Add support for Bun server renderer

Add support for Bun server renderer

Summary:
Three problems popped up during the sync:
- react/react@07f46ecf2 breaks breaks tests
- react/react@6fb8133ed breaks fbsource tests. I added a workaround and created a test for the team that owns the test.
- https://fb.workplace.com/groups/flowlang/permalink/1198137807458547/ enables local type interference in fbsource but not in github React repo and some code breaks. Addressed in react/react#26064

This sync includes the following changes:
- **[17f6912](react/react@17f6912a4 )**: Add flow types to ReactFiberHooks ([#25752](react/react#25752)) //<Samuel Susla>//
- **[f101c2d](react/react@f101c2d0d )**: Remove Reconciler fork (2/2) ([#25775](react/react#25775)) //<Jan Kassens>//
- **[420f0b7](react/react@420f0b7fa )**: Remove Reconciler fork (1/2) ([#25774](react/react#25774)) //<Jan Kassens>//
- **[3ba7add](react/react@3ba7add60 )**: Allow async blocks in `to(Error|Warn)Dev` ([#25338](react/react#25338)) //<Sebastian Silbermann>//
- **[fa11bd6](react/react@fa11bd6ec )**: [ServerRenderer] Add option to send instructions as data attributes ([#25437](react/react#25437)) //<mofeiZ>//
- **[e982254](react/react@e98225485 )**: Add ref cleanup function ([#25686](react/react#25686)) //<Samuel Susla>//
- **[15557fa](react/react@15557fa67 )**: [Fix] properly track `useId` use in StrictMode in development ([#25713](react/react#25713)) //<Josh Story>//
- **[8a23def](react/react@8a23def32 )**: Resubmit Add HydrationSyncLane ([#25711](react/react#25711)) //<Tianyu Yao>//
- **[2655c93](react/react@2655c9354 )**: Fizz Browser: fix precomputed chunk being cleared on Node 18 ([#25645](react/react#25645)) //<Jimmy Lai>//
- **[c08d8b8](react/react@c08d8b804 )**: Revert "Add SyncHydrationLane" ([#25708](react/react#25708)) //<Tianyu Yao>//
- **[56ffca8](react/react@56ffca8b9 )**: Add Bun streaming server renderer ([#25597](react/react#25597)) //<Colin McDonnell>//
- **[f31005d](react/react@f31005d6a )**: Add SyncHydrationLane ([#25698](react/react#25698)) //<Tianyu Yao>//
- **[f284d9f](react/react@f284d9faf )**: Track ThenableState alongside other hooks //<Andrew Clark>//
- **[6b4c031](react/react@6b4c0314e )**: Check thenable instead of thenableState //<Andrew Clark>//
- **[33e3d28](react/react@33e3d2878 )**: Reuse hooks when replaying a suspended component //<Andrew Clark>//
- **[4387d75](react/react@4387d752d )**: Allow more hooks to be added when replaying mount //<Andrew Clark>//
- **[5eb78d0](react/react@5eb78d0a0 )**: Pass ThenableState to replaySuspendedUnitOfWork //<Andrew Clark>//
- **[4a2d86b](react/react@4a2d86bdd )**: Don't reset work loop until stack is unwound //<Andrew Clark>//
- **[9dfbd9f](react/react@9dfbd9fa9 )**: use: Don't suspend if there are pending updates //<Andrew Clark>//
- **[44c4e6f](react/react@44c4e6f4d )**: Force unwind work loop during selective hydration ([#25695](react/react#25695)) //<Andrew Clark>//
- **[7b17f7b](react/react@7b17f7bbf )**: Enable warning for defaultProps on function components for everyone ([#25699](react/react#25699)) //<Sebastian Markbåge>//
- **[6fb8133](react/react@6fb8133ed )**: Turn on string ref deprecation warning for everybody (not codemoddable) ([#25383](react/react#25383)) //<Sebastian Silbermann>//
- **[07f46ec](react/react@07f46ecf2 )**: Turn on key spread warning in jsx-runtime for everyone ([#25697](react/react#25697)) //<Sebastian Markbåge>//
- **[d65b88d](react/react@d65b88d03 )**: Eagerly initialize an mutable object for instance.refs ([#25696](react/react#25696)) //<Sebastian Markbåge>//
- **[c343f80](react/react@c343f8025 )**: [react-float] feature detect getRootNode ([#25689](react/react#25689)) //<Jan Kassens>//
- **[e1dd0a2](react/react@e1dd0a2f5 )**: Remove recoverable error when a sync update flows into a dehydrated boundary ([#25692](react/react#25692)) //<Sebastian Markbåge>//
- **[c54e354](react/react@c54e3541b )**: [DevTools] bug fix for Hydrating fibers ([#25663](react/react#25663)) //<Mengdi Chen>//

Changelog:
[General][Changed] - React Native sync for revisions d1e35c7...17f6912

jest_e2e[run_all_tests]

Reviewed By: makovkastar

Differential Revision: D42804802

fbshipit-source-id: 6a9f00724cc73378025bbd04edb2d17760a87280

… Bun.serve (#32140)

Fixes #32137

### Repro

```ts
Bun.serve({
  port: 3000,
  fetch() {
    const stream = new ReadableStream({
      type: "direct",
      pull(controller) {
        controller.write("SHELL");
        controller.flush();
        setTimeout(() => {       // like React resolving a Suspense boundary
          controller.write("RESOLVED");
          controller.end();
        }, 50);
        // returns undefined synchronously
      },
    });
    return new Response(stream);
  },
});
```

`curl` gets `SHELL` (5 bytes, clean 200) instead of `SHELLRESOLVED`.
With react-dom 19's `renderToReadableStream` (its `server.bun.js` build
uses exactly this shape), the response ends after the shell flush with
the pending marker `<!--$?-->` and the fallback, missing
`</body></html>`, and React logs `error: The render was aborted by the
server without a reason.` because the server cancels the stream
mid-render. Reproduces on 1.0.36 through current main.

### Cause

For a direct `ReadableStream`, `readDirectStream` calls
`underlyingSource.pull(sink)` once and returns `undefined` when pull
returns a non-promise. `Bun.serve`'s `do_render_stream`
(src/runtime/server/RequestContext.rs) then has no way to know the
stream isn't finished: it hits the `"is in progress, but did not return
a Promise. Finalizing request context"` branch, which cancels the stream
(aborting React's render) and finalizes the sink, truncating everything
the producer would have written through the captured controller.

react-dom/server.bun.js depends on the captured-controller pattern:
`pull` writes the shell and returns, then resolved Suspense boundaries
are written later and `end()` is called when the render completes
(react/react#25597, which Bun's SSR guide links).

### Fix

Three pieces, each with its own test:

1. **`readDirectStream`** (src/js/builtins/ReadableStreamInternals.ts):
when `pull()` returns a non-promise and the stream is still readable,
return a promise that settles when the sink closes (`end()`, or abort on
client disconnect). Native consumers already handle a returned promise
through the same pending path async `pull()` uses, so `Bun.serve` keeps
the request context alive and lets the later `end()` complete the
response. Client disconnects still tear the stream down through the
sink's abort path, which invokes the source's `cancel()` (so React
aborts its render on disconnect as before). The async-pull contract
(socket terminates when the promise resolves) and the default-stream
path are unchanged.

2. **`handle_resolve_stream`** (src/runtime/server/RequestContext.rs):
`endFromJS()` can hit transport backpressure right after the HEADERS
frame on QUIC and park a `pending_flush` promise while `onWritable`
drains the remaining bytes. The resolve path destroyed the sink at that
point, discarding the parked bytes and failing the request with
`HTTP3ContentLengthMismatch`. This pre-exists the PR (an `async pull()`
that calls `end()` synchronously fails the same way over h3 on main) and
is the same bug class the undefined-result path already guards (the
`effective_result`/`pending_flush` substitution). Now the resolve path
waits for the parked flush to settle and re-enters.

3. **`detach()`** (src/codegen/generate-jssink.ts): the controller's
detach used `JSC::getCallData` to invoke the stored close callback,
which reports an `AsyncContextFrame` (stream constructed inside
`AsyncLocalStorage.run()`, a common per-request SSR pattern) as not
callable, silently skipping the callback. With the new wait this leaked
the request context, sink, and `ReadableStream` on every request. Route
through `AsyncContextFrame::call` like the generated `onClose` already
does.

### Tests

In `test/js/bun/http/serve-direct-readable-stream.test.ts` (all fail on
the unfixed build; the first two with `This HTTPResponseSink has already
been closed. A "direct" ReadableStream terminates its underlying socket
once 'async pull()' returns.`):

- sync `pull()` that ends later streams the whole body (also asserts the
shell arrives before `end()`, i.e. streaming stays progressive)
- sync `pull()` that writes nothing and ends later still responds
- `cancel()` fires when the client disconnects while waiting for `end()`
- h3: async `pull()` that ends synchronously, and sync `pull()` that
ends from a microtask (fail with `HTTP3ContentLengthMismatch` without
fix 2)
- AsyncLocalStorage variant asserting `heapStats()` ReadableStream
counts stay flat (leaks 20/20 without fix 3)

Also updated:

- `body-stream.test.ts` "Should not crash when not returning a promise
when stream is in progress": `toBeOneOf(["hey", ""])` tightened to
`toBe("hey")` and the timer replaced with condition-driven `end()`, per
review
- `serve-response-stream-sink-leak-fixture.ts`: the fixture relied on
the old truncating fallback (pull never called `end()`, which now means
"keep the response open"); it ends each stream from the client side and
still asserts flat memory over 10k requests (delta 0.0 bytes/request)

Verified the issue's React repro end to end with [email protected]: the
response is the complete 1158-byte document containing
`<span>RESOLVED</span>` and closing `</body></html>`, with no abort
error. Existing suites (`serve.test.ts`, `bun-server.test.ts`,
`body-stream.test.ts` incl. the h3 matrix, `streams.test.js`,
`direct-readable-stream.test.tsx`, spawn stdin ReadableStream suites,
the serve leak tests) show no new failures against the unfixed build.

---------

Co-authored-by: Jarred Sumner <[email protected]>

Add support for Bun server renderer