Update app.py

app.py

@@ -55,7 +55,8 @@ async def generate_image(prompt: str, hf_token: str) -> str | None:
         print(f"Image generation failed: {e}")
         return None
 
-# The full workflow class
+# The full workflow class, now with the required end_story step
+
 class StorytellerWorkflow(Workflow):
     def __init__(self, **kwargs):
         super().__init__(timeout=300, **kwargs)
@@ -116,6 +117,12 @@ class StorytellerWorkflow(Workflow):
         await ctx.store.set("inventory", inventory)
         return StoryContext(story_part=full_story_part, inventory=inventory, is_new_scene=is_new_scene_flag)
 
+    # --- THIS IS THE STEP THAT WAS MISSING ---
+    @step
+    def end_story(self, ev: StoryEnd) -> StopEvent:
+        """This step satisfies the workflow validator by providing a path to a StopEvent."""
+        return StopEvent(result=ev.final_message)
+        
 # These two steps are no longer needed, as Gradio's UI will handle the display logic.
 # @step async def display_scene(...)
 # @step async def get_user_choice(...)