fix(core): guard Deferred waiter cleanup in vendored effect patch - #41858

What

Extends patches/effect@4.0.0-beta.101.patch with a defensive guard in Deferred's _await cleanup, fixing a production crash:

TypeError: undefined is not an object (evaluating 'X.resumes.indexOf')

The race

Deferred._await registers a waiter and returns a cleanup that unregisters it via self.resumes!.indexOf(resume). Completion (doneUnsafe) resumes every waiter and then sets self.resumes = undefined. When a waiter's interrupt cleanup runs after completion — observed on GET /api/session/:id/question long-polls where a request abort interrupts the awaiting fiber while a concurrent completion lands — the cleanup dereferences undefined and the request 500s.

The invariant argument: a cleanup closure only exists if the deferred was pending at registration (resumes was an array), and the only line in the module that ever makes resumes undefined again is completion. The production TypeError is therefore proof that the complete-then-cleanup order is reachable.

Fix

return internalEffect.sync(() => {
  if (!self.resumes) return;
  const index = self.resumes.indexOf(resume);
  if (index >= 0) self.resumes.splice(index, 1);
});

Applied to both dist/Deferred.js (what runs) and src/Deferred.ts (shipped alongside). The bug is unfixed upstream at 4.0.0-beta.107 head; an upstream fix PR is in flight, but this patch stops the 500s at the next opencode release instead of waiting on an effect release + version bump.

Drive-by repair

While regenerating the patch with bun patch, discovered the existing SSE-identifier hunk for src/unstable/httpapi/HttpApiSchema.ts had wrong line offsets (407 vs the real 430), so bun had been fuzz-applying it mid-overload-signature — leaving syntactically broken TypeScript in the vendored src file. Latent (only dist executes), but this PR regenerates that hunk correctly from pristine + the intended edits. The dist output for the SSE change is unchanged.

Testing

• Fresh bun install --force: patch applies cleanly; resolved effect/Deferred module contains the guard.
• Behavioral smoke: complete-then-interrupt on a waiter exits without throwing.
• Vendored src/unstable/httpapi/HttpApiSchema.ts is now valid TypeScript with the SSE change at the intended location.