# Turbopack Dev Server Hang — @vidstack/react + Barrel Circular Import

**Applies when:** Next.js dev server hangs (290%+ CPU, 1GB+ RAM, no HTTP responses), or Turbopack enters infinite recompilation

Three contributing factors found:

1. **Barrel self-import in features/project**: `SubtitleRevisionStep.tsx` imports `TranscriptionEditor` from the barrel `@features/project` which re-exports `SubtitleRevisionStep` itself, creating a circular module evaluation chain. Fix: use direct subpath import.

2. **FSD violation features->widgets**: `SubtitleRevisionStep` imports `TimelinePanel` from `@widgets/`, violating FSD layer direction. Not a direct cause of hang but exacerbates module graph complexity.

3. **@vidstack/react internal dynamic imports**: The library uses 14+ dynamic `import()` calls internally. Combined with Turbopack's inability to create shared chunks between async chunks in dev mode (GitHub issue vercel/next.js#85119), this can cause pathological module duplication during HMR.

**Reproduction**: Issue is intermittent — most reliably triggered when editing files that import from `@vidstack/react` while the browser has the project wizard page open. Fresh server starts work fine.

**Quick fix**: Change `SubtitleRevisionStep.tsx` line 23 from `import { TranscriptionEditor } from "@features/project"` to `import { TranscriptionEditor } from "@features/project/TranscriptionEditor"`.

**Long-term**: Consider upgrading to Next.js 16.2+ which includes 200+ Turbopack fixes.