Watchdog

watchdog

Purpose

Post-deploy monitoring. Receives a deployed URL and list of expected endpoints, runs health checks, measures response times, detects errors, and returns a structured smoke test report.

Called By (inbound)

• deploy (L2): post-deploy monitoring setup
• launch (L1): monitoring as part of launch pipeline
• incident (L2): current system state check during incident triage

Calls (outbound)

None — pure L3 utility.

Executable Instructions

Step 1: Receive Target

Accept input from calling skill:

• base_url — deployed application URL (e.g. https://myapp.com)
• endpoints — list of paths to check (e.g. ["/", "/health", "/api/status"])

If no endpoints provided, default to: ["/", "/health", "/ready"]

Step 2: Health Check

For each endpoint, run an HTTP status check using Bash:

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curl -s -o /dev/null -w "%{http_code}" https://myapp.com/health

• 2xx → HEALTHY
• 3xx → REDIRECT (note final destination)
• 4xx → CLIENT_ERROR (flag as alert)
• 5xx → SERVER_ERROR (flag as critical alert)
• Connection refused / timeout → UNREACHABLE (flag as critical)

Step 3: Response Time

For each endpoint, measure latency using Bash:

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curl -s -o /dev/null -w "%{time_total}" https://myapp.com/health

Thresholds:

• < 500ms → FAST
• 500ms–2000ms → ACCEPTABLE

• 2000ms → SLOW (flag as alert)

Step 4: Performance Signal Analysis

After collecting response times from Step 3, analyze for patterns that indicate root causes:

• Consistently 2x+ slower than baseline (or > 2000ms with no apparent load): flag with PERF_WARN — investigate N+1 query or missing DB index
• Endpoint cluster degradation: if 3+ endpoints share a pattern (all auth endpoints slow, all /api/* slow): flag PERF_WARN — connection pool saturation likely
• Spike after deploy: compare with previous watchdog run if available — if an endpoint that was FAST is now SLOW, flag PERF_REGRESSION — correlate with recent git diff

If no previous baseline exists, skip spike detection and note INFO: no baseline — first run.

Output performance signals into a perf_signals list (separate from alerts).

Step 5: Error Detection

Scan responses for problems:

• 4xx/5xx HTTP codes → log endpoint + status code
• Response time > 2s → log endpoint + measured time
• Connection timeout (curl exits non-zero) → UNREACHABLE
• Empty response body on non-204 endpoints → flag as WARNING

Collect all flagged issues into an alerts list.

Step 6: Report

Output the following report structure:

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## Watchdog Report: [base_url]

### Smoke Test Results
- [endpoint] — [HTTP status] ([response_time]s) — [HEALTHY|REDIRECT|CLIENT_ERROR|SERVER_ERROR|UNREACHABLE]

### Alert Rules Applied
- Response time > 2s → alert
- Any 4xx on non-auth endpoint → alert
- Any 5xx → critical alert
- Unreachable → critical alert

### Alerts
- [CRITICAL|WARNING] [endpoint] — [reason]

### Performance Signals
- [PERF_WARN|PERF_REGRESSION|INFO] [endpoint] — [diagnosis]

### Summary
- Total endpoints checked: [n]
- Healthy: [n]
- Alerts: [n]
- Perf Signals: [n]
- Overall status: ALL_HEALTHY | DEGRADED | DOWN

If no alerts and no perf signals: output Overall status: ALL_HEALTHY.

Output Format

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## Watchdog Report: [base_url]
### Smoke Test Results
- / — 200 (0.231s) — HEALTHY
- /health — 200 (0.089s) — HEALTHY
- /api/status — 500 (1.203s) — SERVER_ERROR

### Alerts
- CRITICAL /api/status — HTTP 500

### Summary
- Total: 3 | Healthy: 2 | Alerts: 1
- Overall status: DEGRADED

Constraints

1. MUST report with specific metrics — not vague "performance seems slow"
2. MUST include baseline comparison when available
3. MUST NOT generate false alarms — precision over recall
4. MUST separate perf signals from error alerts — they are different severity channels
5. MUST NOT call perf skill — watchdog is a detector, not a diagnoser

Sharp Edges

Known failure modes for this skill. Check these before declaring done.

Done When

• All specified endpoints checked (HTTP status + response time measured)
• All 4xx/5xx → alerts list, all SLOW → alerts list
• Performance patterns analyzed → perf_signals list (or INFO: first run)
• Structured Watchdog Report emitted with Alerts + Performance Signals + Summary
• Overall status is ALL_HEALTHY, DEGRADED, or DOWN (never ambiguous)

Cost Profile

~500-1500 tokens input, ~300-800 tokens output. Sonnet for configuration quality.