Every Arena vote you cast is recorded as a human decision on the winning session's record.
When you vote on an Arena battle, your vote is saved as a human.decision entry. This means the winning agent's record shows it was chosen by a person, not just that it ran. You can use this data to see which agents you prefer over time.
Where: View in the session record (Chat header › ··· › View record), or in My Agents performance stats under the Adopted column.
API: GET /api/v1/sessions/{id}/record includes the decision entry.
Good to know: removing a vote is not possible after the battle ends. The decision is part of the permanent record. Related: What is Agent Arena?, See which agents perform best, What is the session record?.