build(android): consume serious_python native-mmap packaging + --android-extract-packages

CHANGELOG.md

@@ -7,6 +7,7 @@
 
 ### Improvements
 
+* **Smaller Android apps with no native-packaging config.** `flet build apk`/`aab` consume serious_python's new Android packaging: Python extension modules load **memory-mapped directly from the APK** (no extraction to disk), and pure Python ships in stored asset zips read via `zipimport`, so the standard library is no longer duplicated per ABI. Apps no longer need `useLegacyPackaging` / `keepDebugSymbols` — the `flet build` Android template drops them; just use `minSdk 23+`. New `--android-extract-packages` flag and `[tool.flet.android].extract_packages` ship "path-hungry" packages — those that read bundled data via `__file__` / `pkg_resources` instead of `importlib.resources` — extracted to disk instead of inside the zip (most packages, including `certifi`, are zip-safe and need no entry). Requires `serious_python` with the native-mmap packaging (dart_bridge 1.4.0).
 * Pyodide is no longer pre-baked into the `flet build` template. Each `flet build web` / `flet publish` run downloads the matching `pyodide-core-<version>.tar.bz2` (plus the runtime `micropip` and `packaging` wheels) into a per-version cache at `~/.flet/pyodide/<version>/` and copies the files into the build output. Subsequent builds reuse the cache; the older `0.27.5` bundle previously shipped in the cookiecutter template is gone ([#6577](https://github.com/flet-dev/flet/pull/6577)) by @FeodorFitsner.
 * The supported Python / Pyodide / dart_bridge versions are loaded on demand from `flet-dev/python-build`'s date-keyed `manifest.json` (fetched once and cached under `~/.flet/cache`), the single source of truth shared with `serious_python` — replacing flet's hand-mirrored version table. `flet build` forwards only `SERIOUS_PYTHON_VERSION` and lets `serious_python` derive the full version / build date / dart_bridge version from its own committed snapshot. The module exposes `get_supported_python_versions()` / `get_default_python_version()` (the previous `SUPPORTED_PYTHON_VERSIONS` / `DEFAULT_PYTHON_VERSION` constants are removed) ([#6577](https://github.com/flet-dev/flet/pull/6577)) by @FeodorFitsner.
 * `flet --version` shows just the Flet and Flutter versions; the static `Pyodide: …` line and the global `flet.version.pyodide_version` export are removed (the supported Python / Pyodide set now lives in python-build's manifest, not the CLI output) ([#6577](https://github.com/flet-dev/flet/pull/6577)) by @FeodorFitsner.

sdk/python/_typos.toml

@@ -4,3 +4,5 @@ AACHE = "AACHE"
 ROUTEROS = "ROUTEROS"
 # OpenType variable font axis tag for width
 wdth = "wdth"
+# Python package name (Mozilla CA bundle)
+certifi = "certifi"

sdk/python/packages/flet-cli/src/flet_cli/commands/build_base.py

@@ -42,6 +42,18 @@
     "v{version}/flet-build-template.zip"
 )
 
+# Android (serious_python native-mmap packaging): pure Python ships in stored zips
+# read via zipimport, which breaks packages that read bundled data through a real
+# filesystem path (__file__ / pkg_resources) instead of importlib.resources. Such
+# packages are shipped extracted to disk via --android-extract-packages or
+# [tool.flet.android].extract_packages.
+#
+# The default set is empty: the common offenders read their data via
+# importlib.resources, which is zip-safe (e.g. certifi.where() works from the zip —
+# importlib.resources.as_file() extracts cacert.pem to a temp file on demand). Add
+# real offenders here as they are found.
+ANDROID_DEFAULT_EXTRACT_PACKAGES: list[str] = []
+
 
 class BaseBuildCommand(BaseFlutterCommand):
     """
@@ -505,6 +517,15 @@ def add_arguments(self, parser: argparse.ArgumentParser) -> None:
             default=[],
             help="The list of Python packages to install from source distributions",
         )
+        parser.add_argument(
+            "--android-extract-packages",
+            dest="android_extract_packages",
+            nargs="+",
+            default=[],
+            help="Android only: Python packages (relative paths) to ship extracted "
+            "to disk instead of inside the app zip — for packages that read bundled "
+            "data via __file__ / pkg_resources rather than importlib.resources",
+        )
         parser.add_argument(
             "--python-version",
             dest="python_version",
@@ -2037,6 +2058,26 @@ def package_python_app(self):
                 source_packages
             )
 
+        # android-extract-packages: path-hungry packages shipped extracted to disk
+        # instead of inside the zip (serious_python Android native-mmap packaging).
+        # A built-in default set covers commonly-broken packages; the user list
+        # (CLI / pyproject) is merged on top. Consumed by the serious_python_android
+        # Gradle split during `flutter build`, so the env var is set on build_env
+        # (see _run_flutter_command), not on the package step.
+        self.android_extract_packages: list[str] = []
+        if self.package_platform == "Android":
+            user_extract_packages = (
+                self.options.android_extract_packages
+                or self.get_pyproject(
+                    f"tool.flet.{self.config_platform}.extract_packages"
+                )
+                or self.get_pyproject("tool.flet.extract_packages")
+                or []
+            )
+            self.android_extract_packages = list(
+                dict.fromkeys(ANDROID_DEFAULT_EXTRACT_PACKAGES + user_extract_packages)
+            )
+
         if self.get_bool_setting(self.options.compile_app, "compile.app", False):
             package_args.append("--compile-app")
 
@@ -2232,6 +2273,13 @@ def _run_flutter_command(self):
                 self.build_dir / "site-packages"
             )
 
+        # Path-hungry packages to ship extracted to disk: consumed by the
+        # serious_python_android Gradle split during `flutter build`.
+        if self.package_platform == "Android" and self.android_extract_packages:
+            build_env["SERIOUS_PYTHON_ANDROID_EXTRACT_PACKAGES"] = ",".join(
+                self.android_extract_packages
+            )
+
         if self.package_platform == "Emscripten" and not self.template_data["no_wasm"]:
             build_args.append("--wasm")
 

sdk/python/templates/build/{{cookiecutter.out_dir}}/android/app/build.gradle.kts

@@ -23,17 +23,10 @@ android {
     compileSdk = flutter.compileSdkVersion
     ndkVersion = flutter.ndkVersion
 
-    packaging {
-        jniLibs {
-            useLegacyPackaging = true
-            keepDebugSymbols += listOf(
-                "*/arm64-v8a/libpython*.so",
-                "*/armeabi-v7a/libpython*.so",
-                "*/x86/libpython*.so",
-                "*/x86_64/libpython*.so",
-            )
-        }
-    }
+    // No native-library packaging config is needed: serious_python loads Python
+    // extension modules directly from the APK (memory-mapped) and ships pure
+    // Python in stored asset zips. Modern packaging (the default at minSdk 23+)
+    // is all that's required.
 
     compileOptions {
         sourceCompatibility = JavaVersion.VERSION_17

sdk/python/templates/build/{{cookiecutter.out_dir}}/pubspec.yaml

@@ -17,13 +17,14 @@ dependencies:
 
   flet:
     path: ../../../../../packages/flet
-  # PythonBridge (in-process dart_bridge FFI transport) ships on the
-  # serious-python `dart-bridge` branch. Swap back to a version pin
-  # (`serious_python: ^2.0.0`) once it's published to pub.dev.
+  # PythonBridge (in-process dart_bridge FFI transport) + the Android
+  # native-mmap packaging ship on the serious-python `android-native-mmap`
+  # branch. Swap back to a version pin (`serious_python: ^2.0.0`) once it's
+  # published to pub.dev.
   serious_python:
     git:
       url: https://github.com/flet-dev/serious-python.git
-      ref: dart-bridge
+      ref: android-native-mmap
       path: src/serious_python
 
   # MsgPack codec used by the dart_bridge FletBackendChannel implementation

website/docs/publish/index.md

@@ -695,6 +695,45 @@ source_packages = ["package1", "package2"]
 </TabItem>
 </Tabs>
 
+### Android extract packages
+
+:::note
+[Android](android.md) only.
+:::
+
+On Android, pure Python ships in a stored zip read in place (`zipimport`) and native modules are
+loaded memory-mapped from the APK. Packages that read their bundled **data files** through a real
+filesystem path — `__file__` / `pkg_resources` instead of
+[`importlib.resources`](https://docs.python.org/3/library/importlib.resources.html) — don't work
+from inside the zip. List such "path-hungry" packages here to ship them **extracted to disk**
+instead.
+
+Most packages that bundle data (including `certifi`) read it through `importlib.resources`, which
+is zip-safe, so they need no entry here — only add packages that actually fail to find their data
+when imported from the zip.
+
+#### Resolution order
+
+1. [`--android-extract-packages`](../cli/flet-build.md#--android-extract-packages)
+2. `[tool.flet.android].extract_packages`
+3. `[tool.flet].extract_packages`
+
+#### Example
+
+<Tabs groupId="flet-build--pyproject-toml">
+<TabItem value="flet-build" label="flet build">
+```bash
+flet build apk --android-extract-packages package1 package2
+```
+</TabItem>
+<TabItem value="pyproject-toml" label="pyproject.toml">
+```toml
+[tool.flet.android]
+extract_packages = ["package1", "package2"]
+```
+</TabItem>
+</Tabs>
+
 ### Icons
 
 :::note[Platform support]