Why are the T4 outputs being created then deleted?

I have a T4 that is generating multiple .html files.

After creating them all it then deletes them. I have seen the files create in both explorer and VS2010 ultimate (the solution explorer bar grows and then shrinks right back).

I have modified Oleg Synch's updated multiple output code as follows:

ProjectItem GetTemplateItem(DTE dte)
{
 return   // Find the .tt file's ProjectItem
 dte.Solution.FindProjectItem(Host.TemplateFile);
}

void SaveOutput(string outputFileName,List<string> savedOutputs)
 {
  string templateDirectory = Path.GetDirectoryName(Host.TemplateFile);
  string outputFilePath = Path.Combine(templateDirectory, outputFileName);  
  var text= this.GenerationEnvironment.ToString();
  WriteDiagnosticLine("Writing:"+text.Length+" characters");
  File.WriteAllText(outputFilePath,text);
  this.GenerationEnvironment = new StringBuilder();  

  ProjectItem templateProjectItem = GetTemplateItem(Dte);

  templateProjectItem.ProjectItems.AddFromFile(outputFilePath);  

  savedOutputs.Add(outputFileName);

  WriteDiagnosticLine("Added:"+outputFileName);
 }

void WriteDiagnosticLine(string line)
{
System.Diagnostics.Debug.WriteLine(line);
}

the initial code to set Dte is

bool AlwaysKeepTemplateDirty = true;
DTE Dte;
var serviceProvider = Host as开发者_如何学JAVA IServiceProvider;

    if (serviceProvider != null) {
        Dte = serviceProvider.GetService(typeof(SDTE)) as DTE;
    }

    // Fail if we couldn't get the DTE. This can happen when trying to run in TextTransform.exe
    if (Dte == null) {
        throw new Exception("T4Generator can only execute through the Visual Studio host");
    }

it happens whether I make a change and hit save, or right click the .tt file and say run custom tool.

In case it's helpful here's my tt declaration:

<#@ template language="C#" hostspecific="True" debug="True" #>
<#@ output extension=".txt" #>
<#@ assembly name="System.Core" #>
<#@ assembly name="System.Xml" #>
<#@ assembly name="Microsoft.VisualStudio.Shell.Interop.8.0" #>
<#@ assembly name="EnvDTE" #>
<#@ assembly name="EnvDTE80" #>
<#@ import namespace="System.IO" #>
<#@ import namespace="System.Linq" #>
<#@ import namespace="System.Collections.Generic" #>
<#@ import namespace="System.Text" #>
<#@ import namespace="System.Text.RegularExpressions" #>
<#@ import namespace="Microsoft.VisualStudio.Shell.Interop" #>
<#@ import namespace="EnvDTE" #>
<#@ import namespace="EnvDTE80" #>

removing

<#@ include file="T4Toolbox.tt" #>

seems to have solved it. pretty bizarre.