Contract Coding: Waterfall Was Never the Problem. The Cost Was.

Agile killed waterfall, for good reasons. Most of those reasons no longer hold when the developer is an agent. This paper makes one narrow claim. The discipline agile threw out, contracts before code, hard gates between phases, and roles that cannot grade their own work, is the discipline an agentic project needs most. The practice has a name here: Contract Coding. It is not a new theory. It is old engineering, made cheap by a new tool. The proof is a working system, RostadVM, where ninety-two faults were found and fixed before a single line of production code existed.