Update app.py

app.py

@@ -41,7 +41,7 @@ from vertexai.preview.vision_models import ImageGenerationModel
 
 # --- Logging Setup ---
 logging.basicConfig(
-    level=logging.INFO, 
+    level=logging.INFO,
     format='%(asctime)s - %(levelname)s - %(message)s'
 )
 logger = logging.getLogger(__name__)
@@ -58,7 +58,7 @@ Generate multiple, branching story timelines from a single theme using AI, compl
 TEXT_MODEL_ID = "models/gemini-1.5-flash"
 AUDIO_MODEL_ID = "models/gemini-1.5-flash"
 AUDIO_SAMPLING_RATE = 24000
-# IMAGE_MODEL_ID is now used with the preview API
+# Pretrained Imagen model used with Vertex AI preview
 IMAGE_MODEL_ID = "imagen-3.0-generate-002"
 DEFAULT_ASPECT_RATIO = "1:1"
 VIDEO_FPS = 24
@@ -79,14 +79,14 @@ except KeyError:
         st.error("🚨 **Google API Key Not Found!** Please configure it.", icon="🚨")
         st.stop()
 
-# For Vertex AI, we also need PROJECT_ID and LOCATION.
+# Vertex AI configuration: Get project and location
 PROJECT_ID = st.secrets.get("PROJECT_ID") or os.environ.get("PROJECT_ID")
 LOCATION = st.secrets.get("LOCATION") or os.environ.get("LOCATION", "us-central1")
 if not PROJECT_ID:
     st.error("🚨 **PROJECT_ID not set!** Please add PROJECT_ID to your secrets.", icon="🚨")
     st.stop()
 
-# Initialize Vertex AI (used for image generation)
+# Initialize Vertex AI
 vertexai.init(project=PROJECT_ID, location=LOCATION)
 
 # --- Initialize Google Clients for text/audio ---
@@ -117,7 +117,7 @@ class StorySegment(BaseModel):
     @field_validator('image_prompt')
     @classmethod
     def image_prompt_no_humans(cls, v: str) -> str:
-        if any(word in v.lower() for word in ["person", "people", "human", "man", "woman", "boy", "girl", "child"]):
+        if any(w in v.lower() for w in ["person", "people", "human", "man", "woman", "boy", "girl", "child"]):
             logger.warning(f"Prompt '{v[:50]}...' may contain humans.")
         return v
 
@@ -265,13 +265,13 @@ def generate_image_imagen(prompt: str, aspect_ratio: str = "1:1", task_id: str =
     """
     Generates an image using Vertex AI's Imagen model via the Vertex AI preview API.
     
-    It calls the ImageGenerationModel from vertexai.preview.vision_models with the pretrained model "imagen-3.0-generate-002" and returns a PIL Image.
+    This function loads the pretrained model "imagen-3.0-generate-002" and attempts to generate an image.
+    If authentication fails, it provides guidance on how to resolve the issue.
     """
     logger.info(f"🖼️ [{task_id}] Requesting image: '{prompt[:70]}...' (Aspect: {aspect_ratio})")
     try:
-        # Load the pretrained Imagen model
+        # Load the pretrained Imagen model from Vertex AI.
         generation_model = ImageGenerationModel.from_pretrained(IMAGE_MODEL_ID)
-        # Generate the image (here we generate one image)
         images = generation_model.generate_images(
             prompt=prompt,
             number_of_images=1,
@@ -281,13 +281,25 @@ def generate_image_imagen(prompt: str, aspect_ratio: str = "1:1", task_id: str =
             safety_filter_level="",
             add_watermark=True,
         )
-        # Return the generated PIL image (using the internal _pil_image attribute)
         image = images[0]._pil_image
         logger.info(f"✅ [{task_id}] Image generated successfully.")
         return image
     except Exception as e:
-        logger.exception(f"❌ [{task_id}] Image generation failed: {e}")
-        st.error(f"Image generation for {task_id} failed: {e}", icon="🖼️")
+        error_str = str(e)
+        if "Unable to authenticate" in error_str:
+            error_msg = (
+                "Authentication error: Unable to authenticate your request. "
+                "If running locally, please run `!gcloud auth login`. "
+                "If running in Colab, try:\n"
+                "    from google.colab import auth\n"
+                "    auth.authenticate_user()\n"
+                "If using a service account or other environment, please refer to "
+                "https://cloud.google.com/docs/authentication for guidance."
+            )
+        else:
+            error_msg = f"Image generation for {task_id} failed: {e}"
+        logger.exception(f"❌ [{task_id}] {error_msg}")
+        st.error(error_msg, icon="🖼️")
         return None
 
 # --- Streamlit UI Elements ---