A retired language-server instance could still act after a replacement started: its close or failed startup published Down (a false "restart failed"), and stop/supervisor cleanup cleared the replacement's diagnostics and progress. Retirement now commits state, status, phase and cleanup together for its own generation, with event callbacks ordered outside state locks, and ordinary diagnostics and task events go through the same retirement queue. Verified on macOS with failing-before/passing-after tests and repeated real-server restarts.
Co-authored-by: arnaud-ritti <[email protected]>