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.

server/store/queue_sql_test.go

@@ -8,13 +8,14 @@ import (
 
 func TestQueueSQLUsesDurableIdempotencyAndOwnerScopedRecovery(t *testing.T) {
 	for query, fragments := range map[string][]string{
-		QueueIdempotencyInsertSQL: {"idempotency_keys", "ON CONFLICT (scope, idempotency_key) DO NOTHING", "payload_digest"},
-		QueueIdempotencySelectSQL: {"scope = $1", "idempotency_key = $2", "FOR UPDATE"},
-		QueueTicketSelectSQL:      {"ticket_id = $1", "player_id = $2"},
-		QueueTicketInsertSQL:      {"player_id", "playlist", "client_build", "protocol_version"},
-		QueueTicketHeartbeatSQL:   {"player_id = $2", "revision = $3", "expires_at > $4", "RETURNING"},
-		QueueTicketCancelSQL:      {"player_id = $2", "revision = $3", "state NOT IN", "RETURNING"},
+		QueueIdempotencyInsertSQL:   {"idempotency_keys", "ON CONFLICT (scope, idempotency_key) DO NOTHING", "payload_digest"},
+		QueueIdempotencySelectSQL:   {"scope = $1", "idempotency_key = $2", "FOR UPDATE"},
+		QueueTicketSelectSQL:        {"ticket_id = $1", "player_id = $2"},
+		QueueTicketInsertSQL:        {"player_id", "playlist", "client_build", "protocol_version"},
+		QueueTicketHeartbeatSQL:     {"player_id = $2", "revision = $3", "expires_at > $4", "RETURNING"},
+		QueueTicketCancelSQL:        {"player_id = $2", "revision = $3", "state NOT IN", "RETURNING"},
 		QueueCandidateProjectionSQL: {"playlist = $1", "predicted_rtt", "expires_at > $2", "LIMIT $3"},
+		RankedParticipantSQL:        {"steam_id", "player_id = ANY($1)", "ORDER BY player_id"},
 	} {
 		for _, fragment := range fragments {
 			if !contains(query, fragment) {
@@ -24,6 +25,12 @@ func TestQueueSQLUsesDurableIdempotencyAndOwnerScopedRecovery(t *testing.T) {
 	}
 }
 
+func TestLoadRankedParticipantsRejectsNonSixPlayerLookupsWithoutDatabase(t *testing.T) {
+	if _, err := LoadRankedParticipants(nil, nil, []string{"player-1"}); err == nil {
+		t.Fatal("partial ranked identity lookup was accepted")
+	}
+}
+
 func TestListQueuedCandidatesRejectsUnscopedOrUnboundedReads(t *testing.T) {
 	now := time.Unix(1000, 0)
 	for _, playlist := range []domain.Playlist{"", "invalid"} {