Declare a row flagged duplicate the primary of its group: the flag and the pointer swap, this row goes back to ok (or no_contact_data), the row it duplicated becomes the duplicate pointing here, every other copy is re-pointed here. Nothing is merged or deleted; reversible: call it on the other row. A row not flagged answers already_primary true. When NOT: removing a copy (delete_person); asking which is primary (duplicate_of_sid on get_person).

Contract:

• MCP tool make_person_primary, registry package mcp.playtables/people, mount playtables.people.
• Operation action, response envelope action.
• Flags: none.