[bugfix] support text + audio mixed output (#843)

Signed-off-by: GG-li <3226868735@qq.com>

vllm_omni/entrypoints/openai/serving_chat.py

@@ -1324,11 +1324,21 @@ class OmniOpenAIServingChat(OpenAIServingChat, AudioMixin):
         prompt_token_ids = None
         kv_transfer_params = None
 
+        # Build requested modalities set for filtering
+        requested_modalities = (
+            set(request.modalities) if hasattr(request, "modalities") and request.modalities else None
+        )
+
         for omni_outputs in final_outputs:
             choices_data = []
             if omni_outputs.request_output is not None and not getattr(omni_outputs.request_output, "finished", False):
                 continue
 
+            # Filter outputs based on requested modalites
+            if requested_modalities is not None and omni_outputs.final_output_type not in requested_modalities:
+                logger.warning(f"final output type: {omni_outputs.final_output_type} is not needed by the request")
+                continue
+
             if omni_outputs.final_output_type == "text":
                 (
                     choices_data,