COG is a markdown-based knowledge management and productivity system powered by AI agents. It provides 17 specialized skills that delegate work to 6 worker agents, all operating on markdown files tracked in Git. The system integrates with AI coding assistants (Claude Code, Cursor, Kiro, Gemini CLI, Codex) through skill files installed in each tool’s plugin directory, allowing them to access the second brain’s capabilities. It also syncs with GitHub, Linear, Slack, and PostHog for broader workflow integration.