fix(runtime): recover a live daemon from a damaged locator

docs/guides/installing-loopx.md

@@ -37,6 +37,12 @@ engine. The same doctor projection exposes `runtime_lifecycle.state` as
 the App can render this projection without inventing a second health model.
 `stopped` is healthy and means the idle-exited runtime will restart on the next
 control-plane request. Validate Node before installing or upgrading LoopX.
+The lifecycle also reports `locator_state` (`missing`, `valid`, or `invalid`)
+and `recorded_pid_alive`. An invalid locator is not treated as an absent one:
+if its loopback endpoint and token still authenticate the recorded PID and
+source revision, the existing runtime is reused instead of starting a second
+daemon. Otherwise the next request cold-starts, while doctor retains the
+locator diagnostic for readback.
 Upgrading from an older Node 22 installation requires restarting the managed
 runtime with `loopx doctor --restart-runtime` after the new Node is on `PATH`.
 SQLite remains opt-in and checks the actual embedded SQLite version before
@@ -56,6 +62,11 @@ Node 堆栈。先核对本机对应的占用或文件系统问题；诊断不会
 修复未知 locator，也不证明所有启动退出都已归因。没有 typed envelope 的退出仍
 保留 `runtime_exited_before_ready`。
 
+中文：`runtime_lifecycle` 同时报告 `locator_state`（`missing`、`valid` 或
+`invalid`）与 `recorded_pid_alive`。无效 locator 不会被当作不存在：若记录的
+loopback 端点与 token 仍能认证相同 PID 和源码修订，则复用现有 runtime，不再
+启动第二个 daemon；否则下一次请求冷启动，同时 doctor 保留 locator 诊断供回读。
+
 The CI and release lanes use Node.js 24 LTS. Node.js 26 remains a non-blocking
 forward-compatibility probe and is not a supported-version promise. After the
 Node.js 22 maintenance window ends, a separate policy change will raise the