Where Did My Claude Code Money Go? I Built a Tool to Find Out

I still remember the message. A developer on my team - sharp, careful - pinged me: "My Claude Code bill spiked $200 this week. Same workflow. Something's off." I had no answer. The built-in usage view showed session totals. The web billing page showed monthly aggregates. But neither could answer the only question that mattered: which specific turn ate the money? How do I improve the way I use Claude Code? That gap - between knowing you spent and seeing exactly why - is what this closes.