Copilot for Xcode is a macOS application that integrates multiple AI code completion and chat services (GitHub Copilot, Codeium, OpenAI, Claude, Google Gemini, Ollama) directly into Xcode as a source editor extension. It provides inline code suggestions, a chat panel with context-aware memory, a prompt-to-code feature, and custom command execution. The architecture is a multi-process system: a host app manages settings and lifecycle, an XPC extension service handles AI requests and workspace state, and an Accessibility-powered widget overlays suggestion and chat panels on Xcode windows. The codebase is heavily modularized into Swift packages (Core, Tool, OverlayWindow) and uses the Composable Architecture (TCA) for state management. While primarily an application, it includes data-centric components like embedding services, vector stores (USearch), and a LangChain-inspired chain abstraction for retrieval-augmented generation, giving it a hybrid character.