LanMountainDesktop/.trae/specs/window-layer-isolation/spec.md

Window Layer Isolation

Goal

Keep fused desktop component windows and Air APP windows in separate z-order roles.

Behavior

• Fused desktop windows are desktop-surface windows. They may use IWindowBottomMostService and region passthrough, must stay attached to the Windows desktop icon host when supported, and must not cover ordinary apps.
• Air APP windows are ordinary application windows. They must not use the fused desktop bottom-most service, must not attach to the desktop icon host, and must not use global Topmost promotion.
• Re-showing or reloading fused desktop widgets refreshes their desktop layer after the window is visible.
• Air APP activation uses normal window activation; repeated-open foreground recovery remains owned by Launcher lifecycle activation.

Out of Scope

• Changing Air APP lifecycle IPC.
• Changing whiteboard note sharing.
• Implementing third-party Air APP SDK behavior.