Bug: DevTools DOM lookup cannot find React-managed title, meta and non-resource link elements

Inizia in packages/react-devtools-facade/src/DevToolsFacadeTreeTools.js, concentrandoti su getHostInstanceForFiber e sul percorso di ricerca HostHoistable. Esegui l'entry point ufficiale dei test di build di DevTools e verifica che gli elementi title, meta e link non associati a risorse vengano risolti tramite la ricerca nel DOM, mentre il controllo associato a una risorsa continui a superare il test.

Summary

getComponentByHostInstance reports that a React-managed metadata element is not managed by React. The same element is present and inspectable by UID in getComponentTree, so DOM-based and UID-based inspection disagree.

Affected version

Current react/react main: 019019be403c3269e15b8d7ebefb57d30f84086b (React source version 19.3.0). The source includes react-devtools-cdt-mcp 0.1.0; this report is verified against the source baseline.

Steps To Reproduce

// Install the facade before initializing React (as documented).
const facade = installFacade();
const tools = createTools(facade);
act(() => root.render(<meta name="facade-test" content="value" />));
const element = document.head.querySelector('meta[name="facade-test"]');
console.log(tools.getComponentByHostInstance(element));
// {error: 'Host instance is not managed by React'}

A runnable repository regression test is included in the linked fix PR.

The current behavior

Lookup fails for title/meta and non-resource link instances. Resource-backed style elements follow a different storage path and can be found.

The expected behavior

A React-managed hoistable DOM element should resolve to its host component, with the same UID and props returned by component-tree inspection.

Root cause and impact

getHostInstanceForFiber handles HostHoistable only through memoizedState.instance. Non-resource hoistables have null memoizedState and store their DOM instance in stateNode (see the HostHoistable commit path).

Source: packages/react-devtools-facade/src/DevToolsFacadeTreeTools.js.

Severity assessment: Medium. getComponentByHostInstance reports that a React-managed metadata element is not managed by React. The same element is present and inspectable by UID in getComponentTree, so DOM-based and UID-based inspection disagree.

Verification

Before: the non-resource hoistable regression fails and the resource-backed control passes through the official DevTools build test entry. After: DevToolsFacade and DevToolsCdtMcp pass 132/132 tests. Prettier, ESLint and Flow pass.

Duplicate check

Searched all Issue/PR states for getHostInstanceForFiber, facade meta and hoistable DevTools. #36820 introduced this lookup; #30584/#30590 and #35741 concern the separate full DevTools renderer backend and its node mapping/lifecycle. No equivalent facade fallback was found.

Compatibility and risks

The resource-record lookup keeps its existing priority. The fallback matches the reconciler stateNode storage for non-resource hoistables. This changes inspection only, not rendering or resource lifetime.