"Stays current" is the requirement that quietly costs the most. Help docs change with product releases, so the index has a freshness SLA nobody writes down, and the failure is silent: the agent confidently cites a page describing last quarter's flow. A deleted doc is worse than a stale one, since the vector keeps answering until something explicitly removes it.

Two things worth making explicit in a guide like this: reindex from the doc-publish webhook rather than a nightly cron, and carry a last-updated field into the chunk so the answer can state how old its source is. On citations, showing the source is only half the value. The other half is measuring whether the cited chunk actually supports the sentence attached to it, which is a separate eval from retrieval recall.