Struct FfiControllerClientHandle 

pub struct FfiControllerClientHandle { /* private fields */ }

Opaque FFI handle that owns one Tokio runtime and one controller client proxy. 拥有一个 Tokio 运行时和一个控制器客户端代理的不透明 FFI 句柄。

Thread Safety Model / 线程安全模型

The pointer value is backed by one private heap allocation and must stay opaque to callers. 这个指针值由一个私有堆分配支撑，对调用方必须始终保持不透明。

All operations on the same handle are serialized internally through the registry state. 同一个 handle 上的所有操作都会通过注册表中的状态在内部串行化。

After free, the handle is removed from the registry, the shell allocation is dropped, and later calls fail safely without dereferencing the stale pointer. 调用 free 后句柄会从注册表移除并释放外层壳体分配，后续调用不会解引用陈旧指针且会安全失败。