# `pack-context` — React context plumbing for the pack registry

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  - [pack-registry-provider](./pack-registry-provider/pack-registry-provider.md) — <!-- begin:auto-docs --> _(no submodules)_- [runtime-override](./runtime-override/runtime-override.md) — <!-- begin:auto-docs --> _(no submodules)_  - [runtime-override](./runtime-override/runtime-override.md) — <!-- begin:auto-docs --> _(no submodules)_- [use-pack-component](./use-pack-component/use-pack-component.md) — <!-- begin:auto-docs --> _(no submodules)_  - [use-pack-component](./use-pack-component/use-pack-component.md) — <!-- begin:auto-docs --> _(no submodules)_- [version-check](./version-check/version-check.md) — <!-- begin:auto-docs --> _(no submodules)_  - [version-check](./version-check/version-check.md) — <!-- begin:auto-docs --> _(no submodules)_- [pack-context](./pack-context.md) — <!-- begin:auto-docs --> _(no submodules)_- pack-registry-provider — <!-- begin:auto-docs --> _(…
- [pack-registry-provider](./pack-registry-provider/pack-registry-provider.md) — <!-- begin:auto-docs --> _(no submodules)_- [runtime-override](./runtime-override/runtime-override.md) — <!-- begin:auto-docs --> _(no submodules)_- [runtime-override](./runtime-override/runtime-override.md) — <!-- begin:auto-docs --> _(no submodules)_- [use-pack-component](./use-pack-component/use-pack-component.md) — <!-- begin:auto-docs --> _(no submodules)_- [use-pack-component](./use-pack-component/use-pack-component.md) — <!-- begin:auto-docs --> _(no submodules)_- [version-check](./version-check/version-check.md) — <!-- begin:auto-docs --> _(no submodules)_- [version-check](./version-check/version-check.md) — <!-- begin:auto-docs --> _(no submodules)_- [pack-context](./pack-context.md) — <!-- begin:auto-docs --> _(no submodules)_- [pack-registry-provider](./pack-registry-provider/pack-registry-provider.md) — <!-- begin:auto-docs --> _(no submodules)_- [runtime-override](./runtime-override/runtime-override.md) — <!-- begin:auto-docs --> _(no submodules)_- [runtime-override](./runtime-override/runtime-override.md) — <!-- begin:auto-docs --> _(no submodules)_- [use-pack-component](./use-pack-component/use-pack-component.md) — <!-- begin:auto-docs --> _(no submodules)_- [use-pack-component](./use-pack-component/use-pack-component.md) — <!-- begin:auto-docs --> _(no submodules)_- [version-check](./version-check/version-check.md) — <!-- begin:auto-docs --> _(no submodules)_- [version-check](./version-check/version-check.md) — <!-- begin:auto-docs --> _(no submodules)_- [pack-context](./pack-context.md) — <!-- begin:auto-docs --> _(no submodules)_- pack-registry-provider — <!-…
- [pack-registry-provider](./pack-registry-provider/pack-registry-provider.md) — <!-- begin:auto-docs --> _(no submodules)_- [runtime-override](./runtime-override/runtime-override.md) — <!-- begin:auto-docs --> _(no submodules)_- [runtime-override](./runtime-override/runtime-override.md) — <!-- begin:auto-docs --> _(no submodules)_- [use-pack-component](./use-pack-component/use-pack-component.md) — <!-- begin:auto-docs --> _(no submodules)_- [use-pack-component](./use-pack-component/use-pack-component.md) — <!-- begin:auto-docs --> _(no submodules)_- [version-check](./version-check/version-check.md) — <!-- begin:auto-docs --> _(no submodules)_- [version-check](./version-check/version-check.md) — <!-- begin:auto-docs --> _(no submodules)_- [pack-context](./pack-context.md) — <!-- begin:auto-docs --> _(no submodules)_- pack-registry-provider — <!-- begin:auto-docs --> _…
- [pack-registry-provider](./pack-registry-provider/pack-registry-provider.md) — <!-- begin:auto-docs --> _(no submodules)_- [runtime-override](./runtime-override/runtime-override.md) — <!-- begin:auto-docs --> _(no submodules)_  - [runtime-override](./runtime-override/runtime-override.md) — <!-- begin:auto-docs --> _(no submodules)_- [use-pack-component](./use-pack-component/use-pack-component.md) — <!-- begin:auto-docs --> _(no submodules)_  - [use-pack-component](./use-pack-component/use-pack-component.md) — <!-- begin:auto-docs --> _(no submodules)_- [version-check](./version-check/version-check.md) — <!-- begin:auto-docs --> _(no submodules)_  - [version-check](./version-check/version-check.md) — <!-- begin:auto-docs --> _(no submodules)_- [pack-context](./pack-context.md) — <!-- begin:auto-docs --> _(no submodules)_
## Purpose

Owns the React `Context` `<PackRegistryProvider>` writes into and the
`usePackComponent` hook reads from. The context carries two slices: a
`packs` map (raw `ComponentPack` references keyed by pack name) and a
`resolved` map (the merged `(packName -> componentName -> Component)`
view that already accounts for runtime overrides). Splitting raw and
resolved lets debugging surfaces inspect either layer.

## Features

- Single source-of-truth context for the chassis pack system
- `null` discriminator drives provider-missing detection in every
  consumer hook
- `displayName` set so React DevTools surfaces the context as
  `ReactUiPackRegistryContext` rather than the generic
  `Context.Provider`
- `resolved` map is computed inside the Provider's `useMemo` so a
  re-render does not rebuild the merged maps unless `packs` or the
  override prop change

## Usage: Basic example

```ts
import { useContext } from "react";
import { PackRegistryContext } from "@suaveplan/react-ui/pack";

function PackInspector() {
    const ctx = useContext(PackRegistryContext);
    if (!ctx) return null;
    return <pre>{[...ctx.packs.keys()].join(", ")}</pre>;
}
```

## Usage: Advanced example

```ts
import { useContext } from "react";
import { PackRegistryContext } from "@suaveplan/react-ui/pack";

function ResolvedView() {
    const ctx = useContext(PackRegistryContext);
    if (!ctx) return null;
    const rows = [];
    for (const [pack, components] of ctx.resolved) {
        for (const componentName of components.keys()) {
            rows.push(`${pack}/${componentName}`);
        }
    }
    return <ul>{rows.map((r) => <li key={r}>{r}</li>)}</ul>;
}
```

## API Reference

- `PackRegistryContext: React.Context<PackRegistryContextValue | null>`
- `interface PackRegistryContextValue`
  - `packs: ReadonlyMap<string, ComponentPack>`
  - `resolved: ReadonlyMap<string, ReadonlyMap<string, ComponentType<unknown>>>`

## Implementation notes

The two-map split allows the consumer-facing `usePackComponent` hook
to read directly from `resolved` (a flat lookup) without walking the
raw pack array. Test fixtures and DevTools surfaces that need to see
the original pack lifecycle hooks consult `packs` instead. The
context default `null` makes provider-missing failures surface at the
hook call site rather than producing a confusing read-from-empty-map
scenario.