test: wait for containment teardown causally

[Ishaan Gangwani (ishaan1124)]

Summary

• replace the fixed 100 ms macOS/Linux containment teardown assertion with the existing exact-identity bounded wait
• prove both the containment owner and escaped descendant are gone before revocation
• retain the fixed-delay survival assertion on platforms where the child is expected to remain alive

Root cause

owner.exited covers only the SIGKILLed server. The macOS responsibility supervisor observes owner death and drains members asynchronously, so 100 ms is not a lifecycle contract. The identical tree passed on the release PR and missed that window once on merged main.

Verification

• exact CI trio: 9 pass, 2 skip, 0 fail
• focused concurrent stress: 4/4 pass
• root typecheck: 7/7
• Prettier and diff-check: clean

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Project	Deployment	Actions	Updated (UTC)
openscience	Ready	Preview	Aug 14, 2026 7:33pm