tiny fix sampling seed for completion api (#15498)

python/sglang/srt/entrypoints/openai/protocol.py

@@ -656,6 +656,7 @@ class ChatCompletionRequest(BaseModel):
             "skip_special_tokens": self.skip_special_tokens,
             "logit_bias": self.logit_bias,
             "custom_params": self.custom_params,
+            "sampling_seed": self.seed,
         }
 
         if self.response_format and self.response_format.type == "json_schema":

python/sglang/srt/entrypoints/openai/serving_completions.py

@@ -152,6 +152,7 @@ class OpenAIServingCompletion(OpenAIServingBase):
             "skip_special_tokens": request.skip_special_tokens,
             "logit_bias": request.logit_bias,
             "custom_params": request.custom_params,
+            "sampling_seed": request.seed,
         }
 
         # Handle response_format constraints