Add new conditional append node Issue #5 recoommendation. Minor fixes and changes Issues #4 and #6.

string_preview_node.py

@@ -4,12 +4,17 @@ class StringPreviewNode:
         return {
             "required": {},
         }
-    
+
     RETURN_TYPES = ("STRING",)
     RETURN_NAMES = ("output_string",)
     FUNCTION = "preview_string"
-    CATEGORY = "utils"
+    CATEGORY = "utils/StringEssentials"
     OUTPUT_NODE = True
 
+    @classmethod
+    def IS_CHANGED(cls, **kwargs):
+        # Force re-evaluation every time to ensure fresh data in PNG metadata
+        return float("nan")
+
     def preview_string(self, input_string=""):
         return {"ui": {"text": (input_string,)}, "result": (input_string,)}