Build hooks and code assets support in Flutter is available in stable since 3.38 and Dart 3.10: flutter create --template=package_ffi [package name].

Ongoing work for tree-shaking and other features related to hooks can be tracked in: Native Assets

A high level tracking issue for supporting native assets.

Native assets enables packages to specify a top-level build.dart that is invoked by launchers (dartdev and flutter_tools) to build/download native libraries and communicate back which native libraries need to be bundled and under which "asset id".

From a Flutter context, the native assets feature will enable testing native code with flutter test, which the FFI plugins do not support. From a Dart+Flutter context packages will be compatible with both Dart and Flutter, removing the need for publishing two versions on pub (one for Dart and one for Flutter).

More details can be found in:

• ☂️ [vm/ffi] Build hooks & Code assets dart-lang/sdk#50565

Current ongoing work can be tracked in: Native Assets

Dart standalone support has landed behind an experimental flag (dart --enable-experiment=native-assets).

This issue tracks implementing native assets in flutter tools

• MacOS
• iOS
  • Native Assets should use Framework instead of dylib on iOS. #140544
• Linux
• Android
  • Flutter app
  • Add2app
• Windows

Use cases that should be supported

• flutter run
  • debug
    • hot reload (1)
    • hot restart (1)
  • release/profile
• flutter build debug/release/profile
• flutter test / dart test
• add-2-app (e.g. flutter build macos-framework for MacOS)
• flutter run -dflutter-tester

Test coverage will be through end-to-end integration tests that exercise the dynamic libraries provided by packages.

Landing plan is to land this behind an experimental flag on the main branch only. This has the following benefits:

• Support for the various OSes can be in separate CLs, simplifying code review.
• We defer settling on the actual build.dart protocol until before we get it out of experimental. Users should not publish packages on pub.dev while this feature is in experimental phase.
• Making this available in experimental enables users to give this feature a spin without having to build their own version of Dart or Flutter. Getting their feedback is important to us to get this feature right.

Please feel free to note additional use cases that we have missed or ask questions on this issue.

Foot notes:

1. This does not bundle new native libraries, but the already bundled native libraries should be accessible.

References:

• Example package with native assets: https://github.com/dart-lang/native/tree/main/pkgs/hooks/example/build
• Dart tracking issue: ☂️ [vm/ffi] Build hooks & Code assets dart-lang/sdk#50565

cc @stuartmorgan @vashworth

Ongoing work related to native assets, build.dart and link.dart hooks:

• Native assets should be able to specify a privacy manifest #140966
  • Support privacy manifests for non-plugin packages calling required reason APIs directly via FFI #147186
• hook/link.dart support in flutter_tools #146263
• hook/build.dart Data assets support #146264
• hook/link.dart consume data assets from pubspec.yaml #146265
• [native_assets] Use kernel concatenation instead of passing in asset-mapping into kernel compilation #146270
  • Kernel snapshot input dependency tracking not working #147643
• [native assets] Inconsistent logging on error. #147544
• Native assets: visionOS support #142933
• [native_assets] There's two errors thrown by Xcode 15.3 when submitting Flutter apps built with native_assets to the App Store. #148044
• [macOS] Code-signing native assets #148051
• [native_assets] flutter clean should delete all native assets #151890
• [native_assets] Stop doing dry run in flutter run #154425
• [native_assets] package_ffi template language options #151646
• [native assets] Support flutter test integration_test #168961