fullscreen_transcript unexpectedly controls whether diffs are truncated #49167

Codex’s terminal UI showed only three lines of a 22-line patch, requiring a mouse click on “Show details” to reveal the changes.

Setting fullscreen_transcript = false under [tui] restored full colored diffs automatically. I tested this and confirmed it works.

This is an unexpected connection. The setting’s name suggests fullscreen behavior, and its description mentions scrolling, selection, and search. Neither explains that it also controls whether changesets are displayed fully or collapsed.

Reproduction

1. Enable tui.fullscreen_transcript and launch Codex.
2. Make a change containing more than three diff lines.
3. Observe the collapsed diff.
4. Set tui.fullscreen_transcript = false and relaunch.
5. Observe that patches now display their full diffs.

Expected: Fullscreen layout and diff expansion should be independently configurable. There should be an explicit, persistent option to always display complete changesets. The current interaction should also be documented.

Environment: Linux, GNOME Terminal, Wayland.