fix assistant prefill logic (+1 squashed commits)

Squashed commits:

[f4963ba] fix prefills

Author: LostRuins

koboldcpp.py

@@ -3104,29 +3104,26 @@ def raise_exception(msg):
                             func["arguments"] = json.loads(args)
                         except Exception:
                             pass
-            # Fix tool content for some templates
-            # if m.get("role") == "tool" and isinstance(m.get("content"), str):
-            #     try:
-            #         m["content"] = json.loads(m["content"])
-            #     except Exception:
-            #         pass
         jinja_env.globals['strftime_now'] = strftime_now
         jinja_env.globals['raise_exception'] = raise_exception
         jinja_env.filters["tojson"] = tojson
         jinja_compiled_template = jinja_env.from_string(cached_chat_template)
         text = None
-        last_assist_msg = messages[-1]["content"]
+        messages_for_render = []
+        assist_should_prefill = False
         chat_template_kwargs = chat_template_kwargs or {}
-        assist_should_prefill = (messages and messages[-1]["role"] == "assistant" and last_assist_msg and isinstance(last_assist_msg, str) and len(last_assist_msg.strip())>0) #avoid single character newline or space content
+        last_assist_msg = ""
+        if messages:
+            last_assist_msg = messages[-1]["content"]
+            assist_should_prefill = (messages and messages[-1]["role"] == "assistant" and last_assist_msg and isinstance(last_assist_msg, str) and len(last_assist_msg.strip())>0) #avoid single character newline or space content
+            last_assist_msg = "" if not assist_should_prefill else last_assist_msg
+            messages_for_render = messages[:-1] if assist_should_prefill else messages
         if tools and len(tools)>0:
-            text = jinja_compiled_template.render(messages=messages, tools=tools, add_generation_prompt=True, bos_token="", eos_token="", **chat_template_kwargs)
+            text = jinja_compiled_template.render(messages=messages_for_render, tools=tools, add_generation_prompt=True, bos_token="", eos_token="", **chat_template_kwargs)
         else:
-            text = jinja_compiled_template.render(messages=messages, add_generation_prompt=True, bos_token="", eos_token="", **chat_template_kwargs)
-
-        if assist_should_prefill and text: # handle prefill continuations
-            lastindex = text.rfind(last_assist_msg)
-            if lastindex != -1:
-                text = text[:lastindex + len(last_assist_msg)]
+            text = jinja_compiled_template.render(messages=messages_for_render, add_generation_prompt=True, bos_token="", eos_token="", **chat_template_kwargs)
+        if assist_should_prefill and text and last_assist_msg: # handle prefill continuations
+            text = text + last_assist_msg
         return text if text else None
     except Exception as e:
         print(f"Jinja formatting failed: {e}")