Agent React Devtools

agent-react-devtools

Skill by ara.so — Devtools Skills collection.

agent-react-devtools is a command-line interface to React DevTools that lets AI agents inspect running React applications. It provides programmatic access to component trees, props, state, hooks, and rendering performance data through a persistent background daemon.

Installation

Install globally:

npm install -g agent-react-devtools

Or use directly with npx:

npx agent-react-devtools start

Core Concepts

• Daemon: A persistent background process (default port 8097) that maintains connection state
• Component IDs: Components are labeled @c1, @c2, etc. for easy reference
• Host Filtering: HTML elements (<div>, <span>) are filtered by default to keep output compact
• LLM-Optimized: Output is token-efficient and structured for AI consumption

Connecting Your React App

Quick Setup (Recommended)

Auto-configure your project:

npx agent-react-devtools init

This detects your framework (Vite, Next.js, CRA) and patches the config automatically.

To undo:

npx agent-react-devtools uninit

Manual Setup - One-Line Import

Add to your entry point (e.g., src/main.tsx):

import "agent-react-devtools/connect";

Place this as the first import in your app entry point.

Manual Setup - Vite Plugin

For Vite projects, use the plugin (no app code changes needed):

// vite.config.ts
import { defineConfig } from "vite";
import react from "@vitejs/plugin-react";
import { reactDevtools } from "agent-react-devtools/vite";

export default defineConfig({
  plugins: [
    reactDevtools(), // Must come before react()
    react()
  ],
});

With custom port:

reactDevtools({ port: 8097, host: "localhost" })

React Native Setup

React Native connects automatically:

agent-react-devtools start
npx react-native start

For physical devices, forward the port:

adb reverse tcp:8097 tcp:8097

Key Commands

Daemon Management

Start the daemon (required first step):

agent-react-devtools start

With custom port:

agent-react-devtools start --port 8097

Check status:

agent-react-devtools status

Stop daemon:

agent-react-devtools stop

Component Inspection

Get full component tree:

agent-react-devtools get tree

Limit tree depth:

agent-react-devtools get tree --depth 3

Include host components (div, span, etc.):

agent-react-devtools get tree --all

Get subtree from specific component:

agent-react-devtools get tree @c5

Inspect component details:

agent-react-devtools get component @c6

Output shows props, state, and hooks:

@c6 [fn] TodoItem key=1
props:
  id: 1
  text: "Buy groceries"
  done: false
  onToggle: ƒ
hooks:
  State: false
  Callback: ƒ

Search for components by name:

agent-react-devtools find TodoItem

Exact name match:

agent-react-devtools find App --exact

Count components by type:

agent-react-devtools count

List components with errors/warnings:

agent-react-devtools errors

Wait Commands (Useful in Scripts)

Wait for app connection:

agent-react-devtools wait --connected --timeout 30

Wait for specific component:

agent-react-devtools wait --component App --timeout 30

These exit with code 0 on success, code 1 on timeout.

Performance Profiling

Start profiling session:

agent-react-devtools profile start

With named session:

agent-react-devtools profile start "user-interaction-test"

Stop profiling:

agent-react-devtools profile stop

Find slowest components:

agent-react-devtools profile slow

Limit results:

agent-react-devtools profile slow --limit 5

Find components that re-render most:

agent-react-devtools profile rerenders

View commit timeline:

agent-react-devtools profile timeline

Inspect specific commit:

agent-react-devtools profile commit 3

Or use commit label:

agent-react-devtools profile commit #3

Get render report for specific component:

agent-react-devtools profile report @c5

Export profiling data:

agent-react-devtools profile export results.json

Compare two profile exports:

agent-react-devtools profile diff before.json after.json

With threshold filter:

agent-react-devtools profile diff before.json after.json --threshold 2.0

Common Workflows

Debugging Component Issues

1. Start daemon and connect app:

agent-react-devtools start
# Run your app (it should auto-connect)
agent-react-devtools status

2. Find the problematic component:

agent-react-devtools find UserProfile

3. Inspect its state and props:

agent-react-devtools get component @c12

4. Check surrounding context:

agent-react-devtools get tree @c12 --depth 2

Performance Investigation

1. Start profiling before interaction:

agent-react-devtools profile start "search-performance"

2. Perform the interaction in your app

3. Stop and analyze:

agent-react-devtools profile stop
agent-react-devtools profile slow --limit 10
agent-react-devtools profile rerenders --limit 10

4. Investigate specific component:

agent-react-devtools profile report @c8

Automated Testing/Monitoring

Script example for CI or monitoring:

#!/bin/bash
agent-react-devtools start
agent-react-devtools wait --connected --timeout 30 || exit 1

# Check for components with errors
if agent-react-devtools errors | grep -q "@c"; then
  echo "Components have errors!"
  agent-react-devtools errors
  exit 1
fi

# Profile a workflow
agent-react-devtools profile start "ci-test"
# ... trigger app interactions ...
agent-react-devtools profile stop
agent-react-devtools profile export ci-results.json

# Check for slow components
SLOW_COUNT=$(agent-react-devtools profile slow --limit 5 | grep -c "avg:")
if [ "$SLOW_COUNT" -gt 3 ]; then
  echo "Too many slow components detected"
  agent-react-devtools profile slow
  exit 1
fi

Using with agent-browser

When combining with agent-browser for automated interactions:

# IMPORTANT: Must use --headed mode
agent-browser --session devtools --headed open http://localhost:5173/
agent-react-devtools status  # Verify connection
agent-react-devtools profile start
# ... agent-browser interactions ...
agent-react-devtools profile stop
agent-react-devtools profile slow

Note: Headless mode does NOT work - the DevTools connection requires a headed browser.

Configuration

Environment Variables

• REACT_DEVTOOLS_PORT - Custom port for React Native apps

Default Port

The daemon uses port 8097 by default. Override with:

agent-react-devtools start --port 9000

Then configure your app connection to match.

Troubleshooting

App Not Connecting

Check daemon status:

agent-react-devtools status

Verify app is in development mode:

• The connection only works in dev builds, not production

Check console for connection errors:

• Look for WebSocket connection messages in browser console

Restart daemon:

agent-react-devtools stop
agent-react-devtools start

"No apps connected" After Init

Verify import order:

• The connect import must be the first import in your entry file

Check Vite plugin order:

• reactDevtools() must come before react() in plugins array

Verify dev server is running:

• The app must be actively running, not just built

Empty Component Tree

Remove host component filtering:

agent-react-devtools get tree --all

Check if app rendered:

agent-react-devtools count

Profile Commands Return No Data

Ensure you stopped profiling:

agent-react-devtools profile stop

Data is only collected after stopping the profile session.

Timeout Waiting for Connection

Increase timeout:

agent-react-devtools wait --connected --timeout 60

Check if port is blocked:

lsof -i :8097

Output Format Notes

• Component IDs (@c1, @c2) are persistent within a daemon session
• Error annotations: ⚠ for warnings, ✗ for errors
• Function indicators: ƒ marks function props/callbacks
• Tree symbols: ├─ for middle children, └─ for last child
• Collapsed indicators: ... +N more when output is truncated

Integration with AI Assistants

Add to your project's AGENTS.md or .cursorrules:

## React Component Inspection

Use `agent-react-devtools` to inspect the running React app:

1. Start daemon: `agent-react-devtools start`
2. Check connection: `agent-react-devtools status`
3. Browse tree: `agent-react-devtools get tree --depth 3`
4. Inspect component: `agent-react-devtools get component @cN`
5. Profile performance: `agent-react-devtools profile start` → interact → `profile stop` → `profile slow`

Always check `status` before other commands to ensure app is connected.

License

MIT