use latest group image for xiaoniu image followups

plugins/ai_auto_response/context_builder.py

@@ -22,6 +22,7 @@ class ContextBuilder:
         reply_mode: str,
         vector_memories: List[Dict],
         quote_context: Dict | None = None,
+        image_context: Dict | None = None,
     ) -> Dict:
         recent_lines = []
         for item in recent_messages[-self.recent_context_size:]:
@@ -45,6 +46,7 @@ class ContextBuilder:
             "vector_memory_prompt": self._build_vector_memory_prompt(vector_memories),
             "group_profile_prompt": self._build_group_profile_prompt(group_profile or {}),
             "quote_prompt": self._build_quote_prompt(quote_context or {}),
+            "image_prompt": self._build_image_prompt(image_context or {}),
             "current_message": f"{sender_name}: {content}",
         }
 
@@ -136,3 +138,14 @@ class ContextBuilder:
             f"被引用内容：{quote_body}" if quote_body else "",
         ]
         return "\n".join([line for line in lines if line])
+
+    @staticmethod
+    def _build_image_prompt(image_context: Dict) -> str:
+        if not image_context:
+            return ""
+        lines = [
+            "已附带最近一张群图片作为上下文。",
+            f"图片发送者：{image_context.get('sender_name', '未知成员')}",
+            f"图片说明：{image_context.get('hint', '')}" if image_context.get("hint") else "",
+        ]
+        return "\n".join([line for line in lines if line])