How do I install the Canary Watch skill?

Run npx skillmds@latest add sheshiyer/canary-watch in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Canary Watch safe to use?

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Which AI agents work with Canary Watch?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Canary Watch free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Canary Watch?

Sheshiyer (@sheshiyer) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Canary Watch by sheshiyer — Agent Skill

Name: Canary Watch
Author: Sheshiyer

Canary Watch

Monitor and verify a deployed URL by checking HTTP endpoints, SSE streams, static assets, console errors, and performance regressions. USE WHEN smoke-testing or canary-watching after a deploy, a risky merge, or a dependency upgrade.

Sheshiyer Updated Sep 17, 2026

File contents

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

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

## 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

---name: canary-watchdescription: Monitor and verify a deployed URL by checking HTTP endpoints, SSE streams, static assets, console errors, and performance regressions. USE WHEN smoke-testing or canary-watching after a deploy, a risky merge, or a dependency upgrade.---# 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 WorksMonitors 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```yamlcritical: # 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 heartbeatwarning: # 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 baselineinfo: # log only - Minor performance variance - New network requests (third-party scripts added?)```### NotificationsWhen 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.```## IntegrationPair 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

Frequently asked questions