fix: claim late-streamed fragments in chained async memos during hydration

[brenelz]

Summary

Fixes an intermittent hydration error that occurs with chained async memos inside a <Loading> boundary under renderToStream:

Hydration completed with 1 unclaimed server-rendered node(s):
  <div _hk="3300000">item 1</div>

Root cause

When a chained async memo (e.g. b = createMemo(() => fetchItems(m())) where m reads a pending async memo a) recomputes after the shell finishes hydrating (sharedConfig.hydrating flips to false) but before the <Loading> boundary's fragment resume fires, readSerializedOrCompute would re-run the compute function (fetchItems(...)) instead of subscribing to the server's serialized deferred Promise.

The new client-side Promise resolves after the boundary's resume window closes, so the <For> renders with hydrating=false and creates a fresh node — orphaning the server fragment that \$df swaps in.

Reproduction:

function Home() {
  const a = createMemo(async () => {
    await sleep(1000);
    return [1];
  });
  const m = createMemo(() => a()[0]);
  const b = createMemo(() => fetchItems(m()));

  return (
    <Loading fallback={<div>loading</div>}>
      <For each={b()}>{(x) => <div>{x}</div>}</For>
    </Loading>
  );
}

Fix

In readSerializedOrCompute (packages/solid/src/client/hydration.ts), track owners whose serialized value has been consumed via a WeakSet. When hydrating is false but the owner's serialized key has not been consumed yet, still read it so the memo subscribes to the server's deferred Promise via handleAsync. The serialized value is only used once; subsequent recomputes (e.g. user interactions) use compute(prev) normally.

Test

Adds packages/solid-web/test/hydration/loading-late-fragment.spec.tsx which reproduces the streaming scenario (shell → hydrate → mid chunk resolves a → late chunk swaps fragment + resolves 3_fr) and asserts:

• only one <div> is present (no orphan)
• no unclaimed server-rendered node warning fires

All existing tests pass:

• solid-web hydration suite: 18 passed
• solid-web server suite: 86 passed
• solid-web main suite: 298 passed
• solid-signals: 751 passed

[changeset-bot]

🦋 Changeset detected

Latest commit: fd8fceb

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 9 packages

Name	Type
solid-js	Patch
@solidjs/element	Patch
@solidjs/h	Patch
@solidjs/html	Patch
@solidjs/universal	Patch
@solidjs/web	Patch
test-integration	Patch
babel-preset-solid	Patch
@solidjs/signals	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[codspeed-hq]

Merging this PR will not alter performance

✅ 118 untouched benchmarks

---

_{Comparing brenelz:fix/loading-late-fragment-hydration (fd8fceb) with next (c943c5c)}