Feature: keep the transcript in main-screen scrollback after exit while staying in fullscreen TUI

Environment

• Claude Code: 2.1.246
• macOS (Darwin 25.6.0), zsh
• ~/.claude/settings.json: "tui": "fullscreen"

Request

I want to keep the fullscreen renderer during the session, but not have the terminal wiped when the session ends. Today, exiting via /exit restores the primary screen and the whole conversation disappears from the terminal — there is nothing left to skim, copy, or Cmd+F after the fact.

The two documented options are all-or-nothing:

• "tui": "fullscreen": nice in-session UI, transcript gone on exit
• "tui": "classic": transcript stays in scrollback, but gives up fullscreen entirely

What's missing is the middle ground: on teardown, before/after leaving the alternate screen buffer, emit the rendered conversation to the main screen so it lands in native scrollback. This is the normal expectation for a long-lived REPL-ish tool, and it's how Claude Code behaved before the alt-screen switch.

Suggested shape

Any of these would solve it:

• don't wipe out the screen by default, or
• a setting like "tuiPreserveScrollbackOnExit": true (or a third tui mode)

Rendering could reuse whatever transcript mode (Ctrl+O) already produces.

Relation to existing issues

#42670 covered in-session scrollback loss and was closed once CLAUDE_CODE_DISABLE_ALTERNATE_SCREEN / the tui setting landed. That fix works only by leaving fullscreen, so it doesn't address this case. A comment on that issue asked for the same thing — "a third mode that does alt-screen rendering but still emits lines to main-screen scrollback" — but it was never split out into its own request. Filing that here.