[FEATURE] A button to turn OFF Research Preview

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

Summary
Add a user-facing toggle to opt out of the "Research Preview" UI and return to the previous (classic) Claude Code interface.

Motivation
The top-left of the app currently shows "Claude Code Research Preview," indicating a new/experimental UI variant. As a user, I'd like the option to revert to the classic UI while the preview matures. Reasons this matters:

• Workflow disruption. UI changes mid-stream interrupt established muscle memory and slow down day-to-day work.
• Stability vs. experimentation. A "preview" label implies the UI is still evolving — users who depend on Claude Code for paid/billable work would prefer the stable surface until the new one is finalized.
• Comparative feedback. If users can flip between classic and preview at will, you'll get much higher-quality feedback (direct A/B comparisons) than from users stuck on one or the other.

Proposed Solution

A simple toggle, ideally in one of:

• Settings / Preferences panel ("Use classic UI")
• An "Exit preview" link near the "Research Preview" label itself (this is the pattern Google, Slack, GitHub, etc. use for opt-outs)
• A profile/account menu entry

The choice should persist across sessions for the signed-in user.

Alternative Solutions

• Searching settings for an existing toggle — couldn't find one.
• Browser-level workarounds (cookies, URL params) — undiscoverable for most users.

Priority

High - Significant impact on productivity

Feature Category

Web UI (claude.ai/code)

Use Case Example

I'm in the middle of an active coding session — debugging a sync job in my time-manager repo, with several open conversations and a mental map of where things live in the existing UI. I open Claude Code in my browser to continue working and notice the header now reads "Claude Code Research Preview." The layout has shifted: panels I rely on are in different spots, and I have to pause and re-learn where things are instead of continuing my debugging.

Step-by-step, here's what I'd do with the toggle:

1. Open Claude Code → see "Research Preview" badge in the top-left.
2. Click my avatar / settings menu → see a "Use classic UI" toggle (or click an "Exit preview" link next to the badge itself).
3. Flip the toggle off → page reloads into the classic UI I was already productive in.
4. Finish my debugging session without losing flow.
5. Later, when I have downtime, flip the toggle back on to explore the preview deliberately and submit informed feedback comparing the two.

Without the toggle, I either eat the context-switch cost mid-task or avoid using Claude Code until the preview is finalized — neither of which is good for me or for the quality of feedback you receive on the new UI.

Additional Context

Environment

• Where I see it: top-left header reads "Claude Code Research Preview"
• Browser / OS: Firefox 150.0 on Windows 11
• URL: https://claude.ai/code

Other preview-related issues that motivate wanting an opt-out (happy to file these as separate bug reports if preferred):

• Frequent session disconnects with messages:

> Session disconnected — The cloud session stopped responding. Resend your message to retry, or start a new session if it keeps happening.
> Lost connection to the cloud session. Resend your message to retry — if it keeps happening, start a new session.

• Right-click hijacked. Right-clicking shows a custom in-app menu instead of the browser/OS context menu, blocking actions like "Inspect," "Save image as," or paste-from-history.