ADR 0076: Capture the Windows-reserved plugin launcher chord in host-core

• Status: Accepted
• Date: 2026-08-12
• Deciders: PI-Desktop core
• Related: D211 · ADR 0072 · E2E-120

Context

Windows reserves Alt+Space for the active window system menu. Electron's globalShortcut may therefore reject the plugin launcher's default binding, and a renderer before-input-event fallback only works while PI-Desktop is focused.

Decision

Host-core installs a narrow Windows WH_KEYBOARD_LL hook for the default Alt+Space binding. It consumes the matching keydown, emits the existing JSON-RPC notification transport with keyboard.shortcut, and lets Electron toggle the plugin launcher. Electron sends the additive keyboard.setGlobalShortcut host method whenever the effective binding changes; the hook is enabled only when the effective Windows binding is Alt+Space. Other platforms and custom bindings retain Electron's normal global shortcut path.

The hook does not inspect or persist text, and it does not expose a new renderer or plugin capability. If hook installation fails, the focused-window fallback remains available and the failure is logged.

Consequences

• The default Windows launcher chord works while another application is foregrounded and does not open that application's system menu.
• The host binary owns a small platform-specific input integration, while Electron remains responsible for window creation and plugin-panel access.
• Protocol version and storage schema remain unchanged because the method and notification are additive and Electron is the only consumer.