Testing: Subagent list items have visually clipped focus outline

Testing #290515

Not sure if this just scoped to subagent rendering, but in the chat part for rendering a list of files or fetched links the focus outline for an item has a weird / buggy visual artifact that makes the corners look clipped.

<img width="393" height="113" alt="Image" src="https://github.com/user-attachments/assets/40bce187-0278-49df-95f8-07740bb377d1" />
