Android: Bevy-native implementation plan

Prerequisite

Phase 1 below cannot start until mir stops depending on honeycrisp unconditionally — unimem links IOSurface and CoreFoundation, so mir does not compile for Android at all. See portable-backends.md P1. Paths in this file predate the bevy/ → shell/ rename and are corrected below.

Principle

Android cyb = desktop cyb. One codebase, one binary, same Bevy app, same worlds, same terminal, same nushell. Android adds nu_plugin_android for hardware APIs. Nothing else differs.

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Phase 1 — Bevy entry point on Android

Replace the current tao + wry Android stub with Bevy's native Android backend.

1.1 Cargo changes

shell/Cargo.toml:

• Add android-activity as optional dep (Bevy's Android backend requires it)
• Android feature activates: bevy/android, android-activity, all nu-* deps (same as desktop minus nu-cli)
• Remove dep:tao and dep:android_logger from android feature — Bevy handles the event loop and logging

shell/Cargo.toml workspace root:

• Add android-activity to workspace deps

1.2 Entry point

shell/src/lib.rs — replace current pub mod android stub with:

#[cfg(target_os = "android")]
#[no_mangle]
fn android_main(app: android_activity::AndroidApp) {
    // Identical to main() — all the same plugins
    let mut app = App::new();
    app.add_plugins(DefaultPlugins.set(WindowPlugin { ... }));
    // ... every plugin desktop uses ...
    app.run();
}

The DefaultPlugins with bevy_winit already handles the Android window lifecycle via android-activity. No custom event loop needed.

1.3 AndroidManifest.xml

shell/gen/android/app/src/main/AndroidManifest.xml:

• Change activity class from WryActivity to com.google.androidgamesdk.GameActivity (android-activity's GameActivity backend, which Bevy uses by default)
• Add required permissions for later phases: ACCESS_FINE_LOCATION, CAMERA, INTERNET

1.4 Delete android/mod.rs

shell/src/android/ directory and lib.rs reference to it are removed entirely. The tao/wry Android entry point is gone.

1.5 Gradle

shell/gen/android/app/build.gradle.kts:

• Add android-games-sdk dependency for GameActivity
• Update CMakeLists / jniLibs to load libcyb.so (already there, no change)

Verification

make android cross-compiles and the app launches showing Bevy's splash world on device.

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Phase 2 — Terminal world on Android

worlds/terminal/mod.rs runs unchanged. sugarloaf uses wgpu → Android Vulkan/GLES. alacritty_terminal is pure Rust. nushell is pure Rust.

2.1 Android environment init

shell/assets/nu-config/android.nu — new file, sourced after env.nu on Android only:

# Android-specific environment setup
$env.PATH = ($env.PATH | prepend ["/system/bin" "/system/xbin" $"($env.HOME)/bin"])
$env.TERM = "xterm-256color"

init_nushell_engine() in terminal.rs:

• Detect Android via #[cfg(target_os = "android")]
• Set $HOME to android_activity::AndroidApp::internal_data_path() (passed in at startup via a resource)
• Source android.nu after config.nu

2.2 Soft keyboard

Bevy's Window::ime_enabled = true triggers Android soft keyboard. The terminal's OnEnter system sets this. Existing process_keyboard_input handles KeyboardInput events from Android IME unchanged — Bevy normalizes them.

Touch tap on terminal surface → Window::ime_position → soft keyboard appears. No extra code.

Verification

Terminal world launches on Android, nushell prompt appears, commands like ls /system/bin, ps, curl https://... work. toybox external commands work via $PATH.

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Phase 3 — nu_plugin_android

New workspace crate: cyb/nu_plugin_android/

Architecture

nushell engine
  └─ registers plugin at startup (Android-only)
       └─ nu_plugin_android (Rust crate)
            └─ JNI bridge
                 └─ Android APIs (Java/Kotlin via JavaVM)

The plugin is not a separate process (standard nushell plugin protocol) — it's registered inline as an InProcessPlugin to avoid the process-spawn overhead on mobile.

Commands

Command	Android API	Permission
android gps [--watch]	LocationManager / Fused Location	ACCESS_FINE_LOCATION
android camera [--front]	CameraX	CAMERA
android sensors list	SensorManager	none
android sensors read <type>	SensorManager	none
android intent --action <a> --data <d>	Intent	none
android clipboard get	ClipboardManager	none
android clipboard set <text>	ClipboardManager	none
android notify --title <t> --body <b>	NotificationManager	POST_NOTIFICATIONS
android contacts	ContentResolver	READ_CONTACTS
android wifi	WifiManager	ACCESS_WIFI_STATE
android battery	BatteryManager	none

Implementation notes

• jni crate (already in Android ecosystem) for JVM calls from Rust
• android-activity gives access to JavaVM — pass it to plugin at init
• Each command blocks on JVM call, returns structured Value (record/table)
• android gps --watch streams records via PipelineData::ListStream

Registration

terminal/mod.rs → init_nushell_engine():

#[cfg(target_os = "android")]
{
    let plugin = nu_plugin_android::AndroidPlugin::new(jvm.clone());
    engine_state.add_plugin(Box::new(plugin));
}

Verification

android battery          # → {level: 87, charging: true, ...}
android gps              # → {lat: 55.75, lon: 37.61, accuracy: 4.2}
android sensors list     # → table of available sensors
android clipboard get    # → "text from clipboard"

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File change summary

File	Change
shell/Cargo.toml	android feature: swap tao/wry for bevy/android + nu-* deps
shell/src/lib.rs	replace pub mod android with android_main fn
shell/src/android/	delete entirely
shell/gen/android/app/src/main/AndroidManifest.xml	GameActivity, add permissions
shell/gen/android/app/build.gradle.kts	GameActivity dep
shell/assets/nu-config/android.nu	new: Android PATH/HOME setup
shell/src/worlds/terminal/mod.rs	add Android HOME init (cfg-gated, ~5 lines)
cyb/nu_plugin_android/	new crate
cyb/Cargo.toml	add nu_plugin_android to workspace
cyb/CLAUDE.md	one binary rule (done)

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Effort estimate

Phase	Sessions
Phase 1 — Bevy entry point	2–3
Phase 2 — Terminal on Android	1
Phase 3 — nu_plugin_android	4–5
Total	7–9

Excludes the prerequisite — portable-backends.md P1 costs 1–2 sessions before any of this compiles.