Add CLAUDE.md

Author: kuzdogan

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Development Commands
+
+- `npm run dev` - Start development server with hot reload (runs on http://localhost:5173)
+- `npm run build` - Build for production (outputs to `build/` directory)
+- `npm start` - Start production server
+- `npm run typecheck` - Run TypeScript type checking
+
+## Architecture Overview
+
+This is a React Router v7 SPA application for smart contract verification using the Sourcify service. The app operates in SPA mode (SSR disabled in react-router.config.ts).
+
+### Key Directories
+
+- `app/` - Main application code
+  - `components/` - Reusable UI components, with verification-specific components in `verification/`
+  - `contexts/` - React contexts for global state (ServerConfig, CompilerVersions, Chains)
+  - `hooks/` - Custom React hooks for form validation and verification state
+  - `routes/` - Route components (home page, job status)
+  - `types/` - TypeScript type definitions
+  - `utils/` - Utility functions for API calls, storage, and business logic
+
+### Core Architecture
+
+**Verification Flow**: The app supports multiple verification methods (single-file, multiple-files, std-json, metadata-json) for both Solidity and Vyper contracts. All methods eventually convert to standard JSON format before submission to Sourcify's v2 API.
+
+**API Integration**: 
+- `sourcifyApi.ts` - Main Sourcify API client with custom headers for client identification
+- `etherscanApi.ts` - Etherscan integration for importing contract data
+- All API calls use custom `sourcifyFetch()` with client identification headers
+
+**State Management**: Uses React Context for global state:
+- `ServerConfigContext` - Manages Sourcify server URLs (default, custom, localStorage sync)
+- `CompilerVersionsContext` - Fetches and caches compiler versions
+- `ChainsContext` - Manages blockchain network data
+
+**Job Tracking**: Verification jobs are tracked via localStorage and polling the `/v2/verify/{verificationId}` endpoint.
+
+### Environment Variables
+
+- `VITE_SOURCIFY_SERVER_URL` - Default Sourcify server URL
+- `VITE_SOURCIFY_REPO_URL` - Sourcify repository URL
+- `VITE_GIT_COMMIT` - Git commit hash for client version tracking
+- `VITE_ENV` - Environment (development/production)
+
+### Build Configuration
+
+- React Router v7 with Vite
+- TailwindCSS v4 for styling
+- TypeScript with strict mode
+- Path alias: `~/*` maps to `./app/*`
+- Web Workers used for bytecode diff calculations (`public/diffWorker.js`)