ref：重构maisaka内置工具逻辑，拆分文件

src/maisaka/builtin_tool/no_reply.py

@@ -0,0 +1,34 @@
+"""no_reply 内置工具。"""
+
+from typing import Optional
+
+from src.core.tooling import ToolExecutionContext, ToolExecutionResult, ToolInvocation, ToolSpec
+
+from .context import BuiltinToolRuntimeContext
+
+
+def get_tool_spec() -> ToolSpec:
+    """获取 no_reply 工具声明。"""
+
+    return ToolSpec(
+        name="no_reply",
+        brief_description="本轮不进行回复，等待其他用户的新消息。",
+        provider_name="maisaka_builtin",
+        provider_type="builtin",
+    )
+
+
+async def handle_tool(
+    tool_ctx: BuiltinToolRuntimeContext,
+    invocation: ToolInvocation,
+    context: Optional[ToolExecutionContext] = None,
+) -> ToolExecutionResult:
+    """执行 no_reply 内置工具。"""
+
+    del context
+    tool_ctx.runtime._enter_stop_state()
+    return tool_ctx.build_success_result(
+        invocation.tool_name,
+        "当前对话循环已暂停，等待新消息到来。",
+        metadata={"pause_execution": True},
+    )