A registered, credentialed connection to an external system — an SFDC instance, an SAP instance, a hospital's EHR — including which protocol it exposes (MCP, REST) and which canonical entities and fields it can answer for.
Low tens per tenant; one per connected system per reference-company subsidiary
Indefinite while active; deactivated rather than deleted, to preserve provenance trace-back for historical requests
Only the control-bearing entities were modelled for lifecycle. Defensible as a starting point, but it does leave the entity model uneven, and this is incompleteness rather than a finding.