Keeping one customer’s data away from another’s in a shared system. It matters more than usual here because the paths are unfamiliar: shared caches, shared vector indexes, shared fine-tuned adapters and logs are all places where data can cross a boundary nobody was watching.
Technical view
Requires per-tenant scoping of retrieval indexes or mandatory metadata filters enforced server-side, cache keys that include tenant identity so prompt caching cannot leak across tenants, separate fine-tuned artefacts, tenant-scoped credentials for tools, and tenant-aware logging with access controls. Threat cases include cache timing inference and prompt injection attempting cross-tenant retrieval. Isolation should be tested adversarially rather than assumed from configuration.
Related
Part of AI Terminology Index, section: Security and Privacy.