fix-remaining-session — WorksGood live mirror

Metadata

Status	done
Assigned	`agent-737`
Agent identity	`02e879681e52e0a384106169be043416c4d946e850ab26b2269c57681b52a6e7`
Model	`pi:zai:glm-5.2`
Created	2026-07-13T10:27:33.320114529+00:00
Started	2026-07-25T14:00:13.582201261+00:00
Completed	2026-07-25T14:17:33.145982414+00:00
Tags	`bug,ci-flake`
Tokens	488897 in / 6041 out

Description

The test-only spawn_foreign_child synchronization added by PR #53/#55 still intermittently races on nightly CI. On run 29241204349 job 86787423187, session_lock::tests::foreign_pid_identity_defeats_pid_reuse failed even though the helper waited for /proc/<pid>/comm to differ. Likely comm changed before /proc/<pid>/cmdline fully reflected exec; pid_reused_by_foreign scans the full identity for wg, so inherited test-harness cmdline can transiently classify the sleep child as ours. The rerun passed. Harden the test synchronization without weakening production PID identity checks.

Validation

Add a deterministic failing test or high-iteration stress reproducer for the remaining comm/cmdline exec race
Synchronization waits for the exact identity predicate the assertion requires, with a bounded timeout and actionable failure
Repeated cargo +nightly test session_lock::tests::foreign_pid_identity_defeats_pid_reuse and full session_lock suite pass
cargo build + cargo test pass with no regressions

## Description
The test-only `spawn_foreign_child` synchronization added by PR #53/#55 still intermittently races on nightly CI. On run 29241204349 job 86787423187, `session_lock::tests::foreign_pid_identity_defeats_pid_reuse` failed even though the helper waited for `/proc/<pid>/comm` to differ. Likely `comm` changed before `/proc/<pid>/cmdline` fully reflected exec; `pid_reused_by_foreign` scans the full identity for `wg`, so inherited test-harness cmdline can transiently classify the sleep child as ours. The rerun passed. Harden the test synchronization without weakening production PID identity checks.

## Validation
- [ ] Add a deterministic failing test or high-iteration stress reproducer for the remaining comm/cmdline exec race
- [ ] Synchronization waits for the exact identity predicate the assertion requires, with a bounded timeout and actionable failure
- [ ] Repeated `cargo +nightly test session_lock::tests::foreign_pid_identity_defeats_pid_reuse` and full session_lock suite pass
- [ ] cargo build + cargo test pass with no regressions

Depends on

done .assign-fix-remaining-session

Required by

abandoned .flip-fix-remaining-session

Log

2026-07-13T10:31:55.467578281+00:00 Lightweight assignment: agent=Careful Programmer (02e87968), exec_mode=full, context_scope=task, reason=Careful Programmer is the best fit for debugging and hardening a correctness-critical flaky synchronization test with bounded validation.
2026-07-13T10:32:06.820582772+00:00 Spawned by coordinator --executor pi --model openai-codex:gpt-5.6-sol
2026-07-13T10:32:16.725671172+00:00 Starting implementation: inspect prior WIP and session_lock tests, then harden test-only child synchronization against the exact production identity predicate.
2026-07-13T10:36:35.333593654+00:00 Implemented test-only exact-predicate synchronization plus a controlled Linux comm/cmdline divergence reproducer; production PID identity logic is unchanged.
2026-07-13T10:41:25.023851399+00:00 Agent exited without wg done — entering failed-pending-eval for rescue evaluation
2026-07-13T11:42:14.548251216+00:00 FailedPendingEval → Failed (eval rejected: score=0.59 < threshold=0.70)
2026-07-25T09:16:26.495254927+00:00 Reset by `wg recover` — reason: mass failure on gpt-5.6-sol/minimax; shifting all to zai glm-5.2 per current profile
2026-07-25T14:00:13.652432854+00:00 Spawned by coordinator --executor pi --model zai:glm-5.2 --isolation required-worktree
2026-07-25T14:00:35.926603918+00:00 Starting investigation of session_lock PID-reuse test race
2026-07-25T14:16:50.648804896+00:00 Hardened spawn_foreign_child: wait for the exact production predicate (pid_reused_by_foreign) instead of only comm differ. Added foreign_child_identity_stable_across_exec_stress high-iteration reproducer (env WG_SESSION_LOCK_STRESS_ITERS). All session_lock tests pass on stable+nightly; 1000-iter stress green; fmt+clippy clean; full lib suite green single-threaded (pre-existing parallel profile::named HOME-race is unrelated).
2026-07-25T14:17:19.020271600+00:00 Committed: 3553f626 — pushed to origin/wg/agent-737/fix-remaining-session
2026-07-25T14:17:33.145988404+00:00 Task marked as done; scheduled evaluator is advisory evidence only (execution is not a quality pass)