Spotify just published the internal setup their engineers use with Claude Code, the one that cut token usage by 90 percent. Here is how it works. The observation behind it: most of what a coding assistant does is not thinking. It opens five files to answer a question about one of them. It writes a test that copies the pattern of the twenty tests sitting next to it. Enormous amounts of work, almost no judgment, and all of it billed at top rates. So they added two cheap assistants. One opens the files and hands back a short summary. The other writes the repetitive code from an example and saves it straight to disk. The expensive model never sees any of it. The clever part is how they made it stick. First the rules were written down as instructions, and the model ignored them. Now anything over 350 lines gets stopped before it opens and sent to the cheap one instead. Written rules are a suggestion. A block is not. Two things stayed expensive. Edits still need the real file. And the cheap worker missed a bug the expensive one caught in seconds.