Remove redo; undo rename on a device

Redo is gone in both file and device mode: the Edit menu entry, Ctrl/Cmd+Y
and Ctrl/Cmd+Shift+Z, and the redo stack. An undone step is dropped.
Undoing past the last save now leaves the saved depth unreachable, so a
new edit cannot be mistaken for the saved state.

Renames on a device are undoable: LiveRenameCommand renames back on the
device first, and warns and clears history if the device refuses.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -47,7 +47,7 @@ not inside the window. Tk always hands it to the system menu bar.
 | `app_state.py` | Preferences, runtime state, widget handles, `mark_dirty`/`mark_clean` | no |
 | `sax_dom.py` | `meta` bit-packing codec, component path resolution | no |
 | `schema.py` | Kit manifest loading, slot inheritance, slot visibility rules | no |
-| `undo.py` | Undo/redo stack of reversible DOM commands | no |
+| `undo.py` | Undo stack of reversible commands (DOM, and the device in live mode) | no |
 | `wiresheet.py` | Grid, component boxes, link routing and painting | yes |
 | `properties.py` | The Properties view: every slot of one component, read and written | yes |
 | `link_view.py` | The Link View: every link touching one component, drawn around it | yes |
@@ -74,7 +74,16 @@ invisible to every other module. Every mutation of "the document changed" goes t
 (which also removes the `<kit>` entry placing it may have added) and
 `DeleteComponentCommand` (which restores the removed `<link>` entries at their original
 indices, reinserting in ascending order so the indices stay valid) and `SlotValueCommand`
-(one Save from the Properties view, however many slots it changed). Nothing in
+(one Save from the Properties view, however many slots it changed). There is no redo.
+
+On a device the same steps are undoable, and each undo is sent there: `undo.py` has
+live subclasses for moves, slot edits and renames, and `sax_file` has
+`LiveComponentCommand` and `LiveLinkCommand`. Deleting a component first reads its
+whole subtree back from the device (config, children, links, place among its
+siblings), so undo can recreate it; the device hands out new ids, which the DOM
+elements take on. An undo that does not fully reach the device warns and clears the
+history, and so does every view change, since opening a sheet rebuilds the DOM from the
+device. Nothing in
 `undo.py` touches Tk; `main` registers a refresh callback at startup, which is what keeps
 `sax_file` and `wiresheet` free to push commands without an import cycle.
 
@@ -84,7 +93,6 @@ Undoing back to the depth of the last save clears the dirty tint rather than lea
 |---|---|
 | `Ctrl`/`Cmd` + `S` | Save (direct overwrite) |
 | `Ctrl`/`Cmd` + `Z` | Undo |
-| `Ctrl`/`Cmd` + `Y` or `Ctrl`/`Cmd` + `Shift` + `Z` | Redo |
 | `Del` / `Backspace` | Delete selected component |
 | `Ctrl`/`Cmd` + `B` | Show or hide the tree/palette column |
 | `Ctrl` + `W` | Tidy Layout: re-flow the open sheet |

app_state.py

@@ -8,7 +8,7 @@ so later rebinding would only ever be seen by the module that did it.
 import configparser
 import os
 
-VERSION = "0.0.0.152"
+VERSION = "0.0.0.153"
 PROPERTIES_FILE = os.path.join(os.path.dirname(os.path.abspath(__file__)), "editor.properties")
 DEFAULT_GRID_SIZE = 10
 DEFAULT_ADD_TIMESTAMP = True

main.py

@@ -186,7 +186,7 @@ def refresh_dirty_display():
 
 
 def refresh_all_views():
-    """Rebuilds tree and canvas from the DOM. Registered as undo/redo's view refresh."""
+    """Rebuilds tree and canvas from the DOM. Registered as undo's view refresh."""
     sax_file.refresh_treeview_from_dom(app_state.xml_root_element)
     wiresheet.render_current_sheet()
 
@@ -559,14 +559,6 @@ def do_undo(event=None):
     return "break"
 
 
-def do_redo(event=None):
-    label = undo.redo()
-    if label is None:
-        return "break"
-    app_state.window.title(f"{_base_title()} — redid {label}")
-    return "break"
-
-
 def _base_title():
     if app_state.live_mode:
         return app_state.base_window_title_live()
@@ -943,7 +935,7 @@ def on_tree_select(event):
     element = app_state.tree_element_map.get(selected_id)
     components_to_render = []
 
-    # Remembered so undo/redo and tidy can repaint this same sheet from the DOM.
+    # Remembered so undo and tidy can repaint this same sheet from the DOM.
     app_state.current_sheet_parent = element
     record_visit(VIEW_SHEET, element)
 
@@ -2754,7 +2746,6 @@ tree_root_context_menu = tk.Menu(window, tearoff=0)
 SHORTCUTS = [
     ("s", do_save),
     ("z", do_undo),
-    ("y", do_redo),
     ("b", toggle_left_column),
     # Zoom, in every spelling the key can arrive as: with and without Shift, and on the
     # numeric keypad.
@@ -2774,10 +2765,6 @@ for key, handler in SHORTCUTS:
     window.bind_all(f"<Command-{key}>", handler)
     window.bind_all(f"<Control-{key}>", handler)
 
-# Redo also as Shift-Z, the usual mac chord.
-window.bind_all("<Command-Shift-Z>", do_redo)
-window.bind_all("<Control-Shift-Z>", do_redo)
-
 # Delete: the mac Delete key reports as BackSpace, the Windows one as Delete.
 window.bind_all("<Delete>", delete_selected_component)
 window.bind_all("<BackSpace>", delete_selected_component)
@@ -2817,7 +2804,6 @@ menu_bar.add_cascade(label="File", menu=menu_file)
 
 menu_edit = tk.Menu(menu_bar, tearoff=0)
 menu_edit.add_command(label="Undo", command=do_undo, accelerator=f"{accel_mod}+Z")
-menu_edit.add_command(label="Redo", command=do_redo, accelerator=f"{accel_mod}+Y")
 menu_edit.add_separator()
 menu_edit.add_command(label="Delete Component", command=delete_selected_component, accelerator="Del")
 menu_bar.add_cascade(label="Edit", menu=menu_edit)

sax_file.py

@@ -462,11 +462,12 @@ def rename_component(comp_element, new_name):
     for link, attr, _, new_ref in link_changes:
         link.set(attr, new_ref)
 
-    if not app_state.live_mode:
-        undo.push(undo.RenameComponentCommand(
-            comp_element, old_name, new_name, link_changes,
-            label=f"rename {old_name} to {new_name}"
-        ))
+    command_class = (undo.LiveRenameCommand if app_state.live_mode
+                     else undo.RenameComponentCommand)
+    undo.push(command_class(
+        comp_element, old_name, new_name, link_changes,
+        label=f"rename {old_name} to {new_name}"
+    ))
 
     app_state.mark_dirty()
     refresh_treeview_from_dom(root)

undo.py

@@ -1,7 +1,8 @@
-"""Undo/redo as a stack of reversible commands.
+"""Undo as a stack of reversible commands. There is no redo: an undone step is gone.
 
-Commands own the DOM mutation in both directions; in live mode they also carry it to the
-device, and raise LiveUndoError when it does not get there. Nothing here touches Tk: the view is
+Commands own the DOM mutation in both directions -- redo() is how a command is first
+applied, undo() takes it back. In live mode they also carry it to the device, and raise
+LiveUndoError when it does not get there. Nothing here touches Tk: the view is
 refreshed through a callback that main registers at startup, which also keeps the
 import graph free of cycles (sax_file and wiresheet both push commands here).
 """
@@ -13,13 +14,12 @@ import schema
 from sax_dom import remove_prop, restore_children, set_prop_value, update_meta_property
 
 _undo_stack = []
-_redo_stack = []
 _saved_depth = 0        # len(_undo_stack) as of the last save
 _refresh_view = None
 
 
 def set_refresh_callback(callback):
-    """Registers how the view should be rebuilt after an undo or redo."""
+    """Registers how the view should be rebuilt after an undo."""
     global _refresh_view
     _refresh_view = callback
 
@@ -36,21 +36,20 @@ def _refresh():
 
 
 def push(command):
-    """Records an already-applied command. Any redo history becomes unreachable."""
+    """Records an already-applied command."""
+    global _saved_depth
+    # Undone past the save, the saved state can no longer be reached by undoing.
+    if len(_undo_stack) < _saved_depth:
+        _saved_depth = -1
     _undo_stack.append(command)
-    _redo_stack.clear()
 
 
 def can_undo():
     return bool(_undo_stack)
 
 
-def can_redo():
-    return bool(_redo_stack)
-
-
 class LiveUndoError(Exception):
-    """A live command's undo or redo did not fully reach the device.
+    """A live command's undo did not fully reach the device.
 
     Raised with what did not happen; live_hooks.last_error holds why.
     """
@@ -65,21 +64,6 @@ def undo():
     except LiveUndoError as failure:
         _abandon_history("Undo", failure)
         return None
-    _redo_stack.append(command)
-    _refresh()
-    return command.label
-
-
-def redo():
-    if not _redo_stack:
-        return None
-    command = _redo_stack.pop()
-    try:
-        command.redo()
-    except LiveUndoError as failure:
-        _abandon_history("Redo", failure)
-        return None
-    _undo_stack.append(command)
     _refresh()
     return command.label
 
@@ -87,8 +71,8 @@ def redo():
 def _abandon_history(title, failure):
     """After a step that did not reach the device, the history no longer matches it.
 
-    The device may hold part of the step, so neither direction can be trusted to land
-    where it says. History is dropped rather than replayed against a state it never saw.
+    The device may hold part of the step, so the steps below it cannot be trusted to land
+    where they say. History is dropped rather than replayed against a state it never saw.
     """
     reset()
     _refresh()
@@ -105,14 +89,13 @@ def reset():
     """Drops all history, for when a different file is loaded."""
     global _saved_depth
     _undo_stack.clear()
-    _redo_stack.clear()
     _saved_depth = 0
 
 
 def reload_schema_registry():
     """Recompiles the slot registry after the <schema> block changed.
 
-    A failure is swallowed: undo and redo only ever land on a state that resolved once
+    A failure is swallowed: undo only ever lands on a state that resolved once
     already, so a missing manifest here means Sedona home moved underneath the session,
     which the next action reports in its own words.
     """
@@ -360,3 +343,19 @@ class RenameComponentCommand:
         self.element.set("name", self.new_name)
         for link, attr, _, new_value in self.link_changes:
             link.set(attr, new_value)
+
+
+class LiveRenameCommand(RenameComponentCommand):
+    """A rename on the device: the old name goes back there before the DOM takes it."""
+
+    def undo(self):
+        if not live_hooks.live_rename_component(self.element, self.old_name):
+            raise LiveUndoError(f"{self.new_name} was not renamed back to {self.old_name} "
+                                "on the device")
+        super().undo()
+
+    def redo(self):
+        if not live_hooks.live_rename_component(self.element, self.new_name):
+            raise LiveUndoError(f"{self.old_name} was not renamed to {self.new_name} "
+                                "on the device")
+        super().redo()