Postiz is a full-stack, open-source social media scheduling and publishing platform that supports 30+ platforms (Instagram, TikTok, LinkedIn, YouTube, X, Facebook, etc.). The system is built as a pnpm monorepo with four main applications: a Next.js frontend (App Router), a NestJS backend REST API, a Temporal-based workflow orchestrator for reliable post publishing and token refresh, and a Chrome extension for cookie-based authentication. It also includes a CLI app, a public SDK (@postiz/node), and a shared libraries layer for business logic, database access (Prisma + PostgreSQL), and integrations. Key architectural patterns include an abstract social provider base class (SocialAbstract) that all platform integrations extend, a Temporal v1.8+ workflow engine with versioned posting workflows (v1.0.1 through v1.0.8), an upload factory abstracting local and Cloudflare storage, an MCP server for AI agent tools (scheduling, content generation via LangGraph), a plug/auto-reply system, and a short-link abstraction with multiple providers. The frontend uses Zustand for state management, SWR for data fetching, CopilotKit for AI textarea integration, and Mantine/Tailwind for UI. The system handles OAuth flows, subscription billing via Stripe, team collaboration, webhooks, and admin monitoring. The codebase demonstrates strong engineering with reusable abstractions for social integrations, storage, email, and short-linking, though it carries some technical debt from organic growth (multiple workflow versions, hardcoded strings, and suppressed TypeScript strictness).