Android: smoother boot (off-main-thread native work) + release pyjnius fix; bump to 4.1.0

.fvmrc

@@ -1,3 +1,3 @@
 {
-  "flutter": "3.44.2"
+  "flutter": "3.44.3"
 }

src/serious_python/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 4.1.0
+
+* **Android:** run first-launch asset unpacking and native library loading off the platform main thread so they no longer block vsync — boot-time animations (e.g. a splash / boot screen spinner) stay smooth while the app starts. Also ship consumer ProGuard rules that keep the pyjnius bootstrap classes, fixing pyjnius in release (minified) Android builds. See `serious_python_android` 4.1.0.
+
 ## 4.0.0
 
 * **App packaging lifted into serious_python.** Your Python app now ships **unpacked inside the application bundle**, next to the Python stdlib and site-packages, on macOS / iOS / Windows / Linux — no first-launch `app.zip` extraction. On **Android** the app ships as a *stored* `app.zip` asset inside the APK and is unpacked once (version-keyed) to the app-support files dir on the first launch after an install/update, like the existing `extract.zip`. Web (Pyodide) is unchanged. The `package` command stages the processed app into **`SERIOUS_PYTHON_APP`** (symmetric with `SERIOUS_PYTHON_SITE_PACKAGES`); each platform's native build copies it into the bundle (Android zips it as a stored asset).

src/serious_python/pubspec.yaml

@@ -2,7 +2,7 @@ name: serious_python
 description: A cross-platform plugin for adding embedded Python runtime to your Flutter apps.
 homepage: https://flet.dev
 repository: https://github.com/flet-dev/serious-python
-version: 4.0.0
+version: 4.1.0
 
 platforms:
   ios:

src/serious_python_android/CHANGELOG.md

@@ -1,3 +1,9 @@
+## 4.1.0
+
+* Run the `extractAsset` / `unzipAsset` / `loadLibrary` method-channel handlers on a background `Executor` (posting the `Result` back on the main looper) instead of inline on the platform main thread. The first-launch asset unpack and the pyjnius native-library load no longer block Android's `Choreographer`, so Flutter's vsync isn't starved and on-screen animations (e.g. a boot/splash spinner) stay smooth while the app starts.
+* Ship consumer ProGuard/R8 keep rules (`-keep class com.flet.serious_python_android.** { *; }`) so release (minified) builds don't obfuscate or strip the classes pyjnius resolves by name at runtime. Without them R8 renamed `PythonActivity` and dropped its static `mActivity` field, breaking pyjnius in release builds with `type object 'C.f' has no attribute 'mActivity'` (debug builds were unaffected).
+* Version bump aligning with the `serious_python_*` 4.1.0 release.
+
 ## 4.0.0
 
 * Ship the app as a *stored* `app.zip` asset in the APK and unpack it once (version-keyed) to `<application-support>/flet/app` on the first launch after install/update, via the new `prepareApp()`. The version-keyed unpack moved out of `run()`; user data in the sibling `<application-support>/data` is preserved across updates.

src/serious_python_android/android/build.gradle.kts

@@ -21,7 +21,7 @@ buildscript {
 }
 
 group = "com.flet.serious_python_android"
-version = "4.0.0"
+version = "4.1.0"
 
 rootProject.allprojects {
     repositories {
@@ -78,6 +78,10 @@ configure<LibraryExtension> {
         ndk {
             abiFilters.addAll(abis)
         }
+        // Keep rules for classes pyjnius / the native runtime resolve by name at
+        // runtime (e.g. PythonActivity.mActivity); merged into the consuming app's
+        // R8 pass so release builds don't obfuscate/strip them.
+        consumerProguardFiles("consumer-rules.pro")
     }
 
     // No jniLibs packaging config needed: the native modules are real ELF .so that

src/serious_python_android/android/consumer-rules.pro

@@ -0,0 +1,10 @@
+# Consumer ProGuard/R8 rules — automatically applied to apps that depend on
+# serious_python_android.
+#
+# pyjnius and the native runtime look these classes (and their members) up by
+# name via JNI/reflection at runtime. Without these keep rules, release-mode R8
+# minification renames/strips them — e.g. PythonActivity -> "C.f" and its static
+# `mActivity` field is dropped — which breaks pyjnius with:
+#   pyjnius: not available on this platform -
+#     type object 'C.f' has no attribute 'mActivity'
+-keep class com.flet.serious_python_android.** { *; }

src/serious_python_android/android/src/main/java/com/flet/serious_python_android/AndroidPlugin.java

@@ -5,6 +5,11 @@
 import androidx.annotation.NonNull;
 import android.system.Os;
 import android.content.Intent;
+import android.os.Handler;
+import android.os.Looper;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 
 import io.flutter.embedding.engine.plugins.FlutterPlugin;
 import io.flutter.embedding.engine.plugins.activity.ActivityAware;
@@ -31,6 +36,25 @@ public class AndroidPlugin implements FlutterPlugin, MethodCallHandler, Activity
   private MethodChannel channel;
   private Context context;
 
+  // Heavy native work (asset extraction/unzipping, native library loading) must
+  // NOT run on the platform main thread: it would block Android's Choreographer
+  // and starve Flutter's vsync, freezing on-screen animations (e.g. the boot
+  // spinner). Run it on a background executor and post the MethodChannel result
+  // back on the main thread (Flutter requires result callbacks there).
+  private final ExecutorService ioExecutor = Executors.newSingleThreadExecutor();
+  private final Handler mainHandler = new Handler(Looper.getMainLooper());
+
+  private void runAsync(@NonNull Result result, String errorCode, Callable<Object> work) {
+    ioExecutor.execute(() -> {
+      try {
+        Object value = work.call();
+        mainHandler.post(() -> result.success(value));
+      } catch (Throwable e) {
+        mainHandler.post(() -> result.error(errorCode, e.getMessage(), null));
+      }
+    });
+  }
+
   @Override
   public void onAttachedToEngine(@NonNull FlutterPluginBinding flutterPluginBinding) {
     channel = new MethodChannel(flutterPluginBinding.getBinaryMessenger(),
@@ -107,19 +131,30 @@ public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
       // Load a native library by name via Java's System.loadLibrary(), which —
       // unlike dart:ffi's dlopen-based DynamicLibrary.open used for
       // libdart_bridge — runs the library's JNI_OnLoad. That's how pyjnius's
-      // helper (libpyjni.so) captures the JavaVM + app ClassLoader. Called from
-      // app code here, so JNI_OnLoad sees the app's class loader.
-      try {
-        System.loadLibrary((String) call.argument("libname"));
-        result.success(null);
-      } catch (Throwable e) {
-        result.error("loadLibrary", e.getMessage(), null);
-      }
+      // helper (libpyjni.so) captures the JavaVM + app ClassLoader.
+      //
+      // Run off the main thread (dlopen + JNI_OnLoad can be slow). System.loadLibrary
+      // resolves the .so via the calling class's loader (AndroidPlugin -> app loader)
+      // regardless of thread, and JNI_OnLoad's FindClass uses that same loader; we
+      // also pin the worker's context loader to the app loader so JNI_OnLoad sees it
+      // if it reads the thread context loader.
+      final String libname = call.argument("libname");
+      runAsync(result, "loadLibrary", () -> {
+        Thread t = Thread.currentThread();
+        ClassLoader prev = t.getContextClassLoader();
+        t.setContextClassLoader(context.getClassLoader());
+        try {
+          System.loadLibrary(libname);
+        } finally {
+          t.setContextClassLoader(prev);
+        }
+        return null;
+      });
     } else if (call.method.equals("extractAsset")) {
       // Stream an APK asset to disk as one whole file (e.g. stdlib.zip).
-      try {
-        String asset = call.argument("asset");
-        String dest = call.argument("dest");
+      final String asset = call.argument("asset");
+      final String dest = call.argument("dest");
+      runAsync(result, "extractAsset", () -> {
         java.io.File destFile = new java.io.File(dest);
         if (destFile.getParentFile() != null) destFile.getParentFile().mkdirs();
         byte[] buf = new byte[1 << 16];
@@ -128,15 +163,13 @@ public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
           int n;
           while ((n = in.read(buf)) > 0) out.write(buf, 0, n);
         }
-        result.success(dest);
-      } catch (Exception e) {
-        result.error("extractAsset", e.getMessage(), null);
-      }
+        return dest;
+      });
     } else if (call.method.equals("unzipAsset")) {
       // Unpack an APK asset zip (e.g. extract.zip) into a directory tree.
-      try {
-        String asset = call.argument("asset");
-        String destDir = call.argument("dest");
+      final String asset = call.argument("asset");
+      final String destDir = call.argument("dest");
+      runAsync(result, "unzipAsset", () -> {
         java.io.File root = new java.io.File(destDir);
         byte[] buf = new byte[1 << 16];
         try (java.io.InputStream in = context.getAssets().open(asset);
@@ -155,10 +188,8 @@ public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
             }
           }
         }
-        result.success(destDir);
-      } catch (Exception e) {
-        result.error("unzipAsset", e.getMessage(), null);
-      }
+        return destDir;
+      });
     } else {
       result.notImplemented();
     }
@@ -167,6 +198,7 @@ public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
   @Override
   public void onDetachedFromEngine(@NonNull FlutterPluginBinding binding) {
     channel.setMethodCallHandler(null);
+    ioExecutor.shutdown();
   }
 
   @Override

src/serious_python_android/pubspec.yaml

@@ -2,7 +2,7 @@ name: serious_python_android
 description: Android implementation of the serious_python plugin
 homepage: https://flet.dev
 repository: https://github.com/flet-dev/serious-python
-version: 4.0.0
+version: 4.1.0
 
 environment:
   sdk: ">=3.0.0 <4.0.0"

src/serious_python_darwin/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 4.1.0
+
+* Version bump aligning with the `serious_python_*` 4.1.0 release.
+
 ## 4.0.0
 
 * **Swift Package Manager support (dual with CocoaPods).** The plugin now builds under SPM as well as CocoaPods, so apps can use either integration (CocoaPods goes read-only in December 2026; Flutter ships SPM on by default since 3.44). A new `darwin/serious_python_darwin/Package.swift` builds the same Swift source as the podspec, with `getResourcePath` resolving `Bundle.module` under SPM (`#if SWIFT_PACKAGE`) and the framework `python.bundle` under CocoaPods.

src/serious_python_darwin/darwin/serious_python_darwin.podspec

@@ -4,7 +4,7 @@
 #
 Pod::Spec.new do |s|
   s.name             = 'serious_python_darwin'
-  s.version          = '4.0.0'
+  s.version          = '4.1.0'
   s.summary          = 'A cross-platform plugin for adding embedded Python runtime to your Flutter apps.'
   s.description      = <<-DESC
   A cross-platform plugin for adding embedded Python runtime to your Flutter apps.

src/serious_python_darwin/pubspec.yaml

@@ -2,7 +2,7 @@ name: serious_python_darwin
 description: iOS and macOS implementations of the serious_python plugin
 homepage: https://flet.dev
 repository: https://github.com/flet-dev/serious-python
-version: 4.0.0
+version: 4.1.0
 
 environment:
   # The Swift Package Manager build path needs Flutter 3.44 / Dart 3.11 (the

src/serious_python_linux/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 4.1.0
+
+* Version bump aligning with the `serious_python_*` 4.1.0 release.
+
 ## 4.0.0
 
 * `prepareApp()` returns `<exeDir>/app`; the app's Python sources ship unpacked next to the bundled stdlib + site-packages (no first-launch extraction). The CMakeLists copies `SERIOUS_PYTHON_APP` into the bundle.

src/serious_python_linux/pubspec.yaml

@@ -2,7 +2,7 @@ name: serious_python_linux
 description: Linux implementations of the serious_python plugin
 homepage: https://flet.dev
 repository: https://github.com/flet-dev/serious-python
-version: 4.0.0
+version: 4.1.0
 
 environment:
   sdk: '>=3.1.3 <4.0.0'

src/serious_python_platform_interface/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 4.1.0
+
+* Version bump aligning with the `serious_python_*` 4.1.0 release.
+
 ## 4.0.0
 
 * Add `prepareApp()` to `SeriousPythonPlatform` — materializes the packaged app on disk (if needed) and returns the directory containing its entry point.

src/serious_python_platform_interface/pubspec.yaml

@@ -2,7 +2,7 @@ name: serious_python_platform_interface
 description: A common platform interface for the serious_python plugin.
 homepage: https://flet.dev
 repository: https://github.com/flet-dev/serious-python
-version: 4.0.0
+version: 4.1.0
 
 environment:
   sdk: ">=3.0.0 <4.0.0"

src/serious_python_windows/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 4.1.0
+
+* Version bump aligning with the `serious_python_*` 4.1.0 release.
+
 ## 4.0.0
 
 * `prepareApp()` returns `<exeDir>/app`; the app's Python sources ship unpacked next to the bundled CPython `Lib`/`DLLs`/`site-packages` (no first-launch extraction). The CMakeLists copies `SERIOUS_PYTHON_APP` into the runner output.

src/serious_python_windows/pubspec.yaml

@@ -2,7 +2,7 @@ name: serious_python_windows
 description: Windows implementations of the serious_python plugin
 homepage: https://flet.dev
 repository: https://github.com/flet-dev/serious-python
-version: 4.0.0
+version: 4.1.0
 
 environment:
   sdk: '>=3.1.3 <4.0.0'