RAG accuracy dropped 12 points in production this week and nobody shipped a prompt change. Debug it.
The classic 'it regressed and the prompt is untouched' triage. The answer that scores walks a decisional tree from retrieval to generation and names the silent culprit most candidates miss: the embedding stack changed under you.
Updated Aug 2026 · Grounded in real Forward Deployed Engineer interview loops and written to a senior-engineer editorial bar.
The classic 'it regressed and the prompt is untouched' triage. The answer that scores walks a decisional tree from retrieval to generation and names the silent culprit most candidates miss: the embedding stack changed under you.
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.
