build: prepare SDL3 bridge for upstream

app/src/main/cpp/sdl3bridge/CMakeLists.txt

@@ -10,6 +10,14 @@ set(SDL_INSTALL OFF CACHE BOOL "" FORCE)
 # The bridge draws nothing (SDL3 runs headless for controllers): no OpenGL ES, so libSDL3.so needs no libGLESv1_CM.so,
 # which DroidDeck's APK check (tools/release/check_android_libraries.py) does not count as a system library.
 set(SDL_OPENGLES OFF CACHE BOOL "" FORCE)
-add_subdirectory(SDL)
+include(FetchContent)
+if(POLICY CMP0135)
+    cmake_policy(SET CMP0135 NEW)
+endif()
+FetchContent_Declare(sdl3
+    URL https://github.com/libsdl-org/SDL/releases/download/release-3.4.18/SDL3-3.4.18.tar.gz
+    URL_HASH SHA256=9c75cf16330322c217dedd2e0609f1124f1b54b8633e763467b4684d0f4334a3
+)
+FetchContent_MakeAvailable(sdl3)
 add_library(main SHARED src/main.c)
 target_link_libraries(main PRIVATE SDL3::SDL3 log)

app/src/test/java/com/example/dsedge/EmbeddedBridgeTest.kt

@@ -0,0 +1,44 @@
+package com.example.dsedge
+
+import android.app.Application
+import android.content.ComponentName
+import android.content.pm.PackageManager
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.RobolectricTestRunner
+import org.robolectric.RuntimeEnvironment
+import org.robolectric.annotation.Config
+
+@RunWith(RobolectricTestRunner::class)
+@Config(sdk = [28], application = Application::class)
+class EmbeddedBridgeTest {
+    @Test
+    fun driverComponentsStayPrivateAndRunOutsideTheSessionProcess() {
+        val app = RuntimeEnvironment.getApplication()
+        val pm = app.packageManager
+        val service = pm.getServiceInfo(ComponentName(app, "com.example.dsedge.BridgeService"), 0)
+        assertFalse(service.exported)
+        assertEquals("${app.packageName}:sdl3", service.processName)
+        for (name in listOf("BridgeActivity", "SdlHostActivity")) {
+            val activity = pm.getActivityInfo(ComponentName(app, "com.example.dsedge.$name"), 0)
+            assertFalse(activity.exported)
+            assertEquals(service.processName, activity.processName)
+        }
+        val usb = pm.getActivityInfo(ComponentName(app, "com.example.dsedge.UsbAttachActivity"),
+            PackageManager.GET_META_DATA)
+        assertTrue(usb.exported)
+        assertEquals(service.processName, usb.processName)
+        assertTrue(usb.metaData.containsKey("android.hardware.usb.action.USB_DEVICE_ATTACHED"))
+    }
+
+    @Test
+    fun embeddedBridgePreferencesDoNotShareDroidDeckSettings() {
+        val app = RuntimeEnvironment.getApplication()
+        assertTrue(Host.embedded(app))
+        assertEquals("sdl3bridge_settings", Host.prefs(app, "settings"))
+        assertEquals("sdl3bridge_engine", Host.prefs(app, "engine"))
+    }
+}

docs/development/sdl3-controllers.md

@@ -0,0 +1,42 @@
+# SDL3 controller bridge
+
+The integrated bridge runs in DroidDeck's `:sdl3` process. Open **Settings → SDL3Bridge**
+or the SDL3Bridge page in the session drawer to configure up to four controllers.
+USB controllers use SDL3's HID drivers; Android input remains the fallback for
+Bluetooth and built-in controllers. Steam Native Hook-up forwards a USB controller's
+identity and reports to Steam so Steam can use its own controller driver.
+
+USB access requires Android's device permission. The optional floating control also
+requires permission to display over other apps. A separate SDL3Bridge installation
+should be stopped before using the integrated bridge with the same USB controller.
+Gyro, touchpad, remapping and lightbar settings belong to Steam while Hook-up is active.
+
+## Source and attribution
+
+The controller implementation is by [pablo89898991](https://github.com/pablo89898991),
+imported from [SdlBridge at 63feeac6](https://github.com/pablo89898991/SdlBridge/tree/63feeac6)
+through [SDLApiDroidDeck at 131f1cef](https://github.com/pablo89898991/SDLApiDroidDeck/tree/131f1cef).
+The imported commit retains Pablo's Git author identity. DroidDeck integration and
+build adjustments are recorded separately.
+
+The port keeps DroidDeck's name, signing, workflows and test failure handling. It
+excludes the fork's ADPF changes, cursor-compositing default, Steam controller-rate
+override, and CI/download fallbacks.
+
+SDL 3.4.18 is downloaded by CMake from its official release archive and verified
+against its SHA-256 digest. Its Android Java classes are imported from the same
+release. `HIDDeviceManager.java` retains the bridge's marked Bluetooth-permission
+adjustment. SDL uses the zlib license, included in
+`app/src/main/assets/licenses/sdl3/LICENSE.txt`; the bridge is distributed under
+DroidDeck's GPLv3 license.
+
+## Hardware checks
+
+Check that the built-in controller still navigates DroidDeck and Steam with the
+SDL3 driver both enabled and disabled. Open the bridge settings and controller test
+screen, then start and stop a session without a USB controller attached.
+
+With a USB controller, grant access and verify hot-plug, buttons, sticks, gyro,
+touchpad and rumble in presented-controller mode. Repeat with Steam Native Hook-up,
+including switching back, disconnecting, and reconnecting. Verify multiple player
+slots and Steam on the desktop when the corresponding hardware is available.