Full Guide: Build An AI Second Brain With Codex

A step-by-step walkthrough for building a personal AI-powered second brain using Codex and Obsidian. The system combines three pillars: a wiki/knowledge base (populated via Obsidian Web Clipper from YouTube, articles, podcasts), a CRM for contact notes, and an AI-grounded journal. Content saved to Obsidian's raw folder is automatically processed by Codex into interlinked wiki pages. Journaling queries are answered using retrieval from the wiki, past journal entries, and CRM data. Automation is set up in Codex to process new files hourly and push backups to a private GitHub repo. The architecture is based on Andrej Karpathy's LLM wiki concept, extended with journaling and CRM layers.