Skill

deploy-check

Instrument a frontend with version fingerprinting (meta tag + /__version endpoint) so LLM-based testing can verify the correct build is deployed before walking. Use when asked to 'add version check', 'deploy verification', 'instrument version', 'add build fingerprint', 'deploy-check', or before running ux-walker on a deploy.

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How this skill is triggered — by the user, by Claude, or both

Slash command

/developer-skill-pack:deploy-check

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Model invocable

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The summary Claude sees in its skill listing — used to decide when to auto-load this skill

Instrument a frontend app with subtle version fingerprinting — a `<meta>` tag in the HTML and a `/__version` JSON endpoint — so automated testing (ux-walker, CI, curl) can confirm the correct build is deployed before testing begins.

SKILL.md

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LanguageShell

Stars0

MaintenanceExcellent

Last CommitJun 8, 2026

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Deploy Check

Instrument a frontend app with subtle version fingerprinting — a <meta> tag in the HTML and a /__version JSON endpoint — so automated testing (ux-walker, CI, curl) can confirm the correct build is deployed before testing begins.

Usage

/deploy-check [--install] [--verify url] [--expected-sha sha]

Parameter	Default	Notes
--install	Auto-detect	Instrument the current project with version fingerprinting
--verify url	None	Check a running app and report what version is deployed
--expected-sha sha	Current HEAD	Fail if the deployed SHA doesn't match

If no flags given, auto-detect: if the project already has fingerprinting, run --verify; otherwise run --install.

What Gets Installed

1. Meta Tag

A <meta> tag injected into the HTML <head> at build time:

<meta name="build-version" content="sha:a1b2c3d timestamp:2026-06-08T12:00:00Z" />

Invisible to users. Readable by agent-browser:

agent-browser snapshot -i | grep 'build-version'
# or via JavaScript:
agent-browser js "document.querySelector('meta[name=build-version]')?.content"

2. Version Endpoint

A /__version route returning JSON:

{
  "git_sha": "a1b2c3d",
  "git_branch": "main",
  "build_timestamp": "2026-06-08T12:00:00Z",
  "version": "1.2.3",
  "dirty": false
}

Readable by curl, fetch, or any HTTP client:

curl -s http://localhost:3000/__version | jq .

3. Build-time Script

A scripts/version-stamp.sh that generates a version.json at build time:

#!/usr/bin/env bash
set -euo pipefail

cat > "${1:-public/version.json}" <<JSON
{
  "git_sha": "$(git rev-parse --short HEAD)",
  "git_branch": "$(git rev-parse --abbrev-ref HEAD)",
  "build_timestamp": "$(date -u +%Y-%m-%dT%H:%M:%SZ)",
  "version": "$(node -p "require('./package.json').version" 2>/dev/null || echo "0.0.0")",
  "dirty": $(git diff --quiet && echo false || echo true)
}
JSON

Install Mode (`--install`)

Detect the framework and instrument accordingly. The orchestrator performs all steps directly — no sub-agents needed.

Step 1: Detect Framework

Read package.json and project structure to identify the framework:

Signal	Framework
`next` in dependencies	Next.js
`vite` in devDependencies	Vite (React/Vue/Svelte)
`@remix-run/dev` in dependencies	Remix
`@angular/core` in dependencies	Angular
`gatsby` in dependencies	Gatsby
`astro` in dependencies	Astro
`nuxt` in dependencies	Nuxt
None of the above	Generic static / Express

Step 2: Create Version Stamp Script

Write scripts/version-stamp.sh (see template above). Make it executable.

Step 3: Framework-Specific Instrumentation

Next.js

Meta tag — add to the root layout (app/layout.tsx or pages/_document.tsx):

import versionData from '../../public/version.json';

// In the <head>:
<meta name="build-version" content={`sha:${versionData.git_sha} timestamp:${versionData.build_timestamp}`} />

Endpoint — create app/api/__version/route.ts (App Router) or pages/api/__version.ts (Pages Router):

import { NextResponse } from 'next/server';
import versionData from '../../../public/version.json';

export async function GET() {
  return NextResponse.json(versionData);
}

Build hook — add to package.json scripts:

{
  "prebuild": "bash scripts/version-stamp.sh public/version.json",
  "predev": "bash scripts/version-stamp.sh public/version.json"
}

Vite (React / Vue / Svelte)

Meta tag — add to index.html:

<!-- In <head>, replaced at build time by vite plugin or prebuild -->
<meta name="build-version" content="__BUILD_VERSION__" />

Create or update vite.config.ts to replace the placeholder:

import { defineConfig } from 'vite';
import fs from 'fs';

export default defineConfig({
  define: {
    __BUILD_VERSION__: JSON.stringify(
      (() => {
        try {
          const v = JSON.parse(fs.readFileSync('public/version.json', 'utf-8'));
          return `sha:${v.git_sha} timestamp:${v.build_timestamp}`;
        } catch { return 'unknown'; }
      })()
    ),
  },
});

Endpoint — Vite dev server middleware via plugin, or just serve public/version.json directly at /__version via a simple redirect/rewrite.

Build hook:

{
  "prebuild": "bash scripts/version-stamp.sh public/version.json",
  "predev": "bash scripts/version-stamp.sh public/version.json"
}

Remix

Meta tag — add to app/root.tsx via the meta export or a direct <meta> in the <head>.

Endpoint — create app/routes/__version.ts:

import { json } from '@remix-run/node';
import versionData from '../../public/version.json';

export function loader() {
  return json(versionData);
}

Generic / Express / Static

Meta tag — find the main HTML file (index.html, public/index.html) and inject the meta tag.

Endpoint — if Express detected (express in dependencies), add middleware:

import versionData from './public/version.json';
app.get('/__version', (req, res) => res.json(versionData));

If static site, the public/version.json file is the endpoint — instruct the user to access it at /version.json.

Step 4: Update `.gitignore`

Add public/version.json to .gitignore — it's generated at build time, not committed.

Step 5: Verify Installation

# Generate the version stamp
bash scripts/version-stamp.sh public/version.json

# Check it was created
cat public/version.json

Report what was installed and which files were modified.

Verify Mode (`--verify`)

Check a running app to confirm the deployed version matches expectations. This is what ux-walker calls before walking.

Step 1: Read Version from Meta Tag

agent-browser open "{url}"
agent-browser js "document.querySelector('meta[name=\"build-version\"]')?.content"

Parse sha:XXXXXX timestamp:YYYY-MM-DDTHH:MM:SSZ from the result.

Step 2: Read Version from Endpoint

curl -s "{url}/__version" 2>/dev/null || curl -s "{url}/version.json" 2>/dev/null

Parse the JSON response.

Step 3: Compare Against Expected

If --expected-sha was provided, compare. Otherwise compare against git rev-parse --short HEAD.

Output:

Deploy Check Results
────────────────────
Meta tag SHA:      a1b2c3d ✓
Endpoint SHA:      a1b2c3d ✓
Expected SHA:      a1b2c3d ✓
Branch:            main
Build timestamp:   2026-06-08T12:00:00Z
Dirty:             false
Status:            VERIFIED — correct version deployed

If mismatch:

Deploy Check Results
────────────────────
Meta tag SHA:      a1b2c3d ✗
Expected SHA:      f4e5d6c
Status:            MISMATCH — deployed version does not match HEAD
                   The app is running an older build. Rebuild and redeploy,
                   or pass --expected-sha a1b2c3d to accept this version.

Step 4: Return Verdict

Return a structured result that callers (ux-walker, CI) can act on:

{
  "status": "verified",
  "deployed_sha": "a1b2c3d",
  "expected_sha": "a1b2c3d",
  "match": true,
  "branch": "main",
  "build_timestamp": "2026-06-08T12:00:00Z",
  "dirty": false
}

Integration with UX Walker

When ux-walker runs its Phase 0 Preflight, it should call deploy-check verify:

Phase 0 — Preflight
├── 0.1 URL Check (existing)
├── 0.1.5 Deploy Check ← NEW
│   └── curl {url}/__version or read meta tag
│   └── Compare SHA against git rev-parse --short HEAD
│   └── If mismatch: warn but continue (don't block — the user may be testing an older deploy intentionally)
│   └── If missing: note "No version fingerprint found — run /deploy-check --install to add one"
├── 0.2 Catalog Check (existing)
└── ...

The version check is advisory, not blocking — if the fingerprint is missing or mismatched, ux-walker warns but proceeds. The user can install fingerprinting with /deploy-check --install when ready.

Constraints

Never commit public/version.json — it's build-time generated
The meta tag must be invisible to end users (no visible UI element)
The /__version endpoint must not leak sensitive information (no env vars, no secrets, no internal paths)
Framework detection must not modify files outside the project
The version stamp script must work on macOS and Linux (use portable date flags)
If the project already has version fingerprinting (e.g., Sentry release, DataDog RUM version), detect it and integrate rather than duplicate

deploy-check

Invocation

Context Preview

SKILL.md

deploy-check

Invocation

Context Preview

SKILL.md

Deploy Check

Usage

What Gets Installed

1. Meta Tag

2. Version Endpoint

3. Build-time Script

Install Mode (--install)

Step 1: Detect Framework

Step 2: Create Version Stamp Script

Step 3: Framework-Specific Instrumentation

Next.js

Vite (React / Vue / Svelte)

Remix

Generic / Express / Static

Step 4: Update .gitignore

Step 5: Verify Installation

Verify Mode (--verify)

Step 1: Read Version from Meta Tag

Step 2: Read Version from Endpoint

Step 3: Compare Against Expected

Step 4: Return Verdict

Integration with UX Walker

Constraints

Similar Skills

Deploy Check

Usage

What Gets Installed

1. Meta Tag

2. Version Endpoint

3. Build-time Script

Install Mode (--install)

Step 1: Detect Framework

Step 2: Create Version Stamp Script

Step 3: Framework-Specific Instrumentation

Next.js

Vite (React / Vue / Svelte)

Remix

Generic / Express / Static

Step 4: Update .gitignore

Step 5: Verify Installation

Verify Mode (--verify)

Step 1: Read Version from Meta Tag

Step 2: Read Version from Endpoint

Step 3: Compare Against Expected

Step 4: Return Verdict

Integration with UX Walker

Constraints

Similar Skills

Install Mode (`--install`)

Step 4: Update `.gitignore`

Verify Mode (`--verify`)

Install Mode (`--install`)

Step 4: Update `.gitignore`

Verify Mode (`--verify`)