A software engineer with a child in a long-running diagnostic process built a homegrown medical-record service for his family, dumped years of accumulated records into Claude Opus, and asked the model to look for missed diagnoses, contraindications, and dosing errors. The model came back with eleven concrete items. Some were trivial: drug interactions an EMR should already have flagged. Some were meaningful: a missing routine test that would have changed a treatment plan, a mislabelled prescription that nobody had reconciled across three different specialists. All of them were verifiable against the records. I want to take this experiment seriously. Not as a verdict on whether AI is going to replace doctors. As something narrower: an indication of which specific kind of medical work an LLM can already do better than the system around it, and why. What was actually done The setup was a personal project, not a clinical product.…