Lemonade Desktop App (Tauri)

A native desktop GUI for interacting with the Lemonade Server.

Overview

This app provides a native desktop experience for managing models and chatting with LLMs running on lemond. It connects to the server via HTTP API and offers a modern, resizable panel-based interface.

It is built with Tauri v2, which embeds the operating system's native webview — WebView2 on Windows, WKWebView on macOS, and webkit2gtk on Linux — instead of bundling Chromium. The renderer is a standard React 19 + TypeScript application served by webpack and shared with the browser-only src/web-app/ build.

Key Features: - Model management (list, pull, load/unload) - Chat interface with markdown/code rendering and LaTeX support - Real-time server log viewer - Persistent layout and inference settings - Custom frameless window with zoom controls - lemonade:// deep-link protocol handler - UDP beacon discovery to find a running lemond server on the local machine

Deployment Topology

The Tauri desktop app is a thin client for a separately-running lemond server. A single lemond can be driven by multiple clients at once, including clients running on other machines.

Consequences that callers of this code need to know about:

Per-client local state. All user-tunable state (inference params, layout sizes, zoom, base URL, API key) lives in ~/.cache/lemonade/app_settings.json on the client, owned by the Rust host (src-tauri/src/settings.rs). It is never stored or proxied through lemond, because two clients against the same server must be able to hold different preferences.
The desktop app does not manage lemond's lifecycle. The server is started independently — on Windows by LemonadeServer.exe (auto-started via the startup folder, tray icon always visible), on Linux/macOS by the user or a service. The Tauri app is opened on demand and must not add itself to autostart, spawn lemond as a subprocess, or assume lemond is on the same machine.
Discovery is best-effort local + explicit remote. beacon.rs listens for a UDP broadcast emitted by a local lemond to auto-populate the base URL. For remote-server use, the user sets baseURL + apiKey in settings and the client talks to that endpoint directly.

Code Structure

src/app/
├── package.json                   # Webpack + Tauri CLI devDependencies
├── webpack.config.js              # Bundler config (target: web)
├── tsconfig.json                  # TypeScript config
├── assets/                        # Icons, logos
│
├── src/
│   ├── global.d.ts                # window.api type declaration
│   └── renderer/                  # React UI (TypeScript)
│       ├── index.tsx              # Renderer entry (imports tauriShim first)
│       ├── tauriShim.ts           # Installs window.api → Tauri invoke() bridge
│       ├── App.tsx                # Root component, layout orchestration
│       ├── TitleBar.tsx           # Custom window controls
│       ├── ModelManager.tsx       # Model list and actions
│       ├── ChatWindow.tsx         # LLM chat interface
│       ├── LogsWindow.tsx         # Server log viewer
│       ├── SettingsPanel.tsx      # Inference parameters
│       └── utils/                 # API helpers and config
│
└── src-tauri/                     # Rust host (Tauri backend)
    ├── Cargo.toml                 # Rust dependencies
    ├── tauri.conf.json            # Window config, bundle settings, plugins
    ├── build.rs                   # tauri_build::build()
    ├── capabilities/default.json  # Tauri permissions
    ├── icons/                     # Generated app icons (32x32/128x128/ico/icns)
    └── src/
        ├── main.rs                # Entry point (binary)
        ├── lib.rs                 # Tauri builder, plugin wiring, deep-link routing
        ├── commands.rs            # #[tauri::command] handlers (window, settings, port)
        ├── events.rs              # Tauri event channel name constants
        ├── settings.rs            # app_settings.json read/write + sanitize
        ├── beacon.rs              # UDP beacon listener (single bound socket)
        ├── tray_launcher.rs       # macOS-only tray auto-start helper
        └── webview_shim.rs        # Per-platform webview hooks (mic permission, link interception)

/health, /system-stats, and /system-info are NOT proxied through Rust. The renderer fetches them directly via serverConfig.fetch(...); see StatusBar.tsx and AboutModal.tsx.

Architecture

┌────────────────────────────────────────────────┐
│  Tauri Rust Host (src-tauri/)                  │
│  Window mgmt, IPC commands, background tasks   │
│  UDP beacon listener, settings file I/O        │
├────────────────────────────────────────────────┤
│  tauriShim.ts (installs window.api in webview) │
│  Maps window.api.* → invoke() / listen()       │
├────────────────────────────────────────────────┤
│  React Renderer (TypeScript)                   │
│  Source lives in src/app/src/; the web-app     │
│  build (src/web-app/) reuses it via webpack    │
│  relative entry/template paths — no symlinks.  │
├────────────────────────────────────────────────┤
│  HTTP API → lemond (C++ server)                │
└────────────────────────────────────────────────┘

Prerequisites

Node.js 20 or higher (webpack)
Rust toolchain via rustup (Rust 1.77+)
Linux only: libwebkit2gtk-4.1-dev, libsoup-3.0-dev, libjavascriptcoregtk-4.1-dev, librsvg2-dev, libayatana-appindicator3-dev — the repo's setup.sh script checks for these and prompts to install them.
Windows only: WebView2 runtime (pre-installed on Windows 10 1803+ and Windows 11).
macOS only: No extra dependencies — WKWebView ships with the OS.

Building

cd src/app

# Install webpack + Tauri CLI dependencies
npm ci

# Run in dev mode (opens a window, hot-reloads webpack)
npm run dev

# Production build (single binary, no OS bundles)
npm run build -- --no-bundle

# Production build with platform bundles (macOS .app, Linux .deb/.rpm, Windows MSI/NSIS)
npm run build

The preferred path for shipping is through CMake, which stages the Tauri output alongside the rest of the server:

cmake --build --preset default --target tauri-app      # Linux / macOS
cmake --build --preset windows --target tauri-app      # Windows

Development Scripts

npm run dev                    # Tauri dev mode (window + hot-reload)
npm run build                  # Tauri production build
npm run tauri icon <path>      # Regenerate icons from a source image
npm run build:renderer         # Build just the renderer (webpack, dev mode)
npm run build:renderer:prod    # Build just the renderer (webpack, production)
npm run watch:renderer         # Webpack watch mode for the renderer only

Testing the Rust host

Unit tests live alongside the Rust modules and cover settings sanitization, beacon parsing, and deep-link URL parsing:

cargo test --manifest-path src-tauri/Cargo.toml