chapter eight
8 Interfaces: Where the product's verbs live
This chapter covers
- The API surface: the full list of a system's endpoints
- Using AI to find the route manifest in any framework (Express, Django, Rails)
- Getting AI to group hundreds of endpoints into a feature map
- Asking AI which endpoints fire for one user action, in order
- Tracing one endpoint from HTTP request to response with AI
The last chapter mapped a codebase's nouns; this chapter reads its verbs. The interface is the list of actions an application exposes to the outside world, which means it's the layer where every change request starts. When you pick up your first ticket at a new job to "stop creating duplicate bookings when users double-click Confirm," the fix itself is probably just a one-line guard. But finding the exact file you need to change is the hard part.