Goose is an open-source AI agent platform that provides a desktop application (Electron/React), CLI (Rust), and SDK (Python, Kotlin) for interacting with large language models through a unified Agent Client Protocol (ACP). In production, it enables users to define sessions with multiple LLM providers (Anthropic, OpenAI, Google, Azure, Bedrock, local models via MLX/GGUF, and 40+ declarative providers), extend capabilities via MCP servers and built-in platform extensions (shell, image, file editing, code analysis, apps creation), and automate workflows through parameterized recipes. The architecture is a hybrid: a Rust backend handles agent state machine orchestration, tool execution, permission management, and provider abstraction, while an Electron frontend provides a rich chat interface with settings, extension management, scheduling, and MCP apps display. Key entry points include the CLI binary (crates/goose-cli/src/main.rs), the ACP server (crates/goose/src/acp/server/), and the desktop renderer (ui/desktop/src/renderer.tsx). Data flows involve user input → state machine processing → LLM provider calls → tool execution → response streaming back to the UI, with telemetry and cost tracking throughout. External dependencies include OpenAI/Anthropic/Google APIs, MCP servers, Whisper for dictation, and optional services like PostHog and Langfuse for observability.