Codex Desktop: newly composed message disappears after submission

Codex Desktop 26.908.40834 (8881); macOS 26.5.2 (25F84), arm64.

Observed

A long new message, typed directly in the composer of an existing thread, disappeared after submission. No existing message was edited. The assistant continued without the new instruction; Undo did not restore it.

Unexpected desktop log sequence:

2026-09-13T23:02:28.639Z method=thread/revert errorCode=null
2026-09-13T23:02:28.791Z method=turn/start errorCode=null

Investigation lead (unconfirmed)

Why a new-message submission coincided with thread/revert is unknown. Static inspection found that the separate edit handler discards replacement text when the original params.input contains no text item; its draft is cleared after submission resolves. Whether that handler was involved in this incident is unconfirmed. No end-to-end reproduction.

Expected

Submit the new message without reverting existing history. On failure, retain the draft and display an error. Preserve a recoverable copy until message persistence is confirmed.

Start by tracing the new-message submission alongside the logged thread/revert and turn/start calls, then inspect the separate edit handler and its handling of params.input with no text item. Done means a new message does not revert existing history, failed submission retains the draft and shows an error, and a recoverable copy remains until persistence is confirmed.