fix: restore remote conversation recovery and clean obsolete agents

Wait for model delivery acknowledgements before completing remote prompts and preserve completed outcomes when idle Runtime cleanup fails. Explicit messages after an unknown outcome now open a fresh binding with history instead of reusing the failed session; recovery remains attach-only.

Run obsolete payload cleanup through the current Agent after activation, retaining history and unresolved process ownership. Live legacy daemons and shared Runtime versions remain deferred. Includes focused regressions, local OpenCode simulation, and isolated Linux validation evidence. Typecheck and lint passed; the full test run timed out.

Release note: Remote conversations can continue after an uncertain result, and completed answers no longer fail solely because Runtime cleanup fails. Updates remove verified inactive Agent payloads and owned orphan processes while retaining active or uncertain installations and conversation history.

docs/features/remote-host/environment-provisioning-technical-design.md

@@ -161,12 +161,15 @@ daemon 参与。两种 acquisition 的差别只在于如何把同一个签名 co
 4. commit 后在同一条已固定身份的 SSH lease 上执行 Agent bootstrap/readiness 和 Runtime
    activate。新 Agent 最多完整验证一次，新 Runtime 最多完整验证一次；注册成功后的
    health、capabilities 和 prompt 启动只读取 registry、签名 manifest 与入口 metadata。
-5. Main 确认 adoption 后显式执行 cleanup。cleanup 失败不回滚已经健康的 Agent/Runtime，
-   也不阻塞下一次更新。
+5. Agent adoption 和所有 Runtime 激活成功后，Main 通过新安装执行 `cleanup-obsolete`，
+   尽力回收已证明停止且无待处理工作的旧 Agent payload。命令返回逐安装的延期原因，
+   不支持该命令的旧包或清理失败不会回滚健康环境。随后显式清理本次 operation staging；
+   staging cleanup 失败也不阻塞下一次更新。
 
-新安装成为 current 后，旧 Agent 排空已有任务再退出，空闲旧 Agent 直接退出；当前 Agent
-可以常驻。Runtime 回收、待答问题与旧任务重连的规则见
-[远程主机技术设计](./technical-design.md)。
+新安装成为 current 后，包含退役逻辑的旧 Agent 排空已有任务再退出；当前 Agent 可以常驻。
+仍存活且缺少退役逻辑的 legacy daemon 不会被升级清理命令终止，不能用无连接推断其空闲。
+共享 Runtime digest 目录、历史和 Workspace 保留。清理条件、延期限制及验证记录见
+[远程主机技术设计](./technical-design.md#升级残留清理)。
 
 这不是两个并行安装管理器，也不存在把 Agent 与 Runtime payload 逐文件走 SFTP 安装的
 第二条路径。两种 acquisition 共享相同的 prepare、commit、adoption、finalize 与 cleanup。