# Studio Plan C: Responsive Studio Default Width

## Summary

Improve the default desktop Studio width for large monitors, especially 4K
32-inch displays. The Studio panel should default to roughly one third of the
workspace width while remaining within the requested `1/4` to `2/5` range.

This plan only changes the workspace panel layout defaults. It does not change
diagnosis report data, evidence grouping, links, or metric rendering.

## Key Changes

- Replace the fixed `studioWidth: 420` desktop default with a responsive default
  derived from the row/container width.
- Use approximately `containerWidth / 3` as the default expanded Studio width.
- Clamp the default so it remains:
  - no smaller than the existing Studio minimum
  - no larger than about `40%` of the container width
- Keep the Sources panel default unchanged.
- Keep user-resized layout as the highest priority once saved.
- Upgrade the desktop layout localStorage key, for example from
  `investibook.workspace.layout.desktop.v1` to
  `investibook.workspace.layout.desktop.v2`, so users stuck on the old `420px`
  default can receive the new default.
- Do not change mobile layout behavior.

## Test Plan

- On a 4K-width viewport, verify the first-load Studio width is between `1/4`
  and `2/5` of the available workspace row.
- On a common desktop viewport around 1440px wide, verify Studio remains usable
  and Chat is not squeezed below its minimum width.
- Resize the Studio panel manually, refresh, and verify the user-selected width
  persists.
- Verify Sources collapse/expand and Studio collapse/expand still work.
- Verify mobile tabs are unchanged.

## Assumptions

- This change affects only new or reset desktop layouts after the storage key
  upgrade.
- User drag-resize preferences should continue to override computed defaults.