Reject empty Vision Model responses

tools/vision_load.py

@@ -116,6 +116,8 @@ class VisionLoad(Tool):
         response, _ = await build_vision_model(self.agent).unified_call(
             messages=[HumanMessage(content=content)],
         )
+        if not str(response or "").strip():
+            raise RuntimeError("Vision Model returned an empty response.")
         return str(response)
 
     def _store_ephemeral_image(self, image: ephemeral_images.EphemeralImage) -> str:

tools/vision_load.py.dox.md

@@ -27,6 +27,7 @@
 - Direct parallel workers inherit the parent's model override generically. This tool uses their recorded parent context only to resolve ephemeral refs and durable chat media.
 - `max_embeds` comes from the model that actually receives the images.
 - Vision Model calls use the selected model's Advanced `kwargs`; this tool does not impose a separate timeout or output-token limit.
+- An empty Vision Model response is reported as an image-analysis error instead of a successful empty capsule.
 - Update this file whenever tool arguments, output shape, `break_loop` behavior, intervention handling, prompt instructions, or side effects change.
 - `VisionLoad` is a `Tool`.
 - `VisionLoad` defines `execute(...)`.