fix: Prevent assistant-message prefill rejected by Claude 4.6

strix/llm/llm.py

@@ -188,6 +188,9 @@ class LLM:
         conversation_history.extend(compressed)
         messages.extend(compressed)
 
+        if messages[-1].get("role") == "assistant":
+            messages.append({"role": "user", "content": "<meta>Continue the task.</meta>"})
+
         if self._is_anthropic() and self.config.enable_prompt_caching:
             messages = self._add_cache_control(messages)