Codex App: add a setting to hide or collapse inline diff previews in chat

Inline diff previews turn the conversation into a second code-review surface. For large edits, they can dominate the transcript, separate instructions from results, and make earlier context harder to find—even when the same changes are already being reviewed in an editor, with Git or on a pull request, or in Codex's Review pane. This request is about presentation, not avoiding review: keep the underlying change data available for review, approval, undo, and auditing while allowing chat to show a compact "Changed N files" summary, or nothing until the user chooses to expand it.

_In plain English:_ _I can see the code either via an editor, ide or by reviewing a git diff. I do not need to see the same information in a Codex window, except where approval is required. After the change has been approved, there is no reason to retain the diff/change preview. Retaining already approved diffs makes the conversation hard to follow, especially when working across multiple agent windows simultaniously._

What variant of Codex are you using?

App

What feature would you like to see?

Add a persistent setting that controls how automatic file-change diff cards are displayed in the chat transcript.

Suggested options:

• Expanded
• Collapsed by default
• Hidden, with only a compact summary such as "Changed 3 files" and a button to open Review

This is specifically about inline diff previews in the conversation, not the separate Review/diff pane. The preference should affect presentation only: Codex should retain the underlying file-change data for review, approvals, undo, and auditing.

Expected behavior:

• The preference is available in Settings.
• It persists across chats.
• Hidden mode retains a compact file/count summary and a way to open the changes in Review.
• Approval prompts, conflicts, and error states remain visible regardless of the preference.

Additional information

Automatic diff cards can become very long and dominate the transcript after a substantial edit. They interrupt the conversational flow and make it harder to find earlier instructions, decisions, and results.

This is not a request to avoid reviewing generated code. Many users keep an editor open beside Codex and inspect the resulting files there. They may also review the canonical diff with Git or on a pull request, or use Codex's dedicated Review pane. Repeating the complete diff inline creates another review surface without necessarily improving scrutiny.

The useful separation is:

• Chat for intent, decisions, progress, and results
• Editor, Git/PR, or Review pane for inspecting code changes

Users who prefer inline diffs could keep the current expanded behavior. Users with an established review workflow could choose a compact or hidden presentation without losing access to the changes.

Related issues:

• #25373 concerns a missing per-file expand/collapse control.
• #31103 concerns the file-list state in the separate Review view.

This request is distinct: it asks for a persistent default governing inline diff cards in the chat transcript.