tldraw is a monorepo providing an open-source infinite-canvas SDK for building collaborative whiteboard/drawing applications in React. The core library (`@tldraw/editor`, `@tldraw/tldraw`) exposes a highly extensible shape/tool/overlay system with signal-based reactivity, real-time synchronization (`@tldraw/sync-core`), and a full UI component library (menus, toolbars, dialogs, style panels, commenting). The repository also includes a production-grade web application (tldraw.com) with authentication (Clerk), file management, real-time sync via Cloudflare Durable Objects, MCP server integration, and a Zero-based relational data layer for multi-user features. Additional assets include a VS Code extension, an AI agent starter kit, a documentation site, an extensive example gallery (~100+ recipes), and deployment infrastructure for Cloudflare Workers, Vercel, and template demos. The architecture is modular—core packages have minimal dependencies—and the codebase demonstrates strong engineering practices: comprehensive unit and e2e testing, a custom validation library with path-aware errors, an efficient small-set implementation (`ArraySet`), and a debounce utility that returns cancelable promises.