feat: build the APK directly from Termux on Android

patches/xbuild/xbuild/src/gradle/mod.rs

@@ -92,7 +92,19 @@ pub fn build(env: &BuildEnv, libraries: Vec<(Target, PathBuf)>, out: &Path) -> R
     }
     std::fs::create_dir_all(&assets)?;
     std::fs::write(gradle.join("build.gradle"), BUILD_GRADLE)?;
-    std::fs::write(gradle.join("gradle.properties"), GRADLE_PROPERTIES)?;
+    // On Android hosts (e.g. Termux), AGP bundles an x86_64 Linux aapt2 that cannot
+    // run on ARM64. If a native aapt2 is available in PATH, override the bundled one.
+    let mut gradle_props = GRADLE_PROPERTIES.to_vec();
+    if cfg!(target_os = "android") {
+        if let Ok(aapt2_path) = which::which("aapt2") {
+            let override_line = format!(
+                "\n# Termux: use native ARM64 aapt2 instead of the x86_64 binary bundled in AGP\nandroid.aapt2FromMavenOverride={}\n",
+                aapt2_path.display()
+            );
+            gradle_props.extend_from_slice(override_line.as_bytes());
+        }
+    }
+    std::fs::write(gradle.join("gradle.properties"), &gradle_props)?;
     std::fs::write(gradle.join("settings.gradle"), SETTINGS_GRADLE)?;
 
     let config = env.config().android();

patches/xbuild/xbuild/src/lib.rs

@@ -51,7 +51,7 @@ pub enum Platform {
 
 impl Platform {
     pub fn host() -> Result<Self> {
-        Ok(if cfg!(target_os = "linux") {
+        Ok(if cfg!(target_os = "linux") || cfg!(target_os = "android") {
             Platform::Linux
         } else if cfg!(target_os = "macos") {
             Platform::Macos

scripts/build-termux.sh

@@ -0,0 +1,95 @@
+#!/data/data/com.termux/files/usr/bin/bash
+# build-termux.sh — Build LocalDesktop APK from Termux on Android
+#
+# Usage:
+#   bash scripts/build-termux.sh
+#
+# The script is idempotent: already-installed packages and already-downloaded
+# SDK components are skipped automatically.
+
+set -e
+
+REPO_ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+ANDROID_HOME="${ANDROID_HOME:-$HOME/.cache/x/Android.sdk}"
+CARGO_BIN="$HOME/.cargo/bin"
+
+echo "==> LocalDesktop Termux build"
+echo "    Repo:         $REPO_ROOT"
+echo "    ANDROID_HOME: $ANDROID_HOME"
+echo ""
+
+# ---------------------------------------------------------------------------
+# 1. Termux dependencies
+# ---------------------------------------------------------------------------
+echo "[1/5] Installing Termux packages..."
+pkg install -y rust openjdk-17 gradle ndk-multilib aapt2 2>/dev/null | tail -3
+
+# ---------------------------------------------------------------------------
+# 2. PATH setup
+# ---------------------------------------------------------------------------
+export PATH="$CARGO_BIN:$HOME/bin:$PATH"
+export ANDROID_HOME
+
+# Fake rustup shim: xbuild calls `rustup target add` to check targets.
+# Termux's Rust already ships the aarch64-linux-android target.
+RUSTUP_SHIM="$HOME/bin/rustup"
+if [ ! -f "$RUSTUP_SHIM" ]; then
+    echo "[2/5] Installing rustup shim..."
+    mkdir -p "$HOME/bin"
+    cat > "$RUSTUP_SHIM" << 'EOF'
+#!/data/data/com.termux/files/usr/bin/bash
+if [ "$1" = "target" ] && [ "$2" = "add" ]; then
+    echo "info: component 'rust-std' for target '${3}' is up to date"
+    exit 0
+fi
+echo "rustup shim: unsupported command: $*" >&2
+exit 1
+EOF
+    chmod +x "$RUSTUP_SHIM"
+else
+    echo "[2/5] rustup shim already present."
+fi
+
+# ---------------------------------------------------------------------------
+# 3. xbuild (patched fork — Android host support + AGP/KGP compatibility)
+# ---------------------------------------------------------------------------
+echo "[3/5] Installing xbuild..."
+# MALLOC_TAG_LEVEL=0 avoids an LLVM/lld crash caused by Android pointer tagging
+MALLOC_TAG_LEVEL=0 cargo install --path "$REPO_ROOT/patches/xbuild/xbuild" --force \
+    2>&1 | grep -E "Compiling xbuild|Replacing|Installed|error" || true
+
+# ---------------------------------------------------------------------------
+# 4. Android SDK build-tools
+# ---------------------------------------------------------------------------
+echo "[4/5] Downloading Android SDK components..."
+mkdir -p "$ANDROID_HOME/licenses"
+# Accept standard SDK licenses
+printf "24333f8a63b6825ea9c5514f83c2829b004d1fee\n8933bad161af4178b1185d1a37fbf41ea5269c55\nd56f5187479451eabf01fb78af6dfcb131a6481e\n" \
+    > "$ANDROID_HOME/licenses/android-sdk-license"
+printf "84831b9409646a918e30573bab4c9c91346d8abd\n" \
+    > "$ANDROID_HOME/licenses/android-sdk-preview-license"
+
+if [ ! -d "$ANDROID_HOME/build-tools/34.0.0" ]; then
+    MALLOC_TAG_LEVEL=0 cargo run --manifest-path "$REPO_ROOT/Cargo.toml" \
+        --bin download_sdk 2>&1 | grep -v "^   Compiling\|^    Checking\|^warning"
+else
+    echo "    build-tools;34.0.0 already present."
+fi
+
+# ---------------------------------------------------------------------------
+# 5. Build APK
+# ---------------------------------------------------------------------------
+echo "[5/5] Building APK..."
+cd "$REPO_ROOT"
+MALLOC_TAG_LEVEL=0 x build --release --platform android --arch arm64 --format apk
+
+APK="$REPO_ROOT/target/x/release/android/localdesktop.apk"
+if [ -f "$APK" ]; then
+    echo ""
+    echo "✅ Build successful!"
+    echo "   APK: $APK"
+    echo "   Size: $(du -h "$APK" | cut -f1)"
+else
+    echo "❌ Build failed — APK not found." >&2
+    exit 1
+fi

src/bin/download_sdk.rs

@@ -0,0 +1,25 @@
+/// One-shot utility: download Android SDK build-tools;34.0.0 into ANDROID_HOME.
+/// Usage: cargo run --bin download_sdk
+use std::path::PathBuf;
+
+fn main() {
+    let android_home = std::env::var("ANDROID_HOME")
+        .unwrap_or_else(|_| format!("{}/.cache/x/Android.sdk", std::env::var("HOME").unwrap()));
+    let sdk_dir = PathBuf::from(&android_home);
+    let build_tools_dir = sdk_dir.join("build-tools").join("34.0.0");
+
+    if build_tools_dir.exists() {
+        println!("build-tools;34.0.0 already present at {}", build_tools_dir.display());
+        return;
+    }
+
+    println!("Downloading build-tools;34.0.0 into {}...", android_home);
+    android_sdkmanager::download_and_extract_packages(
+        &android_home,
+        android_sdkmanager::HostOs::Linux,
+        &["build-tools;34.0.0"],
+        None,
+    );
+
+    println!("Done. build-tools are at {}", build_tools_dir.display());
+}