How to call a code of my assembly from CodeAction

The code of CodeActions is just an ordinary C# code, and you can call any methods or use any types from your assembly. To register your own types from the assembly, you need to call following method from the WorkflowRuntime object.

_runtime.RegisterAssemblyForCodeActions(Assembly.GetAssembly(typeof(some type from your assembly)));

After that, all namespaces from your assembly will be added to new CodeActions.