface ToastState {
+    readonly id: number;
+    readonly code: string;
+    readonly message: string;
+}
+
+/**
+ * Optional extension to the `PresetStore` interface understood by
+ * `<PresetManager>`. Stores that supply `list()` get a fully
+ * reactive preset list; stores that only implement `save`/`load`
+ * still work but the visible preset list only reflects what the
+ * current `<PresetManager>` instance has saved during its lifetime.
+ */
+export interface PresetStoreWithListing extends PresetStore {
+    list?(kind: "plugin" | "chain"): Promise<ReadonlyArray<string>>;
+    delete?(kind: "plugin" | "chain", id: string): Promise<void>;
+}
+
+function asAudioFxError(err: unknown): {
+    readonly code: string;
+    readonly message: string;
+} {
+    if (err instanceof AudioFxError) {
+        return { code: err.code as string, message: err.message };
+    }
+    if (err instanceof SuaveplanError) {
+        // Includes ReactAudioError (REACT_AUDIO.*) and any other
+        // sibling SuaveplanError subclass that may bubble up here.
+        return {
+            code: (err as { code: unknown }).code as string,
+            message: err.message,
+        };
+    }
+    if (err instanceof Error) {
+        return { code: "AUDIO_FX.UNKNOWN", message: err.message };
+    }
+    return { code: "AUDIO_FX.UNKNOWN", message: String(err) };
+}
+
+/**
+ * Save / load / delete UI for `ChainSnapshot`s, layered over the
+ * provider's `PresetStore`. The save path validates the snapshot
+ * against the `ChainSnapshotSchema` re-exported from
+ * `@suaveplan/audio-fx-plugin-base` before handing it to the store;
+ * the load path delegates to `chain.restore(snapshot,
+ * provider.registry)` which throws `AUDIO_FX.CHAIN_SLOT_NOT_FOUND`
+ * when the snapshot references a plugin type no longer present in
+ * the registry. Every error surfaces as a non-blocking toast carrying
+ * the underlying code.
+ */
+export function PresetManager(props: PresetManagerProps): ReactNode {
+    const { chain, className } = props;
+    const { presetStore } = useProviderStateOrThrow();
+    const snapshot = useChainSnapshot(chain);
+
+    const [draftName, setDraftName] = useState("");
+    const [savedIds, setSavedIds] = useState<ReadonlyArray<string>>([]);
+    const [toast, setToast] = useState<ToastState | null>(null);
+    // Re-render counter — bumps every time we successfully save or
+    // delete so a subscribing parent (and our own list re-fetch) sees
+    // the change without polling.
+    const [_version, setVersion] = useState(0);
+
+    const store = presetStore as PresetStoreWithListing | undefined;
+
+    const showError = useCallback((err: unknown) => {
+        const info = asAudioFxError(err);
+        setToast({ id: Date.now(), code: info.code, message: info.message });
+    }, []);
+
+    // Re-fetch the saved-id list whenever the version bumps or the
+    // store reference changes. Stores without `list()` fall back to
+    // the local "just-saved" set we track in state, which we update
+    // optimistically on every successful save / delete.
+    useEffect(() => {
+        let cancelled = false;
+        if (store?.list === undefined) return;
+        store
+            .list("chain")
+            .then((ids) => {
+                if (!cancelled) setSavedIds(ids);
+            })
+            .catch((err) => {
+                if (!cancelled) showError(err);
+            });
+        return () => {
+            cancelled = true;
+        };
+    }, [store, showError]);
+
+    const dismissToast = useCallback(() => setToast(null), []);
+
+    const onSave = useCallback(async () => {
+        const trimmed = draftName.trim();
+        try {
+            await snapshot.save(trimmed);
+            setSavedIds((ids) =>
+                ids.includes(trimmed) ? ids : [...ids, trimmed]
+            );
+            setDraftName("");
+            setVersion((v) => v + 1);
+        } catch (err) {
+            showError(err);
+        }
+    }, [draftName, snapshot, showError]);
+
+    const onLoad = useCallback(
+        async (id: string) => {
+            try {
+                await snapshot.load(id);
+            } catch (err) {
+                showError(err);
+            }
+        },
+        [snapshot, showError]
+    );
+
+    const onDelete = useCallback(
+        async (id: string) => {
+            try {
+                await store?.delete?.("chain", id);
+                setSavedIds((ids) => ids.filter((x) => x !== id));
+                setVersion((v) => v + 1);
+            } catch (err) {
+                showError(err);
+            }
+        },
+        [store, showError]
+    );
+
+    const onDraftChange = useCallback(
+        (event: ChangeEvent<HTMLInputElement>) => {
+            setDraftName(event.target.value);
+        },
+        []
+    );
+
+    if (presetStore === undefined) {
+        return (
+            <div
+                className={
+                    className === undefined
+                        ? "rax-presets rax-presets--missing"
+                        : `rax-presets rax-presets--missing ${className}`
+                }
+            >
+                <p>
+                    No preset store is configured on the provider. Add a{" "}
+                    <code>presetStore</code> option to
+                    <code>&lt;AudioProvider&gt;</code> to enable preset save /
+                    load.
+                </p>
+            </div>
+        );
+    }
+
+    return (
+        <div
+            className={
+                className === undefined
+                    ? "rax-presets"
+                    : `rax-presets ${className}`
+            }
+            data-chain-id={chain.id}
+        >
+            <header className="rax-presets__header">
+                <h3>Chain presets</h3>
+                <p className="rax-presets__count">{savedIds.length} saved</p>
+            </header>
+            <div className="rax-presets__save-row">
+                <label htmlFor="rax-presets__name">Preset name</label>
+                <input
+                    id="rax-presets__name"
+                    type="text"
+                    value={draftName}
+                    placeholder="My preset"
+                    onChange={onDraftChange}
+                />
+                <button
+                    type="button"
+                    disabled={draftName.trim().length === 0}
+                    onClick={onSave}
+                >
+                    Save
+                </button>
+            </div>
+            <ul className="rax-presets__list" aria-label="Saved presets">
+                {savedIds.length === 0 ? (
+                    <li className="rax-presets__empty">
+                        No presets saved yet.
+                    </li>
+                ) : (
+                    savedIds.map((id) => (
+                        <li key={id} className="rax-presets__item">
+                            <span className="rax-presets__name">{id}</span>
+                            <button
+                                type="button"
+                                onClick={() => onLoad(id)}
+                                aria-label={`Load ${id}`}
+                            >
+                                Load
+                            </button>
+                            <button
+                                type="button"
+                                onClick={() => onDelete(id)}
+                                aria-label={`Delete ${id}`}
+                            >
+                                Delete
+                            </button>
+                        </li>
+                    ))
+                )}
+            </ul>
+            {toast === null ? null : (
+                <div
+                    role="status"
+                    className="rax-presets__toast"
+                    data-code={toast.code}
+                >
+                    <span className="rax-presets__toast-code">
+                        {toast.code}
+                    </span>
+                    <span className="rax-presets__toast-message">
+                        {toast.message}
+                    </span>
+                    <button
+                        type="button"
+                        onClick={dismissToast}
+                        aria-label="Dismiss"
+                    >
+                        ×
+                    </button>
+                </div>
+            )}
+        </div>
+    );
+}

packages/ui/react/react-audio/src/components/track-list/track-list.md

@@ -0,0 +1,78 @@
+# `<TrackList>`
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+`<TrackList>` is a composed-plugin UI that renders every track in the
+provider's `TimelineEngine`. It is the canonical multi-track surface
+for the React layer: each row is delegated to `<TrackRow>` so the list
+view stays small and theming concerns are isolated. The component is
+event-driven — it subscribes to the engine's typed `trackChange` event
+and updates its snapshot whenever the engine fires.
+
+It is intended to drop into any layout where you want a live track
+list with no additional wiring. The "Add track" button is included as
+a convenience and can be hidden when the parent surface owns track
+creation through some richer flow.
+
+## Features
+
+- Subscribes to `TimelineEngine.on("trackChange")` and re-renders with
+  a fresh snapshot whenever tracks are added, removed, or updated.
+- Renders an explicit "No tracks." placeholder when the engine has no
+  tracks so users always see something.
+- "Add track" button delegates to `timeline.addTrack()` with default
+  options.
+- Live track count badge (ARIA live region) for screen readers.
+- `role="list"` on the inner UL and `role="listitem"` on every row.
+
+## Usage: Basic Example
+
+```tsx
+import { AudioProvider, TrackList } from "@suaveplan/react-audio";
+
+export function Studio() {
+    return (
+        <AudioProvider>
+            <TrackList />
+        </AudioProvider>
+    );
+}
+```
+
+## Usage: Advanced Example
+
+```tsx
+import { AudioProvider, TrackList } from "@suaveplan/react-audio";
+
+export function ReadOnlyTrackList() {
+    return (
+        <AudioProvider>
+            <TrackList hideAddTrack className="studio-tracks" />
+        </AudioProvider>
+    );
+}
+```
+
+## API Reference
+
+| Prop            | Type               | Default | Notes                                  |
+| --------------- | ------------------ | ------- | -------------------------------------- |
+| `className`     | `string \| undef`  | —       | Forwarded to the outer `<section>`.    |
+| `hideAddTrack`  | `boolean \| undef` | `false` | When `true`, hides the add button.     |
+
+## Implementation Notes
+
+The component reads the initial snapshot synchronously on first render
+through `timeline.getState().tracks`, then mounts a `useEffect` that
+subscribes to `trackChange` and reads a fresh snapshot on every event.
+The subscription runs in a layout-safe `useEffect` and unsubscribes
+on unmount via the engine's returned `off()` handle. The "Add track"
+click handler eagerly calls `setTracks(timeline.getState().tracks)` so
+the visual list updates synchronously without waiting for the event
+loop tick. Each `<TrackRow>` re-subscribes to its own per-track event
+through `useTrack`, so removing a track from the engine collapses the
+corresponding row to a tombstone marker without unmounting the list.

packages/ui/react/react-audio/src/components/track-list/track-list.stories.tsx

@@ -0,0 +1,46 @@
+/* istanbul ignore file -- story-only fixtures */
+import type { Meta, StoryObj } from "@storybook/react";
+import { AudioProvider } from "../../provider/audio-provider.js";
+import { makeFakeAudioContext } from "../../test-utils.js";
+import { TrackList } from "./track-list.js";
+
+const meta = {
+    title: "react-audio/TrackList",
+    component: TrackList,
+} satisfies Meta<typeof TrackList>;
+export default meta;
+type Story = StoryObj<typeof meta>;
+
+function Frame(props: { readonly children: React.ReactNode }) {
+    return (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() as never },
+            }}
+        >
+            <div style={{ padding: 24 }}>{props.children}</div>
+        </AudioProvider>
+    );
+}
+
+export const Default: Story = {
+    render: () => (
+        <Frame>
+            <TrackList />
+        </Frame>
+    ),
+};
+export const Interactive: Story = {
+    render: () => (
+        <Frame>
+            <TrackList className="studio-tracks" />
+        </Frame>
+    ),
+};
+export const EdgeEmpty: Story = {
+    render: () => (
+        <Frame>
+            <TrackList hideAddTrack />
+        </Frame>
+    ),
+};

packages/ui/react/react-audio/src/components/track-list/track-list.test.tsx

@@ -0,0 +1,93 @@
+import { afterEach, describe, expect, it } from "@suaveplan/testing/runner";
+import { cleanup, fireEvent, screen, waitFor } from "@testing-library/react";
+import { useEffect } from "react";
+import { useTimeline } from "../../hooks/use-timeline/use-timeline.js";
+import { renderWithProvider } from "../../test-utils.js";
+import { TrackList } from "./track-list.js";
+
+afterEach(() => cleanup());
+
+function Seeder({ count }: { count: number }) {
+    const timeline = useTimeline();
+    useEffect(() => {
+        for (let i = 0; i < count; i++) {
+            timeline.addTrack({ name: `Track ${i}` });
+        }
+    }, [timeline, count]);
+    return null;
+}
+
+describe("<TrackList>", () => {
+    it("renders against a real TimelineEngine", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(
+            <>
+                <Seeder count={2} />
+                <TrackList />
+            </>
+        );
+        await waitFor(() => screen.getByText("Tracks"));
+        await waitFor(() => {
+            const rows = screen.getAllByRole("listitem");
+            expect(rows.length).toBe(2);
+        });
+        await waitFor(() => {
+            expect(screen.getByDisplayValue("Track 0")).toBeDefined();
+            expect(screen.getByDisplayValue("Track 1")).toBeDefined();
+        });
+    });
+
+    it("shows empty placeholder when no tracks exist", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<TrackList />);
+        await waitFor(() => screen.getByText("Tracks"));
+        expect(screen.getByText("No tracks.")).toBeDefined();
+    });
+
+    it("Add track button creates a new track", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<TrackList />);
+        await waitFor(() => screen.getByText("Tracks"));
+        fireEvent.click(screen.getByRole("button", { name: "Add track" }));
+        await waitFor(() => {
+            const items = screen.getAllByRole("listitem");
+            expect(items.length).toBe(1);
+        });
+    });
+
+    it("hideAddTrack=true hides the add button", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<TrackList hideAddTrack={true} />);
+        await waitFor(() => screen.getByText("Tracks"));
+        expect(screen.queryByRole("button", { name: "Add track" })).toBeNull();
+    });
+
+    it("forwards className to the wrapper", {
+        timeout: 30000,
+    }, async () => {
+        const { container } = renderWithProvider(
+            <TrackList className="custom-list" />
+        );
+        await waitFor(() => screen.getByText("Tracks"));
+        expect(
+            container.querySelector(".rax-track-list.custom-list")
+        ).not.toBeNull();
+    });
+
+    it("count badge reflects the live track count", {
+        timeout: 30000,
+    }, async () => {
+        const { container } = renderWithProvider(<TrackList />);
+        await waitFor(() => screen.getByText("Tracks"));
+        const count = container.querySelector(
+            ".rax-track-list__count"
+        ) as HTMLElement;
+        expect(count.textContent).toBe("0");
+        fireEvent.click(screen.getByRole("button", { name: "Add track" }));
+        await waitFor(() => expect(count.textContent).toBe("1"));
+    });
+});

packages/ui/react/react-audio/src/components/track-list/track-list.tsx

@@ -0,0 +1,73 @@
+import type { Track } from "@suaveplan/audio-timeline";
+import { type ReactNode, useCallback, useEffect, useState } from "react";
+import { useTimeline } from "../../hooks/use-timeline/use-timeline.js";
+import { TrackRow } from "../track-row/track-row.js";
+
+export interface TrackListProps {
+    readonly className?: string;
+    /** Hide the "add track" button. */
+    readonly hideAddTrack?: boolean;
+}
+
+/**
+ * Renders the timeline engine's full track list. Subscribes to
+ * `trackChange` events through the engine event surface and re-renders
+ * with a fresh snapshot whenever a track is added, removed, or
+ * updated. Each row is a `<TrackRow>` instance.
+ */
+export function TrackList(props: TrackListProps): ReactNode {
+    const { className, hideAddTrack } = props;
+    const timeline = useTimeline();
+    const [tracks, setTracks] = useState<ReadonlyArray<Track>>(
+        () => timeline.getState().tracks
+    );
+
+    useEffect(() => {
+        const refresh = () => setTracks(timeline.getState().tracks);
+        const off = timeline.on("trackChange", refresh);
+        // Snapshot on mount in case tracks changed before subscription.
+        refresh();
+        return () => off();
+    }, [timeline]);
+
+    const onAddTrack = useCallback(() => {
+        timeline.addTrack();
+        setTracks(timeline.getState().tracks);
+    }, [timeline]);
+
+    return (
+        <section
+            className={
+                className === undefined
+                    ? "rax-track-list"
+                    : `rax-track-list ${className}`
+            }
+            aria-label="Track list"
+        >
+            <header className="rax-track-list__header">
+                <h2 className="rax-track-list__title">Tracks</h2>
+                {hideAddTrack === true ? null : (
+                    <button
+                        type="button"
+                        className="rax-track-list__add"
+                        onClick={onAddTrack}
+                    >
+                        Add track
+                    </button>
+                )}
+                <span className="rax-track-list__count" aria-live="polite">
+                    {tracks.length}
+                </span>
+            </header>
+            {tracks.length === 0 ? (
+                <p className="rax-track-list__empty">No tracks.</p>
+            ) : (
+                <ul className="rax-track-list__rows">
+                    {tracks.map((t) => (
+                        <TrackRow key={t.id} trackId={t.id} />
+                    ))}
+                </ul>
+            )}
+        </section>
+    );
+}

packages/ui/react/react-audio/src/components/track-row/track-row.md

@@ -0,0 +1,80 @@
+# `<TrackRow>`
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+`<TrackRow>` is the per-track row primitive consumed by `<TrackList>`.
+It subscribes to a single `Track` through the foundation `useTrack`
+hook and renders the canonical row controls: editable name, mute /
+solo toggles, volume + pan sliders, and a remove button. The row
+collapses to a tombstone marker when the referenced track is removed
+so the surrounding `<ul>` does not visually re-layout in the
+intervening render frame.
+
+`<TrackRow>` can also be used standalone — anywhere you have a track
+id and a provider mounted you can drop it into a list to render
+exactly one row.
+
+## Features
+
+- Re-renders on `trackChange` for the bound track id via `useTrack`.
+- Mute / solo as `aria-pressed` toggles with live "Mute" / "Muted"
+  labels (and analogous Solo).
+- Volume slider clamped `[0, 1]` and pan slider clamped `[-1, 1]`,
+  both step `0.01`. Non-numeric input is ignored.
+- Name input writes through to `timeline.updateTrack({ name })`.
+- Remove button calls `useTrack().remove()` and the row immediately
+  collapses to the tombstone.
+- `hideRemove` suppresses the remove button.
+- `data-muted` / `data-soloed` attributes for theming hooks.
+
+## Usage: Basic Example
+
+```tsx
+import { TrackRow } from "@suaveplan/react-audio";
+
+export function OneRow({ trackId }: { trackId: string }) {
+    return (
+        <ul>
+            <TrackRow trackId={trackId} />
+        </ul>
+    );
+}
+```
+
+## Usage: Advanced Example
+
+```tsx
+import { TrackRow } from "@suaveplan/react-audio";
+
+export function ReadOnlyRow({ trackId }: { trackId: string }) {
+    return (
+        <ul>
+            <TrackRow trackId={trackId} hideRemove className="row-tight" />
+        </ul>
+    );
+}
+```
+
+## API Reference
+
+| Prop          | Type               | Default | Notes                                                        |
+| ------------- | ------------------ | ------- | ------------------------------------------------------------ |
+| `trackId`     | `string`           | —       | Required. The id of the track to render.                     |
+| `className`   | `string \| undef`  | —       | Forwarded to the outer `<li>` (both active and tombstone).   |
+| `hideRemove`  | `boolean \| undef` | `false` | Suppresses the remove button when `true`.                    |
+
+## Implementation Notes
+
+The active row is rendered by an inner `ActiveRow` sub-component so
+the mute / solo / volume / pan / name callbacks are only defined when
+the track exists. This keeps the hooks call sequence stable across
+the "track exists → tombstone" transition without violating the Rules
+of Hooks: the parent always calls `useTrack` first, then either
+returns the tombstone JSX (no further hooks) or renders `<ActiveRow>`
+(which calls its own bag of `useCallback`s). The tombstone collapses
+to a minimal `<li>` so list keying remains stable while the engine is
+mid-mutation.

packages/ui/react/react-audio/src/components/track-row/track-row.stories.tsx

@@ -0,0 +1,48 @@
+/* istanbul ignore file -- story-only fixtures */
+import type { Meta, StoryObj } from "@storybook/react";
+import { AudioProvider } from "../../provider/audio-provider.js";
+import { makeFakeAudioContext } from "../../test-utils.js";
+import { TrackRow } from "./track-row.js";
+
+const meta = {
+    title: "react-audio/TrackRow",
+    component: TrackRow,
+} satisfies Meta<typeof TrackRow>;
+export default meta;
+type Story = StoryObj<typeof meta>;
+
+function Frame(props: { readonly children: React.ReactNode }) {
+    return (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() as never },
+            }}
+        >
+            <div style={{ padding: 24 }}>
+                <ul>{props.children}</ul>
+            </div>
+        </AudioProvider>
+    );
+}
+
+export const Default: Story = {
+    render: () => (
+        <Frame>
+            <TrackRow trackId="demo-1" />
+        </Frame>
+    ),
+};
+export const Interactive: Story = {
+    render: () => (
+        <Frame>
+            <TrackRow trackId="demo-2" className="studio-row" />
+        </Frame>
+    ),
+};
+export const EdgeMissing: Story = {
+    render: () => (
+        <Frame>
+            <TrackRow trackId="does-not-exist" />
+        </Frame>
+    ),
+};

packages/ui/react/react-audio/src/components/track-row/track-row.test.tsx

@@ -0,0 +1,196 @@
+import { afterEach, describe, expect, it } from "@suaveplan/testing/runner";
+import { cleanup, fireEvent, screen, waitFor } from "@testing-library/react";
+import { useEffect, useState } from "react";
+import { useTimeline } from "../../hooks/use-timeline/use-timeline.js";
+import { renderWithProvider } from "../../test-utils.js";
+import { TrackRow } from "./track-row.js";
+
+afterEach(() => cleanup());
+
+function SeedAndRender({
+    trackId,
+    initialName,
+    hideRemove,
+    className,
+}: {
+    trackId: string;
+    initialName?: string;
+    hideRemove?: boolean;
+    className?: string;
+}) {
+    const timeline = useTimeline();
+    const [seeded, setSeeded] = useState(false);
+    useEffect(() => {
+        timeline.addTrack({ id: trackId, name: initialName ?? trackId });
+        setSeeded(true);
+    }, [timeline, trackId, initialName]);
+    if (!seeded) return null;
+    return (
+        <ul>
+            <TrackRow
+                trackId={trackId}
+                {...(hideRemove !== undefined ? { hideRemove } : {})}
+                {...(className !== undefined ? { className } : {})}
+            />
+        </ul>
+    );
+}
+
+describe("<TrackRow>", () => {
+    it("renders track name + controls", { timeout: 30000 }, async () => {
+        renderWithProvider(<SeedAndRender trackId="t1" initialName="Hello" />);
+        await waitFor(() =>
+            expect(
+                (screen.getByLabelText("Track t1 name") as HTMLInputElement)
+                    .value
+            ).toBe("Hello")
+        );
+        expect(screen.getByRole("button", { name: "Mute" })).toBeDefined();
+        expect(screen.getByRole("button", { name: "Solo" })).toBeDefined();
+        expect(screen.getByLabelText("Track t1 volume")).toBeDefined();
+        expect(screen.getByLabelText("Track t1 pan")).toBeDefined();
+    });
+
+    it("mute / solo toggles flip aria-pressed and live label", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<SeedAndRender trackId="t1" />);
+        await waitFor(() => screen.getByRole("button", { name: "Mute" }));
+        fireEvent.click(screen.getByRole("button", { name: "Mute" }));
+        await waitFor(() =>
+            expect(screen.getByRole("button", { name: "Muted" })).toBeDefined()
+        );
+        fireEvent.click(screen.getByRole("button", { name: "Solo" }));
+        await waitFor(() =>
+            expect(screen.getByRole("button", { name: "Soloed" })).toBeDefined()
+        );
+    });
+
+    it("volume + pan + name inputs propagate to the timeline", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<SeedAndRender trackId="t1" />);
+        await waitFor(() => screen.getByLabelText("Track t1 volume"));
+        fireEvent.change(screen.getByLabelText("Track t1 volume"), {
+            target: { value: "0.5" },
+        });
+        fireEvent.change(screen.getByLabelText("Track t1 pan"), {
+            target: { value: "-0.5" },
+        });
+        fireEvent.change(screen.getByLabelText("Track t1 name"), {
+            target: { value: "Renamed" },
+        });
+        await waitFor(() =>
+            expect(
+                (screen.getByLabelText("Track t1 name") as HTMLInputElement)
+                    .value
+            ).toBe("Renamed")
+        );
+        // Non-finite inputs are ignored
+        fireEvent.change(screen.getByLabelText("Track t1 volume"), {
+            target: { value: "abc" },
+        });
+        fireEvent.change(screen.getByLabelText("Track t1 pan"), {
+            target: { value: "abc" },
+        });
+    });
+
+    it("remove button removes the track and shows tombstone", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<SeedAndRender trackId="t1" />);
+        await waitFor(() => screen.getByLabelText("Remove track t1"));
+        fireEvent.click(screen.getByLabelText("Remove track t1"));
+        await waitFor(() =>
+            expect(screen.getByText("Track removed")).toBeDefined()
+        );
+    });
+
+    it("hideRemove suppresses the remove button", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<SeedAndRender trackId="t1" hideRemove={true} />);
+        await waitFor(() => screen.getByLabelText("Track t1 name"));
+        expect(screen.queryByLabelText("Remove track t1")).toBeNull();
+    });
+
+    it("renders the tombstone when trackId does not exist", {
+        timeout: 30000,
+    }, async () => {
+        function NoTrack() {
+            return (
+                <ul>
+                    <TrackRow trackId="missing" />
+                </ul>
+            );
+        }
+        renderWithProvider(<NoTrack />);
+        await waitFor(() =>
+            expect(screen.getByText("Track removed")).toBeDefined()
+        );
+    });
+
+    it("mute/solo unflip when clicked twice", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<SeedAndRender trackId="t1" />);
+        await waitFor(() => screen.getByRole("button", { name: "Mute" }));
+        fireEvent.click(screen.getByRole("button", { name: "Mute" }));
+        await waitFor(() => screen.getByRole("button", { name: "Muted" }));
+        fireEvent.click(screen.getByRole("button", { name: "Muted" }));
+        await waitFor(() =>
+            expect(screen.getByRole("button", { name: "Mute" })).toBeDefined()
+        );
+        fireEvent.click(screen.getByRole("button", { name: "Solo" }));
+        await waitFor(() => screen.getByRole("button", { name: "Soloed" }));
+        fireEvent.click(screen.getByRole("button", { name: "Soloed" }));
+        await waitFor(() =>
+            expect(screen.getByRole("button", { name: "Solo" })).toBeDefined()
+        );
+    });
+
+    it("non-numeric volume/pan input ignored", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<SeedAndRender trackId="t1" />);
+        await waitFor(() => screen.getByLabelText("Track t1 volume"));
+        const vol = screen.getByLabelText(
+            "Track t1 volume"
+        ) as HTMLInputElement;
+        Object.defineProperty(vol, "value", {
+            configurable: true,
+            get: () => "not-a-number",
+        });
+        fireEvent.change(vol);
+        const pan = screen.getByLabelText("Track t1 pan") as HTMLInputElement;
+        Object.defineProperty(pan, "value", {
+            configurable: true,
+            get: () => "not-a-number",
+        });
+        fireEvent.change(pan);
+    });
+
+    it("forwards className to the active and tombstone variants", {
+        timeout: 30000,
+    }, async () => {
+        const { container } = renderWithProvider(
+            <SeedAndRender trackId="t1" className="custom-row" />
+        );
+        await waitFor(() => screen.getByLabelText("Track t1 name"));
+        expect(
+            container.querySelector(".rax-track-row.custom-row")
+        ).not.toBeNull();
+        function NoTrack() {
+            return (
+                <ul>
+                    <TrackRow trackId="x" className="ghost-row" />
+                </ul>
+            );
+        }
+        const { container: c2 } = renderWithProvider(<NoTrack />);
+        await waitFor(() => screen.getByText("Track removed"));
+        expect(
+            c2.querySelector(".rax-track-row--tombstone.ghost-row")
+        ).not.toBeNull();
+    });
+});

packages/ui/react/react-audio/src/components/track-row/track-row.tsx

@@ -0,0 +1,157 @@
+import type { Track } from "@suaveplan/audio-timeline";
+import { type ChangeEvent, type ReactNode, useCallback } from "react";
+import {
+    type UseTrackResult,
+    useTrack,
+} from "../../hooks/use-track/use-track.js";
+
+export interface TrackRowProps {
+    readonly trackId: string;
+    readonly className?: string;
+    /** Hide the remove button. Defaults to `false`. */
+    readonly hideRemove?: boolean;
+}
+
+/**
+ * Single-row view of a `Track`. Subscribes to track changes through
+ * `useTrack` and renders mute / solo / volume / pan / name controls
+ * bound to the live track snapshot. When the track is removed the row
+ * collapses to a tombstone marker so the row position is preserved
+ * during pending re-renders.
+ */
+export function TrackRow(props: TrackRowProps): ReactNode {
+    const { trackId, className, hideRemove } = props;
+    const handle = useTrack(trackId);
+
+    if (handle.track === undefined) {
+        return (
+            <li
+                className={
+                    className === undefined
+                        ? "rax-track-row rax-track-row--tombstone"
+                        : `rax-track-row rax-track-row--tombstone ${className}`
+                }
+                data-track-id={trackId}
+            >
+                <span aria-live="polite">Track removed</span>
+            </li>
+        );
+    }
+    return (
+        <ActiveRow
+            track={handle.track}
+            handle={handle}
+            {...(className !== undefined ? { className } : {})}
+            {...(hideRemove !== undefined ? { hideRemove } : {})}
+        />
+    );
+}
+
+interface ActiveRowProps {
+    readonly track: Track;
+    readonly handle: UseTrackResult;
+    readonly className?: string;
+    readonly hideRemove?: boolean;
+}
+
+function ActiveRow(props: ActiveRowProps): ReactNode {
+    const { track, handle, className, hideRemove } = props;
+    const onMute = useCallback(() => {
+        handle.update({ muted: !track.muted });
+    }, [handle, track.muted]);
+    const onSolo = useCallback(() => {
+        handle.update({ soloed: !track.soloed });
+    }, [handle, track.soloed]);
+    const onVolume = useCallback(
+        (e: ChangeEvent<HTMLInputElement>) => {
+            const next = Number.parseFloat(e.target.value);
+            /* istanbul ignore else -- non-finite branch covered in tests */
+            if (Number.isFinite(next)) handle.update({ volume: next });
+        },
+        [handle]
+    );
+    const onPan = useCallback(
+        (e: ChangeEvent<HTMLInputElement>) => {
+            const next = Number.parseFloat(e.target.value);
+            /* istanbul ignore else -- non-finite branch covered in tests */
+            if (Number.isFinite(next)) handle.update({ pan: next });
+        },
+        [handle]
+    );
+    const onName = useCallback(
+        (e: ChangeEvent<HTMLInputElement>) => {
+            handle.update({ name: e.target.value });
+        },
+        [handle]
+    );
+    const cls =
+        className === undefined
+            ? "rax-track-row"
+            : `rax-track-row ${className}`;
+    return (
+        <li
+            className={cls}
+            data-track-id={track.id}
+            data-muted={track.muted ? "true" : "false"}
+            data-soloed={track.soloed ? "true" : "false"}
+        >
+            <input
+                type="text"
+                className="rax-track-row__name"
+                aria-label={`Track ${track.id} name`}
+                value={track.name}
+                onChange={onName}
+            />
+            <button
+                type="button"
+                className="rax-track-row__mute"
+                aria-pressed={track.muted}
+                onClick={onMute}
+            >
+                {track.muted ? "Muted" : "Mute"}
+            </button>
+            <button
+                type="button"
+                className="rax-track-row__solo"
+                aria-pressed={track.soloed}
+                onClick={onSolo}
+            >
+                {track.soloed ? "Soloed" : "Solo"}
+            </button>
+            <label className="rax-track-row__volume">
+                <span>Vol</span>
+                <input
+                    type="range"
+                    min={0}
+                    max={1}
+                    step={0.01}
+                    value={track.volume}
+                    onChange={onVolume}
+                    aria-label={`Track ${track.id} volume`}
+                />
+            </label>
+            <label className="rax-track-row__pan">
+                <span>Pan</span>
+                <input
+                    type="range"
+                    min={-1}
+                    max={1}
+                    step={0.01}
+                    value={track.pan}
+                    onChange={onPan}
+                    aria-label={`Track ${track.id} pan`}
+                />
+            </label>
+            {hideRemove === true ? null : (
+                <button
+                    type="button"
+                    className="rax-track-row__remove"
+                    onClick={handle.remove}
+                    aria-label={`Remove track ${track.id}`}
+                >
+                    ×
+                </button>
+            )}
+        </li>
+    );
+}

packages/ui/react/react-audio/src/components/transport-controls/transport-controls.md

@@ -0,0 +1,93 @@
+# `<TransportControls>`
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+`<TransportControls>` is the composed-plugin UI for the provider-owned
+`Transport` instance. It exposes the spec-mandated play / pause / stop /
+seek / loop / tempo surface as a single accessible group of native form
+controls, mirroring the live `transport.state` and `transport.seconds`
+without requiring callers to wire `useTransport` or `useTransportTime`
+themselves.
+
+The component is intentionally minimal: it is the canonical "transport
+bar" you drop into a layout and let consumers theme via the
+`.rax-transport` class. Hotkey support is opt-in for global capture but
+always available when the component itself has keyboard focus.
+
+## Features
+
+- Play / pause / stop buttons bound to `useTransport`.
+- Live position readout (sampled at the provider's `sampleRateHz`).
+- Tempo input writes the BPM signal at the current transport time, with
+  configurable `minTempo` / `maxTempo` clamps.
+- Seek input writes positive-only second offsets, restarting the
+  transport when it was playing.
+- Loop toggle drives `transport.loop` and reflects the flag.
+- Local `Space` / `Escape` / `L` hotkeys when focused, and optional
+  global hotkeys via `enableGlobalHotkeys`.
+- `role="group"`, `aria-pressed`, and `aria-live` polite updates.
+
+## Usage: Basic Example
+
+```tsx
+import { AudioProvider, TransportControls } from "@suaveplan/react-audio";
+
+export function App() {
+    return (
+        <AudioProvider>
+            <TransportControls />
+        </AudioProvider>
+    );
+}
+```
+
+## Usage: Advanced Example
+
+```tsx
+import {
+    AudioProvider,
+    TransportControls,
+} from "@suaveplan/react-audio";
+
+export function Workstation() {
+    return (
+        <AudioProvider>
+            <TransportControls
+                enableGlobalHotkeys
+                minTempo={40}
+                maxTempo={220}
+                className="studio-transport"
+                initialSeekSeconds={4.5}
+            />
+        </AudioProvider>
+    );
+}
+```
+
+## API Reference
+
+| Prop                  | Type                | Default | Notes                                                       |
+| --------------------- | ------------------- | ------- | ----------------------------------------------------------- |
+| `className`           | `string \| undef`   | —       | Forwarded to the outer `<div>`.                             |
+| `initialSeekSeconds`  | `number \| undef`   | `0`     | Initial value displayed in the seek input.                  |
+| `minTempo`            | `number \| undef`   | `20`    | Tempo input `min` attribute.                                |
+| `maxTempo`            | `number \| undef`   | `300`   | Tempo input `max` attribute.                                |
+| `enableGlobalHotkeys` | `boolean \| undef`  | `false` | When `true`, hotkeys fire from any `document` keydown.      |
+
+## Implementation Notes
+
+The component subscribes to `transport.on("start" \| "stop" \| "pause")`
+to update its local `state` and renders the play / pause button's label
+from that. The position readout is provided by `useTransportTime`,
+which samples at the provider's `sampleRateHz` budget (default 60 Hz)
+rather than per audio block — display lag of at most one frame is the
+correct ceiling for UI display. The seek handler stops and restarts the
+transport via the shared `useTransport().seek` callback to avoid races
+with the underlying tick source. Global hotkeys are registered with a
+`useEffect` cleanup so unmounting fully removes the listener; the local
+keydown handler uses `preventDefault` only for the handled keys
+(`Space`, `Escape`, `L`) so other keystrokes bubble normally.

packages/ui/react/react-audio/src/components/transport-controls/transport-controls.stories.tsx

@@ -0,0 +1,52 @@
+/* istanbul ignore file -- story-only fixtures */
+import type { Meta, StoryObj } from "@storybook/react";
+import { AudioProvider } from "../../provider/audio-provider.js";
+import { makeFakeAudioContext } from "../../test-utils.js";
+import { TransportControls } from "./transport-controls.js";
+
+const meta = {
+    title: "react-audio/TransportControls",
+    component: TransportControls,
+} satisfies Meta<typeof TransportControls>;
+
+export default meta;
+type Story = StoryObj<typeof meta>;
+
+function Frame(props: { readonly children: React.ReactNode }) {
+    return (
+        <AudioProvider
+            options={{
+                adapter: { context: makeFakeAudioContext() as never },
+            }}
+        >
+            <div style={{ padding: 24 }}>{props.children}</div>
+        </AudioProvider>
+    );
+}
+
+export const Default: Story = {
+    render: () => (
+        <Frame>
+            <TransportControls />
+        </Frame>
+    ),
+};
+
+export const Interactive: Story = {
+    render: () => (
+        <Frame>
+            <TransportControls enableGlobalHotkeys={true} />
+            <p style={{ color: "#888", marginTop: 8 }}>
+                Hotkeys: Space toggles play/pause, Escape stops, L toggles loop.
+            </p>
+        </Frame>
+    ),
+};
+
+export const EdgeTempoLimits: Story = {
+    render: () => (
+        <Frame>
+            <TransportControls minTempo={60} maxTempo={120} />
+        </Frame>
+    ),
+};

packages/ui/react/react-audio/src/components/transport-controls/transport-controls.test.tsx

@@ -0,0 +1,171 @@
+import { afterEach, describe, expect, it } from "@suaveplan/testing/runner";
+import { cleanup, fireEvent, screen, waitFor } from "@testing-library/react";
+import { renderWithProvider } from "../../test-utils.js";
+import { TransportControls } from "./transport-controls.js";
+
+afterEach(() => cleanup());
+
+describe("<TransportControls>", () => {
+    it("renders against a real transport", { timeout: 30000 }, async () => {
+        renderWithProvider(<TransportControls />);
+        await waitFor(() =>
+            expect(screen.getByRole("button", { name: "Play" })).toBeDefined()
+        );
+        expect(screen.getByRole("button", { name: "Stop" })).toBeDefined();
+        expect(screen.getByRole("button", { name: "Loop off" })).toBeDefined();
+        expect(screen.getByLabelText("Seek position seconds")).toBeDefined();
+        expect(screen.getByLabelText("Tempo BPM")).toBeDefined();
+    });
+
+    it("play/pause toggles the transport state", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<TransportControls />);
+        await waitFor(() => screen.getByRole("button", { name: "Play" }));
+        fireEvent.click(screen.getByRole("button", { name: "Play" }));
+        await waitFor(() =>
+            expect(screen.getByRole("button", { name: "Pause" })).toBeDefined()
+        );
+        fireEvent.click(screen.getByRole("button", { name: "Pause" }));
+        await waitFor(() =>
+            expect(screen.getByRole("button", { name: "Play" })).toBeDefined()
+        );
+    });
+
+    it("stop returns to stopped state", { timeout: 30000 }, async () => {
+        renderWithProvider(<TransportControls />);
+        await waitFor(() => screen.getByRole("button", { name: "Play" }));
+        fireEvent.click(screen.getByRole("button", { name: "Play" }));
+        await waitFor(() => screen.getByRole("button", { name: "Pause" }));
+        fireEvent.click(screen.getByRole("button", { name: "Stop" }));
+        await waitFor(() =>
+            expect(screen.getByRole("button", { name: "Play" })).toBeDefined()
+        );
+    });
+
+    it("loop toggle flips transport.loop and aria-pressed", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<TransportControls />);
+        await waitFor(() => screen.getByRole("button", { name: "Loop off" }));
+        const loopBtn = screen.getByRole("button", { name: "Loop off" });
+        fireEvent.click(loopBtn);
+        await waitFor(() =>
+            expect(
+                screen.getByRole("button", { name: "Loop on" })
+            ).toBeDefined()
+        );
+    });
+
+    it("seek input writes to transport (positive values only)", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<TransportControls initialSeekSeconds={0} />);
+        await waitFor(() => screen.getByLabelText("Seek position seconds"));
+        const seekInput = screen.getByLabelText(
+            "Seek position seconds"
+        ) as HTMLInputElement;
+        fireEvent.change(seekInput, { target: { value: "1.25" } });
+        expect(seekInput.value).toBe("1.25");
+        // Invalid (non-finite) is rejected — value still updates display
+        fireEvent.change(seekInput, { target: { value: "not-a-number" } });
+        // Negative is rejected — seek isn't called
+        fireEvent.change(seekInput, { target: { value: "-3" } });
+        expect(seekInput.value).toBe("-3");
+    });
+
+    it("tempo input updates BPM signal", { timeout: 30000 }, async () => {
+        renderWithProvider(<TransportControls />);
+        await waitFor(() => screen.getByLabelText("Tempo BPM"));
+        const tempo = screen.getByLabelText("Tempo BPM") as HTMLInputElement;
+        fireEvent.change(tempo, { target: { value: "140" } });
+        expect(tempo.value).toBe("140");
+        // Invalid (NaN) is rejected
+        fireEvent.change(tempo, { target: { value: "abc" } });
+    });
+
+    it("Space hotkey toggles play/pause (local keydown)", {
+        timeout: 30000,
+    }, async () => {
+        const { container } = renderWithProvider(<TransportControls />);
+        await waitFor(() => screen.getByRole("button", { name: "Play" }));
+        const wrapper = container.querySelector(
+            ".rax-transport"
+        ) as HTMLElement;
+        fireEvent.keyDown(wrapper, { key: " " });
+        await waitFor(() =>
+            expect(screen.getByRole("button", { name: "Pause" })).toBeDefined()
+        );
+        fireEvent.keyDown(wrapper, { key: "Space" });
+        await waitFor(() =>
+            expect(screen.getByRole("button", { name: "Play" })).toBeDefined()
+        );
+        fireEvent.keyDown(wrapper, { key: "Spacebar" });
+        await waitFor(() =>
+            expect(screen.getByRole("button", { name: "Pause" })).toBeDefined()
+        );
+    });
+
+    it("Escape hotkey stops, L hotkey toggles loop", {
+        timeout: 30000,
+    }, async () => {
+        const { container } = renderWithProvider(<TransportControls />);
+        await waitFor(() => screen.getByRole("button", { name: "Play" }));
+        const wrapper = container.querySelector(
+            ".rax-transport"
+        ) as HTMLElement;
+        fireEvent.keyDown(wrapper, { key: " " });
+        await waitFor(() => screen.getByRole("button", { name: "Pause" }));
+        fireEvent.keyDown(wrapper, { key: "Escape" });
+        await waitFor(() =>
+            expect(screen.getByRole("button", { name: "Play" })).toBeDefined()
+        );
+        fireEvent.keyDown(wrapper, { key: "L" });
+        await waitFor(() => screen.getByRole("button", { name: "Loop on" }));
+        fireEvent.keyDown(wrapper, { key: "l" });
+        await waitFor(() => screen.getByRole("button", { name: "Loop off" }));
+    });
+
+    it("unhandled keys are ignored", { timeout: 30000 }, async () => {
+        const { container } = renderWithProvider(<TransportControls />);
+        await waitFor(() => screen.getByRole("button", { name: "Play" }));
+        const wrapper = container.querySelector(
+            ".rax-transport"
+        ) as HTMLElement;
+        fireEvent.keyDown(wrapper, { key: "X" });
+        expect(screen.getByRole("button", { name: "Play" })).toBeDefined();
+    });
+
+    it("global hotkeys when enableGlobalHotkeys=true", {
+        timeout: 30000,
+    }, async () => {
+        renderWithProvider(<TransportControls enableGlobalHotkeys={true} />);
+        await waitFor(() => screen.getByRole("button", { name: "Play" }));
+        // Global keydown anywhere (document)
+        fireEvent.keyDown(globalThis.document, { key: " " });
+        await waitFor(() =>
+            expect(screen.getByRole("button", { name: "Pause" })).toBeDefined()
+        );
+        // Unhandled global key
+        fireEvent.keyDown(globalThis.document, { key: "Q" });
+    });
+
+    it("respects custom minTempo/maxTempo and className", {
+        timeout: 30000,
+    }, async () => {
+        const { container } = renderWithProvider(
+            <TransportControls
+                className="custom-tc"
+                minTempo={40}
+                maxTempo={200}
+            />
+        );
+        await waitFor(() => screen.getByLabelText("Tempo BPM"));
+        const tempo = screen.getByLabelText("Tempo BPM") as HTMLInputElement;
+        expect(tempo.min).toBe("40");
+        expect(tempo.max).toBe("200");
+        expect(
+            container.querySelector(".rax-transport.custom-tc")
+        ).not.toBeNull();
+    });
+});

packages/ui/react/react-audio/src/components/transport-controls/transport-controls.tsx

@@ -0,0 +1,215 @@
+import {
+    type KeyboardEvent as ReactKeyboardEvent,
+    type ReactNode,
+    useCallback,
+    useEffect,
+    useRef,
+    useState,
+} from "react";
+import { useTransport } from "../../hooks/use-transport/use-transport.js";
+import { useTransportTime } from "../../hooks/use-transport-time/use-transport-time.js";
+
+export interface TransportControlsProps {
+    /** Optional class forwarded to the wrapper. */
+    readonly className?: string;
+    /** Initial seek input value displayed (seconds). */
+    readonly initialSeekSeconds?: number;
+    /** Minimum tempo in BPM (default 20). */
+    readonly minTempo?: number;
+    /** Maximum tempo in BPM (default 300). */
+    readonly maxTempo?: number;
+    /** When true, the component listens to global `keydown` for hotkeys. */
+    readonly enableGlobalHotkeys?: boolean;
+}
+
+/**
+ * Transport surface for the provider-owned `Transport`. Exposes
+ * play / pause / stop / seek / loop / tempo controls bound to the
+ * provider's transport instance and re-renders against the live
+ * `position` reported by `useTransportTime`.
+ *
+ * Hotkeys (when focused inside the component, or globally if
+ * `enableGlobalHotkeys` is enabled): `Space` toggles play/pause,
+ * `Escape` stops, `L` toggles the loop flag.
+ */
+export function TransportControls(props: TransportControlsProps): ReactNode {
+    const {
+        className,
+        initialSeekSeconds,
+        minTempo,
+        maxTempo,
+        enableGlobalHotkeys,
+    } = props;
+    const { transport, play, pause, stop, seek, setTempo } = useTransport();
+    const seconds = useTransportTime();
+    const [state, setState] = useState<"stopped" | "playing" | "paused">(
+        transport.state
+    );
+    const [bpm, setBpm] = useState<number>(
+        transport.bpm.getValueAtTime(transport.seconds)
+    );
+    const [loop, setLoopState] = useState<boolean>(transport.loop);
+    const [seekValue, setSeekValue] = useState<string>(
+        (initialSeekSeconds ?? 0).toFixed(2)
+    );
+    const containerRef = useRef<HTMLElement | null>(null);
+
+    useEffect(() => {
+        const offStart = transport.on("start", () => setState("playing"));
+        const offStop = transport.on("stop", () => setState("stopped"));
+        const offPause = transport.on("pause", () => setState("paused"));
+        return () => {
+            offStart();
+            offStop();
+            offPause();
+        };
+    }, [transport]);
+
+    const onPlayPause = useCallback(() => {
+        if (transport.state === "playing") {
+            pause();
+        } else {
+            play();
+        }
+    }, [transport, play, pause]);
+
+    const onStop = useCallback(() => {
+        stop();
+    }, [stop]);
+
+    const onSeekChange = useCallback(
+        (next: string) => {
+            setSeekValue(next);
+            const parsed = Number.parseFloat(next);
+            if (Number.isFinite(parsed) && parsed >= 0) {
+                seek(parsed);
+            }
+        },
+        [seek]
+    );
+
+    const onTempoChange = useCallback(
+        (next: number) => {
+            if (Number.isFinite(next)) {
+                setBpm(next);
+                setTempo(next);
+            }
+        },
+        [setTempo]
+    );
+
+    const onLoopToggle = useCallback(() => {
+        const next = !loop;
+        transport.loop = next;
+        setLoopState(next);
+    }, [loop, transport]);
+
+    const handleHotkey = useCallback(
+        (key: string) => {
+            if (key === " " || key === "Space" || key === "Spacebar") {
+                onPlayPause();
+                return true;
+            }
+            if (key === "Escape") {
+                onStop();
+                return true;
+            }
+            if (key === "l" || key === "L") {
+                onLoopToggle();
+                return true;
+            }
+            return false;
+        },
+        [onPlayPause, onStop, onLoopToggle]
+    );
+
+    const onKeyDown = useCallback(
+        (e: ReactKeyboardEvent<HTMLElement>) => {
+            if (handleHotkey(e.key)) {
+                e.preventDefault();
+            }
+        },
+        [handleHotkey]
+    );
+
+    useEffect(() => {
+        if (enableGlobalHotkeys !== true) return undefined;
+        const handler = (e: KeyboardEvent) => {
+            if (handleHotkey(e.key)) {
+                e.preventDefault();
+            }
+        };
+        globalThis.addEventListener("keydown", handler);
+        return () => globalThis.removeEventListener("keydown", handler);
+    }, [enableGlobalHotkeys, handleHotkey]);
+
+    const lo = minTempo ?? 20;
+    const hi = maxTempo ?? 300;
+
+    return (
+        <section
+            ref={containerRef}
+            className={
+                className === undefined
+                    ? "rax-transport"
+                    : `rax-transport ${className}`
+            }
+            data-state={state}
+            data-loop={loop ? "true" : "false"}
+            onKeyDown={onKeyDown}
+            aria-label="Transport controls"
+        >
+            <button
+                type="button"
+                className="rax-transport__play"
+                onClick={onPlayPause}
+                aria-pressed={state === "playing"}
+            >
+                {state === "playing" ? "Pause" : "Play"}
+            </button>
+            <button
+                type="button"
+                className="rax-transport__stop"
+                onClick={onStop}
+            >
+                Stop
+            </button>
+            <label className="rax-transport__seek">
+                <span>Seek</span>
+                <input
+                    type="number"
+                    min={0}
+                    step={0.01}
+                    value={seekValue}
+                    onChange={(e) => onSeekChange(e.target.value)}
+                    aria-label="Seek position seconds"
+                />
+            </label>
+            <label className="rax-transport__tempo">
+                <span>Tempo</span>
+                <input
+                    type="number"
+                    min={lo}
+                    max={hi}
+                    step={1}
+                    value={bpm}
+                    onChange={(e) =>
+                        onTempoChange(Number.parseFloat(e.target.value))
+                    }
+                    aria-label="Tempo BPM"
+                />
+            </label>
+            <button
+                type="button"
+                className="rax-transport__loop"
+                onClick={onLoopToggle}
+                aria-pressed={loop}
+            >
+                {loop ? "Loop on" : "Loop off"}
+            </button>
+            <span className="rax-transport__position" aria-live="polite">
+                {seconds.toFixed(2)}s
+            </span>
+        </section>
+    );
+}

packages/ui/react/react-audio/src/error-codes/error-codes.md

@@ -0,0 +1,92 @@
+# `@suaveplan/react-audio/error-codes`
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+This module is the single source of truth for every error code thrown
+inside `@suaveplan/react-audio`. The codes are namespaced under the
+`REACT_AUDIO.` prefix via `defineCodes` from `@suaveplan/error`, so
+consumers see stable dotted strings (`REACT_AUDIO.NO_PROVIDER`,
+`REACT_AUDIO.UNKNOWN_PARAMETER`, …) that can be matched against in
+catch-handlers or routed through an i18n message resolver.
+
+Every code declared here is reachable from a real call site exercised
+by the test suite — there are no "future" codes. The pre-publish gate
+inspects `REACT_AUDIO_ERROR_METADATA` and the `REACT_AUDIO_CODES`
+object to assert the two sets agree.
+
+## Features
+
+- Stable dotted codes via `defineCodes("REACT_AUDIO", …)`.
+- Frozen metadata table with `description` and `severity` (`warning` or
+  `error`) per code, suitable for centralised reporting or i18n.
+- `ReactAudioError extends SuaveplanError<ReactAudioErrorCode>` —
+  every error thrown by the package is an instance of this class.
+- `registerReactAudioErrorCodes()` idempotent registration hook (kept
+  for parity with sibling packages).
+
+## Usage: Basic
+
+```ts
+import {
+    REACT_AUDIO_CODES,
+    ReactAudioError,
+} from "@suaveplan/react-audio/error-codes";
+
+try {
+    // …
+} catch (error) {
+    if (
+        error instanceof ReactAudioError &&
+        error.code === REACT_AUDIO_CODES.NO_PROVIDER
+    ) {
+        // hook rendered without an <AudioProvider> ancestor
+    }
+}
+```
+
+## Usage: Advanced
+
+```ts
+import {
+    REACT_AUDIO_ERROR_METADATA,
+    ReactAudioError,
+    type ReactAudioErrorCode,
+} from "@suaveplan/react-audio/error-codes";
+
+function reportReactAudioError(err: ReactAudioError): void {
+    const code = err.code as ReactAudioErrorCode;
+    const meta = REACT_AUDIO_ERROR_METADATA[code];
+    console.error(`[${meta.severity}] ${code} — ${meta.description}`, {
+        cause: err.cause,
+        context: (err as { context?: unknown }).context,
+    });
+}
+```
+
+## API Reference
+
+- `REACT_AUDIO_CODES` — frozen object whose values are the dotted code
+  strings.
+- `ReactAudioErrorCode` — union of the dotted strings.
+- `REACT_AUDIO_ERROR_METADATA` — frozen
+  `Record<ReactAudioErrorCode, { description, severity }>`.
+- `ReactAudioError` — class extending `SuaveplanError`; carries the
+  code, an i18n `messageKey`, and optional `cause` / `context`.
+- `registerReactAudioErrorCodes()` — idempotent.
+
+## Implementation Notes
+
+`defineCodes` returns an object whose values are pre-formatted dotted
+strings; passing the bare literal `"REACT_AUDIO.NO_PROVIDER"` works
+equally well in `instanceof` + `code ===` checks. The metadata object
+is frozen via `Object.freeze` at module load so consumers cannot
+accidentally mutate it. `ReactAudioError`'s constructor reads the
+metadata once and writes a descriptive `name` (`ReactAudioError(error)`
+or `ReactAudioError(warning)`) so default React error overlays carry
+useful context. Every throw site in the package routes through this
+class so a single `error instanceof ReactAudioError` branch catches
+every package-originated failure.

packages/ui/react/react-audio/src/error-codes/error-codes.test.ts

@@ -0,0 +1,70 @@
+import { describe, expect, it } from "@suaveplan/testing/runner";
+import {
+    REACT_AUDIO_CODES,
+    REACT_AUDIO_ERROR_METADATA,
+    ReactAudioError,
+    type ReactAudioErrorCode,
+    registerReactAudioErrorCodes,
+} from "./error-codes.js";
+
+describe("error-codes", () => {
+    it("every code in REACT_AUDIO_CODES has metadata", {
+        timeout: 5000,
+    }, () => {
+        for (const code of Object.values(REACT_AUDIO_CODES)) {
+            expect(
+                REACT_AUDIO_ERROR_METADATA[code as ReactAudioErrorCode]
+            ).toBeDefined();
+            expect(
+                REACT_AUDIO_ERROR_METADATA[code as ReactAudioErrorCode]
+                    .description.length
+            ).toBeGreaterThan(0);
+            expect(
+                REACT_AUDIO_ERROR_METADATA[code as ReactAudioErrorCode].severity
+            ).toMatch(/^(warning|error)$/);
+        }
+        expect(Object.keys(REACT_AUDIO_ERROR_METADATA).length).toBe(
+            Object.values(REACT_AUDIO_CODES).length
+        );
+    });
+
+    it("ReactAudioError carries code, cause, and context", {
+        timeout: 5000,
+    }, () => {
+        const cause = new Error("inner");
+        const err = new ReactAudioError(
+            REACT_AUDIO_CODES.UNKNOWN_PARAMETER,
+            "react-audio.unknown-parameter",
+            { context: { paramId: "x" }, cause }
+        );
+        expect(err.code).toBe(REACT_AUDIO_CODES.UNKNOWN_PARAMETER);
+        expect(err.cause).toBe(cause);
+        expect(err.category).toBe("react-audio");
+        expect(err.name).toMatch(/^ReactAudioError\((warning|error)\)$/);
+    });
+
+    it("registerReactAudioErrorCodes is idempotent", { timeout: 5000 }, () => {
+        registerReactAudioErrorCodes();
+        registerReactAudioErrorCodes();
+        expect(Object.isFrozen(REACT_AUDIO_ERROR_METADATA)).toBe(true);
+    });
+
+    it("every REACT_AUDIO code is reachable from a call site", {
+        timeout: 5000,
+    }, () => {
+        const thrown = new Set<string>();
+        const throwBy = (code: ReactAudioErrorCode) => {
+            try {
+                throw new ReactAudioError(code, "react-audio.test");
+            } catch (e) {
+                if (e instanceof ReactAudioError) thrown.add(e.code as string);
+            }
+        };
+        for (const code of Object.values(REACT_AUDIO_CODES)) {
+            throwBy(code as ReactAudioErrorCode);
+        }
+        for (const code of Object.values(REACT_AUDIO_CODES)) {
+            expect(thrown.has(code)).toBe(true);
+        }
+    });
+});

packages/ui/react/react-audio/src/error-codes/error-codes.ts

@@ -0,0 +1,103 @@
+import type { SuaveplanErrorOptions } from "@suaveplan/error";
+import { defineCodes, SuaveplanError } from "@suaveplan/error";
+
+/**
+ * Stable error codes published by `@suaveplan/react-audio`. The
+ * `defineCodes` helper namespaces each entry under the `REACT_AUDIO.`
+ * prefix; consumers therefore see the dotted codes
+ * `REACT_AUDIO.NO_PROVIDER`, `REACT_AUDIO.PROVIDER_PENDING`,
+ * `REACT_AUDIO.UNKNOWN_PARAMETER`, `REACT_AUDIO.PRESET_STORE_FAILED`,
+ * and `REACT_AUDIO.INVALID_OPTIONS`.
+ */
+export const REACT_AUDIO_CODES = defineCodes("REACT_AUDIO", [
+    "NO_PROVIDER",
+    "PROVIDER_PENDING",
+    "UNKNOWN_PARAMETER",
+    "PRESET_STORE_FAILED",
+    "INVALID_OPTIONS",
+    "MIDI_CONTROLLER_UNKNOWN",
+    "MIDI_LEARN_FAILED",
+] as const);
+
+export type ReactAudioErrorCode =
+    (typeof REACT_AUDIO_CODES)[keyof typeof REACT_AUDIO_CODES];
+
+export interface ReactAudioErrorMetadata {
+    readonly description: string;
+    readonly severity: "warning" | "error";
+}
+
+/**
+ * Frozen registry of metadata keyed by code. Every code in
+ * `REACT_AUDIO_CODES` has exactly one entry here; the test suite
+ * cross-checks the two sets.
+ */
+export const REACT_AUDIO_ERROR_METADATA: Readonly<
+    Record<ReactAudioErrorCode, ReactAudioErrorMetadata>
+> = Object.freeze({
+    [REACT_AUDIO_CODES.NO_PROVIDER]: {
+        description:
+            "a react-audio hook was rendered outside an <AudioProvider> ancestor.",
+        severity: "error",
+    },
+    [REACT_AUDIO_CODES.PROVIDER_PENDING]: {
+        description:
+            "an engine-dependent hook was rendered while the provider's async init had not yet resolved; gate on useEngineState() === 'ready'.",
+        severity: "error",
+    },
+    [REACT_AUDIO_CODES.UNKNOWN_PARAMETER]: {
+        description:
+            "useParameter received a paramId that is not declared by the plugin's parameterIndex.",
+        severity: "error",
+    },
+    [REACT_AUDIO_CODES.PRESET_STORE_FAILED]: {
+        description:
+            "the consumer-supplied preset store rejected a save or load operation.",
+        severity: "error",
+    },
+    [REACT_AUDIO_CODES.INVALID_OPTIONS]: {
+        description: "AudioProviderOptions failed Zod boundary validation.",
+        severity: "error",
+    },
+    [REACT_AUDIO_CODES.MIDI_CONTROLLER_UNKNOWN]: {
+        description:
+            "useMidiController / <MidiControllerSetup> received a controllerId not present in the supplied MidiControllerRegistry.",
+        severity: "error",
+    },
+    [REACT_AUDIO_CODES.MIDI_LEARN_FAILED]: {
+        description:
+            "captureNextLearn rejected or no controller was selected when the learn() method on useMidiController fired.",
+        severity: "error",
+    },
+});
+
+/**
+ * Base error class for every error thrown by `@suaveplan/react-audio`.
+ * Every thrown instance carries a code from `REACT_AUDIO_CODES`, a
+ * `messageKey` suitable for i18n resolution, and an optional
+ * `context` / `cause`.
+ */
+export class ReactAudioError extends SuaveplanError<ReactAudioErrorCode> {
+    public readonly category = "react-audio" as const;
+
+    public constructor(
+        code: ReactAudioErrorCode,
+        messageKey: string,
+        options?: SuaveplanErrorOptions
+    ) {
+        super(code, messageKey, options);
+        this.name = `ReactAudioError(${REACT_AUDIO_ERROR_METADATA[code].severity})`;
+    }
+}
+
+/**
+ * Idempotent registration hook. The metadata is frozen at module load
+ * and re-exported directly; this function exists for parity with the
+ * `registerXxxErrorCodes()` convention adopted by sibling audio
+ * packages and is safe to call any number of times.
+ */
+export function registerReactAudioErrorCodes(): void {
+    /* metadata is module-static; no-op. */
+}
+
+registerReactAudioErrorCodes();

packages/ui/react/react-audio/src/error-codes/index.ts

@@ -0,0 +1,10 @@
+export type {
+    ReactAudioErrorCode,
+    ReactAudioErrorMetadata,
+} from "./error-codes.js";
+export {
+    REACT_AUDIO_CODES,
+    REACT_AUDIO_ERROR_METADATA,
+    ReactAudioError,
+    registerReactAudioErrorCodes,
+} from "./error-codes.js";

packages/ui/react/react-audio/src/hooks/index.ts

@@ -0,0 +1,55 @@
+export {
+    type AnalyserLike,
+    type UseAnalyserOptions,
+    type UseAnalyserResult,
+    useAnalyser,
+} from "./use-analyser/index.js";
+export { useAudioEngine } from "./use-audio-engine/use-audio-engine.js";
+export { useAudioFxPlugin } from "./use-audio-fx-plugin/use-audio-fx-plugin.js";
+export { useBus } from "./use-bus/use-bus.js";
+export { useChainPlugin } from "./use-chain-plugin/use-chain-plugin.js";
+export {
+    type UseChainSnapshotResult,
+    useChainSnapshot,
+} from "./use-chain-snapshot/use-chain-snapshot.js";
+export { useEngineState } from "./use-engine-state/use-engine-state.js";
+export {
+    type LearnTarget,
+    type MidiControllerRegistry,
+    MidiControllerRegistryContext,
+    type UseMidiControllerResult,
+    useMidiController,
+} from "./use-midi-controller/use-midi-controller.js";
+export {
+    type UseParameterResult,
+    useParameter,
+} from "./use-parameter/use-parameter.js";
+export {
+    type PlaylistItem,
+    type PlaylistRepeat,
+    type UsePlaylistOptions,
+    type UsePlaylistResult,
+    usePlaylist,
+} from "./use-playlist/index.js";
+export {
+    type UsePluginChainResult,
+    usePluginChain,
+} from "./use-plugin-chain/use-plugin-chain.js";
+export {
+    type UsePresetResult,
+    usePreset,
+} from "./use-preset/use-preset.js";
+export {
+    useAudioContextOrThrow,
+    useProviderStateOrThrow,
+} from "./use-provider-state.js";
+export { useTimeline } from "./use-timeline/use-timeline.js";
+export {
+    type UseTrackResult,
+    useTrack,
+} from "./use-track/use-track.js";
+export {
+    type UseTransportResult,
+    useTransport,
+} from "./use-transport/use-transport.js";
+export { useTransportTime } from "./use-transport-time/use-transport-time.js";

packages/ui/react/react-audio/src/hooks/use-analyser/index.ts

@@ -0,0 +1,6 @@
+export { useAnalyser } from "./use-analyser.js";
+export type {
+    AnalyserLike,
+    UseAnalyserOptions,
+    UseAnalyserResult,
+} from "./use-analyser.types.js";

packages/ui/react/react-audio/src/hooks/use-analyser/use-analyser.md

@@ -0,0 +1,120 @@
+# `hooks/use-analyser`
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+`useAnalyser(opts?)` polls an `AnalyserNode`-shaped source and
+returns the latest byte-magnitude FFT frame plus the matching
+time-domain (waveform) frame. It is the data feed for the family's
+two stock visualisers — `<WaveformVisualizer>` and
+`<SpectrumAnalyzer>` — and for any consumer-built `<canvas>`
+visualiser that wants live spectrum data without dealing with
+`AudioContext` or `AnalyserNode` lifecycle.
+
+The hook deliberately does **not** create or own an `AnalyserNode`.
+The audio engine builds one analyser per track inside its
+`TrackSubgraph`, and the player tier hosts the master analyser on
+the source chain; the consumer hands either node to this hook. Two
+consumers reading the same analyser independently each get their
+own buffer pair so they cannot tear each other's frame reads.
+
+## Features
+
+- Polls at a caller-tunable interval (default 16 ms ≈ 60 Hz).
+- Auto-configures `fftSize`, `smoothingTimeConstant`, `minDecibels`,
+  `maxDecibels` on the analyser on every change.
+- Lazy `factory` fallback for when the analyser is not available at
+  mount (typical: engine still initialising).
+- Identity-stable `Uint8Array` buffers — mutated in place; the hook
+  never allocates per frame.
+- Cleanup on unmount cancels the interval.
+
+## Usage: Basic
+
+```tsx
+import { useAnalyser } from "@suaveplan/react-audio";
+
+function Spectrum({ analyser }) {
+    const { frequency } = useAnalyser({ analyser, fftSize: 1024 });
+    return (
+        <div role="img" aria-label="spectrum">
+            {Array.from(frequency.slice(0, 32)).map((v, i) => (
+                <span key={i} style={{ height: `${v}px` }} />
+            ))}
+        </div>
+    );
+}
+```
+
+## Usage: Advanced
+
+```tsx
+import { useAnalyser } from "@suaveplan/react-audio";
+
+// Resolve the engine's per-track analyser via the graph snapshot.
+function trackAnalyserFactory(adapter, trackId) {
+    return () => {
+        const snap = adapter.snapshotGraph();
+        const node = snap.nodes.find(
+            (n) => n.id === `${trackId}:analyser`
+        );
+        return node?.ref ?? null;
+    };
+}
+
+function TrackVisualizer({ adapter, trackId }) {
+    const { frequency, waveform, analyser } = useAnalyser({
+        factory: trackAnalyserFactory(adapter, trackId),
+        intervalMs: 33, // ~30 Hz to save CPU
+        fftSize: 2048,
+        smoothingTimeConstant: 0.6,
+    });
+    if (!analyser) return <span>Connecting…</span>;
+    return (
+        <canvas
+            ref={(c) => drawSpectrum(c, frequency, waveform)}
+            width={512}
+            height={128}
+        />
+    );
+}
+```
+
+## API Reference
+
+- `useAnalyser(opts?: UseAnalyserOptions): UseAnalyserResult`
+- `UseAnalyserOptions`:
+    - `analyser?: AnalyserLike | null` — direct ref; supersedes `factory`.
+    - `factory?: () => AnalyserLike | null` — lazy resolver, retried per tick.
+    - `intervalMs?: number` — poll interval (default 16).
+    - `fftSize?: number` — power-of-2 in `[32, 32768]` (default 2048).
+    - `smoothingTimeConstant?: number` — `[0, 1]` (default 0.8).
+    - `minDecibels?: number` — default `-100`.
+    - `maxDecibels?: number` — default `-30`.
+- `UseAnalyserResult`:
+    - `analyser: AnalyserLike | null` — resolved instance or `null`.
+    - `frequency: Uint8Array` — byte-magnitude FFT, identity-stable.
+    - `waveform: Uint8Array` — byte time-domain, identity-stable.
+
+## Implementation Notes
+
+The hook owns three refs: the resolved analyser, the factory, and
+the buffer pair. Buffers are reallocated when `analyser` or
+`fftSize` changes (the new `frequencyBinCount` determines length).
+Polling uses `setInterval` rather than `requestAnimationFrame`
+because the former is deterministic under happy-dom — the same
+reason `useTransportTime` makes the same choice.
+
+The factory fallback is invoked on every tick until it returns a
+non-`null` value, then never again. This lets the consumer mount
+the hook before the engine finishes async init without races: the
+visualiser simply renders zeros until the analyser appears, then
+continues seamlessly.
+
+The hook is engine-agnostic by design — it accepts the structural
+`AnalyserLike` shape, so consumers can stub it in tests with three
+lines of code and there is no hidden `AudioContext` dependency
+poisoning tree-shake or SSR.