Agentic UI: fix copy button space in chat

[nightnei]

Related issues

• Fixes STU-2082

How AI was used in this PR

AI assisted with the fix, I reviewed and tested

Proposed Changes

We have a huge space after messages in chat due to the hidden Copy button. This PR fixes it to have a rational space

BEFORE	AFTER

Testing Instructions

1. Open new Agentic UI
2. Send any massege
3. Mouse over that message
4. Assert that the copy button appeared and the UX is good - it's easily achievable and clickable

[wpmobilebot]

📊 Performance Test Results

Comparing f7c98b5 vs trunk

app-size

Metric	trunk	f7c98b5	Diff	Change
App Size (Mac)	1378.85 MB	1381.98 MB	+3.13 MB	🔴 0.2%

site-editor

Metric	trunk	f7c98b5	Diff	Change
load	1048 ms	751 ms	297 ms	🟢 -28.3%

site-startup

Metric	trunk	f7c98b5	Diff	Change
siteCreation	6474 ms	6511 ms	+37 ms	⚪ 0.0%
siteStartup	2380 ms	2382 ms	+2 ms	⚪ 0.0%

---

Results are median values from multiple test runs.

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

[bcotrim]

I found that it overlaps with the next message:

Could we maybe align it to the right?

[nightnei]

Great catch @bcotrim, thanks.
I took a completely different approach to keep copy button inlined to avoid regressions in the future and aligne margins. I think it looks good.
@shaunandrews WDYT?

[bcotrim]

The spacing looks better now, thanks for the adjustment!

It seems we offer the copy option after each "text section" which I think it's too much.
I would say 1 copy after the last agent reply plus another for some particular sections (for example code) would be enough, in my opinion, and it would fix the spacing issue.

Example:

[shaunandrews]

I guess I don't understand; I'm still seeing all this extra whitespace for the invisible copy button. I'm going to try a few things and push some changes if thats ok.

I think this overlap could work if we blur/obscure the content behind it a bit. I'm going to retry this, and reconsider placement entirely—maybe it will work better on top or in the margins.

I'm also going to explore perhaps relying on right click and or double-clicking instead of a visible button.

[shaunandrews]

I've pushed some changes:

The copy button always displays for the latest response from the agent.

--

There's no longer any extra space between messages.

--

Clicking on an older message shows the copy button below the message, animated into view. Selecting a different message hides other copy buttons (except for the latest message). You can also click on a selected message to unselect it, hiding the copy button.

[shaunandrews]

Follow up, introducing a right-click menu for copying messages as well: #4388

[bcotrim]

I like this direction 👍