[Marve10s]

Summary:

AbortSignal.any() currently connects its inputs through public abort listeners. An earlier listener can stop event propagation and leave the combined signal active after its source is cancelled. It can also observe stale cancellation state, or trigger a second source that incorrectly replaces the first abort reason.

Track dependent signals internally and mark all of them aborted before dispatching the source's event. Dispatch the dependent events afterward, in registration order. Flattening nested combinations preserves the same ordering through chains; weak source references and cleanup avoid retaining inputs after cancellation.

This follows the DOM signal-abort algorithm. The failures reproduce headlessly on React Native 0.88.0 and current main.

const first = new AbortController();
const second = new AbortController();
first.signal.addEventListener('abort', () => second.abort('second'));
const combined = AbortSignal.any([first.signal, second.signal]);
first.abort('first');
console.log(combined.reason);

Before: second. After: first, matching native behavior.

Changelog:

[GENERAL] [FIXED] - Preserve AbortSignal.any() cancellation state and the first abort reason before source abort listeners run.

Test Plan:

From the repository root:

./node_modules/.bin/jest --runInBand --watchman=false --runTestsByPath packages/react-native/src/private/webapis/dom/abort-api/__tests__/AbortSignal-any-test.js

All four tests pass. Running these tests against the unchanged main implementation fails all four assertions: propagation suppression, state during the source event, nested event order, and the reentrant first reason.

./node_modules/.bin/eslint --max-warnings 0 packages/react-native/src/private/webapis/dom/abort-api/AbortSignal.js packages/react-native/src/private/webapis/dom/abort-api/__tests__/AbortSignal-any-test.js packages/react-native/src/private/webapis/dom/abort-api/__tests__/AbortController-itest.js
./node_modules/.bin/prettier --check packages/react-native/src/private/webapis/dom/abort-api/AbortSignal.js packages/react-native/src/private/webapis/dom/abort-api/__tests__/AbortSignal-any-test.js packages/react-native/src/private/webapis/dom/abort-api/__tests__/AbortController-itest.js
npx --yes --package=flow-bin@0.337.0 flow focus-check --max-workers 2 packages/react-native/src/private/webapis/dom/abort-api/AbortSignal.js packages/react-native/src/private/webapis/dom/abort-api/__tests__/AbortSignal-any-test.js

ESLint, formatting, and focused Flow checking pass. Additional headless probes of the real runtime passed with native event dispatch enabled and disabled, including nested combinations, duplicate inputs, validation failures, and reference cleanup.

The existing Fantom any() test now runs inside Fantom.runTask because Fantom requires WeakRef construction and dereferencing inside its event loop. Fantom, native builds, the full Jest suite, and full-repository Flow checking were not run.