How do LangChain and LangGraph actually work, and what do their abstractions hide?
Interviewers ask about these by name and listen for whether you have read the source or only the README. The signal is explaining the runnable interface, why an agent needs a cyclic graph rather than a chain, and what the layers hide.
Updated Sep 2026 · Grounded in real GenAI, LLM, and AI/ML engineering interview loops and written to a senior-engineer editorial bar.
Interviewers ask about these by name and listen for whether you have read the source or only the README. The signal is explaining the runnable interface, why an agent needs a cyclic graph rather than a chain, and what the layers hide.
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.
