Summary

supersede #949.

This PR fixes missing diagnostics when a child worker crashes (for example, rspack panic) under tinypool child_process mode. It captures worker stderr at the pool layer, binds output to the active task via worker meta messages, and appends relevant logs to the summary error. The implementation avoids renderer/global stderr monkey-patching and adds e2e coverage for the crash path.

Behavior diff:

+------------------------+------------------------------------------+--------------------------------------------------+
| Area                   | Before                                   | After                                            |
+------------------------+------------------------------------------+--------------------------------------------------+
| Worker crash summary   | only "Worker exited unexpectedly"        | includes "Maybe related stderr" with crash logs |
| Stderr attribution     | no task-scoped stderr binding            | task->pid binding via structured worker meta     |
| Regression coverage    | no panic-specific e2e assertion          | panic fixture + summary assertions added         |
+------------------------+------------------------------------------+--------------------------------------------------+

Changes:

• pool-level stderr capture module
  • new packages/core/src/pool/stderrCapture.ts with ring buffer, truncation, close-wait timeout
• structured worker meta channel
  • new packages/core/src/pool/workerMeta.ts; worker emits meta in packages/core/src/runtime/worker/index.ts
• forks pool error enrichment
  • packages/core/src/pool/forks.ts parses worker meta and appends captured stderr on unexpected worker exit
• e2e crash-path validation
  • new e2e/worker/fixtures/worker.panic.test.ts and assertions in e2e/worker/index.test.ts

Related Links

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).