chf3198 Mem Watchdog Ops Skill
Use this skill when working in constrained Crostini environments where VS Code, Chrome/Playwright, and extension host memory spikes can trigger OOM.
Ground Rules
- Never read or reason from
SwapFreevalues on Crostini. - Prefer
systemctl --useronly — neversudo systemctl. - Treat the mem-watchdog daemon as independent runtime authority.
- For tuning, use extension settings (
memWatchdog.*) so the extension writes config and restarts service safely.
Fast Workflows
Status snapshot
- Use chat participant command:
/memwatchdog status - Or run helper:
~/.copilot/skills/mem-watchdog-ops/watchdog-snapshot.sh
- Use chat participant command:
Recent actions / diagnosis
/memwatchdog logs- Look for action markers in journal:
ACTION(SIGTERM):ACTION(SIGKILL):RECOVERY(SIGTERM):
Apply tuning profile
/memwatchdog tune balanced— general dev use (warn 3.4 GB, emerg 3.8 GB)/memwatchdog tune conservative— earlier intervention (warn 3.0 GB, emerg 3.4 GB)/memwatchdog tune playwright— more headroom for automation (warn 3.8 GB, emerg 4.2 GB)
Manual protective action
/memwatchdog act kill chrome/memwatchdog act restart service
Tuning Guidance
- balanced: general dev use — recommended for Copilot Chat multi-agent workloads that peak at 3.0–3.5 GB
- conservative: earlier intervention, safer on tight RAM — may cause more Chrome kills
- playwright: more headroom for headed browser automation sessions
When recommending profile changes, explain expected trade-off between stability and interruption frequency.
Kill Hierarchy (daemon v20260329.1+)
| Condition | Action |
|---|---|
MemAvailable ≤ 15% |
SIGKILL Chrome/Playwright |
MemAvailable ≤ 25% |
SIGTERM Chrome/Playwright (deferred if Playwright active) |
| PSI full avg10 > 25% | SIGTERM Chrome (deferred if Playwright active) |
| VS Code RSS ≥ 3.8 GB | SIGKILL Chrome (always — even during Playwright sessions); if none → kill_vscode_main() |
| VS Code RSS ≥ 3.4 GB | SIGTERM Chrome (deferred if Playwright active); if none → kill helper (Shared Process, File Watcher, Network Service); if none → cgroup throttle/reclaim |
| RSS velocity spike | Kill lowest-value helper — never a language server or Extension Host at normal severity |
| Chrome PIDs > 3 | SIGKILL oldest excess (skipped when Playwright is active) |
Playwright Awareness (daemon v20260329.1+, Issue #109)
The daemon detects active Playwright sessions via pgrep -f 'node.*playwright'.
When Playwright is active:
CHROME-EXCESScap enforcement is skipped — Playwright legitimately spawns 5-10 Chrome PIDs- Non-critical Chrome kills (WARN, ACCEL, Stage 2-3) are deferred — callers fall through to helper kills or cgroup throttle/reclaim
- EMERGENCY and Stage 4 always kill Chrome regardless — genuine OOM must be prevented
Before launching Playwright automation:
- Check memory status:
/memwatchdog status - If RSS is already above 3.0 GB, consider applying the playwright profile:
/memwatchdog tune playwright - Close any idle Chrome browsers from previous sessions
If the watchdog kills Playwright Chrome during automation:
- This only happens at EMERGENCY level (≥3.8 GB RSS or ≤15% free memory)
- Consider: closing other VS Code windows, reducing open editor tabs, or restarting the Extension Host to reclaim memory before retrying
Key Repo References
- Snapshot helper — the in-repo memory snapshot script shipped with this skill.
The watchdog daemon, extension activation, dashboard actions, config bridge, and the system-stability design doc live in the upstream VS Code extension repository (the canonical home of this skill), not in this harness checkout.