TL;DR — Every AI system decomposes into two things that matter: the model and the harness (the code wrapping it). Claude Code, GitHub Copilot, ChatGPT — those are harnesses, not models. Right now only frontier labs build both halves. That won't last. As harness engineering becomes its own discipline — domain-specialized, model-agnostic — it absorbs most of what we currently call software engineering. The app store becomes the agent store , and our job shifts from writing code for humans ...