fix(assistant): address sidecar review follow-ups

[takeokunn]

Summary

Fix-forward for the independent review of PR #13.

Finding	Fix	Regression test
S2 generation race	Snapshot pending generation under state-lock; poll and worker paths use locked snapshots; I/O remains outside the lock.	discards-a-stale-sidecar-pending-before-the-next-request records fake-sidecar input and asserts stale is absent and fresh is delivered.
S1 EOF cleanup	EOF reaps the process and enters idempotent stop cleanup; channels are closed, sibling threads joined, and self-join is avoided.	stops-cleanly-when-init-gate-rejects-a-live-reader.
B1 response silence timeout	Poll reads +assistant-sidecar-response-timeout-seconds+ (90 seconds) once per poll. If no event arrives for 90 seconds after the last event, it stops the sidecar and publishes a Japanese terminal error; each received event extends the deadline.	does-not-time-out-while-response-events-continue; stops-and-delivers-a-terminal-event-after-response-silence.
S3 startup TOCTOU	Startup claim/check is one state-lock interval; process and cleanup operations stay outside the lock. Cleanup preserves starting during the startup transition and advances the generation consistently. If pre-thread handoff fails, starting-p is cleared under the lock so a later start retries.	clears-starting-state-when-startup-handoff-fails.
S4 version probe diagnostics	Capture bounded stdout/stderr diagnostics and include them in the user-facing failure reason.	reports-version-probe-output-when-the-sidecar-exits-with-an-error.
S5-S7 test robustness	%assistant-test-await-state uses a time deadline; added stale-payload and SIGTERM-ignoring child cleanup coverage.	discards-a-stale-sidecar-pending-before-the-next-request; kills-a-sidecar-that-ignores-sigterm.
Review formatting	Normalized S3 stop-state/startup lambda indentation and B1 polling branch indentation.	Formatting-only fixups folded into S3 and B1.

Commit mapping

Finding	Commit
Test cleanup	22d3e29
S2	4c3b32f
S1	01efabe
B1	2cae770
S4	29a5189
S3	1faa6b0
Test strengthening	8ede0e8

Verification

• Local nix build .#checks.aarch64-darwin.default -L: passed, 2293 passed, 34 skipped, 0 todo, 0 failed, 0 errored, 2327 total.
• Commit hook gitleaks passed for the fixup commits.
• CI run 36603297088: all 4 jobs passed: nix flake check, build release binary, integration tests, and source coverage.
• e2e-main-wait-returns-background-status did not hang in this CI run; the earlier gate hang was an existing defect fixed by PR fix: reap completed background jobs before reading status #22 SIGCHLD handling.

[takeokunn]

Fix-forward report

• S2: pending generation is snapshotted under state-lock; stale-payload regression records fake-sidecar input.
• S1: reader EOF reaps the process, closes the write channel, stops the handle, joins sibling workers, and avoids self-join; cleanup is idempotent.
• B1: added a 60-second request deadline. Timeout publishes AI 応答がタイムアウトしました（N 秒） and stops the sidecar. The existing 「まだ待つ」 choice does not extend this fixed deadline.
• S3: startup claim/check is one mutex interval.
• S4: bounded version probe stdout/stderr diagnostics are included in the terminal failure reason.
• Tests: deadline-based await helper, stale payload receive-log assertion, EOF worker cleanup, timeout event, version diagnostics, and SIGKILL/process-group fallback coverage were added.

Verification:

• Commit hook gitleaks: PASS, 0 commits scanned, no leaks.
• git diff --check: PASS.
• Local nix develop -c sbcl --script run-tests.lisp: started but remained blocked in first-time Nix dependency provisioning; no exit status obtained.
• CI run 36529053731: nix flake check and build release binary failed with exit code 1; GitHub has not exposed their job logs while the run remains in progress. integration tests (x86_64-linux) and source coverage (x86_64-linux) are still in progress. Failure root cause and final run result remain pending log availability.

[takeokunn]

CI update: corrected follow-up commit caba9e2 is pushed. Run 36531314414: build release binary PASS; nix flake check FAIL after 5m37s; integration tests and source coverage are still in progress. GitHub has not exposed the completed flake log while the run remains active. Local forced ASDF load now exits 0 and confirms MAKE-ASSISTANT-SIDECAR-BOUNDARY is fbound.

[takeokunn]

AI sidecar follow-up run status: incomplete.

• B1 remains staged but uncommitted. The staged stat contains the 11 B1 files only; S3 remains unstaged in src/infrastructure/assistant-sidecar-stream.lisp.
• The canonical local gate nix build .#checks.aarch64-darwin.default -L started with a non-empty suite but failed with exit 124 after the nshell test check exceeded its 1800 second limit. The log shows SIGTERM followed by SIGKILL; no completed test-count summary was emitted.
• This run cannot attribute the timeout to B1 alone because the Nix source archive included the separate unstaged S3 worktree changes.
• Read-only review confirmed S3's current mutex scope keeps starting-state claim/update atomic and keeps I/O, channel waits, and joins outside the state mutex. S4 review found version-probe output and reader exception text were previously discarded; uncommitted follow-up edits now preserve diagnostic fields, but they were not committed or gate-verified.
• Test-strengthening edits were prepared in t/unit/test-assistant-model-boundary.lisp, but their tests were not run successfully.

No commit, push, rebase, PR-body update, or merge was performed. CI run ID: not available because no new push was made.

[takeokunn]

Follow-up after isolating B1 with stash SHA 6d01879b50ebafa3fdc61cd0d6da648cfe61cf2e:

• The stash was applied and dropped successfully. B1 is staged only; S4, S3, and test-strengthening changes are restored unstaged.
• The canonical gate was rerun with only B1 in the source archive. It again timed out at 1800s and exited 137 after SIGTERM/SIGKILL. No test summary was emitted.
• Focused evidence: e2e name-filter selected 115 tests, all passed; e2e-main-command-merges-stderr-with-pipe-and-ampersand passed in 0.870s; startup-cold-asdf-load-under-budget passed in 0.783s. These are not the source of the full-gate timeout.
• Because the canonical gate is not green and no B1-specific failing test was identified, B1 was not committed or pushed. No S4/S3/test-strengthening commit was started.

CI run ID: unavailable; no push was made.

[takeokunn]

Final review follow-up

修正を反映し、マージせずに push と検証を完了しました。

• S3: %assistant-sidecar-start のスレッド引き渡し前を unwind-protect で保護し、失敗時は starting-p を同一世代のロック内で nil に戻すようにしました。回帰テスト clears-starting-state-when-startup-handoff-fails で、次の start が再試行されることを確認しています。
• S3/B1: 指摘された setf、startup lambda、polling if の字下げを各対象コミットへ fixup し、autosquash しました。
• 最終コミット: S3 1faa6b0、B1 2cae770、テスト強化 8ede0e8。

検証結果:

• ローカル gate: 2293 passed, 34 skipped, 0 todo, 0 failed, 0 errored, 2327 total
• CI run 36603297088: 4/4 ジョブ成功
  • nix flake check
  • build release binary
  • integration tests
  • source coverage
• e2e-main-wait-returns-background-status のハングは今回の CI では発生していません。
• PR はマージしていません。

[takeokunn]

Squash merge completed. The merge commit on main is a95a0ad810268c38e3292943ea8dc35b58a5c613.