## Summary
Fixes shard 3 failures from runs 29258546612 + 29259574946 (FN-7936
drift).
## Fixes
### `package-config.test.ts` — stale TRANSITIVE_EXTERNALS entry
FN-7936 aliased `@fusion/core` to a runtime shim in bundled plugin
outputs; it's no longer a tsup external. Removed the stale allowlist
entry.
### `bundle-output.test.ts` — stale dashboard client hash ENOENT
**Root cause:** Two test files (`bundle-output.test.ts` +
`extension-integration.test.ts`) call
`buildCliWithRealDashboardAssets()` which triggers concurrent vite/tsup
builds. Vitest runs them in parallel (`pool: "forks"`, `fileParallelism:
true`). Without coordination, two builds clean and write `dist/client`
simultaneously, causing `ENOENT` on content-hashed chunk files.
**Fix (3 parts):**
1. **`workspace-tools.ts buildDashboardClient`** — `rm dist/client`
before vite build. Prevents stale content-hash references from previous
builds.
2. **`bundle-output-helpers.ts`** — atomic `mkdirSync` file lock around
`buildCliWithRealDashboardAssets()`. Winner builds; losers poll with
`Atomics.wait`, then re-check `hasBuiltDashboardAssets()`. On timeout,
**throws** (never builds without owning the lock).
3. Lock uses `Atomics.wait(new Int32Array(new SharedArrayBuffer(4)), 0,
0, 500)` for sync sleep — no child process spawning.
## Verification
- Gate: exit 0 ✅
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Bug Fixes**
* Improved dashboard asset builds by removing stale files before
rebuilding.
* Prevented concurrent builds from producing incomplete or corrupted
dashboard assets.
* Added safeguards to detect stalled asset builds and fail with clearer
errors.
* **Tests**
* Updated package validation checks to reflect current runtime bundling
behavior.
* Improved reliability of CLI build-related test execution.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
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