fix: server: drop <think> tag in chat template

ktransformers/server/backend/interfaces/transformers.py

@@ -170,7 +170,7 @@ class TransformersInterface(BackendInterfaceBase):
         for m in messages[1:]:
             if m["role"] == "user" and new_messages[-1]["role"] == "user":
                 logger.warning("merge two adjacent user messages")
-                new_messages[-1]["content"] += m["content"]
+                new_messages[-1]["content"] += '\n' + m["content"]
             else:
                 new_messages.append(m)
         # if (self.last_request_id is not None) and self.last_request_id == thread_id:
@@ -179,7 +179,11 @@ class TransformersInterface(BackendInterfaceBase):
         #     input_ids = self.tokenizer.apply_chat_template(
         #         new_messages, return_tensors="pt", add_generation_prompt=True
         #     ).to(self.args.device)
-        input_ids = self.tokenizer.apply_chat_template(new_messages,return_tensors='pt',add_generation_prompt=True).to(self.args.device)
+        input_str: str = self.tokenizer.apply_chat_template(new_messages,tokenize=False,add_generation_prompt=True)
+        # drop <think> token in chat template
+        if input_str.endswith('<think>\n'):
+            input_str = input_str[:-len('<think>\n')]
+        input_ids = self.tokenizer.encode(input_str, return_tensors="pt").to(self.args.device)
         if (self.last_request_id is not None) and self.last_request_id == thread_id:
             x = self.generated_ids[:,:self.seq_length]
             y = input_ids[:,:self.seq_length]
@@ -360,6 +364,7 @@ class TransformersInterface(BackendInterfaceBase):
             #input_ids = torch.tensor([[6366]], device=input_ids.device)
         else:
             raise ValueError("local_messages should be List or str")
+        
         if Config().user_force_think:
             token_thinks = torch.tensor([self.tokenizer.encode("<think>\n",add_special_tokens=False)],device=input_ids.device)
             input_ids = torch.cat(