Flaky: server/file-pool.test.ts hangs CI Fast checks when its readGate thread is ended before it opens the FIFO #2296

server/file-pool.test.ts hung in CI's Fast checks on run 40779586477 (#2293 @414ae278, a PR that does not touch it): the only one of 535 unit files that never reported; last output 22:28:20 UTC, job cancelled at its 10-minute limit at 22:35:38.

Cause

The test "keeps a descriptor its thread is reading open until that thread is gone, when the last server stops" holds its file thread with the fake worker's readGate (server/file-worker.fake.ts). That gate says the thread is reading (Atomics.notify on cell 1) before it opens the FIFO for reading, a blocking open(2). The test then ends the thread (release()) and opens the FIFO's writer with a blocking openSync(fifo, "w") on the test's main thread. A thread ended between the notify and its own open never opens the reader, so the writer's open waits forever, and Bun's per-test timeout cannot fire while the main thread is blocked in a system call. #2265's PR body already named this gap as a candidate flake.

Reproduction

A 500 ms Atomics.wait added in the fake's readGate between the notify and the FIFO open (scratch, not committed) on main 72f2edf: timeout 30 bun test server/file-pool.test.ts is killed at 30 s (exit 124), stopped in that test.

Product code (server/file-pool.ts) is not affected: the server's thread never waits on a file thread (it posts, terminates without awaiting, and closes descriptors).