feat: persist authenticated queue probe RTT

server/domain/queue.go

@@ -163,6 +163,34 @@ func (q *Queue) Expire(now time.Time) []QueueTicket {
 	return q.expireLocked(now)
 }
 
+// RecordProbe stores server-computed RTT metadata on the player's active
+// ticket. It never accepts client-provided latency and refuses expired or
+// non-queueable tickets.
+func (q *Queue) RecordProbe(playerID, region string, rtt time.Duration, now time.Time) error {
+	if playerID == "" || (region != "EU" && region != "NA") || rtt < 0 || now.IsZero() {
+		return fmt.Errorf("invalid probe recording")
+	}
+	q.mu.Lock()
+	defer q.mu.Unlock()
+	ticketID, ok := q.byPlayer[playerID]
+	if !ok {
+		return ErrTicketNotFound
+	}
+	ticket, ok := q.tickets[ticketID]
+	if !ok || (ticket.State != Queued && ticket.State != Proposed) {
+		return ErrTicketNotFound
+	}
+	if !now.Before(ticket.ExpiresAt) {
+		return ErrTicketExpired
+	}
+	if ticket.Candidate.PredictedRTT == nil {
+		ticket.Candidate.PredictedRTT = make(map[string]float64)
+	}
+	ticket.Candidate.PredictedRTT[region] = float64(rtt) / float64(time.Millisecond)
+	q.tickets[ticketID] = ticket
+	return nil
+}
+
 func (q *Queue) expireLocked(now time.Time) []QueueTicket {
 	var expired []QueueTicket
 	for id, ticket := range q.tickets {