added mime checks, minor logic improvements in recording

packages/devtools_app/lib/src/screens/network/har_data_entry.dart

@@ -122,6 +122,9 @@ class HarDataEntry {
           };
         }).toList();
 
+    final isBinary = !isTextMimeType(e.type);
+    final responseBodyBytes = e.encodedResponse;
+
     return <String, Object?>{
       NetworkEventKeys.startedDateTime.name:
           e.startTimestamp.toUtc().toIso8601String(),
@@ -155,8 +158,14 @@ class HarDataEntry {
         NetworkEventKeys.content.name: <String, Object?>{
           NetworkEventKeys.size.name: e.responseBody?.length,
           NetworkEventKeys.mimeType.name: e.type,
-          NetworkEventKeys.text.name: e.responseBody,
+          if (responseBodyBytes != null && isBinary) ...{
+            NetworkEventKeys.text.name: base64.encode(responseBodyBytes),
+            'encoding': 'base64',
+          } else if (e.responseBody != null) ...{
+            NetworkEventKeys.text.name: e.responseBody,
+          },
         },
+
         NetworkEventKeys.redirectURL.name: '',
         NetworkEventKeys.headersSize.name: calculateHeadersSize(
           e.responseHeaders,

packages/devtools_app/lib/src/screens/network/network_controller.dart

@@ -77,9 +77,8 @@ class NetworkController extends DevToolsScreenController
       debugPrint('No valid request data to export');
       return '';
     }
-
+    // Build the HAR object
     try {
-      // Build the HAR object
       final har = HarNetworkData(_httpRequests!);
       return ExportController().downloadFile(
         json.encode(har.toJson()),
@@ -205,8 +204,11 @@ class NetworkController extends DevToolsScreenController
         shouldLoad: (data) => !data.isEmpty,
         loadData: (data) => loadOfflineData(data),
       );
-    }
-    if (serviceConnection.serviceManager.connectedState.value.connected) {
+    } else if (serviceConnection
+        .serviceManager
+        .connectedState
+        .value
+        .connected) {
       await startRecording();
     }
   }

packages/devtools_app/lib/src/shared/http/http_request_data.dart

@@ -102,8 +102,27 @@ class DartIOHttpRequestData extends NetworkRequest {
             );
         _request = updated;
         final fullRequest = _request as HttpProfileRequest;
-        _responseBody = utf8.decode(fullRequest.responseBody!);
-        _requestBody = utf8.decode(fullRequest.requestBody!);
+        final responseMime =
+            responseHeaders?['content-type']?.toString().split(';').first;
+        final requestMime =
+            requestHeaders?['content-type']?.toString().split(';').first;
+
+        if (fullRequest.responseBody != null) {
+          if (isTextMimeType(responseMime)) {
+            _responseBody = utf8.decode(fullRequest.responseBody!);
+          } else {
+            _responseBody = base64.encode(fullRequest.responseBody!);
+          }
+        }
+
+        if (fullRequest.requestBody != null) {
+          if (isTextMimeType(requestMime)) {
+            _requestBody = utf8.decode(fullRequest.requestBody!);
+          } else {
+            _requestBody = base64.encode(fullRequest.requestBody!);
+          }
+        }
+
         notifyListeners();
       }
     } finally {

packages/devtools_app/lib/src/shared/primitives/utils.dart

@@ -1126,3 +1126,18 @@ String devtoolsAssetsBasePath({required String origin, required String path}) {
   pathParts.removeLast();
   return '$trimmedOrigin${pathParts.join(separator)}';
 }
+
+/// Returns `true` if the given [mimeType] is considered textual and can be
+/// safely decoded as UTF-8 without base64 encoding.
+///
+/// This function is useful for determining whether the content of an HTTP
+/// request or response can be directly included in a HAR or JSON file as
+/// human-readable text.
+bool isTextMimeType(String? mimeType) {
+  if (mimeType == null) return false;
+  return mimeType.startsWith('text/') ||
+      mimeType == 'application/json' ||
+      mimeType == 'application/javascript' ||
+      mimeType == 'application/xml' ||
+      mimeType == 'application/x-www-form-urlencoded';
+}