Initial skills documentation — 25 categories, all SKILL.md + references + scripts

2026-07-15 17:42:20 -04:00
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+# Service Health Check (no_agent watchdog)
+
+A reusable pattern for no_agent cron jobs that monitor ALL critical services and only report on failure.
+
+## Design
+
+```bash
+#!/bin/bash
+# silent on success, report failures only
+
+CHECKS=()
+FAILED=0
+
+# Each check:
+command || { CHECKS+=("Service Name"); FAILED=1; }
+
+if [ $FAILED -eq 1 ]; then
+    echo "⚠️  Service Health Alert — $(date)"
+    for c in "${CHECKS[@]}"; do echo "  ❌ $c"; done
+    exit 1
+fi
+exit 0
+```
+
+## What to check
+
+- Systemd services (caddy, mysql-tunnel)
+- Docker containers (docker ps --format)
+- Local HTTP endpoints (curl -sf)
+- Remote reachability (ping through tunnel, SSH)
+- Database connectivity (mysql -e "SELECT 1")
+- API token validity (curl + verify response)
+
+## Pitfalls
+
+- **Must be no_agent: true** in cron config — LLM processing is wasted on binary health checks and causes typing indicators
+- **Include the exit code** — exit 0 = silent, exit 1 = output delivered. Without the right exit code, cron can't tell success from failure
+- **Test with `bash script.sh` and check `echo $?`** before deploying
+- **MySQL checks need `--skip-ssl`** for local tunnel connections
+- **Don't check too many things** — 10-12 checks is the sweet spot. More than 15 and the script gets brittle
+- **SSH checks need `-o BatchMode=yes -o ConnectTimeout=5`** to avoid hanging on unreachable hosts