Errors, Stale Results, and Shutdown

Errors become editor-visible state

Job futures return anyhow::Result. A failed ordinary spawned job is reported through the event/status system; a failed waited job becomes Async job failed in the editor or propagates during final draining. The application loop remains alive because one optional feature failed.

Versioning separates completion from validity

Documents increment an LSP version on each real change. Async commands commonly capture a document ID, version, selection, or rope snapshot. Their callbacks must re-find the document and decide whether a result still applies. Completion only means “the service answered”; it does not prove the answer describes the current buffer.

Redraw pressure is coalesced

request_redraw wakes the editor, but wait_event schedules a redraw timer rather than rendering once for every producer notification. This converts a potential event storm into a bounded frame rate while still allowing urgent foreground event handling.

Shutdown distinguishes protocol courtesy from process control

close_language_servers enqueues shutdown and exit for every server, then waits only until those bytes are flushed to each server’s stdin. The wait has a timeout. It does not wait indefinitely for an external process to behave; process handles are configured to be reaped when dropped.

Jobs opt into wait_before_exiting. Final drain executes their callbacks when the necessary mutable references still exist and can enqueue follow-up waited jobs. Clean exit is therefore an explicit transitive obligation, not “sleep a little and hope.”