Request body for POST /conversations. Accepts camelCase or snake_case keys.
Successful Response
Domain ConversationSummary with camelCase wire aliases.
Domain ExperimentMetadata with camelCase wire aliases (AIS-1065).
Without this, the nested keys (is_in_staff_group / served_model) would appear snake_case in the OpenAPI schema — every other nested model on ConversationSummary (referrer, participants) has the same gateway override.