react-devtools-facade

Experimental, private package that defines building blocks for querying React runtime state.

The facade installs the __REACT_DEVTOOLS_GLOBAL_HOOK__ that React looks for at initialization time — enabling fiber-root tracking without the overhead of the full DevTools backend — and exposes a small, framework-agnostic library API that integrators compose into tools.

This package is intentionally low-level. It does not install any tool globals and it does not decide how tools are surfaced. It installs the hook, tracks fiber roots, and hands back building blocks; the integrator (for example, a chrome-devtools-mcp integration) decides everything else — including whether to expose anything else on globals.

API

installFacade(target = globalThis): Facade

Installs __REACT_DEVTOOLS_GLOBAL_HOOK__ on target and returns a Facade handle holding the hook plus the runtime state it tracks (fiberRoots, rendererInternals, profilingState). Building blocks read from the returned Facade; they never reach for globals.

Call this before React initializes so the hook captures the first commit:

import {installFacade} from 'react-devtools-facade';

const facade = installFacade();
// ...load React, render your app...

installFacade installs only the DevTools hook. It does not install __REACT_TOOLS__, __REACT_LLM_TOOLS__, or any other global. Once the tool building blocks land, an integrator composes them from the returned Facade and decides whether to expose anything on globals.

Source: packages/react-devtools-facade/README.md