BoringdroidSystemUI

A PC-class SystemUI for boringdroid. BoringdroidSystemUI is loaded into the stock AOSP SystemUI process as a SystemUI plugin, so it inherits SystemUI's permissions, UID and signature without forking SystemUI itself. The plugin replaces the navigation bar with a desktop taskbar and layers a notch of desktop-class surfaces on top of it — Start menu, Action Center, Calendar, Overview.

Architecture

flowchart TB
    subgraph Host["com.android.systemui host (AOSP, uid 1000)"]
        Overlay["SystemUIOverlay (plugin entry point)"]
        Taskbar["TaskbarWindow<br>TYPE_NAVIGATION_BAR<br>providedInsets = 72dp"]
        AllApps["AllAppsWindow<br>start menu"]
        Action["ActionCenterWindow<br>notifications + QS"]
        Calendar["CalendarClockWindow<br>clock + calendar"]
        A11y["AccessibilityManager<br>GLOBAL_ACTION_ACCESSIBILITY_ALL_APPS<br>Meta key opens Start menu"]
        Overlay --- Taskbar
        Overlay --- AllApps
        Overlay --- Action
        Overlay --- Calendar
        Overlay --- A11y
    end

    subgraph Plugin["com.boringdroid.systemui (own process)"]
        Overview["BoringdroidOverviewService<br>bound by OverviewProxyService<br>owns OverviewWindow (TYPE_APPLICATION_OVERLAY)"]
        Mirror["BoringdroidNotificationMirror<br>NotificationListenerService"]
    end

    Overlay -- "ACTION_TOGGLE_OVERVIEW broadcast" --> Overview
    Mirror -- "NotificationFeedIpc broadcast" --> Action

Loading

Two processes are involved:

1. SystemUI host (com.android.systemui, uid 1000). The plugin runs here. Everything that needs to draw on the taskbar/status-bar layer — the taskbar itself, Start menu, Action Center, Calendar — is owned by SystemUIOverlay in this process. It talks to the framework via system-signature APIs (WindowManager, AccessibilityManager, NotificationListenerService bindings).

2. Plugin package (com.boringdroid.systemui). Hosts the Overview binder (BoringdroidOverviewService, the IOverviewProxy that SystemUI's OverviewProxyService binds to) and the notification mirror. Runs in its own process because OverviewProxyService requires the recents component to live outside SystemUI.

Keep that split in mind when wiring new flows: a broadcast that needs to reach the overview window must be addressed to the plugin package, not the SystemUI host.

Key surfaces

• Taskbar (taskbar/Taskbar.kt). Compose-first, pinned via TaskbarWindow as a TYPE_NAVIGATION_BAR — chosen so WMS propagates the providedInsets it carries. Advertises the taskbar height plus the panel_taskbar_gap as a navigation-bar inset so Launcher3 and other full-height apps leave room above it.
• Start menu (AllAppsLayout.kt, AllAppsWindow.kt). Search pill, pinned grid, user rail (lock / sign out / power). Toggled by clicking the start button, tapping the taskbar search pill, or pressing the Meta (Windows) key.
• Action Center (actioncenter/ActionCenterLayout.kt). Big clock header, 3x3 QS tile grid backed by QsController / QsTileStore, a media card, and a LazyColumn of notifications fed by NotificationFeed. ACTION_CLEAR_ALL broadcast + in-panel "Clear all" button.
• Calendar panel (calendar/CalendarClockLayout.kt). Clock + month grid + agenda. Mutually exclusive with Action Center. Backed by CalendarContract.Instances in a background loader.
• Overview (overview/OverviewLayout.kt). macOS-Mission-Control-style expo — thumbnails fly from their real window bounds to a common-scale grid and back. The window itself is owned by BoringdroidOverviewService in the plugin process (see above); SystemUIOverlay triggers it via ACTION_TOGGLE_OVERVIEW broadcast.

Framework dependency: one surviving frameworks/base patch

BoringdroidSystemUI is almost pure plugin. On AOSP 14 it still depends on one four-line edit inside the stock framework:

• File: frameworks/base/packages/SystemUI/src/com/android/systemui/navigationbar/NavigationBarController.java
• What it does: early-returns from createNavigationBar(Display) when SystemProperties.getBoolean("persist.sys.systemuiplugin.enabled", false) is true (the prop is set by vendor/boringdroid/boringdroid.mk).
• Why it has to exist: BoringdroidSystemUI renders its own TYPE_NAVIGATION_BAR taskbar window. Without this guard, AOSP also creates its own NavigationBar on displayId=0, producing double-bar visual collisions and inset-accounting bugs.
• Why it can't be an overlay: there is no product-overlay or RRO mechanism in AOSP 14 that suppresses NavigationBar creation per-display from outside the framework. config_showNavigationBar is read by WMS at DisplayPolicy construction time — before product overlays are guaranteed to be applied — so flipping it via overlay is unreliable for our use case. A WindowManager-side suppression hook would itself be a forked-AOSP patch, and strictly larger than the current one.
• Maintainer note: do not delete this patch as part of a "framework-patch-free" cleanup. It is intentionally the smallest survivable diff. The edit is wrapped in // region boringdroid / // endregion so it's trivial to locate. If a future AOSP release adds a per-display NavigationBar suppression hook (or makes config_showNavigationBar overlay-honoring at the right lifecycle point), this patch can be retired — until then, keep it.

Build

BoringdroidSystemUI ships as an AOSP module — the build is Soong. From the AOSP root:

source build/envsetup.sh
lunch boringdroid_x86_64-userdebug
m BoringdroidSystemUI BoringdroidSystemUITests

Android.bp declares both the plugin APK and its instrumentation APK via the standard android_app / android_test module types, with platform_apis: true and certificate: "platform" so the plugin loads inside SystemUI's UID on the signed image.

For IDE iteration Android Studio can import the module directly via Soong's IntelliJ integration (idegen); the in-tree Gradle project has been retired — running the full tree build is the source of truth for both the plugin APK and its test APK.

Tests

Instrumentation suite (UiAutomator) lives under app/src/androidTest and builds as BoringdroidSystemUITests.apk:

m BoringdroidSystemUI BoringdroidSystemUITests
bash .claude/scripts/run-boringdroid-tests.sh

The script builds the APKs, installs them against a running boringdroid_x86_64-userdebug emulator, restarts SystemUI to pick up the plugin, drops adb to shell uid (so cmd notification post works), restarts Launcher so it re-reads the taskbar's navigation-bar inset, and runs every class in com.boringdroid.systemui.test.