Move docs/ package mirror into document-navigator plugin

Relocate the ~6k-file docs tree from the repo root into
plugins/document-navigator/docs/ so the plugin is self-contained and
portable. docs/superpowers/ (specs and plans) stays at the repo root.

Moved via cp+rm rather than git mv because directory rename() fails with
EPERM on this WSL /mnt DrvFs mount; git rename-detection pairs the
identical-content files at commit time.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plugins/document-navigator/docs/foundation/data/media/README.md

@@ -0,0 +1,112 @@
+# @suaveplan/media - Universal media detection, metadata extraction, and constraint validation. Magic-byte signature registry (pluggable), MIME-keyed type detection via @suaveplan/mime, Zod-validated constraints, typed MediaError hierarchy with stable MEDIA.* codes, OTel counters + histogram, injectable observability bundle, and an async validation pipeline supporting custom predicates.
+
+Universal media detection, metadata extraction, and constraint
+validation. Combines a pluggable magic-byte `SignatureRegistry` with the
+MIME database from `@suaveplan/mime` to identify image, video, and audio
+artefacts from raw bytes, filenames, or both. Ships typed errors via
+`@suaveplan/error`, OpenTelemetry instrumentation, Zod-validated
+constraints, and an async validation pipeline that supports custom
+predicates and format-specific metadata extractors.
+
+<!-- begin:auto-docs -->
+## Documentation tree
+
+- [detection](./src/detection/detection.md) — Byte-level and filename-level media type detection. The module pairs the pluggable `SignatureRegistry` from `signatures…
+  - [detection](./src/detection/detection.md) — Byte-level and filename-level media type detection. The module pairs the pluggable `SignatureRegistry` from `signatures…
+- [errors](./src/errors/errors.md) — Owns the stable error-code registry, per-code metadata table, and the `MediaError` class that every public entrypoint t…
+  - [errors](./src/errors/errors.md) — Owns the stable error-code registry, per-code metadata table, and the `MediaError` class that every public entrypoint t…
+- [metadata](./src/metadata/metadata.md) — Builds a `MediaMetadata` bundle (type, MIME, size, matched signature label) from raw bytes. The sync helper produces th…
+  - [metadata](./src/metadata/metadata.md) — Builds a `MediaMetadata` bundle (type, MIME, size, matched signature label) from raw bytes. The sync helper produces th…
+- [observability](./src/observability/observability.md) — Constructs the OpenTelemetry instrument bundle threaded through every public entrypoint in `@suaveplan/media`. Each det…
+  - [observability](./src/observability/observability.md) — Constructs the OpenTelemetry instrument bundle threaded through every public entrypoint in `@suaveplan/media`. Each det…
+- [signatures](./src/signatures/signatures.md) — Owns the magic-byte signature registry that powers byte-level detection. The module ships a frozen `BUILTIN_SIGNATURES`…
+  - [signatures](./src/signatures/signatures.md) — Owns the magic-byte signature registry that powers byte-level detection. The module ships a frozen `BUILTIN_SIGNATURES`…
+- [validation](./src/validation/validation.md) — Validates media bytes against a `MediaConstraints` rule set covering size floors and ceilings, type allowlists, MIME al…
+  - [validation](./src/validation/validation.md) — Validates media bytes against a `MediaConstraints` rule set covering size floors and ceilings, type allowlists, MIME al…
+<!-- end:auto-docs -->
+
+## Install
+
+```bash
+bun add @suaveplan/media
+```
+
+## Quick start
+
+```ts
+import {
+    detectMediaType,
+    getMetadata,
+    validateMedia,
+} from "@suaveplan/media";
+
+const png = new Uint8Array([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a]);
+
+detectMediaType(png); // "image"
+
+const meta = getMetadata(png, { filename: "logo.png" });
+// { type: "image", mimeType: "image/png", size: 6, signatureLabel: "PNG" }
+
+const result = validateMedia(png, {
+    maxSize: 1_000_000,
+    allowedTypes: ["image"],
+});
+if (!result.valid) console.warn(result.errors);
+```
+
+## Modules
+
+- [`detection/detection.md`](./src/detection/detection.md) — byte +
+  filename detection helpers.
+- [`metadata/metadata.md`](./src/metadata/metadata.md) — sync + async
+  metadata extraction.
+- [`validation/validation.md`](./src/validation/validation.md) —
+  constraint checking, async predicate support, assert helper.
+- [`signatures/signatures.md`](./src/signatures/signatures.md) —
+  pluggable magic-byte registry.
+- [`errors/errors.md`](./src/errors/errors.md) — `MEDIA_CODES`,
+  `MediaError`, metadata table.
+- [`observability/observability.md`](./src/observability/observability.md)
+  — OpenTelemetry bundle factory.
+- [`types/media.types.md`](./src/types/media.types.md) — public type
+  contracts + Zod schemas.
+
+## Features
+
+- Magic-byte detection covering PNG, JPEG, GIF, BMP, WEBP/RIFF, MP4/MOV,
+  WebM/MKV, MP3 (ID3 + sync), FLAC, OGG.
+- Pluggable `SignatureRegistry` with `register` / `unregister` / `list`
+  / `match` / `detect`; duplicate labels rejected with
+  `MEDIA.DUPLICATE_SIGNATURE`.
+- MIME-keyed filename detection via `@suaveplan/mime`.
+- Zod-validated `MediaConstraints` (`minSize`, `maxSize`, `allowedTypes`,
+  `allowedMimeTypes`, `minWidth`/`maxWidth`, `minHeight`/`maxHeight`,
+  `maxDuration`, custom predicate).
+- Async metadata extractor hook for layering width / height / duration
+  / codec onto the base bundle.
+- `assertValidMedia` throwing variant for guard sites.
+- Eight stable `MEDIA.*` error codes with per-code HTTP / severity /
+  retryable metadata.
+- Four counters + two histograms emitted from every public entrypoint.
+
+## Error codes
+
+| Code                              | HTTP | Retryable | Severity |
+| --------------------------------- | ---- | --------- | -------- |
+| `MEDIA.EMPTY_INPUT`               | 400  | no        | warning  |
+| `MEDIA.INVALID_CONSTRAINTS`       | 400  | no        | error    |
+| `MEDIA.VALIDATION_FAILED`         | 422  | no        | warning  |
+| `MEDIA.UNSUPPORTED_TYPE`          | 415  | no        | warning  |
+| `MEDIA.PREDICATE_FAILED`          | 500  | no        | error    |
+| `MEDIA.DUPLICATE_SIGNATURE`       | 409  | no        | error    |
+| `MEDIA.METADATA_EXTRACTOR_FAILED` | 500  | no        | error    |
+| `MEDIA.INVALID_SIGNATURE`         | 400  | no        | error    |
+
+## Observability
+
+Four counters: `media_detect_total`, `media_metadata_total`,
+`media_validate_total`, `media_error_total`. Two histograms:
+`media_op_latency_ms`, `media_input_size_bytes`. Wire your meter via
+`createMediaObservability({ meter })` and thread the bundle into every
+call.
+

plugins/document-navigator/docs/foundation/data/media/src/detection/detection.md

@@ -0,0 +1,70 @@
+# Detection
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+Byte-level and filename-level media type detection. The module pairs the
+pluggable `SignatureRegistry` from `signatures/` with the MIME database
+exposed by `@suaveplan/mime` so consumers can identify image, video, and
+audio artefacts whether they have the bytes, the filename, or both.
+
+## Features
+
+- `detectMediaType(input, opts?)` — magic-byte detection via the registry.
+- `detectSignature(input, opts?)` — return the matched `MediaSignature`
+  record, not just its `type`.
+- `detectMediaTypeFromName(filename, opts?)` — MIME-database lookup.
+- `inferMimeFromSignature(sig)` — canonical MIME for a matched signature
+  with a sane fallback when no signature matched.
+- `defaultMimeForType(type)` — coarse fallback when only the
+  category is known.
+- Counters and latency histograms emitted on every invocation.
+
+## Usage: Basic
+
+```ts
+import { detectMediaType } from "@suaveplan/media";
+
+const png = new Uint8Array([0x89, 0x50, 0x4e, 0x47, 0x0d]);
+detectMediaType(png); // "image"
+```
+
+## Usage: Advanced
+
+```ts
+import {
+    detectSignature,
+    inferMimeFromSignature,
+    SignatureRegistry,
+} from "@suaveplan/media";
+
+const reg = new SignatureRegistry();
+reg.register({
+    type: "image",
+    label: "AVIF",
+    bytes: [0x66, 0x74, 0x79, 0x70, 0x61, 0x76, 0x69, 0x66],
+    offset: 4,
+});
+const sig = detectSignature(myBytes, { registry: reg });
+const mime = inferMimeFromSignature(sig); // canonical MIME
+```
+
+## API Reference
+
+- `DetectOptions` — `{ registry?, observability? }`.
+- `detectMediaType(input, opts?)` — `MediaType`.
+- `detectSignature(input, opts?)` — `MediaSignature | null`.
+- `detectMediaTypeFromName(filename, opts?)` — `MediaType`.
+- `inferMimeFromSignature(sig)` — canonical MIME string.
+- `defaultMimeForType(type)` — coarse fallback MIME.
+
+## Implementation Notes
+
+`detectMediaType` and `detectMediaTypeFromName` both record an
+`op_latency_ms` histogram entry in a `finally` block so the cost of a
+detection call is always measured, even when the registry throws. The
+filename pathway uses `@suaveplan/mime`'s `getMimeType` so the database
+behind detection stays in lock-step with the rest of the project.

plugins/document-navigator/docs/foundation/data/media/src/errors/errors.md

@@ -0,0 +1,67 @@
+# Errors
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+Owns the stable error-code registry, per-code metadata table, and the
+`MediaError` class that every public entrypoint throws or wraps. Every
+failure path in `@suaveplan/media` surfaces one of eight `MEDIA.*` codes
+so consumers (loggers, retry policies, telemetry pipelines, UI surfaces)
+can classify failures programmatically without parsing message strings.
+
+## Features
+
+- Frozen `MEDIA_CODES` registry created via `defineCodes("MEDIA", […])`.
+- Per-code `MediaCodeMetadata` record (`httpStatus`, `retryable`,
+  `severity`, `description`) frozen at module load.
+- `MediaError` extending `SuaveplanError<MediaErrorCode>` — cause chain,
+  redaction, OTel span-event adapter inherited.
+- `asMediaError(code, cause, fallback)` lift helper for `catch` sites.
+
+## Usage: Basic
+
+```ts
+import { MediaError, MEDIA_CODES } from "@suaveplan/media";
+
+throw new MediaError(MEDIA_CODES.EMPTY_INPUT, "input is empty");
+```
+
+## Usage: Advanced
+
+```ts
+import { asMediaError, MEDIA_CODES, MEDIA_ERROR_METADATA } from "@suaveplan/media";
+
+try {
+    /* boundary work */
+} catch (cause) {
+    const err = asMediaError(
+        MEDIA_CODES.PREDICATE_FAILED,
+        cause,
+        "predicate threw"
+    );
+    const meta = MEDIA_ERROR_METADATA[err.code];
+    if (meta.retryable) {
+        // schedule retry
+    }
+}
+```
+
+## API Reference
+
+- `MEDIA_CODES` — frozen code registry with eight namespaced keys.
+- `MediaErrorCode` — union of registry values.
+- `MEDIA_ERROR_METADATA` — frozen record keyed by code.
+- `MediaCodeMetadata` — per-code metadata shape.
+- `MediaError` — concrete `SuaveplanError` subclass with `.metadata` getter.
+- `asMediaError(code, cause, fallback)` — lift helper.
+
+## Implementation Notes
+
+`defineCodes` produces namespaced keys (`MEDIA.EMPTY_INPUT`, …). The
+metadata table is `Object.freeze`'d at module top level so consumers
+cannot tamper at runtime. `asMediaError` preserves the original error as
+`.cause` when it's an `Error` instance, otherwise it wraps the stringified
+value so the cause chain is always populated.

plugins/document-navigator/docs/foundation/data/media/src/metadata/metadata.md

@@ -0,0 +1,65 @@
+# Metadata
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+Builds a `MediaMetadata` bundle (type, MIME, size, matched signature
+label) from raw bytes. The sync helper produces the base bundle in a
+single pass; the async helper layers a user-supplied
+`MediaMetadataExtractor` over the base so callers can fill in
+format-specific fields (width, height, duration) without forking the
+package.
+
+## Features
+
+- `getMetadata(input, opts?)` — synchronous, no extractor.
+- `getMetadataAsync(input, opts?)` — awaits the optional extractor and
+  merges its return into the base bundle.
+- MIME resolution prefers the explicit `filename` field; otherwise it
+  falls back to `inferMimeFromSignature`.
+- Signature label exposed via `metadata.signatureLabel` for downstream
+  diagnostics.
+- Extractor errors are wrapped in `MediaError(MEDIA.METADATA_EXTRACTOR_FAILED)`
+  with the original error chained as `.cause`.
+
+## Usage: Basic
+
+```ts
+import { getMetadata } from "@suaveplan/media";
+
+const meta = getMetadata(new Uint8Array([0x89, 0x50, 0x4e, 0x47]), {
+    filename: "logo.png",
+});
+console.log(meta.type, meta.mimeType, meta.size, meta.signatureLabel);
+```
+
+## Usage: Advanced
+
+```ts
+import { getMetadataAsync } from "@suaveplan/media";
+
+const meta = await getMetadataAsync(buf, {
+    filename: "clip.mp4",
+    extractor: async (_bytes, base) => {
+        const { width, height, duration } = await probe(buf);
+        return { ...base, width, height, duration };
+    },
+});
+```
+
+## API Reference
+
+- `MetadataOptions` — `{ filename?, registry?, observability?, extractor? }`.
+- `getMetadata(input, opts?)` — synchronous `MediaMetadata`.
+- `getMetadataAsync(input, opts?)` — `Promise<MediaMetadata>`.
+
+## Implementation Notes
+
+The base bundle is built inside a private helper so both entrypoints
+share signature detection + MIME resolution. The async variant only
+forks off the base when an extractor is supplied, so unused await paths
+incur near-zero overhead. Latency histograms are recorded in a
+`finally` block so failed extractor calls still produce telemetry.

plugins/document-navigator/docs/foundation/data/media/src/observability/observability.md

@@ -0,0 +1,60 @@
+# Observability
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+Constructs the OpenTelemetry instrument bundle threaded through every
+public entrypoint in `@suaveplan/media`. Each detection, metadata, and
+validation call increments a counter, records a latency histogram, and
+optionally emits a span. Consumers can inject their own meter / tracer
+to wire instruments into a shared telemetry pipeline.
+
+## Features
+
+- Four counters: `media_detect_total`, `media_metadata_total`,
+  `media_validate_total`, `media_error_total`.
+- Two histograms: `media_op_latency_ms`, `media_input_size_bytes`.
+- Injectable meter / tracer or a pre-built `MediaObservability`.
+- Falls back to the global no-op providers when nothing is supplied,
+  keeping the bundle safe to construct from library code.
+
+## Usage: Basic
+
+```ts
+import { createMediaObservability } from "@suaveplan/media";
+
+const obs = createMediaObservability();
+obs.counters.detectTotal.add(1, { kind: "magic-bytes" });
+```
+
+## Usage: Advanced
+
+```ts
+import { metrics } from "@opentelemetry/api";
+import { createMediaObservability } from "@suaveplan/media";
+
+const meter = metrics.getMeter("my-app");
+const obs = createMediaObservability({ meter });
+obs.histograms.opLatencyMs.record(12.4, { op: "validateMedia" });
+obs.counters.errorTotal.add(1, { code: "MEDIA.VALIDATION_FAILED" });
+```
+
+## API Reference
+
+- `MediaCounters` — counter set.
+- `MediaHistograms` — histogram set.
+- `MediaObservability` — bundle.
+- `MediaObservabilityOptions` — `{ meter?, tracer?, observability? }`.
+- `createMediaObservability(opts?)` — bundle factory.
+
+## Implementation Notes
+
+When `opts.observability` is supplied, it short-circuits before any
+instrument creation so injected bundles round-trip without mutation.
+Otherwise the function resolves a meter and tracer (defaulting to the
+global providers) and creates instruments via the helpers in
+`@suaveplan/opentelemetry` so naming + unit conventions stay consistent
+across the project.

plugins/document-navigator/docs/foundation/data/media/src/signatures/signatures.md

@@ -0,0 +1,71 @@
+# Signatures
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+Owns the magic-byte signature registry that powers byte-level detection.
+The module ships a frozen `BUILTIN_SIGNATURES` list covering common image
+(PNG, JPEG, GIF, BMP, WEBP, RIFF), video (MP4/MOV, WebM/MKV), and audio
+(MP3, FLAC, OGG) formats, plus a mutable `SignatureRegistry` class that
+lets downstream consumers add or remove entries without forking the
+package.
+
+## Features
+
+- Frozen built-in registry covering twelve canonical formats.
+- `SignatureRegistry` class with `register`, `unregister`, `list`,
+  `match`, and `detect` methods.
+- Per-entry `offset` so ftyp-style signatures (MP4) and RIFF chunk markers
+  (WebP) can match at non-zero positions.
+- Duplicate-label detection: `register` throws
+  `MEDIA.DUPLICATE_SIGNATURE` if a second entry uses the same label.
+- Byte validation: registration rejects empty byte arrays and non-byte
+  numbers with `MEDIA.INVALID_SIGNATURE`.
+- Process-wide `defaultSignatureRegistry` seeded with the built-ins.
+
+## Usage: Basic
+
+```ts
+import { defaultSignatureRegistry } from "@suaveplan/media";
+
+const png = new Uint8Array([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a]);
+const sig = defaultSignatureRegistry.match(png);
+console.log(sig?.label); // "PNG"
+```
+
+## Usage: Advanced
+
+```ts
+import { SignatureRegistry } from "@suaveplan/media";
+
+const reg = new SignatureRegistry();
+reg.register({
+    type: "image",
+    label: "AVIF",
+    bytes: [0x66, 0x74, 0x79, 0x70, 0x61, 0x76, 0x69, 0x66],
+    offset: 4,
+});
+const type = reg.detect(myBytes);
+```
+
+## API Reference
+
+- `BUILTIN_SIGNATURES` — readonly array of twelve canonical signatures.
+- `SignatureRegistry` — mutable registry class.
+  - `register(sig)` — add entry; throws on duplicate label / invalid bytes.
+  - `unregister(label)` — remove by label; returns whether removed.
+  - `list()` — frozen snapshot.
+  - `match(input)` — first matching `MediaSignature` or `null`.
+  - `detect(input)` — `MediaType`, defaulting to `"unknown"`.
+- `defaultSignatureRegistry` — process-wide default.
+
+## Implementation Notes
+
+`match` honours each signature's `offset` so non-zero-anchored formats
+work correctly. The built-in list orders longer / more-specific
+signatures before shorter ones (RIFF is listed after WEBP because the
+WEBP marker lives inside a RIFF container at offset 8). The registry's
+internal array is private so external mutation cannot break ordering.

plugins/document-navigator/docs/foundation/data/media/src/types/media.types.md

@@ -0,0 +1,69 @@
+# Media Types
+
+## Purpose
+
+Defines every public type and Zod schema exported by `@suaveplan/media`.
+These contracts pin the package's surface so downstream consumers can write
+runtime-validated boundaries and compile against stable shapes. Types
+covered include `MediaType`, `MediaSignature`, `MediaMetadata`,
+`MediaConstraints`, `MediaResult`, the constraint predicate, and the async
+metadata-extractor hook.
+
+## Features
+
+- `MediaType` discriminated union (`image | video | audio | unknown`).
+- `MediaTypeSchema` and `MediaConstraintsSchema` Zod parsers for boundary
+  validation.
+- `MediaSignature` model for magic-byte registry entries with optional
+  non-zero offset.
+- Extended `MediaConstraints` (size floor + ceiling, MIME allowlist,
+  duration ceiling, custom predicate).
+- `MediaMetadataExtractor` hook used by the metadata pipeline.
+
+## Usage: Basic
+
+```ts
+import { MediaTypeSchema, type MediaMetadata } from "@suaveplan/media";
+
+const parsed = MediaTypeSchema.parse("image");
+const meta: MediaMetadata = {
+    type: parsed,
+    mimeType: "image/png",
+    size: 1024,
+};
+```
+
+## Usage: Advanced
+
+```ts
+import {
+    MediaConstraintsSchema,
+    type MediaConstraints,
+} from "@suaveplan/media";
+
+const constraints: MediaConstraints = MediaConstraintsSchema.parse({
+    maxSize: 2_000_000,
+    allowedTypes: ["image"],
+    allowedMimeTypes: ["image/png", "image/jpeg"],
+    predicate: (m) => (m.size > 0 ? null : "empty"),
+});
+```
+
+## API Reference
+
+- `MediaType` — recognised media categories.
+- `MediaTypeSchema` — Zod enum for `MediaType`.
+- `MediaSignature` — magic-byte registry entry.
+- `MediaMetadata` — extracted metadata bundle.
+- `MediaConstraints` / `MediaConstraintsSchema` — validation rule set.
+- `MediaResult` — validation result with errors array.
+- `MediaConstraintPredicate` — custom validation function.
+- `MediaMetadataExtractor` — async metadata extension hook.
+
+## Implementation Notes
+
+All schemas use `z` default-imported per Bun-safety. The predicate field
+in `MediaConstraintsSchema` uses `z.custom` because Zod cannot statically
+describe arbitrary function shapes. Arrays surface as `readonly` arrays in
+TypeScript so consumers cannot mutate constraint collections after
+construction.

plugins/document-navigator/docs/foundation/data/media/src/validation/validation.md

@@ -0,0 +1,78 @@
+# Validation
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+Validates media bytes against a `MediaConstraints` rule set covering
+size floors and ceilings, type allowlists, MIME allowlists, width /
+height / duration limits, and an optional custom predicate. The module
+exposes a synchronous helper for cheap byte-level checks and an async
+helper that also honours the constraint predicate plus the metadata
+extractor hook.
+
+## Features
+
+- `validateMedia(input, constraints, opts?)` — sync validation.
+- `validateMediaAsync(input, constraints, opts?)` — async validation
+  that runs the predicate hook.
+- `assertValidMedia(...)` — throwing variant that yields
+  `MediaError(MEDIA.VALIDATION_FAILED)` on failure.
+- Zod-validated constraints — malformed input throws
+  `MediaError(MEDIA.INVALID_CONSTRAINTS)`; use `skipConstraintValidation`
+  to opt out on hot paths.
+- Predicate failure wrapping — caller exceptions surface as
+  `MediaError(MEDIA.PREDICATE_FAILED)` with the original error chained.
+- OTel `media_validate_total` counter + `media_op_latency_ms` histogram
+  emitted on every invocation.
+
+## Usage: Basic
+
+```ts
+import { validateMedia } from "@suaveplan/media";
+
+const result = validateMedia(myBytes, {
+    maxSize: 1_000_000,
+    allowedTypes: ["image"],
+});
+if (!result.valid) {
+    console.warn(result.errors);
+}
+```
+
+## Usage: Advanced
+
+```ts
+import { validateMediaAsync } from "@suaveplan/media";
+
+const result = await validateMediaAsync(myBytes, {
+    maxSize: 5_000_000,
+    allowedTypes: ["image", "video"],
+    allowedMimeTypes: ["image/png", "video/mp4"],
+    maxWidth: 4096,
+    maxHeight: 4096,
+    maxDuration: 60,
+    predicate: async (meta) =>
+        meta.size === 0 ? "empty payload" : null,
+});
+```
+
+## API Reference
+
+- `ValidateOptions` — extends `MetadataOptions` with
+  `skipConstraintValidation`.
+- `validateMedia(input, constraints, opts?)` — sync `MediaResult`.
+- `validateMediaAsync(input, constraints, opts?)` —
+  `Promise<MediaResult>`.
+- `assertValidMedia(input, constraints, opts?)` — `MediaMetadata`,
+  throws on validation failure.
+
+## Implementation Notes
+
+`checkConstraints` is shared between the sync and async paths so the
+rule semantics are identical. Empty input is rejected up-front with
+`MEDIA.EMPTY_INPUT` before any metadata work happens. The predicate
+runs after every other check so callers can rely on the base errors
+being populated first.