In my previous blog post Speccing Is the New Coding, I claimed that source code will not entirely vanish in an agentic world but will change jobs, from the substance of applications to the seam between them. The promise was to come back and dive deeper into the matter.
Let's take a look.
The way it used to be
In classical software development, when two systems need to talk to each other, a developer reads one system's API documentation, then writes integration code for the other system that calls those APIs in the right order with fittingly structured data. It works, and we have decades of practice at it. But the calling system never actually understands the API it is calling. Only the developer does. The system is just faithfully carrying out instructions written by a human during design time.
That arrangement has already started to look somewhat quaint. When at least the calling system is agentic, deciding at runtime what it needs from the other system, the human in the middle must go.
