So, I've been using WSPBuilder to create my solutions, such a great add on for Visual Studio. I created a WSPBuilder Project and loaded up some app pages and web parts. I then realized I needed a workflow. So I right clicked on the project, selected Add then New Item. I selected Sequential Workflow Feature and clicked Add.

It added all of the wonder files and references itself. I did have to combine the new feature.xml file with my existing so this would install under a single feature.

When I went to open the workflow, the page errored:

The service 'System.Workflow.ComponentModel.Compiler.ITypeProvider' must be installed for this operation to succeed.  Please ensure that this service is available.

The reference to the DLL is in the project and is a good link. After searching the web for about 2 minutes I came across the following link:

http://www.codeplex.com/wspbuilder/Thread/View.aspx?ThreadId=27794

The GUIDs they were referencing didn't work, it broke my project. But I followed their lead. I created a new temporary WSPBuilder Project with Workflow project. I edited the .csproj file for the new project and copied the contents of the following tag, and then updated my original project csproj file.

<project>
  <PropertyGroup>
    <ProjectTypeGuids>{14822709-B5A1-4724-98CA-57A101D1B079};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>

It works like a charm! I can edit and update my workflow with ease.