Desktop app: live per-file diff updates during agent runs are gone — changes appear only after the turn completes

What version of the Codex App are you using (From "About Codex" dialog)?

26.810.50856 (macOS). Also affected on 26.810.41047.

What subscription do you have?

Pro

What platform is your computer?

Darwin 27.0.0 arm64

What issue are you seeing?

During an agent run that edits files, the desktop conversation used to show the file changes live: each file being written appeared as its own cell with the diff content updating roughly every half second as the agent worked. Since a recent silent app update this is gone — while the turn is running there are no per-file updates at all. The file-change cells only materialize after the turn completes, showing the end-state diffs.

A few observations that may help narrow it down:

• The official changelog has no entry for the affected builds: its last desktop-app entry is 26.727 (2026-07-30); 26.803 and 26.810 shipped without release notes.
• The app's internal event stream changed across builds: the client still subscribes to a per-file change-delta event, but that event has not fired once in my logs (10+ days), while a new aggregate "turn diff" event only appears in the newest build.
• The client bundle is effectively unchanged between 26.810.41047 and 26.810.50856 (byte-level diff is ~500 bytes); the behavior change sits in the app-server side.

This makes long autonomous runs hard to follow — you can't catch a wrong-file edit mid-run, only after the turn is over.

What steps can reproduce the bug?

1. Open a thread in a Git repository in the Codex desktop app (macOS).
2. Ask the agent to make a multi-file change (e.g., "add a small utility function to three files").
3. Watch the conversation while the turn is running.

Expected earlier behavior: each edited file appears as its own cell while the turn is in progress, with the diff updating live as the agent writes.

Actual behavior: nothing updates until the turn completes, then the "N files edited" card and diffs appear at once.

What is the expected behavior?

While a turn is running, file-change cells should appear and update live as the agent writes each file, so users can follow the work and catch mistakes mid-run.

Additional information

Related existing reports: #31157 (desktop review pane shows empty diffs while the chat card still shows changed files), #5143 (missing diff in summary — sometimes only line counts shown), #35156 (diff not showing — VS Code review pane crash, reportedly fixed in a newer build).

Happy to provide session IDs or log excerpts on request.