src-* README

src-core/README.md

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+This package is Rust backend, which can be wrapped in [Tauri](/src-tauri) (using [WebView](/src-react) frontend).
+
+Some other ways to consume this package include [Flutter Rust Bridge](https://cjycode.com/flutter_rust_bridge/), see <https://github.com/patarapolw/cjdic2/tree/flutter-rust-bridge/flutter_app/rust>.

src-tauri/README.md

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+# Tauri + Vite
+
+Using Vite + React frontend at [/src-react](/src-react). Backend is decoupled from Tauri (frontend agnostic) at [/src-core](/src-core).
+
+## Development
+
+### Desktop (Windows, macOS, Linux)
+
+Run the development server:
+```bash
+pnpm dev:desktop
+```
+
+Build for production:
+```bash
+pnpm build:desktop
+```
+
+### Android Setup
+
+#### Prerequisites
+
+1. **Java Development Kit (JDK 17 or later)** - Download from [oracle.com](https://www.oracle.com/java/technologies/downloads/) or use a package manager
+2. **Android SDK** - Install via Android Studio or command line tools
+3. **NDK (Native Development Kit)** - Required for Rust compilation
+4. **Rust** - Install from [rustup.rs](https://rustup.rs/) with Android targets:
+   ```bash
+   rustup target add aarch64-linux-android armv7-linux-androideabi x86_64-linux-android i686-linux-android
+   ```
+5. **Rust Analyzer** for IDE support (optional but recommended)
+
+#### Environment Variables
+
+Set these environment variables:
+```bash
+# Windows (PowerShell)
+$env:JAVA_HOME = "C:\Program Files\Java\jdk-17" # Adjust path as needed
+$env:ANDROID_HOME = "$env:USERPROFILE\AppData\Local\Android\Sdk"
+$env:NDK_HOME = "$env:ANDROID_HOME\ndk\25.2.9519653" # Adjust NDK version as needed
+
+# macOS/Linux
+export JAVA_HOME=/path/to/jdk-17
+export ANDROID_HOME=$HOME/Android/Sdk
+export NDK_HOME=$ANDROID_HOME/ndk/25.2.9519653
+```
+
+#### Initial Setup
+
+Initialize the Android project:
+```bash
+pnpm init:android
+```
+
+#### Development & Testing
+
+Start development server for Android:
+```bash
+pnpm dev:android
+```
+
+Build debug APK:
+```bash
+pnpm build:android
+```
+
+Install APK on connected device:
+```bash
+pnpm install:android
+```
+
+Ensure you have a device connected via USB with USB debugging enabled, or an Android emulator running.
+
+#### Signing Release Builds
+
+Android APKs must be signed with a digital certificate to be installable on devices. See the [official Tauri Android signing documentation](https://v2.tauri.app/distribute/sign/android/) for detailed instructions.
+
+**Quick Summary:**
+
+1. **Create a keystore** using `keytool` (PKCS12 format is recommended over JKS):
+   ```bash
+   keytool -genkey -v -keystore ~/upload-keystore.p12 -keyalg RSA -keysize 2048 -validity 10000 -alias upload -storetype PKCS12
+   ```
+
+2. **Create a keystore.properties file** at `src-tauri/gen/android/keystore.properties`:
+   ```properties
+   password=<password from keytool>
+   keyAlias=upload
+   storeFile=<path to upload-keystore.p12>
+   ```
+   > Keep both the keystore and properties file private; don't commit them to version control.
+
+3. **Configure Gradle** in `src-tauri/gen/android/app/build.gradle.kts` to use the signing key for release builds.
+
+For CI/CD environments (e.g., GitHub Actions), use secrets to securely pass the keystore and credentials.
+
+#### Testing Mobile Screen Size on Desktop
+
+To test responsive design for mobile during development without deploying to a device:
+
+**Using Tauri Mobile Configuration:**
+   - Edit `src-tauri/tauri.mobile.conf.json` to adjust the window size for testing
+   - Run `pnpm dev:mobile` to test with mobile-specific settings