Scope What You Are Actually Building

Page count is a poor proxy for engineering effort.

Start with what the user sees, then work downward: data objects, state changes, business rules, external systems, and operational controls. That is where the estimate lives.

Start with the product surfaces

Name the core data objects

Write down the nouns the business cares about. In a class-booking product, the list may include:

Write the state changes

The nouns are not enough. A booking moves through states, and every transition creates rules: who may trigger it, what must be true, what is recorded, and how failure is recovered.

Trace the main workflows

Walk through each important workflow in plain language before drawing architecture.

Then break the happy path. Two users request the last seat. The payment succeeds but the write fails. The instructor cancels an hour before class. These are not edge decorations; they are part of the product.

Unit Quiz