feat: enable guarded ranked matcher role

server/store/queue_sql.go

@@ -44,6 +44,40 @@ WHERE state = 'QUEUED' AND playlist = $1 AND expires_at > $2
 ORDER BY enqueued_at, ticket_id
 LIMIT $3`
 
+const RankedParticipantSQL = `SELECT player_id, steam_id
+FROM identities
+WHERE player_id = ANY($1)
+ORDER BY player_id`
+
+// LoadRankedParticipants resolves the verified identity metadata required by
+// ranked admission. The caller must compare the returned set with the formed
+// candidate set; a partial lookup is not a valid ranked roster.
+func LoadRankedParticipants(ctx context.Context, db *sql.DB, playerIDs []string) ([]domain.RankedParticipant, error) {
+	if db == nil || len(playerIDs) != 6 {
+		return nil, fmt.Errorf("ranked admission requires six players")
+	}
+	rows, err := db.QueryContext(ctx, RankedParticipantSQL, playerIDs)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	participants := make([]domain.RankedParticipant, 0, len(playerIDs))
+	for rows.Next() {
+		var participant domain.RankedParticipant
+		if err := rows.Scan(&participant.PlayerID, &participant.SteamID); err != nil {
+			return nil, err
+		}
+		participants = append(participants, participant)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	if len(participants) != len(playerIDs) {
+		return nil, fmt.Errorf("ranked identity metadata is incomplete")
+	}
+	return participants, nil
+}
+
 // ListQueuedCandidates is an authoritative, expiry-filtered source for the
 // matcher projection. It deliberately does not claim rows; CreateProposal is
 // the transaction that performs the competing claim with SKIP LOCKED fences.