diff -r 466ea227e00d -r a4ff8a787202 src/Pure/System/session.scala
--- a/src/Pure/System/session.scala	Thu Sep 01 11:33:44 2011 +0200
+++ b/src/Pure/System/session.scala	Thu Sep 01 13:34:45 2011 +0200
@@ -22,7 +22,7 @@
   case object Global_Settings
   case object Perspective
   case object Assignment
-  case class Commands_Changed(nodes: Set[String], commands: Set[Command])
+  case class Commands_Changed(nodes: Set[Document.Node.Name], commands: Set[Command])
 
   sealed abstract class Phase
   case object Inactive extends Phase
@@ -63,7 +63,7 @@
   private val (_, command_change_buffer) =
     Simple_Thread.actor("command_change_buffer", daemon = true)
   {
-    var changed_nodes: Set[String] = Set.empty
+    var changed_nodes: Set[Document.Node.Name] = Set.empty
     var changed_commands: Set[Command] = Set.empty
     def changed: Boolean = !changed_nodes.isEmpty || !changed_commands.isEmpty
 
@@ -134,23 +134,22 @@
   private val global_state = new Volatile(Document.State.init)
   def current_state(): Document.State = global_state()
 
-  def snapshot(name: String, pending_edits: List[Text.Edit]): Document.Snapshot =
+  def snapshot(name: Document.Node.Name, pending_edits: List[Text.Edit]): Document.Snapshot =
     global_state().snapshot(name, pending_edits)
 
 
   /* theory files */
 
-  def header_edit(name: String, master_dir: String,
-    header: Document.Node_Header): Document.Edit_Text =
+  def header_edit(name: Document.Node.Name, header: Document.Node_Header): Document.Edit_Text =
   {
     def norm_import(s: String): String =
     {
       val thy_name = Thy_Header.base_name(s)
       if (thy_load.is_loaded(thy_name)) thy_name
-      else thy_load.append(master_dir, Thy_Header.thy_path(Path.explode(s)))
+      else thy_load.append(name.master_dir, Thy_Header.thy_path(Path.explode(s)))
     }
     def norm_use(s: String): String =
-      thy_load.append(master_dir, Path.explode(s))
+      thy_load.append(name.master_dir, Path.explode(s))
 
     val header1: Document.Node_Header =
       header match {
@@ -167,12 +166,12 @@
 
   private case class Start(timeout: Time, args: List[String])
   private case object Interrupt
-  private case class Init_Node(name: String, master_dir: String,
+  private case class Init_Node(name: Document.Node.Name,
     header: Document.Node_Header, perspective: Text.Perspective, text: String)
-  private case class Edit_Node(name: String, master_dir: String,
+  private case class Edit_Node(name: Document.Node.Name,
     header: Document.Node_Header, perspective: Text.Perspective, edits: List[Text.Edit])
   private case class Change_Node(
-    name: String,
+    name: Document.Node.Name,
     doc_edits: List[Document.Edit_Command],
     previous: Document.Version,
     version: Document.Version)
@@ -185,7 +184,7 @@
 
     /* perspective */
 
-    def update_perspective(name: String, text_perspective: Text.Perspective)
+    def update_perspective(name: Document.Node.Name, text_perspective: Text.Perspective)
     {
       val previous = global_state().tip_version
       val (perspective, version) = Thy_Syntax.edit_perspective(previous, name, text_perspective)
@@ -206,7 +205,7 @@
 
     /* incoming edits */
 
-    def handle_edits(name: String, master_dir: String,
+    def handle_edits(name: Document.Node.Name,
         header: Document.Node_Header, edits: List[Document.Node.Edit[Text.Edit, Text.Perspective]])
     //{{{
     {
@@ -215,7 +214,7 @@
 
       prover.get.cancel_execution()
 
-      val text_edits = header_edit(name, master_dir, header) :: edits.map(edit => (name, edit))
+      val text_edits = header_edit(name, header) :: edits.map(edit => (name, edit))
       val result = Future.fork { Thy_Syntax.text_edits(syntax, previous.join, text_edits) }
       val change =
         global_state.change_yield(_.continue_history(previous, text_edits, result.map(_._2)))
@@ -354,20 +353,20 @@
         case Interrupt if prover.isDefined =>
           prover.get.interrupt
 
-        case Init_Node(name, master_dir, header, perspective, text) if prover.isDefined =>
+        case Init_Node(name, header, perspective, text) if prover.isDefined =>
           // FIXME compare with existing node
-          handle_edits(name, master_dir, header,
+          handle_edits(name, header,
             List(Document.Node.Clear(),
               Document.Node.Edits(List(Text.Edit.insert(0, text))),
               Document.Node.Perspective(perspective)))
           reply(())
 
-        case Edit_Node(name, master_dir, header, perspective, text_edits) if prover.isDefined =>
+        case Edit_Node(name, header, perspective, text_edits) if prover.isDefined =>
           if (text_edits.isEmpty && global_state().tip_stable &&
               perspective.range.stop <= global_state().last_exec_offset(name))
             update_perspective(name, perspective)
           else
-            handle_edits(name, master_dir, header,
+            handle_edits(name, header,
               List(Document.Node.Edits(text_edits), Document.Node.Perspective(perspective)))
           reply(())
 
@@ -396,13 +395,11 @@
 
   def interrupt() { session_actor ! Interrupt }
 
-  // FIXME simplify signature
-  def init_node(name: String, master_dir: String,
+  def init_node(name: Document.Node.Name,
     header: Document.Node_Header, perspective: Text.Perspective, text: String)
-  { session_actor !? Init_Node(name, master_dir, header, perspective, text) }
+  { session_actor !? Init_Node(name, header, perspective, text) }
 
-  // FIXME simplify signature
-  def edit_node(name: String, master_dir: String, header: Document.Node_Header,
-    perspective: Text.Perspective, edits: List[Text.Edit])
-  { session_actor !? Edit_Node(name, master_dir, header, perspective, edits) }
+  def edit_node(name: Document.Node.Name,
+    header: Document.Node_Header, perspective: Text.Perspective, edits: List[Text.Edit])
+  { session_actor !? Edit_Node(name, header, perspective, edits) }
 }