Remember Agentic UI preview path per site when switching sites

[sejas]

Related issues

• Fixes STU-1971

The in-app browser preview kept the current URL path when switching sites: viewing /about on one site and then opening a different site loaded that site's /about instead of its home page — confusing, and a 404 when the path doesn't exist on the new site.

How AI was used in this PR

AI assisted with the implementation and tests; the change was reviewed and verified manually.

Proposed Changes

• The preview now remembers the last visited path per site. Switching to a site you haven't previewed opens its home page; switching back to a site restores where you left off (e.g. site A on /about, site B on /blog, and returning to A shows /about again). The old site's path never leaks onto the new site.
• Path memory is in-memory only — it resets when the app restarts.

Testing Instructions

• Run npm start enable the Agentic UI
• Open a session for site A and navigate the preview to a subpage, e.g. /about.
• Switch to a session on site B: the preview opens site B at its home page, not the carried-over path.
• Navigate site B to another page, then switch back to site A: the preview restores site A's last path. Return to site B and confirm its path is restored too.

Before

preview-path-before.mp4

After

preview-path-after.mp4

Pre-merge Checklist

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

[wpmobilebot]

📊 Performance Test Results

Comparing 9f7f5e8 vs trunk

app-size

Metric	trunk	9f7f5e8	Diff	Change
App Size (Mac)	1362.04 MB	1362.04 MB	+0.00 MB	⚪ 0.0%

site-editor

Metric	trunk	9f7f5e8	Diff	Change
load	1078 ms	1053 ms	25 ms	⚪ 0.0%

site-startup

Metric	trunk	9f7f5e8	Diff	Change
siteCreation	7012 ms	7010 ms	2 ms	⚪ 0.0%
siteStartup	2356 ms	2349 ms	7 ms	⚪ 0.0%

---

Results are median values from multiple test runs.

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

[bcotrim]

This is a very nice improvement, thanks!
I found an issue: if you navigate away from a site while it is starting it can change the preview of another site

Screen.Recording.2026-07-23.at.13.56.44.mov

[nightnei]

Great improvement, works perfectly 👍

[bcotrim]

I can no longer replicate the issue I flagged.
There was an error with some of my local worktrees that also probably caught this test.

Approved 👍