Drag links out of slots on the wiresheet; hide @palette=false types

Hovering a slot row highlights the half under the pointer and shows a
direction cursor. Pressing on a slot drags a rubber band; dropping on
another slot links them, dropping on a title bar opens the Link dialog
with the dragged slot preselected, and a no-entry cursor marks a slot
that would refuse the link. A right click that never moves still opens
the context menu.

The palette now leaves out types whose facets carry @palette=false, and
kits with nothing placeable left.

Also points the default device host at 192.168.1.251.

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

main.py

@@ -10,6 +10,7 @@ import threading
 import app_state
 import connect_dialog
 import device_session
+import link_drag
 import link_view
 import live_hooks
 import manage_kits
@@ -1201,8 +1202,12 @@ def _slot_linkable(slot_flags, slot_type, readonly, is_target):
     return True
 
 
-def open_link_dialog(source_element, target_element):
-    """Opens a dialog to select source and target slots, validates types, and creates a link."""
+def open_link_dialog(source_element, target_element, source_slot=None, target_slot=None):
+    """Opens a dialog to select source and target slots, validates types, and creates a link.
+
+    source_slot / target_slot pre-select a slot on that side, as when a link dragged out
+    of a slot is dropped on a component's title bar rather than on one of its slots.
+    """
     window = app_state.window
 
     sides = [source_element, target_element]
@@ -1346,6 +1351,11 @@ def open_link_dialog(source_element, target_element):
     ttk.Button(mid_frame, text="⇄", width=3, command=on_swap).pack(pady=5)
 
     refresh_panels()
+    for var, slot, info, is_target in ((src_var, source_slot, src_slot_info, False),
+                                       (tgt_var, target_slot, tgt_slot_info, True)):
+        if slot in info and _slot_linkable(info[slot][1], info[slot][0], info[slot][2],
+                                           is_target):
+            var.set(slot)
 
     status_label = tk.Label(main_frame, textvariable=status_var, anchor="w", fg="#333333")
     status_label.grid(row=1, column=0, columnspan=3, sticky="w", pady=(8, 0))
@@ -2804,7 +2814,11 @@ def refresh_palette_kits():
     if _schema_has_incomplete_checksums():
         palette_kit_names = []
     else:
-        palette_kit_names = sorted(app_state.active_schema_kits.keys())
+        # A kit with nothing placeable (all abstract or @palette=false) is left out.
+        palette_kit_names = [
+            kit_name for kit_name in sorted(app_state.active_schema_kits.keys())
+            if palette.list_component_types(kit_name)
+        ]
 
     labels = []
     for kit_name in palette_kit_names:
@@ -2966,12 +2980,13 @@ canvas.pack(fill=tk.BOTH, expand=True)
 canvas_vscroll.config(command=canvas.yview)
 canvas_hscroll.config(command=canvas.xview)
 
-canvas.bind("<ButtonPress-1>", on_canvas_click)
-canvas.bind("<B1-Motion>", on_canvas_drag)
-canvas.bind("<ButtonRelease-1>", on_canvas_release)
 canvas.bind("<Configure>", lambda e: wiresheet.draw_grid())
 
-canvas.bind("<ButtonPress-3>", on_canvas_right_click)
+# Either button pressed on a slot row drags out a new link. Elsewhere the left button
+# selects and moves boxes and a plain right click is the menu, as before.
+link_drag.install(canvas, on_canvas_right_click,
+                  on_canvas_click, on_canvas_drag, on_canvas_release,
+                  link_dialog=open_link_dialog)
 canvas.bind("<ButtonPress-2>", on_canvas_right_click)
 canvas.bind("<Double-1>", on_canvas_double_click)