[BUG] AskUserQuestion preview: 'n'+Enter drops highlighted option, ships only the note

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report
• [x] I am using the latest version of Claude Code

What's Wrong?

When AskUserQuestion is invoked with at least one option whose preview field is set, the UI switches to side-by-side layout (option list on the left, preview pane on the right) and exposes an "add note" affordance on every option (the n keybinding). Pressing n on a highlighted option opens note-editing mode. Typing a note and pressing Enter once submits the entire response as (no option selected) notes: <text>.

The typed note text is preserved, but the highlighted option — and with it the binding indicating which option the note belongs to — is dropped.

Plain AskUserQuestion invocations (where no option has a preview field) are not affected.

What Should Happen?

The flow should be a clean two-step interaction:

1. Arrow to highlight an option.
2. Press n → note-editing mode opens.
3. Type the note.
4. Press Enter → exits note mode; the note is saved bound to the highlighted option; the user is returned to option-navigation mode and can still arrow to change selection or revise notes on other options.
5. Press Enter again (option highlighted, not in note mode) → submits the response: <highlighted option> + note.

Current behavior collapses steps 4 and 5 into a single Enter that submits with the option dropped.

Error Messages/Logs

(no option selected) notes: Press `n`, typed these, then hitting `Enter` once..

Steps to Reproduce

1. Trigger an AskUserQuestion with 2–4 single-select options, at least one of which has a preview field set (the side-by-side layout kicks in for the whole question as soon as any one option has a preview).
2. Arrow to highlight any option.
3. Press n → type any text → Enter.
4. Observe the response payload: (no option selected) notes: <text> — the highlighted option is dropped and only the note survives.

Originally reproduced 4× on 2.1.121 in both default and fullscreen TUI renderers (/tui default and /tui fullscreen). Re-confirmed live on 2.1.156 and again on 2.1.167.

Claude Model

Opus — Claude Opus 4.8 (claude-opus-4-8, 1M context)

Is this a regression?

Yes, this worked in a previous version.

Last Working Version

Around 2.1.119 or earlier (exact build uncertain).

Claude Code Version

2.1.167 (Claude Code)

Platform

Anthropic API

Operating System

macOS 26.3.1 (Darwin 25.3.0, arm64)

Terminal/Shell

VS Code integrated terminal (1.122.1), zsh

Additional Information

Cross-reference anthropics/claude-code#57005 (the feature request for the proper Tab/Space-to-comment-on-selected-option flow). This bug is about the existing n affordance becoming incoherent on preview-enabled questions, not the missing feature.