[Frontend][Model] Qwen3Rerank API Server backward compatibility

tests/entrypoints/openai/test_score.py

@@ -7,7 +7,7 @@
 import torch.nn.functional as F
 from torch import tensor
 
-from vllm.entrypoints.openai.protocol import ScoreResponse
+from vllm.entrypoints.openai.protocol import RerankResponse, ScoreResponse
 
 from ...utils import RemoteOpenAIServer
 
@@ -29,11 +29,35 @@
         "name": "BAAI/bge-base-en-v1.5",
         "is_cross_encoder": False
     },
+    {
+        "name": "Qwen/Qwen3-Reranker-0.6B",
+        "is_cross_encoder": True,
+        "is_qwen3_reranker": True,
+    },
 ]
 DTYPE = "half"
 
 
+def _run_qwen3_reranker_hf(hf_model, text_pairs, instruction):
+    """Helper to run Qwen3 reranker with HF, applying the template."""
+    prefix = '<|im_start|>system\nJudge whether the Document meets the requirements based on the Query and the Instruct provided. Note that the answer can only be "yes" or "no".<|im_end|>\n<|im_start|>user\n'
+    suffix = "<|im_end|>\n<|im_start|>assistant\n<think>\n\n</think>\n\n"
+
+    formatted_pairs = []
+    for query, doc in text_pairs:
+        q_formatted = f"{prefix}<Instruct>: {instruction}\n<Query>: {query}\n"
+        d_formatted = f"<Document>: {doc}{suffix}"
+        formatted_pairs.append([q_formatted, d_formatted])
+
+    return hf_model.predict(formatted_pairs).tolist()
+
+
 def run_transformers(hf_model, model, text_pairs):
+    if model.get("is_qwen3_reranker"):
+        # The default instruction used in the server fixture.
+        default_instruction = "Given a web search query, retrieve relevant passages that answer the query"
+        return _run_qwen3_reranker_hf(hf_model, text_pairs,
+                                      default_instruction)
     if model["is_cross_encoder"]:
         return hf_model.predict(text_pairs).tolist()
     else:
@@ -53,21 +77,51 @@
 
 @pytest.fixture(scope="class")
 def server(model: dict[str, Any]):
-    args = ["--enforce-eager", "--max-model-len", "100", "--dtype", DTYPE]
+    args = ["--enforce-eager", "--max-model-len", "256", "--dtype", DTYPE]
+    if model.get("is_qwen3_reranker"):
+        import json
+        prefix = '<|im_start|>system\nJudge whether the Document meets the requirements based on the Query and the Instruct provided. Note that the answer can only be "yes" or "no".<|im_end|>\n<|im_start|>user\n'
+        suffix = "<|im_end|>\n<|im_start|>assistant\n<think>\n\n</think>\n\n"
+        default_instruction = "Given a web search query, retrieve relevant passages that answer the query"
+
+        hf_overrides = {
+            "architectures": ["Qwen3ForSequenceClassification"],
+            "classifier_from_token": ["no", "yes"],
+            "is_original_qwen3_reranker": True,
+            "score_template": {
+                "query_template":
+                f"{prefix}<Instruct>: {{instruction}}\n<Query>: {{query}}\n",
+                "document_template": f"<Document>: {{document}}{suffix}",
+                "default_context": {
+                    "instruction": default_instruction
+                }
+            }
+        }
+        args.extend(["--hf-overrides", json.dumps(hf_overrides)])
 
     with RemoteOpenAIServer(model["name"], args) as remote_server:
         yield remote_server
 
 
 @pytest.fixture(scope="class")
 def runner(model: dict[str, Any], hf_runner):
-    kwargs = {
-        "dtype": DTYPE,
-        "is_cross_encoder" if model["is_cross_encoder"]\
-              else "is_sentence_transformer": True
-    }
+    model_name = model["name"]
+    kwargs = {"dtype": DTYPE}
+    if model.get("is_qwen3_reranker"):
+        # For the HF reference, use the pre-converted Sequence Classification
+        # model to simplify the runner logic.
+        model_name = "tomaarsen/Qwen3-Reranker-0.6B-seq-cls"
+        hf_runner_kwargs = {
+            "dtype": DTYPE,
+            "is_cross_encoder": True,
+            "trust_remote_code": True,
+        }
+    elif model["is_cross_encoder"]:
+        hf_runner_kwargs = {"dtype": DTYPE, "is_cross_encoder": True}
+    else:
+        hf_runner_kwargs = {"dtype": DTYPE, "is_sentence_transformer": True}
 
-    with hf_runner(model["name"], **kwargs) as hf_model:
+    with hf_runner(model_name, **hf_runner_kwargs) as hf_model:
         yield hf_model
 
 
@@ -191,3 +245,75 @@
         assert score_response.status_code == 400
         assert "Please, select a smaller truncation size." in \
             score_response.text
+
+    def test_rerank_with_template(self, server: RemoteOpenAIServer,
+                                  model: dict[str, Any], runner):
+        if not model.get("is_qwen3_reranker"):
+            pytest.skip("Test only for Qwen3 Reranker with template support.")
+
+        instruction = "Find the document that is most relevant to the query about national capitals."
+        query = "What is the capital of China?"
+        documents = [
+            "The capital of France is Paris.",
+            "The capital of China is Beijing."
+        ]
+
+        # vLLM run with custom instruction via kwargs
+        rerank_response = requests.post(
+            server.url_for("rerank"),
+            json={
+                "model": model["name"],
+                "query": query,
+                "documents": documents,
+                "score_template_kwargs": {
+                    "instruction": instruction
+                }
+            })
+        rerank_response.raise_for_status()
+        response_data = RerankResponse.model_validate(rerank_response.json())
+        vllm_outputs = {
+            res.document.text: res.relevance_score
+            for res in response_data.results
+        }
+
+        # HF reference run with the same custom instruction
+        text_pairs = [[query, doc] for doc in documents]
+        hf_outputs = _run_qwen3_reranker_hf(runner, text_pairs, instruction)
+
+        for i, doc in enumerate(documents):
+            assert vllm_outputs[doc] == pytest.approx(hf_outputs[i],
+                                                      rel=0.01)
+
+    def test_score_with_template(self, server: RemoteOpenAIServer,
+                                 model: dict[str, Any], runner):
+        if not model.get("is_qwen3_reranker"):
+            pytest.skip("Test only for Qwen3 Reranker with template support.")
+
+        instruction = "Find the document that is most relevant to the query about national capitals."
+        text_1 = "What is the capital of China?"
+        text_2 = [
+            "The capital of France is Paris.",
+            "The capital of China is Beijing."
+        ]
+
+        # vLLM run with custom instruction via kwargs
+        score_response = requests.post(
+            server.url_for("score"),
+            json={
+                "model": model["name"],
+                "text_1": text_1,
+                "text_2": text_2,
+                "score_template_kwargs": {
+                    "instruction": instruction
+                }
+            })
+        score_response.raise_for_status()
+        response_data = ScoreResponse.model_validate(score_response.json())
+        vllm_outputs = [res.score for res in response_data.data]
+
+        # HF reference run with the same custom instruction
+        text_pairs = [[text_1, doc] for doc in text_2]
+        hf_outputs = _run_qwen3_reranker_hf(runner, text_pairs, instruction)
+
+        for i in range(len(vllm_outputs)):
+            assert vllm_outputs[i] == pytest.approx(hf_outputs[i], rel=0.01)

vllm/entrypoints/openai/protocol.py

@@ -1194,7 +1194,16 @@ class ScoreRequest(OpenAIBaseModel):
             "default: 0). Any priority other than 0 will raise an error "
             "if the served model does not use priority scheduling."),
     )
-
+    score_template: Optional[dict[str, str]] = Field(
+        default=None,
+        description=("A dictionary containing query_template and "
+                     "document_template to format the scorer input."))
+    score_template_kwargs: Optional[dict[str, Any]] = Field(
+        default=None,
+        description=(
+            "Additional keyword args to pass to the template renderer. "
+            "Will be accessible by the score template."),
+    )
     # --8<-- [end:score-extra-params]
 
     def to_pooling_params(self):
@@ -1220,7 +1229,16 @@ class RerankRequest(OpenAIBaseModel):
             "default: 0). Any priority other than 0 will raise an error "
             "if the served model does not use priority scheduling."),
     )
-
+    rerank_template: Optional[dict[str, str]] = Field(
+        default=None,
+        description=("A dictionary containing query_template and "
+                     "document_template to format the reranker input.")
+    )
+    rerank_template_kwargs: Optional[dict[str, Any]] = Field(
+        default=None,
+        description=("A dictionary of key-value pairs to be formatted into "
+                     "the rerank model's template.")
+    )
     # --8<-- [end:rerank-extra-params]
 
     def to_pooling_params(self):

vllm/entrypoints/openai/serving_score.py

@@ -54,7 +54,7 @@
         texts_1: list[str],
         texts_2: list[str],
         request: Union[RerankRequest, ScoreRequest],
-        request_id=str,
+        request_id: str,
         tokenization_kwargs: Optional[dict[str, Any]] = None,
         lora_request: Optional[Union[LoRARequest, None]] = None,
         prompt_adapter_request: Optional[Union[PromptAdapterRequest,
@@ -139,31 +139,58 @@
 
         return final_res_batch
 
-    async def _cross_encoding_score(
+    async def _preprocess_score(
         self,
-        tokenizer: Union[AnyTokenizer],
+        request: Union[RerankRequest, ScoreRequest],
+        tokenizer: AnyTokenizer,
         texts_1: list[str],
         texts_2: list[str],
-        request: Union[RerankRequest, ScoreRequest],
-        request_id=str,
         tokenization_kwargs: Optional[dict[str, Any]] = None,
-        lora_request: Optional[Union[LoRARequest, None]] = None,
-        prompt_adapter_request: Optional[Union[PromptAdapterRequest,
-                                               None]] = None,
-        trace_headers: Optional[Mapping[str, str]] = None,
-    ) -> list[PoolingRequestOutput]:
-
+    ) -> tuple[list[str], list[TokensPrompt]]:
         request_prompts: list[str] = []
         engine_prompts: list[TokensPrompt] = []
 
         if len(texts_1) == 1:
             texts_1 = texts_1 * len(texts_2)
 
-        input_pairs = [(t1, t2) for t1, t2 in zip(texts_1, texts_2)]
+        def identity_processor(t1: str, t2: str) -> tuple[str, str]:
+            return t1, t2
 
-        if isinstance(tokenizer, MistralTokenizer):
-            raise ValueError(
-                "MistralTokenizer not supported for cross-encoding")
+        pair_processor = identity_processor
+
+        template_config = (request.score_template
+                           or self.model_config.hf_config.get(
+                               "score_template"))
+
+        if isinstance(template_config, dict):
+
+            def template_processor(t1: str, t2: str) -> tuple[str, str]:
+                default_context = template_config.get("default_context", {})
+                context = default_context.copy() if isinstance(
+                    default_context, dict) else {}
+                if request.score_template_kwargs:
+                    context.update(request.score_template_kwargs)
+
+                context['query'] = t1
+                context['document'] = t2
+
+                query_template = template_config.get("query_template",
+                                                     "{query}")
+                doc_template = template_config.get("document_template",
+                                                   "{document}")
+
+                formatted_t1 = query_template.format(
+                    **context) if "query_template" in template_config else t1
+                formatted_t2 = doc_template.format(
+                    **context
+                ) if "document_template" in template_config else t2
+                return formatted_t1, formatted_t2
+
+            pair_processor = template_processor
+
+        input_pairs = [
+            pair_processor(t1, t2) for t1, t2 in zip(texts_1, texts_2)
+        ]
 
         tokenize_async = make_async(tokenizer.__call__,
                                     executor=self._tokenizer_executor)
@@ -186,6 +213,28 @@
 
             request_prompts.append(request_prompt)
             engine_prompts.append(engine_prompt)
+        return request_prompts, engine_prompts
+
+    async def _cross_encoding_score(
+        self,
+        tokenizer: AnyTokenizer,
+        texts_1: list[str],
+        texts_2: list[str],
+        request: Union[RerankRequest, ScoreRequest],
+        request_id: str,
+        tokenization_kwargs: Optional[dict[str, Any]] = None,
+        lora_request: Optional[Union[LoRARequest, None]] = None,
+        prompt_adapter_request: Optional[Union[PromptAdapterRequest,
+                                               None]] = None,
+        trace_headers: Optional[Mapping[str, str]] = None,
+    ) -> list[PoolingRequestOutput]:
+
+        if isinstance(tokenizer, MistralTokenizer):
+            raise ValueError(
+                "MistralTokenizer not supported for cross-encoding")
+
+        request_prompts, engine_prompts = await self._preprocess_score(
+            request, tokenizer, texts_1, texts_2, tokenization_kwargs)
 
         # Schedule the request and get the result generator.
         generators: list[AsyncGenerator[PoolingRequestOutput, None]] = []