fix: use cache_salt for gpt-oss (#23186)

Signed-off-by: Marko Rosenmueller <5467316+dr75@users.noreply.github.com>

tests/entrypoints/openai/test_serving_chat.py

@@ -282,9 +282,11 @@ async def test_serving_chat_could_load_correct_generation_config():
     assert mock_engine.generate.call_args.args[1].repetition_penalty == 1.05
 
 
+@pytest.mark.parametrize("model_type", ["gpt_oss", "any"])
 @pytest.mark.asyncio
-async def test_serving_chat_did_set_correct_cache_salt():
+async def test_serving_chat_did_set_correct_cache_salt(model_type):
     mock_model_config = MockModelConfig()
+    mock_model_config.hf_config.model_type = model_type
 
     mock_engine = MagicMock(spec=MQLLMEngineClient)
     mock_engine.get_tokenizer.return_value = get_tokenizer(MODEL_NAME)

vllm/entrypoints/openai/serving_chat.py

@@ -1483,4 +1483,9 @@ class OpenAIServingChat(OpenAIServing):
         # Render prompt token ids.
         prompt_token_ids = render_for_completion(messages)
         engine_prompt = EngineTokensPrompt(prompt_token_ids=prompt_token_ids)
+
+        # Add cache_salt if provided in the request
+        if request.cache_salt is not None:
+            engine_prompt["cache_salt"] = request.cache_salt
+
         return messages, [prompt_token_ids], [engine_prompt]

vllm/entrypoints/openai/serving_responses.py

@@ -408,6 +408,11 @@ class OpenAIServingResponses(OpenAIServing):
             request, prev_response)
         prompt_token_ids = render_for_completion(messages)
         engine_prompt = EngineTokensPrompt(prompt_token_ids=prompt_token_ids)
+
+        # Add cache_salt if provided in the request
+        if request.cache_salt is not None:
+            engine_prompt["cache_salt"] = request.cache_salt
+
         return messages, [prompt_token_ids], [engine_prompt]
 
     async def responses_full_generator(