[New Model]: Add sensenova u1 support (#3319)

Signed-off-by: princepride <wangzhipeng628@gmail.com>
Signed-off-by: 汪志鹏 <wangzhipeng628@gmail.com>

vllm_omni/diffusion/diffusion_engine.py

@@ -69,6 +69,34 @@ def supports_audio_output(model_class_name: str) -> bool:
     return bool(getattr(model_cls, "support_audio_output", False))
 
 
+def get_extra_body_params(model_class_name: str) -> frozenset[str]:
+    """Return the set of extra_body keys accepted by a pipeline.
+
+    Each pipeline can declare ``EXTRA_BODY_PARAMS: ClassVar[frozenset[str]]``
+    to advertise which request-level parameters should be forwarded from
+    ``extra_body`` to ``OmniDiffusionSamplingParams.extra_args``.
+    Returns an empty frozenset when the pipeline does not declare any.
+    """
+    model_cls = DiffusionModelRegistry._try_load_model_cls(model_class_name)
+    if model_cls is None:
+        return frozenset()
+    return frozenset(getattr(model_cls, "EXTRA_BODY_PARAMS", frozenset()))
+
+
+def get_extra_output_params(model_class_name: str) -> frozenset[str]:
+    """Return the set of custom_output keys to expose in API response metrics.
+
+    Each pipeline can declare ``EXTRA_OUTPUT_PARAMS: ClassVar[frozenset[str]]``
+    to advertise which ``DiffusionOutput.custom_output`` keys should be
+    copied into the response ``metrics`` dict.
+    Returns an empty frozenset when the pipeline does not declare any.
+    """
+    model_cls = DiffusionModelRegistry._try_load_model_cls(model_class_name)
+    if model_cls is None:
+        return frozenset()
+    return frozenset(getattr(model_cls, "EXTRA_OUTPUT_PARAMS", frozenset()))
+
+
 class DiffusionEngine:
     """The diffusion engine for vLLM-Omni diffusion models."""
 
@@ -230,6 +258,11 @@ class DiffusionEngine:
             "postprocess_time_ms": postprocess_time * 1000,
         }
 
+        # Detect text output: when the pipeline returns a string (e.g.,
+        # SenseNova-U1 / BAGEL single-stage img2text / text2text), wrap it
+        # as a text-type response instead of an image.
+        is_text_output = isinstance(output_data, str) and custom_output.get("text_output") is not None
+
         # Handle single request or multiple requests
         is_audio_output = supports_audio_output(self.od_config.model_class_name)
         if is_audio_output and model_audio_sample_rate is None:
@@ -247,6 +280,19 @@ class DiffusionEngine:
             prompt = request.prompts[0]
             request_id = request.request_ids[0] if request.request_ids else ""
 
+            if is_text_output:
+                return [
+                    OmniRequestOutput.from_diffusion(
+                        request_id=request_id,
+                        images=[],
+                        prompt=prompt,
+                        metrics=metrics,
+                        custom_output=custom_output,
+                        final_output_type="text",
+                        stage_durations=output.stage_durations,
+                        peak_memory_mb=output.peak_memory_mb,
+                    ),
+                ]
             if is_audio_output:
                 request_audio_payload = outputs[0] if len(outputs) == 1 else outputs
                 return [