Revert IS_CHANGED storage - trigger input required

IS_CHANGED doesn't have access to computed input values yet.
The trigger input is required to ensure execution order.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

__init__.py

@@ -61,10 +61,7 @@ class SetVariable:
     OUTPUT_NODE = True
 
     @classmethod
-    def IS_CHANGED(cls, variable_name, value=None):
-        # Store the value during IS_CHANGED phase (runs before all node execution)
-        # This ensures GetVariable nodes can find values even without trigger connection
-        _variable_storage[variable_name] = value
+    def IS_CHANGED(cls, **kwargs):
         return time.time()
 
     def set_var(self, variable_name, value=None):
@@ -74,12 +71,18 @@ class SetVariable:
 
 
 class GetVariable:
-    """Retrieve data by variable name - shows preview on node"""
+    """Retrieve data by variable name - shows preview on node
+
+    Connect SetVariable's output to 'trigger' to ensure proper execution order.
+    """
     @classmethod
     def INPUT_TYPES(cls):
         return {
             "required": {
                 "variable_name": ("STRING", {"default": "my_var"}),
+            },
+            "optional": {
+                "trigger": (ANY,),
             }
         }
     RETURN_TYPES = (ANY,)
@@ -90,10 +93,9 @@ class GetVariable:
 
     @classmethod
     def IS_CHANGED(cls, **kwargs):
-        # Always re-execute to get latest variable value
         return time.time()
 
-    def get_var(self, variable_name):
+    def get_var(self, variable_name, trigger=None):
         if variable_name not in _variable_storage:
             available = list(_variable_storage.keys())
             preview = f"{variable_name} = NOT SET (available: {available})"