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watch: post-reboot, new subagent JSONLs go untracked → watchdog 'stalled' loop, watcher pegged ~90% CPU

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#734 2 comments 0 reactions 0 assignees View on GitHub

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
48/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Active
Tech stack
python
Domain
backend, devops, observability

Research direction

Start with the brainlayer watch --poll 1.0 entry point and reproduce from ~/Library/Logs/brainlayer/ using watcher-health.json, throughput-watchdog.out.log, and watch.err.log; compare discovery and offset seeding against ~/.local/share/brainlayer/offsets.json. Done means new subagents/*.jsonl files are tracked, health reports untracked_recent_files, and watchdog restarts do not create a CPU-burning loop.

Written by the indexing model from the issue text.

Description

Observed 2026-08-24 (post-reboot), reported from the cmuxlayer lead seat

  • com.brainlayer.watch (brainlayer watch --poll 1.0) sustained 76–97% CPU (pid 31924, relaunched 16:54; launchd last exit = -15). com.brainlayer.drain also last exit −15. hotlane_brainbar_daemon ~17%.
  • throughput-watchdog.out.log alternates "stalled" / "progress" each minute with pending_bytes ≈ 3.0–3.4MB, pending_files 1–3, untracked_recent_files: 2.
  • watcher-health.json says healthy (files_tracked 4235, no ingestion failures, ~70 entries/min) — it does not see the problem.
  • offsets.json: 8,401 historical subagents/… paths tracked, but for today's active session 9aca6d01-… only the main JSONL is tracked — 0 of the 8 subagents/agent-*.jsonl files on disk (largest 3.17MB, actively written).
  • watch.err.log alarms are stale (mtime 04:00): FileNotFound deferrals for deleted worktree transcripts — separate, pre-reboot.

Hypothesis

Post-reboot the watcher is not discovering newly created subagents/ transcripts (directory enumeration/offset seeding for new session dirs), so their bytes stay pending forever; the throughput-watchdog interprets that as a stall and SIGTERMs/relaunches; each relaunch re-walks ~14.8K tracked paths at a 1s poll. The user-visible symptom is typing lag in cmux.

Asks

  1. Confirm why subagents/ files under a new session dir are not picked up (enumeration vs. offset seeding vs. glob).
  2. Make watcher-health report untracked_recent_files so the watcher's own view agrees with the watchdog.
  3. Consider watchdog restart backoff — repeated SIGTERM on a non-stall is what turns a tracking gap into a CPU burn.

Evidence commands are reproducible from ~/Library/Logs/brainlayer/ and ~/.local/share/brainlayer/offsets.json.

— cmuxlayerClaude (lead, surfacing per "surprises bubble up")
🤖 Generated with Claude Code

Dominant language
Python
Stars
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Forks
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Avg merge
4h 50m
Merged PRs (30d)
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