Get a content edit URL as a string without UrlHelpers or Orchard tokens

I'm trying to get the edit URL of a content as a string from backend, the catch is I'm inside a workflow activity, so I can't use Url.Action... or Url.ItemEditLink... or other UrlHelpers as if it were a controller or a view. Also, although I'm inside a workflow, the contents I need it for are not part of the workflowContext or the activityContext, so I can't use those or tokens either.

A solution could be to get the content metadata and the site baseUrl and try to build it manually, but I think this way is prone to errors.

Thanks.

This is how I build a Uri in an activity:

public class MyClass : Task
{
    private readonly RequestContext _requestContext;
    ...

    public MyActivity(RequestContext requestContext, ...)
    {
        _requestContext = requestContext;
        ...
    }

    ...

    public override IEnumerable<LocalizedString> Execute(WorkflowContext workflowContext, ActivityContext activityContext)
    {
        var content = ... get using ID
        var helper = new UrlHelper(_requestContext);
        var baseurl = new Uri(_orchardServices.WorkContext.CurrentSite.BaseUrl);
        Uri completeurl = new Uri(baseurl, helper.ItemDisplayUrl(content));

        yield return T("Done");
    }
}

Turns out that I actually do build the Uri semi-manually, but I haven't had issues with this method. You may be able to use just the ItemDisplayUrl for navigation inside of Orchard; I had to get the full URL because the string gets sent to an outside program (Slack).