[BUG]: Mobile prompt input buttons overflow on narrow viewports

[athal7]

Description

On mobile viewports (375px), the prompt input button bar overflows or clips buttons, making some controls inaccessible.

Affected buttons:

• Agent selector (Build/Plan/Docs)
• Model selector
• Thinking variant selector
• Context usage indicator
• Attach file
• Send/Stop

Fix

• Use CSS contents pattern for responsive single-row layout on mobile
• Replace thinking variant Button with Select dropdown
• Hide text labels on mobile, show icons only
• Fix model selector dialog centering and highlight state

Screenshots

See PR for before/after screenshots at 375px and 1280px viewports.

Operating System

iOS / Mobile browsers

OpenCode version

1.1.48

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• [BUG]: Session turn status button overflows on mobile (web/app) #10485: Session turn status button overflows on mobile (web/app)
• web: mobile & touch devices cannot access context details #10443: web: mobile & touch devices cannot access context details
• web: mobile layout could be tighter #10919: web: mobile layout could be tighter
• Poor mobile web experience. #7990: Poor mobile web experience

Feel free to ignore if none of these address your specific case.