Rigid implies you are trying to change something into something else in a controlled way. Eg a refactoring that does nothing but enable for a future feature. Agents does not change code to refactor anything, they write code to solve the new feature directly. And if you are good at prompting they might overwrite code that exist so that the end result looks like a refactoring. But no clay was reshaped.
The agent looks at the previous code base to extract specs. So reuse of some tokkens?