Fixes silent data loss in the TUI when /undo, /compress, /retry, or
rollback.restore runs during an in-flight agent turn. The version-
guard at prompt.submit:1449 would fail the version check and silently
skip writing the agent's result — UI showed the assistant reply but
DB / backend history never received it, causing UI↔backend desync
that persisted across session resume.
Changes (tui_gateway/server.py):
- session.undo, session.compress, /retry, rollback.restore (full-history
only — file-scoped rollbacks still allowed): reject with 4009 when
session.running is True. Users can /interrupt first.
- prompt.submit: on history_version mismatch (defensive backstop),
attach a 'warning' field to message.complete and log to stderr
instead of silently dropping the agent's output. The UI can surface
the warning to the user; the operator can spot it in logs.
Tests (tests/test_tui_gateway_server.py): 6 new cases.
- test_session_undo_rejects_while_running
- test_session_undo_allowed_when_idle (regression guard)
- test_session_compress_rejects_while_running
- test_rollback_restore_rejects_full_history_while_running
- test_prompt_submit_history_version_mismatch_surfaces_warning
- test_prompt_submit_history_version_match_persists_normally (regression)
Validated: against unpatched server.py the three 'rejects_while_running'
tests fail and the version-mismatch test fails (no 'warning' field).
With the fix, all 6 pass, all 33 tests in the file pass, 74 TUI tests
in total pass. Live E2E against the live Python environment confirmed
all 5 patches present and guards enforce 4009 exactly as designed.
bf5d7462ba