How do you stop AI coding assistants from hallucinating fake dependencies or outdated packages?

Every time I ask an agent to scaffold a utility or integrate a service, it loves to pull in packages that either don't exist, are heavily deprecated, or use completely outdated syntax. You spend more time debugging ghost imports than it would have taken to write the boilerplate yourself.

For developers working with fast-moving tech stacks daily how do you feed context or set rules so the model sticks to your actual dependency tree?

How do you keep your AI agents from recommending or importing phantom packages?