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?

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
1critical:  # immediate alert
2  - HTTP status != 200
3  - Console error count > 5 (new errors only)
4  - LCP > 4s
5  - API endpoint returns 5xx
6
7warning:   # flag in report
8  - LCP increased > 500ms from baseline
9  - CLS > 0.1
10  - New console warnings
11  - Response time > 2x baseline
12
13info:      # log only
14  - Minor performance variance
15  - 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
1## Canary Report — myapp.com — 2026-03-23 03:15 PST
2
3### Status: HEALTHY ✓
4
5| Check | Result | Baseline | Delta |
6|-------|--------|----------|-------|
7| HTTP | 200 ✓ | 200 | — |
8| Console errors | 0 ✓ | 0 | — |
9| LCP | 1.8s ✓ | 1.6s | +200ms |
10| CLS | 0.01 ✓ | 0.01 | — |
11| API /health | 145ms ✓ | 120ms | +25ms |
12
13### 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