Stop Tuning Prompts. Build a Harness.

Anthropic shipped a piece earlier this month called How Claude Code Works in Large Codebases . I have not read anything more useful about coding agents this year. The core claim, in their words: “the ecosystem built around the model—the harness—determines how Claude Code performs more than the model alone.” In my phrasing: in a real codebase, the model is the smaller variable.