ADR 0123: Use native taskbar minimize for Windows/Linux window controls

• Status: Accepted
• Date: 2026-08-25
• Deciders: PI-Desktop core
• Related: D216, D230, D252, D256, E2E-124, ADR 0078, ADR 0090, ADR 0117

Context

Windows/Linux use a frameless window with renderer-drawn minimize, maximize, and close controls. The minimize action was calling window.hide(), which removed the window from the taskbar and made the action behave like a close-to-tray operation. The close button already has an independent, persisted tray/quit choice, so two different controls were unexpectedly using the same hidden-window behavior.

Decision

1. The Windows/Linux renderer window-control minimize action calls Electron's native BrowserWindow.minimize() transition. The Windows/Linux native-menu minimize action uses the same transition.
2. The main-window minimize event does not convert Windows/Linux native minimization into hide(). The operating system keeps the taskbar entry so the user can restore the same window normally.
3. macOS keeps its existing traffic-light tray-resident minimize behavior. Windows/Linux close behavior remains owned by ADR 0090: the close button hides to the tray for tray and exits for quit.
4. The resident tray, close-behavior persistence, IPC action allowlists, host protocol, and background-process lifetime do not change.

Consequences

• The three Windows/Linux window buttons now match the expected desktop model: minimize goes to the taskbar, maximize toggles the window, and close follows the user's remembered tray/quit choice.
• The tray remains available for close-to-tray and for macOS's existing minimize behavior; no second tray lifecycle is introduced.
• No new privileged bridge or protocol version is required because the existing minimize action changes only its Main-owned Electron effect.

Alternatives considered

• Keep explicit minimize as hide-to-tray: rejected because it makes the minimize and close controls indistinguishable when close-to-tray is selected and removes the standard taskbar restore path.
• Remove the resident tray: rejected because close-to-tray and macOS minimize still need a reliable restore surface.