ce-test-browser

name	ce-test-browser
description	Run browser tests on pages affected by current PR or branch. Use when running browser tests, testing pages affected by a PR, or when the user says 'test this in the browser', 'run browser tests', or 'check this page'.
argument-hint	[PR number, branch name, 'current', or --port PORT]

Browser Test Skill

Run end-to-end browser tests on pages affected by a PR or branch changes using the agent-browser CLI.

Use agent-browser Only For Browser Automation

This workflow uses the agent-browser CLI exclusively. Do not use any alternative browser automation system, browser MCP integration, or built-in browser-control tool. If the platform offers multiple ways to control a browser, always choose agent-browser.

Use agent-browser for: opening pages, clicking elements, filling forms, taking screenshots, and scraping rendered content.

Platform-specific hints:

• In Codex, do not substitute unrelated browsing tools.

Prerequisites

• Local development server running (e.g., bin/dev, rails server, npm run dev)
• agent-browser CLI installed (see Setup below)
• Git repository with changes to test

Setup

Check whether agent-browser is installed:

command -v agent-browser >/dev/null 2>&1 && echo "Installed" || echo "NOT INSTALLED"

If not installed, inform the user that agent-browser is not installed. Then stop — this skill cannot function without agent-browser.

Workflow

1. Verify Installation

Before starting, verify agent-browser is available:

command -v agent-browser >/dev/null 2>&1 && echo "Ready" || echo "NOT INSTALLED"

If not installed, inform the user that agent-browser is not installed. Then stop.

2. Ask Browser Mode

Pipeline mode (mode:pipeline): Skip this step entirely. Default to headless — no question, no blocking. Proceed directly to step 3.

Manual mode: Ask the user whether to run headed or headless using the the question tool.g., Codex edit modes) — not because a schema load is required. Never silently skip the question:

Do you want to watch the browser tests run?

1. Headed (watch) - Opens visible browser window so you can see tests run
2. Headless (faster) - Runs in background, faster but invisible

Store the choice and use the --headed flag when the user selects option 1.

3. Determine Test Scope

If PR number provided:

gh pr view [number] --json files -q '.files[].path'

If 'current' or empty:

git diff --name-only main..HEAD

If branch name provided:

git diff --name-only main..[branch]

4. Map Files to Routes

Map changed files to testable routes:

File Pattern	Route(s)
app/views/users/*	/users, /users/:id, /users/new
app/controllers/settings_controller.rb	/settings
app/javascript/controllers/*_controller.js	Pages using that Stimulus controller
app/components/*_component.rb	Pages rendering that component
app/views/layouts/*	All pages (test homepage at minimum)
app/assets/stylesheets/*	Visual regression on key pages
app/helpers/*_helper.rb	Pages using that helper
src/app/* (Next.js)	Corresponding routes
src/components/*	Pages using those components

Build a list of URLs to test based on the mapping.

5. Detect and Claim a Free Port

Pipeline mode only (mode:pipeline): When invoked from LFG or another automated pipeline, always find a port that is actually free — never assume 3000 is available, as multiple agents may be running in parallel on the same machine.

Manual mode (no mode:pipeline): Use the preferred port as-is. Do not scan for alternatives — the user controls their own server.

Determine the preferred port using this priority:

1. Explicit argument — if the user passed --port 5000, use that directly (skip free-port scan)
2. Project instructions — check AGENTS.md, or other instruction files for port references
3. package.json — check dev/start scripts for --port flags
4. Environment files — check .env, .env.local, .env.development for PORT=
5. Default — fall back to 3000

In pipeline mode, verify the preferred port is free and scan upward if not. In manual mode, use the preferred port directly.

# Step 1: Determine preferred port
PORT="${EXPLICIT_PORT:-}"
if [ -z "$PORT" ]; then
 PORT=$(grep -Eio '(port\s*[:=]\s*|localhost:)([0-9]{4,5})' AGENTS.md 2>/dev/null | grep -Eo '[0-9]{4,5}' | head -1)
fi
if [ -z "$PORT" ]; then
 PORT=$(grep -Eio '(port\s*[:=]\s*|localhost:)([0-9]{4,5})' AGENTS.md 2>/dev/null | grep -Eo '[0-9]{4,5}' | head -1)
fi
if [ -z "$PORT" ]; then
 PORT=$(grep -Eo '\-\-port[= ]+[0-9]{4,5}' package.json 2>/dev/null | grep -Eo '[0-9]{4,5}' | head -1)
fi
if [ -z "$PORT" ]; then
 PORT=$(grep -h '^PORT=' .env .env.local .env.development 2>/dev/null | tail -1 | cut -d= -f2)
fi
PORT="${PORT:-3000}"

# Step 2 (pipeline mode only): scan for a free port
if [ "${PIPELINE_MODE}" = "1" ]; then
 find_free_port {
 local p=$1
 while lsof -i ":$p" -sTCP:LISTEN -t >/dev/null 2>&1; do
 p=$((p + 1))
 done
 echo $p
 }
 PORT=$(find_free_port "$PORT")
fi
echo "Using dev server port: $PORT"

Set PIPELINE_MODE=1 in your shell when the argument mode:pipeline is present.

6. Start Dev Server if Not Running, Then Verify

Pipeline mode only: If no server is already listening on $PORT, start one automatically in the background. In manual mode, inform the user and stop.

if lsof -i ":${PORT}" -sTCP:LISTEN -t >/dev/null 2>&1; then
 echo "Server already running on port ${PORT}"
else
 if [ "${PIPELINE_MODE}" = "1" ]; then
 # Auto-start in pipeline — pick the right command for this project
 echo "Starting dev server on port ${PORT}.."
 if [ -f "bin/dev" ]; then
 PORT=${PORT} bin/dev > /tmp/dev-server-${PORT}.log 2>&1 &
 elif [ -f "bin/rails" ]; then
 bin/rails server -p ${PORT} > /tmp/dev-server-${PORT}.log 2>&1 &
 elif [ -f "package.json" ]; then
 PORT=${PORT} npm run dev > /tmp/dev-server-${PORT}.log 2>&1 &
 fi
 # Wait up to 30 seconds for server to become ready
 for i in $(seq 1 30); do
 lsof -i ":${PORT}" -sTCP:LISTEN -t >/dev/null 2>&1 && break
 sleep 1
 done
 if ! lsof -i ":${PORT}" -sTCP:LISTEN -t >/dev/null 2>&1; then
 echo "Server did not start in 30s. Last output:"
 tail -20 /tmp/dev-server-${PORT}.log 2>/dev/null
 exit 1
 fi
 else
 # Manual mode — ask the user to start the server
 echo "Server not running on port ${PORT}"
 echo ""
 echo "Please start your development server:"
 echo " Rails: bin/dev or rails server -p ${PORT}"
 echo " Node/Next.js: npm run dev"
 echo " Custom port: run this skill again with --port <your-port>"
 exit 0
 fi
fi

agent-browser open http://localhost:${PORT}
agent-browser snapshot -i

7. Test Each Affected Page

For each affected route:

Navigate and capture snapshot:

agent-browser open "http://localhost:${PORT}/[route]"
agent-browser snapshot -i

For headed mode:

agent-browser --headed open "http://localhost:${PORT}/[route]"
agent-browser --headed snapshot -i

Verify key elements:

• Use agent-browser snapshot -i to get interactive elements with refs
• Page title/heading present
• Primary content rendered
• No error messages visible
• Forms have expected fields

Test critical interactions:

agent-browser click @e1
agent-browser snapshot -i

Take screenshots:

agent-browser screenshot page-name.png
agent-browser screenshot --full page-name-full.png

8. Human Verification (When Required)

Pause for human input when testing touches flows that require external interaction:

Flow Type	What to Ask
OAuth	"Please sign in with [provider] and confirm it works"
Email	"Check your inbox for the test email and confirm receipt"
Payments	"Complete a test purchase in sandbox mode"
SMS	"Verify you received the SMS code"
External APIs	"Confirm the [service] integration is working"

Ask the user (using the platform's question tool, or present numbered options and wait):

Human Verification Needed

This test touches [flow type]. Please:
1. [Action to take]
2. [What to verify]

Did it work correctly?
1. Yes - continue testing
2. No - describe the issue

9. Handle Failures

When a test fails:

1. Document the failure:

• Screenshot the error state: agent-browser screenshot error.png
• Note the exact reproduction steps

2. Ask the user how to proceed:

Test Failed: [route]

Issue: [description]
Console errors: [if any]

How to proceed?
1. Fix now - debug and fix the failing test
2. Skip - continue testing other pages

3. If "Fix now": investigate, propose a fix, apply, re-run the failing test
4. If "Skip": log as skipped, continue

10. Test Summary

After all tests complete, present a summary:

## Browser Test Results

**Test Scope:** PR #[number] / [branch name]
**Server:** http://localhost:${PORT}

### Pages Tested: [count]

| Route | Status | Notes |
|-------|--------|-------|
| `/users` | Pass | |
| `/settings` | Pass | |
| `/dashboard` | Fail | Console error: [msg] |
| `/checkout` | Skip | Requires payment credentials |

### Console Errors: [count]
- [List any errors found]

### Human Verifications: [count]
- OAuth flow: Confirmed
- Email delivery: Confirmed

### Failures: [count]
- `/dashboard` - [issue description]

### Result: [PASS / FAIL / PARTIAL]

Quick Usage Examples

# Test current branch changes (auto-detects port)
/ce-test-browser

# Test specific PR
/ce-test-browser 847

# Test specific branch
/ce-test-browser feature/new-dashboard

# Test on a specific port
/ce-test-browser --port 5000

agent-browser CLI Reference

Run agent-browser --help for all commands.

Key commands:

# Navigation
agent-browser open <url> # Navigate to URL
agent-browser back # Go back
agent-browser close # Close browser

# Snapshots (get element refs)
agent-browser snapshot -i # Interactive elements with refs (@e1, @e2, etc.)
agent-browser snapshot -i --json # JSON output

# Interactions (use refs from snapshot)
agent-browser click @e1 # Click element
agent-browser fill @e1 "text" # Fill input
agent-browser type @e1 "text" # Type without clearing
agent-browser press Enter # Press key

# Screenshots
agent-browser screenshot out.png # Viewport screenshot
agent-browser screenshot --full out.png # Full page screenshot

# Headed mode (visible browser)
agent-browser --headed open <url> # Open with visible browser
agent-browser --headed click @e1 # Click in visible browser

# Wait
agent-browser wait @e1 # Wait for element
agent-browser wait 2000 # Wait milliseconds