canary-watch

# Canary Watch — Post-Deploy Monitoring ## When to Use - After deploying to production or staging - After merging a risky PR - When you want to verify a fix actually fixed it - Continuous monitoring during a launch window - After dependency upgrades ## How It Works Monitors a deployed URL for regressions. Runs in a loop until stopped or until the watch window expires. ### What It Watches ``` 1. HTTP Status — is the page returning 200? 2. Console Errors — new errors that weren't there before? 3. Network Failures — failed API calls, 5xx responses? 4. Performance — LCP/CLS/INP regression vs baseline? 5. Content — did key elements disappear? (h1, nav, footer, CTA) 6. API Health — are critical endpoints responding within SLA? 7. Static Assets — are JS, CSS, image, and font requests returning 2xx/3xx with expected content types? 8. SSE Streams — do event-stream endpoints connect and receive an initial event or heartbeat? ``` ### Watch Modes **Quick check** (default): single pass, report results ``` /canary-watch https://myapp.com ``` **Sustained watch**: check every N minutes for M hours ``` /canary-watch https://myapp.com --interval 5m --duration 2h ``` **Diff mode**: compare staging vs production ``` /canary-watch --compare https://staging.myapp.com https://myapp.com ``` ### Alert Thresholds ```yaml critical: # immediate alert - HTTP status != 200 - Console error count > 5 (new errors only) - LCP > 4s - API endpoint returns 5xx - Static asset returns 4xx/5xx - SSE endpoint cannot connect or drops before first heartbeat warning: # flag in report - LCP increased > 500ms from baseline - CLS > 0.1 - New console warnings - Response time > 2x baseline - Static asset content type changed unexpectedly - SSE heartbeat latency > 2x baseline info: # log only - Minor performance variance - New network requests (third-party scripts added?) ``` ### Notifications When a critical threshold is crossed: - Desktop notification (macOS/Linux) - Optional: Slack/Discord webhook - Log to `~/.claude/canary-watch.log` ## Output ```markdown ## Canary Report — myapp.com — 2026-03-23 03:15 PST ### Status: HEALTHY ✓ | Check | Result | Baseline | Delta | |-------|--------|----------|-------| | HTTP | 200 ✓ | 200 | — | | Console errors | 0 ✓ | 0 | — | | LCP | 1.8s ✓ | 1.6s | +200ms | | CLS | 0.01 ✓ | 0.01 | — | | API /health | 145ms ✓ | 120ms | +25ms | | Static assets | 42/42 ✓ | 42/42 | — | | SSE /events | connected ✓ | connected | +80ms heartbeat | ### No regressions detected. Deploy is clean. ``` ## Integration Pair with: - `/browser-qa` for pre-deploy verification - Hooks: add as a PostToolUse hook on `git push` to auto-check after deploys - CI: run in GitHub Actions after deploy step