Knowledge Graph Staleness Has a Different SLA Than Vector Staleness
The vector index is wrong by approximately ten percent and nobody panics. The knowledge graph is wrong by one missing edge and somebody ships a wrong answer to a regulator. The two failure modes look identical from the data engineering org chart — both are "the index is stale" — and they sit behind the same change-data-capture pipeline with the same lag tolerance. The pipeline was sized for the vector workload because that was the louder consumer. The graph silently inherited those defaults, and the silence is the bug.
Vector retrieval and graph retrieval fail differently under staleness, and treating them as the same kind of lag problem is how you end up with a system that scores well on RAG benchmarks and is silently wrong on multi-hop queries — the silently-wrong case being, of course, the one users notice last. The fix is not faster pipelines. The fix is recognizing that "stale" means two different things, designing freshness tiers per edge class, and building the eval that catches the difference before a regulator does.
