The native purge fixture helper returned only code and output, so a failure could not distinguish its own deadline callback from an observed child signal or another exit. Retain an immutable lifecycle snapshot with the owned PID, configured timeout, deadline marker, elapsed time including pipe drain, and actual signal. Emit fixed-field observations on deadline and nonzero exit so existing parent assertions retain those facts.
The allowlist, child command, original guards, output strings, cleanup, and production purge code remain unchanged. A deadline marker and signal are separate observations, not a causal verdict.
Validation: an actual private five-millisecond deadline produced SIGKILL/137 with the marker; the original 165-second seal scenario completed normally with no marker or signal. Both children were reaped, and the original seal success marker was checked. Buddy Pickier and runtime/test types pass. Separate root Spec and Standards passes confirm this observation-only scope; independent final review was unavailable.
The original #53 exit 137 remains unexplained. Its temporary process/phase probe passed and was restored byte-for-byte. This PR improves future failure evidence. The #53 cause remains unresolved, and deadlines are unchanged.
Depends on #55 and #54 through the current parent. After those reach main, the remaining diff is one test helper. Exact-head CI is pending.
Qualified on exact head 6d3a9ad by all five jobs in CI 39724088100. The terminal log was retained once: 3010279 bytes, SHA-256 1dabcf0fb06304429fbeeb79deb0d5a68c56231187cab39aa801b72f820adfae. This is diagnostics only; #53 remains unresolved.