Architecture overview

Understand how the Tauri shell, local Harness service, and embedded web UI work together.

DeepSeek Harness Desktop is a Tauri 2 application that manages a local Harness service and displays its web interface inside a native window.

Architecture diagram

This diagram shows the local runtime path: the desktop UI communicates with the Rust backend through Tauri commands. The backend manages a separate Harness service process, and the embedded client accesses it through a loopback address.

+---------------------------+      +---------------------------+
| Tauri window / WebView    |      | Native backend            |
| Desktop UI (React)        |<---->| Rust / Tauri 2            |
| Settings, profiles, etc.  | IPC  | Runtime & service manager |
|                           |      +-------------+-------------+
| +-----------------------+ |                    |
| | Embedded Harness UI   | |          launch / stop / health
| | (iframe)              | |                    |
| +-----------+-----------+ |                    v
+-------------|-------------+      +---------------------------+
              +------------------->| Local Harness service     |
                 127.0.0.1:<port>  | Node.js / dsh             |
                                   | Sessions, tools, plugins  |
                                   +-------------+-------------+
                                                 |
                                   +-------------+-------------+
                                   |                           |
                                   v                           v
                          +----------------+          +----------------+
                          | Local data &   |          | Model provider |
                          | workspace      |          | APIs           |
                          +----------------+          +----------------+

IPC represents commands and events between the desktop UI and native backend. Local data includes profiles and sessions. Component boundaries are not security sandboxes: tools and plugins can still execute local code.

Main layers

Layer	Technology	Responsibility
Desktop UI	React 19, TypeScript, Vite, Tailwind CSS 4	Setup, settings, profiles, plugins, updates, and native window states
Native backend	Rust and Tauri 2	Runtime discovery, downloads, service lifecycle, files, CLI integration, and OS APIs
Harness service	Managed or compatible local dsh core	Sessions, tools, profiles, plugins, and the local web application
Embedded client	Harness web UI at a loopback URL	The primary session experience inside the desktop window

Startup flow

1. Resolve configuration

   Rust derives release or debug paths, the active profile, preferred core, and port.
2. Prepare dependencies

   Reuse compatible local tools or prepare managed Node.js, pnpm, and the core. First startup downloads missing dependencies over the network.
3. Ensure plugins

   Check and restore built-in plugins in the active profile before starting the service.
4. Launch and probe Harness

   The selected Node launches the Harness entry with --profile <id> --port <port> --no-open, then the backend waits for health.
5. Load the client

   Switch from setup or loading state to the local Harness UI. Default ports are 3080 for release and 3081 for debug; an occupied port can trigger fallback.

Trust boundaries

The web client, Rust backend, Harness process, plugins, model providers, and opened workspace are separate components, not separate security sandboxes. Tauri commands narrow native capabilities; Harness tools and plugins can still execute local code with the user’s permissions. Profiles are not operating-system sandboxes.

Next, inspect Runtime and data or the Plugin system.