[huntie]

Summary

Add a "Suspense ⚛" panel which renders the React DevTools Suspense tab: Suspense boundaries as a minimap and reveal timeline, plus what each boundary suspended on.

Notes

• The minimap and timeline place a boundary by the rects of its host nodes. On React Native, the backend can only measure a host node once its public instance exists, such as after a ref attaches, so a boundary around plain <View> and <Text> content is left out. The tree and the inspector are unaffected; the fix belongs in the React DevTools backend.

Test Plan

Repeat all verification from #289, then:

A temporary RNTester Playground screen, not part of this PR, nests named Suspense boundaries that resolve after 0.5 s, 2 s, 3.5 s (a React.lazy component) and 4.5 s, plus one that never resolves. Each card has a ref, per the note above.

iPhone 18 Pro: loading

iPhone 18 Pro: resolved	Suspense panel	Boundary selected
Temporary Suspense demo in Playground tab

✅ Suspense ⚛ appears after Profiler ⚛ and opens directly with panel=react-devtools-suspense.
✅ The boundary map and reveal timeline show Page, Feed, Comments and Sidebar in reveal order; the Ads boundary stays suspended.
✅ Selecting Comments shows it suspended on lazy, with its props and owner stack.

Test screen

function SuspenseDemo(): React.Node {
  return (
    <Suspense name="Page" fallback={<Fallback title="Page" />}>
      <DataCard title="Header" color="#bfdbfe" delay={500} />
      <Suspense name="Feed" fallback={<Fallback title="Feed" />}>
        <DataCard title="Feed" color="#bbf7d0" delay={2000} />
        <Suspense name="Comments" fallback={<Fallback title="Comments" />}>
          <LazyComments />
        </Suspense>
      </Suspense>
      <Suspense name="Sidebar" fallback={<Fallback title="Sidebar" />}>
        <DataCard title="Sidebar" color="#fbcfe8" delay={4500} />
      </Suspense>
      <Suspense name="Ads" fallback={<Fallback title="Ads (never loads)" />}>
        <DataCard title="Ads" color="#e5e7eb" delay={1e9} />
      </Suspense>
    </Suspense>
  );
}

[vzaidman]

the fix belongs in the React DevTools backend?

Could you elaborate? Who works on that? Is it worth shipping if that's the case?