# Canary: Post-Deploy Visual Monitor (canary)

> After a deploy, drives a browser over live pages and compares screenshots, console errors, load times and broken links to a baseline.

- Category: [Monitoring & Ops](https://www.myskills.tools/en/categories/monitoring-ops/)
- Source: Community · Garry Tan
- Repository: https://github.com/garrytan/gstack/tree/main/canary (commit 3e4240a · v1.0.0)
- SKILL.md: https://github.com/garrytan/gstack/blob/main/canary/SKILL.md
- Install command: `npx skills add garrytan/gstack --skill canary`
- License: MIT
- Compatible with: Claude Code, Codex, Cursor, Copilot
- Permissions: read-repo ✓, write-files ✓, shell ✓, network ✓
- Status: Scan passed
- A rule scan cannot catch every risk. Read this skill's SKILL.md and check its permissions before installing.
- ⚠ It prefers driving the user's real browser and signed-in sessions via Aside; the fallback browser needs a one-time ./setup that may install bun.

## Core rule

Alert on changes against the baseline, not absolutes, and only when a pattern persists across two or more consecutive checks.

## Execution Phases

1. **Setup and baseline** — Create .gstack/canary-reports/; with --baseline, capture screenshots, console errors, load times and text for each page before deploying.
2. **Discover pages** — Auto-discover same-origin nav links, propose the top five plus the homepage for confirmation, and take a starting snapshot if no baseline exists.
3. **Monitoring loop** — Check every page every 60 seconds for the set duration; when a critical or high issue repeats on two checks, ask the user how to proceed.
4. **Health report** — Give a HEALTHY, DEGRADED or BROKEN verdict, save Markdown and JSON reports in .gstack/canary-reports/, and offer a baseline update if healthy.

## Permissions (summarised from SKILL.md)

| Capability | Needed | Details |
|---|---|---|
| File writes | Limited | Writes only screenshots, baselines and reports under .gstack/canary-reports/ and history in the gstack state directory; code is not modified unless asked. |
| Command execution | Limited | Runs aside repl or gstack's own headless browser, gstack helper scripts, and commands such as copying screenshots. |
| Network outbound | Limited | Visits only the user-named site and same-origin links; mutating actions on non-local sites need the user's consent first. |

## SKILL.md frontmatter (YAML)

```yaml
---
name: canary
preamble-tier: 2
version: 1.0.0
description: Post-deploy canary monitoring. (gstack)
allowed-tools:
  - Bash
  - Read
  - Write
  - Glob
  - AskUserQuestion
triggers:
  - monitor after deploy
  - canary check
  - watch for errors post-deploy
---
```

Home: https://www.myskills.tools/en/ · URL: https://www.myskills.tools/en/skills/canary/