Why Your AI Code Review Misses Stateful Bugs (and the 3-Context Fix)

A lot of AI code reviews look sharp right up until they miss the bug that actually matters. They catch naming noise, dead comments, maybe a missing null check. But they miss the regression caused by a cache key change, the migration that no longer matches the model, or the new flag that breaks the retry path two services away. The pattern I've noticed is simple: the model isn't bad at review, it's under-contextualized. Most review prompts only include the diff. Stateful bugs usually live outside the diff. Why the diff alone isn't enough A diff shows what changed.