Fix Session Host startup logging after WinRT shutdown

docs/windows-session-runtime.md

@@ -78,6 +78,8 @@ Session Host 每次连接新建一个进程，不常驻、不复用运行时，
 
 任一步失败都必须关闭包通道并收敛为 Disconnected，只返回有界脱敏错误；未完成握手的 Session Host 最多等待 15 秒后退出。
 
+Session Host 的路径读取和启动失败日志必须在同一次 WinRT 初始化周期内完成；`RoUninitialize` 后不能再次查询缓存的 `ApplicationData` factory。没有 package identity 的裸启动快速、安全退出，不进入握手、不启动 backend，也不回退到普通用户数据目录。
+
 ## 会合记录
 
 `LocalState/vcore/windows/rendezvous.json` 最大 4 KiB：

src/bin/windows_session_host.rs

@@ -2,9 +2,7 @@
 
 #[cfg(windows)]
 fn main() {
-    if let Err(error) = vcore::windows::session::run() {
-        vcore::windows::session::log_startup_failure(&error);
-    }
+    let _ = vcore::windows::session::run();
 }
 
 #[cfg(not(windows))]

src/windows/session.rs

@@ -64,6 +64,15 @@ impl Drop for WinRtGuard {
 #[doc(hidden)]
 pub fn run() -> io::Result<()> {
     let _winrt = WinRtGuard::enter()?;
+    let result = run_initialized();
+    if result.is_err() {
+        // Cached WinRT factories must not be queried after RoUninitialize.
+        log_startup_failure();
+    }
+    result
+}
+
+fn run_initialized() -> io::Result<()> {
     let (local_folder, installed_folder) = package_folders()?;
     log::append(&local_folder, "session", "Session Host starting");
     let runtime = tokio::runtime::Builder::new_current_thread()
@@ -83,8 +92,7 @@ pub fn run() -> io::Result<()> {
     result
 }
 
-#[doc(hidden)]
-pub fn log_startup_failure(_error: &io::Error) {
+fn log_startup_failure() {
     if let Ok((local_folder, _)) = package_folders() {
         log::append(&local_folder, "session", "Session Host startup failed");
     }

tests/windows_session_startup.rs

@@ -0,0 +1,52 @@
+#![cfg(all(windows, feature = "ffi"))]
+
+use std::{
+    os::windows::process::CommandExt,
+    process::{Command, Stdio},
+    ptr, thread,
+    time::{Duration, Instant},
+};
+
+#[link(name = "kernel32")]
+unsafe extern "system" {
+    fn GetCurrentPackageFullName(length: *mut u32, name: *mut u16) -> i32;
+    fn SetErrorMode(mode: u32) -> u32;
+}
+
+#[test]
+fn unpackaged_session_host_exits_without_crashing() {
+    let mut length = 0;
+    // Do not activate a packaged session or touch package-local runtime data.
+    assert_eq!(
+        unsafe { GetCurrentPackageFullName(&mut length, ptr::null_mut()) },
+        15700,
+        "this test requires an unpackaged process"
+    );
+
+    // Child processes inherit this mode; suppress loader and crash dialogs.
+    let previous = unsafe { SetErrorMode(0x8003) };
+    let spawned = Command::new(env!("CARGO_BIN_EXE_vcore-windows-session-host"))
+        .stdin(Stdio::null())
+        .stdout(Stdio::null())
+        .stderr(Stdio::null())
+        .creation_flags(0x08000000)
+        .spawn();
+    unsafe { SetErrorMode(previous) };
+    let mut child = spawned.expect("start the session host");
+    let deadline = Instant::now() + Duration::from_secs(10);
+    loop {
+        if let Some(status) = child.try_wait().expect("read session host status") {
+            assert!(
+                status.success(),
+                "unpackaged startup must exit cleanly: {status}"
+            );
+            break;
+        }
+        if Instant::now() >= deadline {
+            child.kill().expect("terminate the timed-out test process");
+            child.wait().expect("reap the timed-out test process");
+            panic!("unpackaged startup must not wait for a VPN session");
+        }
+        thread::sleep(Duration::from_millis(20));
+    }
+}