24. The parity contract and the four gates

Together, the two graphs and the marked-up specification form the parity contract: the agreed definition of how the new system must behave, which the agents must follow. Neither the recorded legacy behavior nor the target architecture can change during the project. Migration agents write the new code one module at a time, from the specification and the Target-state ontology. Every piece of migrated code then passes through four validation gates, each run by its own agent. The architecture gate checks conformance to the target blueprint's architecture. The design gate checks the design system and UI guidelines. The standards gate checks security rules and coding standards. The functional gate checks that the new code behaves like the legacy code recorded in the Source-state ontology. Code that fails any gate goes back with the gate's evidence attached, until all four gates pass. Nine named agents cover five stages: Discover, Document, Migrate, Validate and Maintain. People check the work at two points: the decisions in the specification before migration, and a modernization expert's review of the code that has passed the gates. The five stages run on a platform called ASIMOV.

On the site: The Parity Contract · Named Agents · Validation Stage Agents