ASP.NET Core Razor Pages tt file to generate a site page class. Based on https://gist.github.com/niaher/bfa87f0aeda1204091fe

SitePages.tt

// This is an auto-generated file.
<#@ template language="C#" hostSpecific="true" debug="True" #>
<#@ output extension="cs" #>
<#@ assembly name="System.Core" #>
<#@ assembly name="EnvDte" #>
<#@ import namespace="System.Linq" #>
<#@ import namespace="System.IO" #>
<#@ import namespace="System.Collections.Generic" #>
<#@ import namespace="System.Text.RegularExpressions" #>
<#@ import namespace="System" #>
<#
  var visualStudio = (this.Host as IServiceProvider).GetService(typeof(EnvDTE.DTE)) as EnvDTE.DTE;
  var project = visualStudio.Solution.FindProjectItem(this.Host.TemplateFile).ContainingProject as EnvDTE.Project;

  string root = Host.ResolvePath("");
  var projectItems = GetProjectItemsRecursively(project.ProjectItems);
#>
namespace <#=System.Runtime.Remoting.Messaging.CallContext.LogicalGetData("NamespaceHint")#>
{
	public static class SitePages
	{
<#ListPages("/Pages", "cshtml", projectItems);#>

	}
}

<#+
	public void ListPages(string path, string fileType, List<string> projectItems)
	{
		var root = Host.ResolvePath("");
		
		var fileNames = Directory.EnumerateFiles(root + path, "*." + fileType, SearchOption.AllDirectories)
			.Select(x => x.Replace("\\", "/"))
			.Where(x => projectItems.Any(p => p.Equals(x, StringComparison.OrdinalIgnoreCase)))
			.Select(x => x.Substring(root.Length))
			.Select(x => x.Replace("/Pages/", ""))
			.Select(x => x.Replace(".cshtml", ""))
			.OrderBy(x => x)
			.ToList();

		foreach(string fileName in fileNames)
		{
			if (fileName.Contains("_"))
				WriteLine("\t\tpublic static string " + fileName.Replace("/", "") + " => @\"" + fileName + "\";");
			else
				WriteLine("\t\tpublic static string " + fileName.Replace("/", "") + " => @\"/" + fileName + "\";");
		}
	}

	public List<string> GetProjectItemsRecursively(EnvDTE.ProjectItems items)
	{
		var ret = new List<string>();
		if (items == null) return ret;

		foreach(EnvDTE.ProjectItem item in items)
		{
			string result = item.FileNames[1].Replace("\\", "/");
			
			// If not folder.
			if (result[result.Length - 1] != '\\')
			{
				ret.Add(result);
			}
						
			ret.AddRange(GetProjectItemsRecursively(item.ProjectItems));
		}

		return ret;
	}
#>