anchor.diff:        return _returnFailure(
             request, 'Query parameter $CONTEXT_QUERY_PARAM required');
       }
  +    InternalAnalysisContext context = null;
       Folder folder = _findFolder(analysisServer, contextFilter);
       if (folder == null) {
  -      return _returnFailure(request, 'Invalid context: $contextFilter');
  +      context = _getSdkContext(analysisServer, contextFilter);
  +      if (context == null) {
  +        return _returnFailure(request, 'Invalid context: $contextFilter');
  +      }
  +    } else {
  +      context = analysisServer.folderMap[folder];
       }
   
       List<String> priorityNames = <String>[];
  
positive.code:    * Write diagnostic information about the given [context] to the given
     * [buffer].
     */
    void _writeContextDiagnostics(
        StringBuffer buffer, InternalAnalysisContext context) {
      AnalysisDriver driver = (context as AnalysisContextImpl).driver;
      List<WorkItem> workItems = driver.currentWorkOrder?.workItems;
  
      buffer.write('<p>');
      buffer.write(makeLink(CONTEXT_VALIDATION_DIAGNOSTICS_PATH,
          {CONTEXT_QUERY_PARAM: context.name}, 'Run validation'));
      buffer.write('</p>');
  
      buffer.write('<h3>Most Recently Perfomed Tasks</h3>');
  
negative.code:       return _returnFailure(
            request, 'Query parameter $CONTEXT_QUERY_PARAM required');
      }
      InternalAnalysisContext context = null;
      Folder folder = _findFolder(analysisServer, contextFilter);
      if (folder == null) {
        context = _getSdkContext(analysisServer, contextFilter);
        if (context == null) {
          return _returnFailure(request, 'Invalid context: $contextFilter');
        }
      } else {
        context = analysisServer.folderMap[folder];
      }
  
      _writeResponse(request, (StringBuffer buffer) {
        _writePage(buffer, 'Analysis Server - Context Diagnostics',
            ['Context: $contextFilter'], (StringBuffer buffer) {
          _writeContextDiagnostics(buffer, context, contextFilter);
        });
      });
    }
  