Sim is a comprehensive AI agent and workflow platform built as a TypeScript monorepo. The core application (apps/sim) is a Next.js 16 App Router application providing a visual/conversational workflow builder, real-time collaboration via Socket.io, and API endpoints for workflow execution. It integrates 1000+ external services through a block/tool/trigger system, supports knowledge bases with RAG (pgvector), file processing, and structured table workflows. The platform self-hosts via Docker Compose or Helm (Kubernetes), with background jobs handled by Trigger.dev and code execution via isolated-vm or E2B. A separate PII detection service (apps/pii) uses Microsoft Presidio. Internal packages provide reusable infrastructure: structured logging (@sim/logger), utilities (@sim/utils), security primitives (@sim/security), database layer (@sim/db), workflow persistence (@sim/workflow-persistence), rate limiting, idempotency, async job queues, file upload handling, tokenization, and a virtual filesystem for the Copilot agent. The codebase demonstrates strong architectural discipline with clear package boundaries, comprehensive testing infrastructure, automated documentation generation from source, and enterprise features cleanly separated in apps/sim/ee/.