fix: prevent iOS composer focus zoom

[gigq]

What Changed

Prevents the chat composer from triggering iOS Safari's automatic page zoom when the editor is focused on mobile.
The fix does two things:

• Sets the composer editor text size to 16px on coarse-pointer devices, which avoids the common iOS auto-zoom trigger.
• Adds a small iOS-specific focus guard that temporarily locks the viewport while the composer is focused, then restores the original viewport
  settings on blur.
  This is scoped only to the composer and includes a small unit test for the viewport helper.

Why

On iPhone, tapping into the composer caused the page to zoom in slightly when the keyboard opened, which left the UI at the wrong zoom level
afterward and made the mobile experience feel broken.
This approach keeps the fix narrow:

• It only affects the composer, not the whole app.
• It preserves the normal viewport configuration outside of composer focus.
• It handles iOS/iPadOS specifically instead of applying a global zoom restriction.

UI Changes

Behavior change only. The composer no longer causes the page to zoom when focused on iPhone.

Checklist

• This PR is small and focused
• I explained what changed and why
• I included before/after screenshots for any UI changes
• I included a video for animation/interaction changes

ScreenRecording_03-29-2026.20-19-55_1.mp4

ScreenRecording_03-29-2026.20-23-01_1.mp4

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Note

Medium Risk
Adds iOS-specific viewport meta manipulation on focus/blur and adjusts editor font sizing; mistakes could impact mobile zoom/scroll behavior if the viewport content isn’t restored correctly.

Overview
Prevents iOS Safari from auto-zooming when the chat composer is focused by raising the composer font size to 16px on coarse-pointer devices and wiring new focus/blur/touch handlers into ComposerPromptEditor.

Introduces a new usePreventIosInputZoom hook that, on iOS/iPadOS, temporarily locks the page viewport (maximum-scale=1, user-scalable=no) while the editor is focused and restores the original viewport on blur/unmount, with unit tests covering platform detection and viewport content rewriting.

^{Written by Cursor Bugbot for commit 5df2283. This will update automatically on new commits. Configure here.}

Note

Prevent iOS composer input zoom by locking viewport on focus

• Adds a usePreventIosInputZoom hook that mutates the viewport meta tag (maximum-scale=1, user-scalable=no) when a focusable element is focused on iOS/iPadOS, restoring the original viewport on blur.
• Detects iOS/iPadOS via user agent or MacIntel platform with multiple touch points.
• Sets the composer font size to 16px on coarse-pointer devices (preventing iOS auto-zoom) and 14px otherwise, replacing the hardcoded text-[14px] Tailwind class.
• Risk: Setting user-scalable=no temporarily disables pinch-to-zoom globally while the composer is focused, which may affect accessibility.

^{Macroscope summarized 5df2283.}

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