The prototype-plan-stack development pattern

As an industry, we’ve been struggling with what to do about the gap between engineers’ ability to review code and the quantity of code an LLM can produce in a day. We’re debating what will come of self-review (reading your own code before shipping it) and code review (someone else reviewing your code). In speaking with friends at various companies, I mostly hear about abandoning review. While agents generate nearly all of the code we ship to production at B12, we haven’t given up on reviewing their output and understanding how it works, and have been looking for ways to make that review process more palatable. In the past few months, we’ve settled on a development pattern we call prototype-plan-stack. In the prototyping phase, 1-3 engineers implement a feature end-to-end in our codebase, prioritizing a working demo with reduced focus on some architecture/implementation details. Those engineers, paired with agentic coding assistants, might generate 5000-10000 lines of code without yet…