#  context-pack builder layer (file-selector / builder / index)P09 

VERDICT-B (per-phase JSDoc opt-in via tsconfig.checkjs.json). No runtime change.

## Files annotated (3 .mjs newly added to checkjs)

| File | Lines | Notes |
|------|------:|-------|
| `web-ai/context-pack/file-selector.mjs` | 195 | `FileSelectorInput` typedef; `ReadContextFileResult` discriminated union (`ok: true \| false`); helpers (`parseContextFile`, `excluded`, `normalizeList`, `unique`, `looksLikeGlob`, `toPosix`, `isBinaryLike`) typed |
| `web-ai/context-pack/builder.mjs` | 90 | `BuilderInput` widened typedef including `inlineCharLimit`; helpers `overBudgetError`, `inlineLimitError` typed |
| `web-ai/context-pack/index.mjs` | 6 | `// @ts-check`  re-export shim |only 

## Single typedef-only adjustment to existing P08 file
 `attachments: /** @type {{path:string,displayPath:string,sizeBytes:number}[]} */ ([])`. JSDoc cast on empty array literal so consumers (builder.mjs) can mutate `result.attachments = [...]` later without `never[]` error. No runtime change.

## Why no `ContextPackResult` import?
The renderer's actual return shape is wider than `ContextPackResult` (e.g., `transport: string` from `resolveContextTransport`, `excluded: Array<Record<string, unknown>>`). Forcing the narrow typedef would require runtime narrowing or unsafe casts. Per Pro's P08 guidance ("consumer-side widening of producer's literal union is pragmatic"), we let TS infer the renderer's return shape and use a local `BuilderInput` typedef on inputs only.

## tsconfig.checkjs.json
 37 .mjs entries.

## Gates
 0 errors
 0 errors
 0 errors
 ok
 473 passed, 12 skipped