[mcollina]

Summary

A tasks/result request whose client had already disconnected left an entry in TaskWaiters that was never removed. handleTasksResult aborts its controller before waiting when the response is already destroyed. TaskWaiters.wait then still registered the waiter and attached an abort listener to a signal that had already fired, so the listener never ran. Only a local notify() could remove the entry, and that never happens for a task that finishes on another instance or expires. A caller with one long-running task could grow server memory this way.

Fix

• TaskWaiters.wait (src/stores/task-store.ts): when signal.aborted is already true, it rejects at once and registers nothing. It also removes its abort listener when a notify() resolves it, so a long-lived signal does not keep listeners from settled waits.
• awaitTaskTerminal (src/handlers.ts): calls signal.throwIfAborted() before waiting, so a client that is already gone causes no waiter, poll or store read. The existing catch in handleTasksResult returns the usual "Client disconnected" or "Server shutting down" error.

Both changes are needed. The first makes TaskWaiters safe for every caller. The second makes the handler skip the wait for a client that is already gone.

Tests (test/tasks-result-lifecycle.test.ts)

• Unit: wait() with an already-aborted signal rejects and leaves the waiter map empty. Before the fix it never settled and left one entry. Another unit test checks that an abort after registration still removes the entry.
• Integration, memory and Redis: the store's get is patched to destroy the server-side socket right after handleTasksResult reads the task, which reproduces the window where the response is already destroyed. The test then checks that no waiter is left while the task is still running. It failed before the fix with 1 waiter left on each backend.
• npm run lint, npm run typecheck and the full npm run test all pass (770/770).

Fixes #333

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https://claude.ai/code/session_01LmhsFjk8W96X2PvmShmDm9