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 {

server/domain/queue_test.go

@@ -136,3 +136,24 @@ func TestQueueConcurrentCreateKeepsOneActiveTicketPerPlayer(t *testing.T) {
 		t.Fatalf("concurrent creates succeeded %d times", succeeded)
 	}
 }
+
+func TestQueueRecordProbeBindsServerRTTToActivePlayerTicket(t *testing.T) {
+	now := time.Unix(1000, 0).UTC()
+	queue := NewQueue()
+	if _, err := queue.Create("player-a", "ticket-a", "create-key-123456", Candidate{PlayerID: "player-a", TicketID: "ticket-a", Playlist: Casual, EnqueuedAt: now}, now); err != nil {
+		t.Fatal(err)
+	}
+	if err := queue.RecordProbe("player-a", "EU", 42*time.Millisecond, now); err != nil {
+		t.Fatal(err)
+	}
+	ticket, err := queue.Get("player-a", "ticket-a", now)
+	if err != nil || ticket.Candidate.PredictedRTT["EU"] != 42 {
+		t.Fatalf("ticket=%+v err=%v", ticket, err)
+	}
+	if err := queue.RecordProbe("player-a", "NA", time.Millisecond, now.Add(QueueExpiryWindow)); err != ErrTicketExpired {
+		t.Fatalf("expired record err=%v", err)
+	}
+	if err := queue.RecordProbe("player-other", "EU", time.Millisecond, now); err != ErrTicketNotFound {
+		t.Fatalf("unknown player err=%v", err)
+	}
+}