# Tech Stack & Constraints

## Overview
This project is a desktop application built with **Tauri**. It functions as an **Agentic Code Assistant** capable of safely executing tools on the host system.

## Core Stack
*   **Backend:** Rust (Tauri Core)
    *   **MSRV:** Stable (latest)
    *   **Framework:** Tauri v2
*   **Frontend:** TypeScript + React
    *   **Build Tool:** Vite
    *   **Styling:** CSS Modules or Tailwind (TBD - Defaulting to CSS Modules)
    *   **State Management:** React Context / Hooks
    *   **Chat UI:** Rendered Markdown with syntax highlighting.

## Agent Architecture
The application follows a **Tool-Use (Function Calling)** architecture:
1.  **Frontend:** Collects user input and sends it to the LLM.
2.  **LLM:** Decides to generate text OR request a **Tool Call** (e.g., `execute_shell`, `read_file`).
3.  **Tauri Backend (The "Hand"):**
    *   Intercepts Tool Calls.
    *   Validates the request against the **Safety Policy**.
    *   Executes the native code (File I/O, Shell Process, Search).
    *   Returns the output (stdout/stderr/file content) to the LLM.

## LLM Provider Abstraction
To support both Remote and Local models, the system implements a `ModelProvider` abstraction layer.

*   **Strategy:**
    *   Abstract the differences between API formats (OpenAI-compatible vs Anthropic vs Gemini).
    *   Normalize "Tool Use" definitions, as each provider handles function calling schemas differently.
*   **Supported Providers:**
    *   **Anthropic:** Focus on Claude 3.5 Sonnet for coding tasks.
    *   **Google:** Gemini 1.5 Pro for massive context windows.
    *   **Ollama:** Local inference (e.g., Llama 3, DeepSeek Coder) for privacy and offline usage.
*   **Configuration:**
    *   Provider selection is runtime-configurable by the user.
    *   API Keys must be stored securely (using OS native keychain where possible).

## Tooling Capabilities

### 1. Filesystem (Native)
*   **Scope:** Strictly limited to the user-selected `project_root`.
*   **Operations:** Read, Write, List, Delete.
*   **Constraint:** Modifications to `.git/` are strictly forbidden via file APIs (use Git tools instead).

### 2. Shell Execution
*   **Library:** `tokio::process` for async execution.
*   **Constraint:** We do **not** run an interactive shell (repl). We run discrete, stateless commands.
*   **Allowlist:** The agent may only execute specific binaries:
    *   `git`
    *   `cargo`, `rustc`, `rustfmt`, `clippy`
    *   `npm`, `node`, `yarn`, `pnpm`, `bun`
    *   `ls`, `find`, `grep` (if not using internal search)
    *   `mkdir`, `rm`, `touch`, `mv`, `cp`

### 3. Search & Navigation
*   **Library:** `ignore` (by BurntSushi) + `grep` logic.
*   **Behavior:**
    *   Must respect `.gitignore` files automatically.
    *   Must be performant (parallel traversal).

## Coding Standards

### Rust
*   **Style:** `rustfmt` standard.
*   **Error Handling:** Custom `AppError` type deriving `thiserror`. All Commands return `Result<T, AppError>`.
*   **Concurrency:** Heavy tools (Search, Shell) must run on `tokio` threads to avoid blocking the UI.

### TypeScript / React
*   **Style:** Prettier / ESLint standard.
*   **Types:** Shared types with Rust (via `tauri-specta` or manual interface matching) are preferred to ensure type safety across the bridge.

## Libraries (Approved)
*   **Rust:**
    *   `serde`, `serde_json`: Serialization.
    *   `ignore`: Fast recursive directory iteration respecting gitignore.
    *   `walkdir`: Simple directory traversal.
    *   `tokio`: Async runtime.
    *   `reqwest`: For LLM API calls (if backend-initiated).
    *   `uuid`: For unique message IDs.
    *   `chrono`: For timestamps.
    *   `tauri-plugin-dialog`: Native system dialogs.
    *   `tauri-plugin-store`: Persistent key-value storage.
*   **JavaScript:**
    *   `@tauri-apps/api`: Tauri Bridge.
    *   `@tauri-apps/plugin-dialog`: Dialog API.
    *   `@tauri-apps/plugin-store`: Store API.
    *   `react-markdown`: For rendering chat responses.

## Safety & Sandbox
1.  **Project Scope:** The application must strictly enforce that it does not read/write outside the `project_root` selected by the user.
2.  **Human in the Loop:**
    *   Shell commands that modify state (non-readonly) should ideally require a UI confirmation (configurable).
    *   File writes must be confirmed or revertible.