agent-react-devtools

CLI that connects to a running React or React Native app via the React DevTools protocol and exposes the component tree, props, state, hooks, and profiling data in a token-efficient format.

Core Workflow

• Ensure connection — check agent-react-devtools status . If the daemon is not running, start it with agent-react-devtools start . Use agent-react-devtools wait --connected to block until a React app connects.

• Inspect — get the component tree, search for components, inspect props/state/hooks.

• Profile — start profiling, trigger the interaction (or ask the user to), stop profiling, analyze results.

• Act — use the data to fix the bug, optimize performance, or explain what's happening.

Essential Commands

Daemon

agent-react-devtools start # Start daemon (auto-starts on first command) agent-react-devtools stop # Stop daemon agent-react-devtools status # Check connection, component count, last event agent-react-devtools wait --connected # Block until a React app connects agent-react-devtools wait --component App # Block until a component appears

Component Inspection

agent-react-devtools get tree # Full component hierarchy (labels: @c1, @c2, ...) agent-react-devtools get tree --depth 3 # Limit depth agent-react-devtools get component @c5 # Props, state, hooks for a specific component agent-react-devtools find Button # Search by display name (fuzzy) agent-react-devtools find Button --exact # Exact match agent-react-devtools count # Count by type: fn, cls, host, memo, ... agent-react-devtools errors # List components with errors or warnings

Performance Profiling

agent-react-devtools profile start # Start recording agent-react-devtools profile stop # Stop and collect data agent-react-devtools profile slow # Slowest components by avg render time agent-react-devtools profile slow --limit 10 # Top 10 agent-react-devtools profile rerenders # Most re-rendered components agent-react-devtools profile report @c5 # Detailed report for one component agent-react-devtools profile timeline --limit 10 # First 10 commits (use --limit; uncapped can dump 300+ lines) agent-react-devtools profile timeline --limit 10 --offset 10 # Next 10 (pagination) agent-react-devtools profile timeline --sort duration --limit 5 # Top 5 most expensive commits agent-react-devtools profile timeline --sort timeline --limit 5 # Explicit chronological order (same as default) agent-react-devtools profile commit 3 # Detail for commit #3 agent-react-devtools profile export profile.json # Export as React DevTools Profiler JSON agent-react-devtools profile diff before.json after.json # Compare two exports

Understanding the Output

Component Labels

Every component gets a stable label like @c1 , @c2 . Use these to reference components in follow-up commands:

@c1 [fn] App ├─ @c2 [fn] Header ├─ @c3 [fn] TodoList │ ├─ @c4 [fn] TodoItem key=1 │ └─ @c5 [fn] TodoItem key=2 └─ @c6 [host] div

Type abbreviations: fn = function, cls = class, host = DOM element, memo = React.memo, fRef = forwardRef, susp = Suspense, ctx = context.

Components with errors or warnings show annotations: ⚠2 = 2 warnings, ✗1 = 1 error. Use agent-react-devtools errors to list only affected components.

Inspected Component

@c3 [fn] TodoList props: items: [{"id":1,"text":"Buy milk"},{"id":2,"text":"Walk dog"}] onDelete: ƒ state: filter: "all" hooks: useState: "all" useMemo: [...] useCallback: ƒ

ƒ = function value. Values over 60 chars are truncated.

Profiling Output

Slowest (by avg render time): @c3 [fn] ExpensiveList avg:12.3ms max:18.1ms renders:47 causes:props-changed changed: props: items, filter @c4 [fn] TodoItem avg:2.1ms max:5.0ms renders:94 causes:parent-rendered, props-changed changed: props: onToggle

Render causes: props-changed , state-changed , hooks-changed , parent-rendered , force-update , first-mount .

When specific changed keys are available, a changed: suffix shows exactly which props, state keys, or hooks triggered the render (e.g. changed: props: onClick, className state: count hooks: #0 ).

Common Patterns

Wait for the app to connect after a reload

agent-react-devtools wait --connected --timeout 10 agent-react-devtools get tree

Use this after triggering a page reload or HMR update to avoid querying empty state.

Diagnose slow interactions

agent-react-devtools profile start

User interacts with the app (or use agent-browser to drive the UI)

agent-react-devtools profile stop agent-react-devtools profile slow --limit 5 agent-react-devtools profile rerenders --limit 5

Then inspect the worst offenders with get component @cN and profile report @cN .

Browse a long timeline in chunks

agent-react-devtools profile timeline --limit 20 # commits 0–19 agent-react-devtools profile timeline --limit 20 --offset 20 # commits 20–39 agent-react-devtools profile timeline --offset 30 --limit 10 # skip warm-up, show 30–39

Use profile commit <N> to drill into a specific commit once you spot a spike.

Find a component and check its state

agent-react-devtools find SearchBar agent-react-devtools get component @c12

Verify a fix worked

agent-react-devtools profile start

Repeat the interaction

agent-react-devtools profile stop agent-react-devtools profile slow --limit 5

Compare render counts and durations to the previous run

Using with agent-browser

When using agent-browser to drive the app while profiling or debugging, you must use headed mode (--headed ). Headless Chromium does not execute ES module scripts the same way as a real browser, which prevents the devtools connect script from running properly.

agent-browser --session devtools --headed open http://localhost:5173/ agent-react-devtools status # Should show 1 connected app

Important Rules

• Labels reset when the app reloads or components unmount/remount. After a reload, use wait --connected then re-check with get tree or find .

• status first — if status shows 0 connected apps, the React app is not connected. The user may need to run npx agent-react-devtools init in their project first.

• Headed browser required — if using agent-browser , always use --headed mode. Headless Chromium does not properly load the devtools connect script.

• Profile while interacting — profiling only captures renders that happen between profile start and profile stop . Make sure the relevant interaction happens during that window.

• Use --depth on large trees — a deep tree can produce a lot of output. Start with --depth 3 or --depth 4 and go deeper only on the subtree you care about.

References

File When to read

commands.md Full command reference with all flags and edge cases

profiling-guide.md Step-by-step profiling workflows and interpreting results

setup.md How to connect different frameworks (Vite, Next.js, Expo, CRA)