[cliffhall]

Closes #2412

Problem

consumeMethodOutcome's long-lived stream path (resources/subscribe and the other stream methods) registered only SIGINT/SIGTERM handlers. When the reader exits early (| head, | grep -m1, quitting less), the next stdout write fails with EPIPE. With no 'error' listener on stdout, that became an unhandled 'error' event that crashed the process. The code carried its own TODO(#1432) for this.

Reproduced on v2/main by piping a stream outcome that writes every 5ms into head -n 2:

{"i":0}
{"i":1}
node:events:505
    throw er; // Unhandled 'error' event
Error: write EPIPE

With this branch, the same run prints the two lines and exits 0.

Change

clients/cli/src/handlers/consume-outcome.ts: the stream path now listens for stdout 'error' for as long as the stream is open, and attaches that listener before start() runs.

• EPIPE: unsubscribes and resolves, so the CLI exits cleanly, as it already does on a signal.
• Any other stdout error: unsubscribes and rejects, which sends it through the CLI's existing error path.
• Every exit (signal, stdout error, or start() throwing): removes all three listeners.

The TODO is gone, and the doc comment now describes this behavior.

Tests

New clients/cli/__tests__/consume-outcome-stream.test.ts covers:

• EPIPE resolving: unsubscribes exactly once and detaches the stdout, SIGINT and SIGTERM listeners
• a non-EPIPE error rejecting with the original error
• a non-Error value on stdout being treated as a failure, not as a broken pipe
• SIGTERM also detaching the stdout listener
• start() throwing and leaving no listeners behind

Like the existing test in run-method.test.ts, these call the registered listeners directly instead of emitting process-wide.

npm run local:gate is green. An earlier run failed on a web SkillsScreen test under load. This diff touches no web code, and that test passes 3/3 when run alone.

🤖 Generated with Claude Code

[Copilot]

Copilot review overview

🟢 Approval recommended

The implementation addresses the reported failure with focused cleanup and comprehensive tests.

Review effort: Balanced
Findings: None

What changed in this PR

Fixes CLI stream crashes when downstream readers close stdout early.

Changes:

• Handles EPIPE as a clean stream termination.
• Propagates other stdout errors and consistently removes listeners.
• Adds coverage for errors, signals, cleanup, and startup failures.

File	Description
clients/​cli/​src/​handlers/​consume-outcome.ts	Adds stream-scoped stdout error handling and cleanup.
clients/​cli/​__tests__/​consume-outcome-stream.test.ts	Tests stream termination and listener cleanup paths.

---

💡 Add a code-review agent skill for context-aware, tailored reviews. Learn more in the docs.

[cliffhall]

Copilot review loop closed: round 1 was clean (no inline comments, no findings in the body, no suppressed comments), so no further round was requested.