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AI Chat Flutter

Chat app for OpenRouter.ai and VseGPT.ru written in Flutter (Dart). Builds into an Android APK right on GitHub Actions - no local Android SDK, JDK, or macOS required.

Twin project: the same app implemented in Python (Flet) - see android_flet_aichat.

Features

• Chat with OpenRouter.ai and VseGPT.ru models, balance in $ or ₽ depending on the provider
• 4-digit PIN login: on first launch you enter your API key, the app detects the provider by the key prefix (sk-or-v1- - OpenRouter, sk-or-vv- - VseGPT), checks the balance and generates a PIN. The key and the PIN hash are stored in SQLite
• PIN login on subsequent launches: a wrong PIN shows an error, "Reset key" suggests entering a new one
• Multi-page app with bottom navigation - 4 pages:
  • Chat - the main page with the model selector and per-message cost
  • Provider settings - current provider, masked key, balance refresh, key reset
  • Token statistics - messages, tokens and spending per model
  • Spending chart - bar chart of daily spending for the last 14 days
• Chat history in SQLite, JSON export, copy to clipboard
• Dark theme, Material 3

Screenshots

First login: API key entry

Generated PIN: shown once, required for the next login

Next launches: 4-digit PIN login, key reset button

Chat page: OpenRouter, balance, AI response, per-message cost

Chat page: VseGPT

Provider settings: OpenRouter, masked key, balance, reset

Provider settings: VseGPT

Token statistics: messages, tokens and spending per model

Spending chart: daily costs for the last 14 days

Installing the APK

The ready-to-install APK is available in the releases of this repository:

1. Open the Releases page and download the APK from the attachments of the latest release (Assets)
2. Install the APK on an Android device
3. Allow installing from unknown sources on first launch

You can also grab a fresh build from Actions:

1. Open the Actions tab of this repository
2. Pick the latest Build APK run and download the aichat-apk artifact
3. Install the APK on an Android device

Authentication

The login screen works in two modes:

• First login - enter the API key. The app detects the provider by the prefix: sk-or-vv-... - VseGPT, sk-or-v1-... - OpenRouter. Any other prefix is rejected. The key is validated through the balance endpoint (/balance for VseGPT, /credits for OpenRouter). For a valid key the app generates a random 4-digit PIN and shows it once in a dialog - remember it for the next login. If the balance is not positive, a warning is shown but the login is allowed
• PIN login - enter the 4-digit PIN. The PIN is checked against the SHA-256 hash stored in SQLite; a wrong PIN shows an error. The "Reset key" button deletes the saved key and PIN and switches the screen back to key entry

Key validation errors are distinguished by cause: "Key not found or invalid" (API responded 401/403) or "No connection to the provider server" - no internet or blocking.

Project structure

├── lib/
│   ├── api/
│   │   └── api_client.dart       - unified API client, provider detection
│   │                               by key prefix, key validation
│   ├── models/
│   │   └── message.dart          - message model with tokens and cost
│   ├── providers/
│   │   ├── auth_provider.dart    - PIN/key login state
│   │   └── chat_provider.dart    - chat state, models, balance, history
│   ├── services/
│   │   ├── auth_service.dart     - PIN generation, SHA-256 hashing
│   │   ├── database_service.dart - SQLite: messages + auth table (v2)
│   │   └── analytics_service.dart - usage statistics
│   ├── screens/
│   │   ├── login_screen.dart     - PIN/key login (first and repeat)
│   │   ├── home_screen.dart      - bottom navigation shell (4 pages)
│   │   ├── chat_screen.dart      - main chat page
│   │   ├── settings_screen.dart  - provider settings, key management
│   │   ├── stats_screen.dart     - token statistics per model
│   │   └── spending_screen.dart  - daily spending chart (fl_chart)
│   └── main.dart                 - entry point, theme, AuthGate
├── .github/workflows/
│   └── build-apk.yml             - GitHub Actions: flutter build apk
├── assets/                       - app icon
├── android/                      - Android platform files
├── pubspec.yaml                  - dependencies
└── README.md

Building locally (optional)

flutter pub get
flutter build apk --release

The APK is saved to build/app/outputs/flutter-apk/app-release.apk. A local Flutter SDK (3.47.2) and an Android SDK are required.

License

MIT