AskUserQuestion: built-in "Other" free-text input not rendered when options have preview fields

Environment

• Claude Code v2.1.217, Windows 11 Pro (10.0.26200), terminal CLI (Git Bash / Windows Terminal)

Bug

The AskUserQuestion tool description states:

Users will always be able to select "Other" to provide custom text input

This does not hold when any option carries a preview field. With previews, the UI switches to the side-by-side layout (option list left, preview pane right) — and in that layout the built-in "Other" free-text input is not rendered. The user can only pick one of the model-supplied options; there is no way to type a custom answer.

Reproduction (A/B verified in a single session)

1. Model calls AskUserQuestion with 2 options, each carrying a preview field → side-by-side layout renders, no "Other" inputbox.
2. Same question re-asked immediately with identical options minus the preview fields → stacked layout renders, "Other" inputbox present.

Only variable changed between the two calls was the presence of preview.

Impact

The tool description actively encourages models to attach previews ("ASCII mockups of UI layouts", "code snippets showing different implementations"), so models add them unprompted on exactly the kinds of design/plan questions where a custom typed answer is most likely needed. Result: users silently lose the free-text escape hatch on the questions that most need it.

Expected

The "Other" free-text input renders in the preview (side-by-side) layout too, matching the tool description.