How much of your codebase should AI write? A trust-zone breakdown (opens in new tab)

Around 70% of the Rails code I ship is AI-written. The 30% I keep under my own hands is the part that names the system: what things are, who is allowed to do what with them, where value moves between them. Any AI agent will generate code faster than anyone can read it. The project vernacular has to stay in someone's head, and that someone is me. One important takeaway from one year of intense agentic coding: The code was never the asset; the vocabulary was. Everything downstream of the labels...