聊天缓存以可为空的标识为键,以及五个表面错误地报告缺失的球体

Found while auditing every wallet surface for its behavior under a lock. All of these are byte-identical to `main` — none was introduced by the graceful-lock branch, and none is reachable by a user now that locked chat surfaces are gated. They are grouped here because they share one root cause and one blast radius.