DX

DX, developer experience, is the quality of a developer's day: how quickly a tool gets out of the way, how readable the errors are, how fast the feedback loop runs, how much of the setup is remembered for you. It is a design goal for tools, libraries and codebases alike, and for years it was the main lens for judging whether a workflow was any good.

AI coding adds a second lens. A codebase can have great DX and still be hostile to an agent: conventions that live in people's heads, a test suite that needs a running database nobody documented, a monorepo where the right command depends on which folder you're in. Humans absorb those by osmosis. An agent starts every session knowing none of it and has to be told, or it guesses.

In practice the two pull the same direction more often than not. Fast tests, clear errors, one command to run everything and written conventions are good for people and essential for agents. When you invest in DX now, ask the second question too: could an agent with a clean context and the tools in this repo do the task? That question has its own name, AX, and it is where the next round of leverage lives.