The public API is Pigeon-based and intentionally uses a generic JSON profile boundary. Flutter can add strongly typed editors over time while the native API stays stable across sing-box protocol/schema updates.

Current state:

Builds sing-box JSON for multiple simultaneous profile outbounds.
Creates one authenticated local SOCKS inbound per active profile.
Returns runtime endpoint metadata for Gecko container proxy integration.
Exposes status/log callbacks.
Starts libbox via reflection against the io.nekohasekai.libbox.* classes shipped in the AAR — if the AAR is missing, the plugin still compiles but start reports an IllegalStateException at runtime.

Building official sing-box libbox

The plugin does not commit binary AARs. Build them from the official sing-box checkout before release/F-Droid builds:

packages/flutter_singbox_proxy/scripts/build-libbox-android.sh \
  --source /path/to/sing-box

By default the script looks for ../../../sing-box relative to this package, which matches the local workspace layout used during development. It copies libbox.aar into android/libs/; Gradle consumes that AAR automatically when present.

For F-Droid metadata, call the package-local prebuild script:

packages/flutter_singbox_proxy/scripts/fdroid-prebuild.sh \
  --source /path/to/sing-box

The build requires OpenJDK 17, Go, Android SDK/NDK, and gomobile/gobind. If JAVA_HOME is unset and /usr/lib/jvm/java-17-openjdk exists, the script uses that automatically. If gomobile/gobind are missing, the script installs the official SagerNet gomobile tools with go install.

Version compatibility

The script pins github.com/sagernet/gomobile/cmd/gomobile@v0.1.12 and gobind@v0.1.12. The sing-box source itself is whatever you point --source at; the runtime accesses io.nekohasekai.libbox.* via reflection, so API drift across sing-box releases surfaces as a NoSuchMethodException at start time rather than a build failure. When bumping sing-box:

Rebuild the AAR with the new tag.
Smoke-test start/stop on a profile to catch missing/renamed setup methods (notably SetupOptions.setOomKillerDisabled / setOomKillerEnabled — LibboxRuntime falls back between the two).
Update this README with the verified sing-box tag if relying on it for a release.