fix(workers-ai-provider): honor abort signals for binding streams

[mikemikimike]

Related issue

Fixes #640

Background

Workers AI binding streams can stall while a ReadableStreamDefaultReader.read() is pending. The provider forwarded the AI SDK abort signal to binding.run, but the stream-mapping pipeline did not observe it, so SDK timeouts and caller aborts could hang forever.

Changes

• Race pending binding stream reads against the abort signal before SSE decoding.
• Preserve signal.reason so TimeoutError and AbortError semantics remain intact.
• Cancel the underlying reader when aborted and add a regression test for a stalled stream.
• Added a patch changeset for workers-ai-provider.

Compatibility

Only binding-backed streaming responses are affected. Responses without an abort signal retain the existing behavior; normal stream completion and downstream cancellation remain supported.

Verification

• git diff --check — passed.
• pnpm install --frozen-lockfile — attempted, but npm registry downloads were too slow and the dependency installation did not complete.
• Focused Vitest, type-check, and build — not run because installation did not finish and vitest was unavailable.

[changeset-bot]

🦋 Changeset detected

Latest commit: 80b6b46

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

This PR includes changesets to release 1 package

Name	Type
workers-ai-provider	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