diff --git a/CLAUDE.md b/CLAUDE.md
new file mode 100644
index 0000000..1a19eec
--- /dev/null
+++ b/CLAUDE.md
@@ -0,0 +1,129 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Development Commands
+
+### Running the Application
+```bash
+npm run dev              # Start development server with hot reload
+npm run build            # Full build with type checking
+npm run build:win        # Build Windows executable
+npm run build:mac        # Build macOS DMG
+npm run build:linux      # Build Linux AppImage
+```
+
+### Code Quality
+```bash
+npm run lint             # ESLint check
+npm run format           # Prettier format
+npm run typecheck        # TypeScript check (both main and renderer)
+npm run typecheck:node   # TypeScript check for main process only
+npm run typecheck:web    # TypeScript check for renderer only
+```
+
+### Testing
+```bash
+npm run test             # Run unit tests (Vitest)
+npm run test:coverage    # Run tests with coverage report
+npm run test:e2e         # Run E2E tests (Playwright)
+npm run test:e2e:ui      # Run E2E tests with UI
+npm run test:e2e:report  # Show E2E test report
+```
+
+## Architecture Overview
+
+ERPAuto is an **Electron desktop application** for automating ERP system data processing. The application follows the classic Electron architecture with three distinct processes:
+
+### Process Structure
+
+1. **Main Process** (`src/main/`)
+   - Node.js environment managing application lifecycle
+   - Entry point: `src/main/index.ts`
+   - Registers all IPC handlers via `registerIpcHandlers()`
+   - Loads environment variables from `.env` at startup
+
+2. **Preload Script** (`src/preload/`)
+   - Security bridge between main and renderer processes
+   - Exposes type-safe APIs via `contextBridge` as `window.electron` and `window.api`
+   - Central API surface organized by domain (auth, extractor, cleaner, database, etc.)
+
+3. **Renderer Process** (`src/renderer/`)
+   - React 19 + TypeScript UI
+   - Uses exposed preload APIs for all main process communication
+   - Authentication-based routing with role-based access control
+
+### Service Architecture
+
+The main process is organized around domain-specific services in `src/main/services/`:
+
+- **ERP Services** (`services/erp/`): Browser automation using Playwright
+  - `ExtractorService` - Downloads material plan data
+  - `CleanerService` - Deletes specified materials with dry-run support
+  - `ErpAuthService` - Handles ERP authentication
+  - `OrderResolverService` - Validates and resolves order numbers
+  - `locators.ts` - ERP element selectors
+
+- **Database Services** (`services/database/`): Dual database support
+  - `MySqlService` / `mysql.ts` - MySQL operations
+  - `SqlServerService` / `sql-server.ts` - SQL Server operations
+  - DAO pattern: `discrete-material-plan-dao.ts`, `materials-to-be-deleted-dao.ts`
+
+- **User Services** (`services/user/`): Authentication and session management
+  - `BipUsersDao` - User data access
+  - `SessionManager` - Active session tracking
+
+- **Other Services**:
+  - `config/` - Configuration management
+  - `excel/` - Excel file parsing
+
+### IPC Handler Pattern
+
+All IPC communication follows a consistent pattern:
+- Handlers are in `src/main/ipc/`, organized by domain (8 modules)
+- Each handler module exports a `register*Handlers()` function
+- All handlers are registered in `src/main/ipc/index.ts`
+- Channel naming follows `domain:action` convention (e.g., `extractor:run`, `auth:login`)
+
+### Authentication Flow
+
+The application implements a multi-stage authentication system:
+
+1. **Silent Login**: On startup, attempts automatic login using computer name
+2. **Fallback**: Shows login dialog if silent login fails
+3. **Admin User Selection**: Admin users can switch to other user accounts
+4. **Session Management**: Persistent sessions with role-based permissions (Admin/User/Guest)
+
+Admin users see logout buttons and can access user switching. Non-admin users have restricted access based on the user who initiated their session.
+
+### Type System
+
+- Separate TypeScript configs: `tsconfig.node.json` (main/preload) and `tsconfig.web.json` (renderer)
+- Types are co-located with features: `src/main/types/` contains domain-specific type definitions
+- The preload script exposes a typed API surface that's available in renderer
+
+### Path Aliases
+
+- `@renderer` → `src/renderer/src` (renderer process)
+- `@main` → `src/main` (main process, tests only)
+- `@services` → `src/main/services` (main process, tests only)
+- `@types` → `src/main/types` (main process, tests only)
+
+## Environment Configuration
+
+The application requires a `.env` file in the project root. Reference `.env.example` for the full structure. Key configurations:
+
+- **ERP Settings**: URL, credentials, headless mode, HTTPS error handling
+- **Database**: MySQL and SQL Server connection configs (dual support)
+- **App Settings**: Log level, download/temp directories
+
+## Key Technologies
+
+- **Electron 39** - Desktop framework
+- **React 19** - UI framework
+- **TypeScript 5.9** - Type safety
+- **Playwright 1.58** - Browser automation for ERP interaction
+- **electron-vite + Vite 7** - Build tooling
+- **Zod** - Runtime validation
+- **Vitest** - Unit tests
+- **Playwright Test** - E2E tests