copyberry · Oct 1, 2026 · Oct 1, 2026
diff --git a/codex-rs/app-server-daemon/src/backend/pid_start.rs b/codex-rs/app-server-daemon/src/backend/pid_start.rs
@@ -1,5 +1,6 @@
 //! Detached process launch and PID publication. Hold the reservation lock until
 //! the record is published, and on Windows until an updater acknowledges startup.
+//! Windows children use a separate working directory to preserve the state directory ACL.
 //! Recover a deleted Unix cwd without changing workspace defaults for usable directories.
 
 use super::PidBackend;
@@ -25,6 +26,21 @@ impl PidBackend {
                 .await
                 .with_context(|| format!("failed to create pid directory {}", parent.display()))?;
         }
+        #[cfg(windows)]
+        let workdir = {
+            let workdir = self
+                .pid_file
+                .parent()
+                .context("daemon pid path has no parent")?
+                .join("workdir");
+            fs::create_dir_all(&workdir).await.with_context(|| {
+                format!(
+                    "failed to create daemon working directory {}",
+                    workdir.display()
+                )
+            })?;
+            workdir
+        };
         let reservation_lock = self.acquire_reservation_lock().await?;
         loop {
             match fs::OpenOptions::new()
@@ -157,6 +173,10 @@ impl PidBackend {
         {
             use windows_sys::Win32::System::Threading::CREATE_BREAKAWAY_FROM_JOB;
             use windows_sys::Win32::System::Threading::DETACHED_PROCESS;
+            // A Windows process pins its working directory for its lifetime.
+            // Keep both managed children out of the launching project's directory.
+            // Sandbox setup may broaden the cwd ACL, so do not use the private state directory.
+            command.current_dir(&workdir);
             // Never retry inside the parent's Job Object: that would report a
             // successful launch that dies when the terminal/SSH session closes.
             command.creation_flags(DETACHED_PROCESS | CREATE_BREAKAWAY_FROM_JOB);

diff --git a/codex-rs/app-server-daemon/src/backend/pid_tests.rs b/codex-rs/app-server-daemon/src/backend/pid_tests.rs
@@ -705,6 +705,61 @@ async fn stale_creation_time_never_stops_reused_pid() {
     }
 }
 
+#[cfg(windows)]
+#[tokio::test]
+async fn managed_children_launch_in_workdir_without_changing_private_state_directory() {
+    if is_elevated_test_process().expect("query administrator membership") {
+        return;
+    }
+    let temp = TempDir::new().expect("temp dir");
+    let state_dir = temp.path().join("state");
+    let codex_bin = temp.path().join("codex.cmd");
+    tokio::fs::write(
+        &codex_bin,
+        "@echo off\r\n\
+         if \"%3\"==\"--help\" exit /b 1\r\n\
+         echo ready > launched.cwd\r\n\
+         if defined CODEX_DAEMON_SHUTDOWN_FILE (for %%F in (\"%CODEX_DAEMON_SHUTDOWN_FILE%\") do type nul > \"%%~dpnF.ready\")\r\n\
+         for /l %%i in (1,1,10000000) do @rem\r\n",
+    )
+    .await
+    .expect("write daemon fixture");
+    let backends = [
+        PidBackend::new(
+            codex_bin.clone(),
+            state_dir.join("app-server.pid"),
+            /*remote_control_enabled*/ false,
+        ),
+        PidBackend::new_update_loop(
+            codex_bin,
+            state_dir.join("updater.pid"),
+            /*restore_release*/ None,
+        ),
+    ];
+    for backend in backends {
+        backend.start().await.expect("launch managed child");
+        let marker = state_dir.join("workdir/launched.cwd");
+        let launched_in_workdir = tokio::time::timeout(Duration::from_secs(5), async {
+            while !marker.exists() {
+                sleep(Duration::from_millis(10)).await;
+            }
+        })
+        .await;
+        backend
+            .stop_with_grace(/*grace_seconds*/ 0)
+            .await
+            .expect("stop managed child");
+        launched_in_workdir.expect("child did not write its relative marker in workdir");
+        codex_uds::prepare_private_socket_directory(&state_dir)
+            .await
+            .expect("state directory remains private");
+        assert!(!backend.pid_file.exists());
+        tokio::fs::remove_file(marker)
+            .await
+            .expect("remove marker before next child launch");
+    }
+}
+
 #[cfg(windows)]
 #[tokio::test]
 async fn failed_updater_handoff_preserves_predecessor_record() {