diff --git a/server/cmd/api/api/fs.go b/server/cmd/api/api/fs.go
index 33d5a9dd..4e2f8764 100644
--- a/server/cmd/api/api/fs.go
+++ b/server/cmd/api/api/fs.go
@@ -686,9 +686,17 @@ func (s *ApiService) UploadFiles(ctx context.Context, request oapi.UploadFilesRe
 			}
 			return idx, field, true
 		}
-		// forms like files.0.file
+		// forms like files.0.file OR files.file (no index → index 0)
 		if strings.HasPrefix(name, "files.") {
 			parts := strings.Split(name, ".")
+			if len(parts) == 2 {
+				// comma/no-index format: files.dest_path or files.file
+				field := parts[1]
+				if field == "file" || field == "dest_path" {
+					return 0, field, true
+				}
+				return 0, "", false
+			}
 			if len(parts) != 3 {
 				return 0, "", false
 			}
diff --git a/server/cmd/api/api/fs_test.go b/server/cmd/api/api/fs_test.go
index f8ddee44..119858b6 100644
--- a/server/cmd/api/api/fs_test.go
+++ b/server/cmd/api/api/fs_test.go
@@ -347,6 +347,33 @@ func TestUploadFilesMultipleAndOutOfOrder(t *testing.T) {
 	}
 }
 
+func TestUploadFilesCommaFormat(t *testing.T) {
+	t.Parallel()
+	ctx := context.Background()
+	svc := &ApiService{}
+
+	tmp := t.TempDir()
+	dest := filepath.Join(tmp, "comma.txt")
+
+	// SDK "comma" array format: files.dest_path, files.file (no index)
+	reader := buildUploadMultipart(t,
+		map[string]string{"files.dest_path": dest},
+		map[string]string{"files.file": "hello comma"},
+	)
+
+	resp, err := svc.UploadFiles(ctx, oapi.UploadFilesRequestObject{Body: reader})
+	if err != nil {
+		t.Fatalf("UploadFiles error: %v", err)
+	}
+	if _, ok := resp.(oapi.UploadFiles201Response); !ok {
+		t.Fatalf("unexpected response type: %T", resp)
+	}
+	data, err := os.ReadFile(dest)
+	if err != nil || string(data) != "hello comma" {
+		t.Fatalf("uploaded file mismatch: %v %q", err, string(data))
+	}
+}
+
 func TestUploadZipSuccess(t *testing.T) {
 	t.Parallel()
 	ctx := context.Background()