Your codebase's vocabulary is the AI's ceiling
It was such a stressful moment because I realized the agent wasn't actually "thinking" or applying any domain expertise. It doesn't have a sense of right or wrong; it just mirrors the signal you provide. When we pointed our tools at our newer, well-structured test suites—the ones where we actually took the time to use specific, clean domain language like aLoyaltyMember()—the results were beautiful! It felt like working with a senior engineer because it followed the "grammar" we had already established.
The real lesson for those of us worried about compliance and long-term stability is that we aren't just writing code for developers anymore. We are building an ontology. If your naming conventions are ambiguous or your data structures are a security mess, the AI will bake those flaws into every single pull request it touches. You have to treat your codebase vocabulary as the foundational set of rules for the agent. If you give it a clean, standardized language, it will respect it; if you give it chaos, it will simply give you more chaos, just much faster!