This works in a constrained runspace, but performance poor as PSES continuously attempts to resolve missing cmdlets.

Author: dkattan

src/PowerShellEditorServices.Hosting/Commands/StartEditorServicesCommand.cs

@@ -351,7 +351,7 @@ private EditorServicesConfig CreateConfigObject()
             var profile = (PSObject)GetVariableValue("profile");
 
             var hostInfo = new HostInfo(HostName, HostProfileId, HostVersion);
-            var initialSessionState = InitialSessionState ?? Runspace.DefaultRunspace.InitialSessionState;
+            var initialSessionState = Runspace.DefaultRunspace.InitialSessionState;
             var editorServicesConfig = new EditorServicesConfig(hostInfo, Host, SessionDetailsPath, bundledModulesPath, LogPath)
             {
                 FeatureFlags = FeatureFlags,

src/PowerShellEditorServices/Services/PowerShellContext/PowerShellContextService.cs

@@ -215,7 +215,8 @@ public static PowerShellContextService Create(
 
             if (hostStartupInfo.InitialSessionState.LanguageMode != PSLanguageMode.FullLanguage)
             {
-                hostStartupInfo.InitialSessionState.ImportPSModule((IEnumerable<Commands.ModuleSpecification>)hostStartupInfo.AdditionalModules);
+                if(hostStartupInfo.AdditionalModules.Count > 0)
+                    hostStartupInfo.InitialSessionState.ImportPSModule(hostStartupInfo.AdditionalModules as string[]);
                 hostStartupInfo.InitialSessionState.ImportPSModule(new string[] { s_commandsModulePath });
             }
             Runspace runspace = PowerShellContextService.CreateRunspace(psHost, hostStartupInfo.InitialSessionState);
@@ -441,7 +442,7 @@ public void Initialize(
                 this.PromptContext = new LegacyReadLineContext(this);
             }
 
-            if (VersionUtils.IsWindows)
+            if (VersionUtils.IsWindows && initialRunspace.InitialSessionState.LanguageMode == PSLanguageMode.FullLanguage)
             {
                 this.SetExecutionPolicy();
             }
@@ -2714,7 +2715,7 @@ Runspace IHostSupportsInteractiveSession.Runspace
         {
             get
             {
-                return this.CurrentRunspace.Runspace;
+                return this.CurrentRunspace?.Runspace;
             }
         }