Agentic UI: Keep app-wide toasts above the composer when the sidebar is closed

[bcotrim]

Related issues

• Fixes STU-2173

How AI was used in this PR

AI traced the root cause, wrote the fix and the test, and verified the resulting geometry live in studio ui (light + dark). I reviewed the diff.

Proposed Changes

• With the sidebar closed, app-wide toasts covered the chat composer instead of stacking above it. They now sit just above the composer and ride up with it as it grows — wrapped text, attachments, or the drag handle.
• Fullscreen preview keeps toasts on the panel's footer band, since no composer is visible there.

Light	Dark

Testing Instructions

• Close the sidebar in a chat session and trigger a toast (start or stop a site). It should sit above the composer, with the input fully usable.
• Type a multi-line draft, then drag the composer's resize handle. The toast should track the composer's top edge in both directions.
• Repeat in fullscreen preview (⋮ → Full preview). Toasts should sit at the bottom-left of the panel.
• Check both light and dark.

Pre-merge Checklist

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

[wpmobilebot]

📊 Performance Test Results

Comparing 59eaf99 vs trunk

app-size

Metric	trunk	59eaf99	Diff	Change
App Size (Mac)	1406.26 MB	1406.26 MB	+0.00 MB	⚪ 0.0%

site-editor

Metric	trunk	59eaf99	Diff	Change
load	1047 ms	1018 ms	29 ms	⚪ 0.0%

site-startup

Metric	trunk	59eaf99	Diff	Change
siteCreation	7552 ms	7558 ms	+6 ms	⚪ 0.0%
siteStartup	2872 ms	2871 ms	1 ms	⚪ 0.0%

---

Results are median values from multiple test runs.

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

[katinthehatsite]

The issue is fixed for me in this PR but I am wondering if we can find a better position in general for these toasts when the sidebar is closed. To me, it feels like it obscures the chat field and gets into the content flow. Some possible options:

• top of the main panel, below the header OR
• top right of the viewport

What do you think?

If we want to proceed fast, we can merge this to fix an immediate bug but I think it might be a good approach to revise the position in general

[bcotrim]

The issue is fixed for me in this PR but I am wondering if we can find a better position in general for these toasts when the sidebar is closed. To me, it feels like it obscures the chat field and gets into the content flow. Some possible options:

* top of the main panel, below the header OR

* top right of the viewport

What do you think?

I don't have a strong opinion, but maybe the top right of the composer view would be good.
Toasts can be dismissed so the users can work around it, but I agree that if users find that placement annoying it's something they will have to deal with often.
Any thoughts @shaunandrews ?

If we want to proceed fast, we can merge this to fix an immediate bug but I think it might be a good approach to revise the position in general

Yes, if this fixed the bug and we agree it's an improvement overall let's ship it for the beta while we discuss a better alternative.

Thanks for the review and for bringing up the discussion!

[katinthehatsite]

Yes, if this fixed the bug and we agree it's an improvement overall let's ship it for the beta while we discuss a better alternative.

This sounds good to me 👍 I will approve the changes now and we can iterate on the placement later

[shaunandrews]

In my experience, I don't get many toasts while I'm focused in the chat with the sidebar off. And if I do, I think its helpful to see them near where my focus is—the chat composer, without obscuring my writing.

They seem rare in this scenario, They go away on their own. And they are easily dismissible.

Lets see what users say.