hold_open (d21baa2) kept each connection open for up to two seconds after its final frame, reading and dropping anything the peer sent, to hide a test client that set a read timeout after the handler had closed. On macOS that call fails with EINVAL; the clients now allow for it (00a85c1,d7009dc), so the handler goes back to closing at once. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>