Fix Chess960: seed RNG and use proper castling notation

nakama/go-modules/main.go

@@ -82,6 +82,9 @@ type MatchLabel struct {
 }
 
 func InitModule(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, initializer runtime.Initializer) error {
+	// Seed random number generator for Chess960 positions
+	rand.Seed(time.Now().UnixNano())
+
 	logger.Info("Initializing realms.india Nakama Go modules")
 
 	// Register custom authentication hook
@@ -170,10 +173,16 @@ func generateChess960Position() (string, int) {
 	pieces[remaining[1]] = 'K'
 	pieces[remaining[2]] = 'R'
 
-	// Build FEN
+	// Build FEN with Chess960 castling rights
 	whitePieces := string(pieces)
 	blackPieces := strings.ToLower(whitePieces)
-	fen := fmt.Sprintf("%s/pppppppp/8/8/8/8/PPPPPPPP/%s w KQkq - 0 1", blackPieces, whitePieces)
+
+	// Find rook positions for Chess960 castling notation
+	// remaining[0] is queenside rook, remaining[2] is kingside rook
+	castling := fmt.Sprintf("%c%c%c%c",
+		'A'+remaining[2], 'A'+remaining[0], // White kingside, queenside
+		'a'+remaining[2], 'a'+remaining[0]) // Black kingside, queenside
+	fen := fmt.Sprintf("%s/pppppppp/8/8/8/8/PPPPPPPP/%s w %s - 0 1", blackPieces, whitePieces, castling)
 
 	// Calculate position ID
 	positionID := (lightBishopIdx*4+darkBishopIdx)*6*10*10 + queenIdx*10*10 + knight1Idx*10 + knight2Idx