# PRD: GemmaTrans Desktop Client

## 1. Project Overview
**GemmaTrans** is a lightweight, high-performance desktop translation client built with **Tauri** and **Vue 3**. It is designed to act as a modern frontend for the **TranslateGemma** model running on a local or remote **Ollama** instance (including over private networks like Tailscale). The application prioritizes speed, privacy, and a professional "Google Translate" aesthetic.

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## 2. Technical Stack
* **Core Framework:** [Tauri](https://tauri.app/) (Rust backend for system-level API access).
* **Frontend Framework:** [Vue 3](https://vuejs.org/) (Composition API).
* **Styling:** [Tailwind CSS](https://tailwindcss.com/) (Minimalist, modern utility-first CSS).
* **Package Manager:** `pnpm`.
* **State Management:** [Pinia](https://pinia.vuejs.org/) (To persist user settings and prompt templates).
* **Icons:** [Lucide Vue Next](https://lucide.dev/).

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## 3. User Interface (UI) Requirements
The UI should be **Modern, Minimalist, and Functional**, mimicking the clean layout of Google Translate.

### 3.1 Main Translation Interface
* **Split-Pane Layout:**
    * **Left (Source):** Input text area with a header for language selection.
    * **Right (Target):** Read-only text area for the translation result, with a header for the target language selection.
* **Language Selection:** Dropdowns supporting both **Full Name** (e.g., English) and **ISO Code** (e.g., en).
* **Actions:** * "Translate" button (with loading state).
    * "Copy" button on the target pane.
    * "Clear" button on the source pane.

### 3.2 Settings View
* **API Configuration:** A text input for the `Ollama API Address` (e.g., `http://100.x.y.z:11434`).
* **Output Control:** A toggle switch for `Enable Streaming` (renders text as it is generated).
* **Prompt Engineering:** A large text area for the `System Prompt Template`.

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## 4. Functional Requirements

### 4.1 Prompt Engineering Engine
The application must dynamically inject variables into the user-provided template before sending the request to the Ollama API.

**Default Template:**
> You are a professional {SOURCE_LANG} ({SOURCE_CODE}) to {TARGET_LANG} ({TARGET_CODE}) translator. Your goal is to accurately convey the meaning and nuances of the original {SOURCE_LANG} text while adhering to {TARGET_LANG} grammar, vocabulary, and cultural sensitivities.
> Produce only the {TARGET_LANG} translation, without any additional explanations or commentary. Please translate the following {SOURCE_LANG} text into {TARGET_LANG}:
> 
> {TEXT}

### 4.2 Template Variables
The engine must support and correctly replace the following tokens:
* `{SOURCE_LANG}`: Full name of the input language (e.g., "Chinese").
* `{SOURCE_CODE}`: Short code of the input language (e.g., "zh-Hans").
* `{TARGET_LANG}`: Full name of the output language (e.g., "English").
* `{TARGET_CODE}`: Short code of the output language (e.g., "en").
* `{TEXT}`: The actual content provided by the user.

### 4.3 Ollama Integration
* Support for the `/api/generate` endpoint.
* Ability to handle both `stream: true` (progressive UI updates) and `stream: false` (batch updates).
* Support for connecting to any valid URL provided in Settings, ensuring compatibility with Tailscale IPs.

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## 5. Technical Implementation Details

### 5.1 Language Mapping (Default Configuration)
The application will provide a default list of languages:
| Language | Code |
| :--- | :--- |
| English | en |
| Chinese | zh-Hans |
| Japanese | ja |
| Spanish | es |
| French | fr |
| German | de |

### 5.2 Persistence
* All settings (API Address, Stream Toggle, and Custom Prompt Template) must be stored in the user's local application data folder to ensure they are remembered across restarts.

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## 6. Success Metrics
* **Connectivity:** Seamless communication with an Ollama instance over a Tailscale network.
* **UX:** The "Streaming" mode should feel responsive with no UI lag during high-token-per-second generation.

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