agent-sessions-layout

When working on the Agents workbench layout, always follow these guidelines: The authoritative specification for the Agents layout lives at: src/vs/sessions/LAYOUT.md Before making any changes to the layout code, read and understand the current spec. It defines: If you modify the layout implementation, you must update LAYOUT.md to reflect those changes. The spec should always match the code. This includes: Update the Revision History table at the bottom of LAYOUT.md with a dated entry describing what changed. When proposing or implementing changes, follow these rules from the spec: After modifying layout code: - The fixed layout structure (grid tree, part positions, default sizes) - Which parts are included/excluded and their visibility defaults - Titlebar configuration and custom menu IDs - Editor modal overlay behavior and sizing - Part visibility API and events - Agent session part classes and storage keys - Workbench contributions and lifecycle - CSS classes and file structure - Adding/removing parts or changing their positions - Changing default visibility or sizing - Adding new actions, menus, or contributions - Modifying the grid structure - Changing titlebar configuration - Adding new CSS classes or file structure changes - Maintain fixed positions — Do not add settings-based position customization - Panel must span the right section width — The grid structure places...