Claude Code Costs, Act IV — The mistakes catalogue & cheat sheet (opens in new tab)

This act consolidates everything into two reference artifacts: a catalogue of the mistakes (each with its symptom, cost, and fix) for revision, and a one-page cheat sheet. The mistakes catalogue Ordered roughly by how much money they cost and how often they happen. 1. Routing per turn instead of per conversation. Symptom: a "cost-saving" router that bounces models mid-conversation. Cost: a cold prefix write on the first switch + a catch-up write on every re-entry; for Sonnet, a net loss (+2.1...