src/Tools/VSCode/src/preview_panel.scala

             resources.get_model(file) match {
               case Some(model) =>
                 val snapshot = model.snapshot()
                 if (snapshot.is_outdated) m
                 else {
-                  val html_context = new Presentation.HTML_Context
+                  val html_context =
+                    new Presentation.HTML_Context {
+                      override def root_dir: Path = Path.current
+                      override def theory_session(name: Document.Node.Name): Sessions.Info =
+                        resources.sessions_structure(resources.session_base.theory_qualifier(name))
+                    }
                   val document =
                     Presentation.html_document(snapshot, html_context, Presentation.elements2)
                   channel.write(LSP.Preview_Response(file, column, document.title, document.content))
                   m - file
                 }