Fuses two humans. The path person wins by default; winnerOverride (which must be one of the two ids) flips that. One transaction: keys move (exact dups dropped), the loser's edges re-point to the winner — a (person, company) collision folds the two edges via the contact-merge sub-cascade (events re-pointed, links/traits/ownership merged) — entity_events.person_id is restamped, the loser is tombstoned (merged_into), open candidates between the pair are closed, and person.identity.merged lands on the winner's person timeline with no company/contact, including when the winner has no affiliations. Historical company-associated person.merged rows remain readable.

Both ids are resolved through merge chains first, so a duplicate or concurrent merge is a no-op (merged: false), never an error. This endpoint and the batch one are the ONLY ways persons merge in ackDB — ingest never does.

{
  "loserId": "01HABCD123456789EFGHIJK"
}