I suggest to implement the following feature:
Execute the ReportServerDesigner.exe,
showing directly the editor, without going through authentication.
For example using parameters in exe execution to pass the TemplateID, server, user, pass, etc.
I have a c++ application and i like in my application execute directly ReportServerDesigner editor passing information parameters.
With this feature i can have the list of reports in my application using the API rest service and when choose one to edition execute ReportServerDesigner.exe to this report.