added claude.md

CLAUDE.md

@@ -0,0 +1,67 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+Antigravity Claude Proxy is a Node.js proxy server that exposes an Anthropic-compatible API backed by Antigravity's Cloud Code service. It enables using Claude models (`claude-sonnet-4-5-thinking`, `claude-opus-4-5-thinking`) with Claude Code CLI.
+
+The proxy translates requests from Anthropic Messages API format → Google Generative AI format → Antigravity Cloud Code API, then converts responses back to Anthropic format with full thinking/streaming support.
+
+## Commands
+
+```bash
+# Install dependencies
+npm install
+
+# Start server (runs on port 8080)
+npm start
+
+# Start with file watching for development
+npm dev
+
+# Account management
+npm run accounts         # Interactive account management
+npm run accounts:add     # Add a new Google account via OAuth
+npm run accounts:list    # List configured accounts
+npm run accounts:verify  # Verify account tokens are valid
+
+# Run all tests (server must be running on port 8080)
+npm test
+
+# Run individual tests
+npm run test:signatures    # Thinking signatures
+npm run test:multiturn     # Multi-turn with tools
+npm run test:streaming     # Streaming SSE events
+npm run test:interleaved   # Interleaved thinking
+npm run test:images        # Image processing
+```
+
+## Architecture
+
+**Request Flow:**
+```
+Claude Code CLI → Express Server (server.js) → CloudCode Client → Antigravity Cloud Code API
+```
+
+**Key Modules:**
+
+- **server.js**: Express server exposing Anthropic-compatible endpoints (`/v1/messages`, `/v1/models`, `/health`, `/accounts`)
+- **cloudcode-client.js**: Makes requests to Antigravity Cloud Code API with retry/failover logic, handles both streaming and non-streaming
+- **format-converter.js**: Bidirectional conversion between Anthropic and Google Generative AI formats, including thinking blocks and tool calls
+- **account-manager.js**: Multi-account pool with round-robin rotation, rate limit handling, and automatic cooldown
+- **oauth.js**: Google OAuth implementation for adding accounts
+- **token-extractor.js**: Extracts tokens from local Antigravity app installation (legacy single-account mode)
+- **constants.js**: API endpoints, model mappings, configuration values
+
+**Multi-Account Load Balancing:**
+- Round-robin rotation across configured accounts
+- Automatic switch on 429 rate limit errors
+- Configurable cooldown period for rate-limited accounts
+- Account state persisted to `~/.config/antigravity-proxy/accounts.json`
+
+## Testing Notes
+
+- Tests require the server to be running (`npm start` in separate terminal)
+- Tests are CommonJS files (`.cjs`) that make HTTP requests to the local proxy
+- Test runner supports filtering: `node tests/run-all.cjs <filter>` to run matching tests