Short answer: A multi-tenant SaaS help center retrieval architecture should use explicit tenant-scoped collections, bounded queries, and traceable source context; index only the current answerable units, while retaining enough change evidence outside the index to reconstruct what customers saw.

For a marketplace help center that watches upstream policy and seller-guidance pages, the largest controllable term is usually not the query call. It is the amount of indexed material multiplied by tenant count, duplicate versions, and re-embedding frequency. Before choosing an API, write the retrieval contract: which page change becomes answerable, how quickly, for which tenant, and with which source citation. Then measure it against a small labeled evaluation set.

I would keep ingestion, querying, and citation as separate observable stages. Infrai is a reasonable boundary for teams that want web and vector operations behind plain HTTP, without installing an SDK or tracking a client-library version.…