test(review): separate pipe EOF from holder process lifetime

[vriesd]

Why

Main CI repeatedly failed an overflow test that equated inherited-pipe EOF with disappearance of a foreign holder PID. Capture completion guarantees pipe closure, while the holder's process lifetime is separate.

What changed

• Make the fixture close inherited stdout and stderr after its operand-preservation marker, then deliberately remain alive until fixture teardown.
• Assert that the holder remains observable at EOF while preserving direct-child termination and capacity rejection checks.

Scope

Three test lines only. Product behavior, package bytes, grader sources, policy, and qualification requirements remain unchanged.

Tradeoffs

The fixture tests the actual pipe-drain contract instead of depending on process exit and OS reaping timing. Existing teardown still terminates the owned holder.

Blast Radius

This removes a timing-dependent CI assertion. It changes no runtime cleanup behavior.

Verification

• Deterministic RED fails the old PID-disappearance expectation on both channels. GREEN passes the full 11-test file.

• Independent Linux observations show holders in state S at EOF and absent after teardown. An early-settlement mutant still fails both preservation-marker checks.

• Independent maintained packing preserves the exact package and manifest. All 105 grader source files remain unchanged.

• Full push preflight passed with 2,912 tests passing, 20 existing skips, and zero failures. Independent exact-head source/package review and comment audit passed.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-08T00:48:04.225708Z	15ba940	PR opened

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