The lastTenantId field on a User record in Skarn Suite (the platform auth hub: SSO, tenancy, billing, entitlements, internal event bus) stores a specific piece of the data; it scopes the record to a single tenant, enforcing the multi-tenant isolation that keeps each organization's data private from every other tenant on the platform. In everyday use this is part of how User records are created, displayed, validated, and reported, and it is grounded strictly in the real schema fact User.lastTenantId: String.
Technical section
Data model, API, and internals — visible to developers.