Deploy check

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.

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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