Andrej Karpathy, the CEO of Obsidian, and Claude Code just built the smartest second brain on earth. It started with a 1-page gist that 21M people read. Karpathy frame flips everything you know about notes: Obsidian is the IDE, Claude Code is the programmer, and your notes are the codebase. You don’t ask AI questions it forgets by tomorrow you make it maintain a living wiki. 3 commands run the whole system. Ingest: drop an article, a podcast, a PDF, and Claude splits it into atomic pages linked to everything you already know. Query: ask anything and it answers from your own notes, in your own words, citing your own pages instead of guessing from training data. Lint: once a week Claude walks the entire vault, flags contradictions, kills stale claims, and wires orphan notes back in. Then Steph Ango made his move. The Obsidian CEO didn’t bolt an “Ask AI” button onto the app he shipped 5 skill files that teach Claude to write Obsidian’s native language: wikilinks, Canvas, Bases, the CLI. The repo crossed 13,900 stars in weeks and sits at 41,000 now. Karpathy runs it on his own reading: 100 articles and 400,000 words, cross-linked and maintained while he sleeps. No vector database, no embeddings, no $20 a month memory app just a folder of plain markdown and an agent that never gets tired of the boring part: the linking, the filing, the upkeep that killed every Zettelkasten since 1965. Your vault has 3,000 notes nobody will ever reopen. His read all of themselves by breakfast. Every app promised a second brain this is the first one that thinks.