How do you change or remove a feature without breaking the models that depend on it?
A data engineer renames a column and three production models quietly begin scoring on garbage. Features form a shared contract, and altering them demands the same care as a breaking API change. Here is the discipline it takes.
Updated Sep 2026 · Grounded in real GenAI, LLM, and AI/ML engineering interview loops and written to a senior-engineer editorial bar.
A data engineer renames a column and three production models quietly begin scoring on garbage. Features form a shared contract, and altering them demands the same care as a breaking API change. Here is the discipline it takes.
Lead with where the obvious approach breaks, because that is the judgment they are screening for — most candidates jump straight to the happy path and lose the room.
Then walk the failure back through the pipeline in order, naming the one metric the customer's exec sponsor actually cares about before you propose the fix.
