Fix missing-assets detection race, 16 KB page alignment, and Android audio backend

- QuestShockActivity now actually blocks the native engine from starting
  when game data is missing, closing three gaps found via on-device
  testing: super.onCreate() must run unconditionally first (Android
  throws SuperNotCalledException otherwise); SDLActivity.mBrokenLibraries
  is now set provisionally before the storage-permission check, since
  onWindowFocusChanged() closing the permission dialog could otherwise
  start the engine before the async onRequestPermissionsResult() callback
  ran; and a new GameSurface (SDLSurface subclass) closes the actual gap
  that let the init_popups NULL-deref crash through even with
  mBrokenLibraries set - SDLSurface.surfaceChanged() starts the native
  thread directly without ever checking that flag.
- Force Android to use SDL2's openslES audio backend instead of AAudio
  (android/engine-patches/05-android-audio-driver.patch): AAudio only
  allows one open playback device at a time, but the engine opens two
  (cutscene audio via SDL_OpenAudioDevice, SFX/MIDI via Mix_OpenAudio),
  hitting an assertion failure on real hardware.
- Add 16 KB ELF page-size alignment (-Wl,-z,max-page-size=16384) to every
  Android shared library - the four prebuilts (SDL2, SDL2_mixer,
  fluidsynth-lite, gl4es, in build-image/Dockerfile) and the engine's own
  libmain.so (build.gradle) - matching Google's Play Store requirement
  for Android 15+ and clearing Android Studio's compatibility warning.
- Add a stageEngine Gradle task that automatically re-stages the patched
  engine/ copy and prebuilt libraries before any Android Studio build
  (hooked into preBuild, with proper up-to-date checking), so source/
  patch changes can't silently go stale in the build/android-engine
  scratch copy - previously a manual, easy-to-forget step. Skips
  automatically inside the build-image container so make apk/CI are
  unaffected.

android/app/build.gradle

@@ -27,6 +27,49 @@ if (prebuiltDir == null) {
 def questshockVersionName = project.hasProperty('questshockVersionName') ? project.property('questshockVersionName') : '0.0.0-dev'
 def questshockVersionCode = project.hasProperty('questshockVersionCode') ? project.property('questshockVersionCode').toInteger() : 1
 
+// Auto-refreshes the staged, patched engine/ copy and prebuilt libraries
+// (see build-image/prepare-android-project.sh --host-paths, and the
+// engineDir/prebuiltDir properties read above) so a plain Android Studio
+// build/run can never silently compile against a stale scratch copy after
+// engine/ or android/engine-patches/ change - previously a manual, easy to
+// forget re-run. inputs/outputs are declared so Gradle skips the (Docker-
+// invoking, not free) step entirely when nothing relevant actually changed,
+// keeping pure-Java edit/run cycles fast.
+def repoRoot = file("${projectDir}/../..")
+def stageEngineTask = tasks.register("stageEngine", Exec) {
+    group = "build setup"
+    description = "Refreshes the patched engine/ scratch copy and prebuilt libraries for a native Android Studio build (build-image/prepare-android-project.sh --host-paths)."
+    workingDir repoRoot
+    commandLine "./run-image.sh", "bash", "build-image/prepare-android-project.sh", "--host-paths"
+
+    // /opt/prebuilt/android only ever exists inside the build-image
+    // container itself (baked in at image-build time, never on the host -
+    // see build-image/Dockerfile). Its presence means this build is
+    // build-apk.sh's own gradlew call, running INSIDE that container, which
+    // already staged everything itself in container mode before invoking
+    // gradlew - re-running this task there would try to `docker run` from
+    // inside a container with no docker socket, breaking make apk/CI. Only
+    // a genuine host-side Android Studio build (where this path is absent)
+    // needs this task.
+    onlyIf { !file('/opt/prebuilt/android').isDirectory() }
+
+    inputs.dir("${repoRoot}/engine")
+    inputs.dir("${projectDir}/../engine-patches")
+    inputs.file("${repoRoot}/build-image/Dockerfile")
+    outputs.dir("${repoRoot}/build/android-engine")
+    outputs.dir("${repoRoot}/build/android-prebuilt")
+    outputs.file("${projectDir}/../engine.properties")
+}
+
+// preBuild is what every variant's compile/native-build tasks already
+// transitively depend on, regardless of AGP version's exact CMake task
+// naming - the simplest reliable hook to run before any of them.
+afterEvaluate {
+    tasks.named("preBuild").configure {
+        dependsOn stageEngineTask
+    }
+}
+
 android {
     namespace "de.ladkau.questshock"
     // compileSdk/buildToolsVersion/ndkVersion must all match what
@@ -67,6 +110,11 @@ android {
                 // which would otherwise miss our custom-installed SDL2 (see
                 // build-image/Dockerfile's SDL2_mixer build, which hit the
                 // exact same thing).
+                // -Wl,-z,max-page-size=16384: NDK 26 doesn't 16 KB-align ELF
+                // LOAD segments by default (only automatic in NDK 28+) - see
+                // build-image/Dockerfile's ANDROID_16KB_LDFLAGS, which does
+                // the same for the prebuilt SDL2/SDL2_mixer/fluidsynth-lite/
+                // gl4es .so's this links against.
                 arguments "-DENABLE_SDL2=ON", "-DENABLE_SOUND=BUNDLED", "-DENABLE_FLUIDSYNTH=BUNDLED", \
                     "-DANDROID_PREBUILT_DIR=${prebuiltDir}", \
                     "-DCMAKE_PREFIX_PATH=${prebuiltDir}/sdl2", \
@@ -74,6 +122,7 @@ android {
                     "-DCMAKE_FIND_ROOT_PATH_MODE_PACKAGE=BOTH", \
                     "-DCMAKE_FIND_ROOT_PATH_MODE_LIBRARY=BOTH", \
                     "-DCMAKE_FIND_ROOT_PATH_MODE_INCLUDE=BOTH", \
+                    "-DCMAKE_SHARED_LINKER_FLAGS=-Wl,-z,max-page-size=16384", \
                     "-DANDROID_EXTRA_SOURCES=${projectDir}/src/main/cpp/questshock_native.c"
                 abiFilters 'arm64-v8a'
             }

android/app/src/main/java/de/ladkau/questshock/QuestShockActivity.java

@@ -2,10 +2,12 @@ package de.ladkau.questshock;
 
 import android.Manifest;
 import android.app.AlertDialog;
+import android.content.Context;
 import android.content.pm.PackageManager;
 import android.content.res.AssetManager;
 import android.os.Bundle;
 import android.util.Log;
+import android.view.SurfaceHolder;
 import androidx.core.app.ActivityCompat;
 import java.io.File;
 import java.io.FileOutputStream;
@@ -13,16 +15,26 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import org.libsdl.app.SDLActivity;
+import org.libsdl.app.SDLSurface;
 
 /**
- * Everything here runs before super.onCreate() (which is what loads the
- * native libraries and eventually calls Shockolate's own main()) - see
- * android/engine-patches/ for why: engine/ itself is never modified, so
- * this Java-side setup is the only place left to prepare
- * /sdcard/questshock/ the way Shockolate's plain relative-path file I/O
- * ("res/data/...", confirmed via grep - none of it goes through SDL_RWops,
- * so Android's asset-manager fallback for SDL_RWFromFile doesn't apply
- * here) expects to find it.
+ * Prepares /sdcard/questshock/ the way Shockolate's plain relative-path
+ * file I/O ("res/data/...", confirmed via grep - none of it goes through
+ * SDL_RWops, so Android's asset-manager fallback for SDL_RWFromFile
+ * doesn't apply here) expects to find it - see android/engine-patches/ for
+ * why this is done from Java instead of patching engine/ itself, which is
+ * never modified.
+ *
+ * super.onCreate() (SDLActivity's) must always run first and unconditionally
+ * - Android throws SuperNotCalledException otherwise, checked right after
+ * onCreate() returns, regardless of what this subclass does afterwards.
+ * SDLActivity's own onCreate() only loads libraries, sets up JNI and the
+ * surface - the actual native SDL_main thread doesn't start until later, from
+ * one of several lifecycle paths (onResume(), onWindowFocusChanged(), and
+ * SDLSurface.surfaceChanged() - see GameSurface below for why that last one
+ * needs its own fix) - so it's safe to do our own checks (and set
+ * SDLActivity.mBrokenLibraries, which most - but not all - of those paths
+ * gate on) afterwards.
  */
 public class QuestShockActivity extends SDLActivity {
     private static final String TAG = "QuestShock";
@@ -45,8 +57,6 @@ public class QuestShockActivity extends SDLActivity {
     // has no public chdir() (confirmed against the actual API 34 stub jar).
     private static native void nativeChdir(String path);
 
-    private Bundle mSavedInstanceState;
-
     @Override
     protected String[] getLibraries() {
         return new String[] {
@@ -57,9 +67,52 @@ public class QuestShockActivity extends SDLActivity {
         };
     }
 
+    // SDLSurface.surfaceChanged() (org/libsdl/app/, vendored from SDL2's own
+    // template) starts the native SDL thread directly - unlike onResume()/
+    // onWindowFocusChanged(), it never checks SDLActivity.mBrokenLibraries
+    // first. Since surfaceChanged() fires on essentially every launch
+    // regardless of that flag, setting mBrokenLibraries alone (see onCreate()/
+    // setUpGameDirAndContinue()) does NOT actually stop the engine from
+    // starting - confirmed on-device: the missing-assets crash still happened
+    // with mBrokenLibraries set, from exactly this path. Route through a
+    // subclass that adds the missing check instead of patching the vendored
+    // file directly.
+    private static class GameSurface extends SDLSurface {
+        GameSurface(Context context) {
+            super(context);
+        }
+
+        @Override
+        public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
+            if (SDLActivity.mBrokenLibraries) {
+                return;
+            }
+            super.surfaceChanged(holder, format, width, height);
+        }
+    }
+
+    @Override
+    protected SDLSurface createSDLSurface(Context context) {
+        return new GameSurface(context);
+    }
+
     @Override
     protected void onCreate(Bundle savedInstanceState) {
-        mSavedInstanceState = savedInstanceState;
+        super.onCreate(savedInstanceState);
+        if (SDLActivity.mBrokenLibraries) {
+            // SDLActivity's own onCreate() already showed its "SDL Error"
+            // dialog for this - nothing left for us to do.
+            return;
+        }
+        // Provisionally block the native engine from starting - cleared only
+        // once setUpGameDirAndContinue() confirms game data is present. Must
+        // happen before requestPermissions() below: the storage-permission
+        // dialog closing can fire onWindowFocusChanged(true) - which starts
+        // the native SDLThread - before the async onRequestPermissionsResult()
+        // callback (which is what actually calls setUpGameDirAndContinue())
+        // gets a chance to run, so mBrokenLibraries has to already be true
+        // going into that race, not set afterwards.
+        SDLActivity.mBrokenLibraries = true;
         if (ActivityCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE)
                 != PackageManager.PERMISSION_GRANTED) {
             ActivityCompat.requestPermissions(this,
@@ -102,19 +155,28 @@ public class QuestShockActivity extends SDLActivity {
         // and, on a fresh install with no game data copied in yet, that
         // fails deep inside startup (init_popups(), which doesn't NULL-check
         // the load) as a hard native crash instead of a message. Catch the
-        // missing-data case here instead, before super.onCreate() ever
-        // starts Shockolate's native main().
+        // missing-data case here instead, before Shockolate's native
+        // SDL_main ever starts.
         if (!isNonEmptyDir(new File(gameDir, "res/data")) || !isNonEmptyDir(new File(gameDir, "res/sound"))) {
+            // mBrokenLibraries is already true (set in onCreate()) - leave it
+            // that way. Every path that starts the native SDL_main thread
+            // (onWindowFocusChanged(), resumeNativeThread(), etc.) already
+            // checks this flag before doing anything native, so this
+            // reliably prevents the engine from starting without having to
+            // duplicate all of SDLActivity's own lifecycle guards ourselves.
             showMissingAssetsDialog();
             return;
         }
 
         // chdir() is process-wide, not per-thread - already in effect for
         // every thread (including the one that will run Shockolate's own
-        // SDL_main) by the time super.onCreate() below starts it.
+        // SDL_main) by the time the native thread actually starts. Done
+        // before clearing mBrokenLibraries below so the engine can never
+        // start pre-chdir.
         nativeChdir(GAME_DIR);
 
-        super.onCreate(mSavedInstanceState);
+        // Assets confirmed present - safe to let the native engine start now.
+        SDLActivity.mBrokenLibraries = false;
     }
 
     private static boolean isNonEmptyDir(File dir) {

android/engine-patches/05-android-audio-driver.patch

@@ -0,0 +1,20 @@
+--- a/src/MacSrc/Shock.c
++++ b/src/MacSrc/Shock.c
+@@ -162,6 +162,17 @@
+ void InitSDL() {
+     SDL_SetHint(SDL_HINT_NO_SIGNAL_HANDLERS, "1");
+     SDL_SetHint(SDL_HINT_RENDER_DRIVER, "opengl");
++#ifdef __ANDROID__
++    // SDL2 2.28.5's AAudio backend (Android's default since API 26) only
++    // ever allows one open non-capture (playback) device at a time - it
++    // keeps a single static handle and asserts on a second open
++    // ('SDL_assert((audioDevice == NULL) || iscapture)' in
++    // src/audio/aaudio/SDL_aaudio.c). SDLSound.c opens two: one directly via
++    // SDL_OpenAudioDevice() for cutscene audio, one via Mix_OpenAudio() for
++    // SFX/MIDI. The older OpenSL ES backend has no such limitation, so force
++    // it instead of AAudio.
++    SDL_SetHint(SDL_HINT_AUDIODRIVER, "openslES");
++#endif
+     if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER | SDL_INIT_AUDIO) < 0) {
+         DEBUG("%s: Init failed", __FUNCTION__);
+     }

build-image/Dockerfile

@@ -46,6 +46,13 @@ ARG ANDROID_COMPILE_SDK_VERSION=34
 ARG ANDROID_BUILD_TOOLS_VERSION=34.0.0
 ARG ANDROID_NDK_VERSION=26.1.10909125
 ARG ANDROID_CMAKE_VERSION=3.22.1
+# NDK 26 doesn't yet default to 16 KB-aligned ELF LOAD segments (that only
+# became automatic in NDK 28+) - Google requires this for Play Store
+# submissions targeting Android 15+ as of Nov 2025, and it's cheap/harmless
+# to do regardless of Play Store status. Passed to every Android shared-lib
+# CMake configure below, and to the engine's own build via
+# android/app/build.gradle's externalNativeBuild.cmake.arguments.
+ARG ANDROID_16KB_LDFLAGS="-Wl,-z,max-page-size=16384"
 # GL4ES (https://github.com/ptitSeb/gl4es) - translates the engine's
 # desktop-style immediate-mode OpenGL calls into real GLES/EGL calls, so
 # engine/src/MacSrc/OpenGL.cc needs no immediate-mode rewrite on Android.
@@ -182,6 +189,7 @@ RUN curl -sSLO "https://www.libsdl.org/release/SDL2-${ANDROID_SDL2_VERSION}.tar.
         -DANDROID_ABI="${ANDROID_ABI}" -DANDROID_PLATFORM="android-${ANDROID_PLATFORM_VERSION}" \
         -DCMAKE_INSTALL_PREFIX=/opt/prebuilt/android/sdl2 -DBUILD_SHARED_LIBS=ON \
         -DSDL_STATIC=OFF \
+        -DCMAKE_SHARED_LINKER_FLAGS="${ANDROID_16KB_LDFLAGS}" \
     && cmake --build build-sdl2-android -j"$(nproc)" \
     && cmake --install build-sdl2-android \
     && rm -rf "SDL2-${ANDROID_SDL2_VERSION}" "SDL2-${ANDROID_SDL2_VERSION}.tar.gz" build-sdl2-android
@@ -207,6 +215,7 @@ RUN curl -sSLO "https://www.libsdl.org/projects/SDL_mixer/release/SDL2_mixer-${A
         -DSDL2MIXER_FLAC=OFF -DSDL2MIXER_GME=OFF -DSDL2MIXER_MOD=OFF \
         -DSDL2MIXER_MP3=OFF -DSDL2MIXER_MIDI=OFF -DSDL2MIXER_OPUS=OFF -DSDL2MIXER_VORBIS=OFF \
         -DSDL2MIXER_WAVPACK=OFF \
+        -DCMAKE_SHARED_LINKER_FLAGS="${ANDROID_16KB_LDFLAGS}" \
     && cmake --build build-sdl2mixer-android -j"$(nproc)" \
     && cmake --install build-sdl2mixer-android \
     && rm -rf "SDL2_mixer-${ANDROID_SDL2_MIXER_VERSION}" "SDL2_mixer-${ANDROID_SDL2_MIXER_VERSION}.tar.gz" build-sdl2mixer-android
@@ -222,6 +231,7 @@ RUN git clone https://github.com/EtherTyper/fluidsynth-lite.git fluidsynth-lite-
     && cmake -S fluidsynth-lite-android -B build-fluidsynth-android \
         -DCMAKE_TOOLCHAIN_FILE="${ANDROID_NDK_TOOLCHAIN}" \
         -DANDROID_ABI="${ANDROID_ABI}" -DANDROID_PLATFORM="android-${ANDROID_PLATFORM_VERSION}" \
+        -DCMAKE_SHARED_LINKER_FLAGS="${ANDROID_16KB_LDFLAGS}" \
     && cmake --build build-fluidsynth-android -j"$(nproc)" \
     && mkdir -p /opt/prebuilt/android/fluidsynth-lite/lib /opt/prebuilt/android/fluidsynth-lite/include \
     && cp -a build-fluidsynth-android/src/libfluidsynth.so* /opt/prebuilt/android/fluidsynth-lite/lib/ \
@@ -254,6 +264,7 @@ RUN git clone --branch "v${ANDROID_GL4ES_VERSION}" --depth 1 \
         -DCMAKE_TOOLCHAIN_FILE="${ANDROID_NDK_TOOLCHAIN}" \
         -DANDROID_ABI="${ANDROID_ABI}" -DANDROID_PLATFORM="android-${ANDROID_PLATFORM_VERSION}" \
         -DANDROID=ON -DUSE_ANDROID_LOG=ON -DSTATICLIB=OFF \
+        -DCMAKE_SHARED_LINKER_FLAGS="${ANDROID_16KB_LDFLAGS}" \
     && cmake --build build-gl4es-android -j"$(nproc)" \
     && mkdir -p /opt/prebuilt/android/gl4es/lib /opt/prebuilt/android/gl4es/include \
     && cp -a gl4es-android/lib/libGL.so.1 /opt/prebuilt/android/gl4es/lib/libGL.so \