Agentic UI: Add AI tab with agentic features toggle to settings

[bcotrim]

Related issues

• Related to STU-1882

How AI was used in this PR

Implemented with Claude Code (settings-view exploration, panel implementation, tests), reviewed and verified by a human.

Proposed Changes

Part of the application-settings series for the agentic UI (STU-1882).

• Adds an AI tab to the agentic UI settings, giving agentic features a dedicated home ahead of the follow-up series (chat notifications, default model, tool permissions).
• The tab hosts an Agentic features toggle: switching it off returns Studio to the classic interface. The copy is honest about what happens — the app reloads into the classic UI immediately (no restart), matching the existing "Switch to classic" behavior.
• The former "Studio experience" section with the "Switch to classic" button moves out of the Settings tab into the new AI tab, so there's a single control for the flag.

Light	Dark

Testing Instructions

1. Enable the new Studio experience (beta feature) and open Settings.
2. Confirm the new AI tab appears between Settings and Skills, with the "Agentic features" toggle switched on. Check light and dark mode.
3. Toggle it off: the window should reload into the classic Studio UI.
4. In classic UI, switch back to the new experience and confirm the toggle shows as on again.

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?

[wpmobilebot]

📊 Performance Test Results

Comparing 45b6317 vs trunk

app-size

Metric	trunk	45b6317	Diff	Change
App Size (Mac)	1362.01 MB	1362.02 MB	+0.00 MB	⚪ 0.0%

site-editor

Metric	trunk	45b6317	Diff	Change
load	1044 ms	1101 ms	+57 ms	🔴 5.5%

site-startup

Metric	trunk	45b6317	Diff	Change
siteCreation	7013 ms	7006 ms	7 ms	⚪ 0.0%
siteStartup	2354 ms	2358 ms	+4 ms	⚪ 0.0%

---

Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change (<50ms diff)

[sejas]

@bcotrim , will this replace the switch to classic in the main settings? I find very misleading having an AI tab which has only a toggle to disable it. 🤔
I would expect having Skills, MCP, Usage under that tab. Maybe it's a matter of renaming the tab to Experimental features or Beta features and moving it to the last position in the tab order. WDYT?

[bcotrim]

@bcotrim , will this replace the switch to classic in the main settings? I find very misleading having an AI tab which has only a toggle to disable it. 🤔 I would expect having Skills, MCP, Usage under that tab. Maybe it's a matter of renaming the tab to Experimental features or Beta features and moving it to the last position in the tab order. WDYT?

Yes it will replace that switch. You can check the exploration PR: #3975 to see the options the AI tab will have in the future. I agree this is a very small start, but it was intentional for an easy review

[sejas]

Sounds good. I see Shauns exploration has only the sounds/alerts:

We can consider moving there the new Instructions textbox of Studio Code. Maybe the new disable AI should be the last element in that page.