[FEATURE] Configurable max content width for the terminal TUI (re-request of #85860)

Preflight Checklist

• [ ] I have searched existing requests and this feature hasn't been requested yet — searched; prior requests exist but all are closed/locked: #85860 (closed Sep 21 as inactive; closing comment asks for a new issue if still relevant), #28326 (closed as duplicate of #12734), #12734 (closed, locked)
• [x] This is a single feature request (not multiple features)

Problem Statement

Re-requesting #85860, which closed for inactivity, not on the merits — demand is ongoing (see also #28326, #12734).

In a fullscreen terminal on an ultrawide monitor, Claude Code wraps text to the full terminal width, so lines run several hundred characters and I have to turn my head to read a single line. There's no way to get a readable width without shrinking or splitting the terminal.

Proposed Solution

A setting that caps the rendered width, e.g. "maxWidth": 140 in settings.json or a CLAUDE_CODE_MAX_WIDTH env var. At minimum it should cover prose and the input box; exempting code blocks, diffs, and tables (as #85860 proposed) is fine. Optional: center the capped column.

Alternative Solutions

• Split panes / non-fullscreen window: changes my whole layout to fix one app.
• Terminal side padding (Ghostty window-padding-x, iTerm2 side margins): per-terminal and affects every other program.
• stty cols 140 before launching: fragile — any resize resets it, and text stays left-aligned.

Priority

Medium - Would be very helpful

Feature Category

Interactive mode (TUI)

Use Case Example

1. Fullscreen terminal on an ultrawide monitor, run claude.
2. Ask a question that gets a multi-paragraph answer.
3. Today each line spans the whole screen; with maxWidth: 140 it wraps at a readable width.

Additional Context

The same cap has been requested for other Claude surfaces: #63813 (VS Code chat panel), #48171 (VS Code line length), #57991 and #39712 (desktop app). This asks for it in the terminal CLI.