Validate maxSessions/maxChannels/maxSkipReasons as non-negative finite values, make 0 produce zero rows, and add regression coverage. No architecture/protocol flow changes; diagram files reviewed and no updates were needed.
Diagrams reviewed: docs/architecture/AGENT_DIAGRAM.md, docs/architecture/GATEWAY_SESSIONS_AND_QUEUE.md, docs/api/PROTOCOL.md (no changes required).