[FEATURE] Add focus mode to the Claude Code web interface

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When I use Claude Code on the web (claude.ai/code), the transcript is cluttered with intermediate work — tool calls, command output, file reads, and background agent activity. For longer agent sessions this makes it hard to follow what's actually happening and to find the meaningful output. I just want to see my prompt, a brief summary of what Claude did, and its final response.

The terminal already solves this with focus mode (/focus / Ctrl+O), but there's no equivalent on the web, so the web experience feels noticeably noisier and harder to scan than the terminal for the same work.

Proposed Solution

Add a focus-mode toggle to the web interface that mirrors the terminal's /focus behavior:

• A visible toggle/control (and ideally a keyboard shortcut) that collapses tool-execution details and intermediate steps, leaving my prompt, a one-line summary of the tools Claude used, and the final response.
• Expandable on demand, so I can click into a collapsed step to see the full detail when I need it.
• Persisted as a setting that syncs with the terminal's focus-mode preference, so I don't have to re-enable it every session or per device.

Alternative Solutions

• On the terminal I use /focus (Ctrl+O), but that doesn't carry over to the web at all.
• I've tried reducing verbosity another way — using output styles (e.g. "Proactive") and CLAUDE.md instructions to make responses more concise — but that only changes how Claude writes; it doesn't collapse the tool-call/intermediate UI noise, which is the actual problem.
• Otherwise I just scroll past the intermediate output manually, which doesn't scale for long sessions.

Priority

High - Significant impact on productivity

Feature Category

Interactive mode (TUI)

Use Case Example

1. I kick off a multi-step task in a web session — say, refactoring a module — and Claude runs many tool calls (greps, file reads, edits, test runs).
2. The transcript fills with intermediate tool output, and I have to scroll to find Claude's actual summary and result.
3. With focus mode on the web, I'd toggle it once and the session would show only my prompt, a compact summary of the tools used, and the final response.
4. When something looks off, I'd expand a specific collapsed step to inspect the detail.
5. This saves time scanning long sessions and makes the web experience match the cleaner terminal flow I already rely on.

Additional Context

Reference: the terminal already implements this as focus mode, toggled via /focus or Ctrl+O — this request is to bring the same capability to claude.ai/code. Ideally the two share a single setting so the preference is consistent across terminal and web.