Building a Chess Coach Magnus Carlsen's app needed to explain chess moves, not just evaluate them. LLMs hallucinate when asked to reason about positions, so they split the work. Stockfish evaluates, detectors extract tactical concepts, the LLM just translates into English. Sub 3 seconds on Gemini Flash. https://youtube.com/watch?v=FlzpEGHNVKQ The feedback loop is the interesting part. Users flag bad commentary in the app, it posts to Slack and injects into a running Claude Code session…