6 files changed, 98 insertions, 2 deletions
diff --git a/src/platform/client_state.rs b/src/platform/client_state.rs
new file mode 100644
index 00000000..d339bae8
--- /dev/null
+++ b/src/platform/client_state.rs
@@ -0,0 +1,32 @@
+use std::path::Path;
+
+#[cfg(not(windows))]
+pub(crate) fn create_private_state_file(path: &Path) -> std::io::Result<std::fs::File> {
+    super::create_remote_ssh_config_file(path)
+}
+
+#[cfg(windows)]
+pub(crate) fn create_private_state_file(path: &Path) -> std::io::Result<std::fs::File> {
+    super::windows::create_remote_ssh_config_file(path)
+}
+
+#[cfg(not(windows))]
+pub(crate) fn replace_file(source: &Path, destination: &Path) -> std::io::Result<()> {
+    std::fs::rename(source, destination)
+}
+
+#[cfg(windows)]
+pub(crate) fn replace_file(source: &Path, destination: &Path) -> std::io::Result<()> {
+    super::windows::replace_file(source, destination)
+}
+
+#[cfg(not(windows))]
+pub(crate) fn sync_parent_directory(path: &Path) -> std::io::Result<()> {
+    std::fs::File::open(path)?.sync_all()
+}
+
+#[cfg(windows)]
+pub(crate) fn sync_parent_directory(_path: &Path) -> std::io::Result<()> {
+    // replace_file uses MOVEFILE_WRITE_THROUGH on Windows.
+    Ok(())
+}
diff --git a/src/platform/linux.rs b/src/platform/linux.rs
index 8efe7357..6c09667a 100644
--- a/src/platform/linux.rs
+++ b/src/platform/linux.rs
@@ -17,7 +17,7 @@ pub(crate) use super::unix_common::{
     create_remote_ssh_config_file, hostname, local_datetime, remote_bridge_endpoint_path,
     remote_private_temp_base, remote_reattach_argument, remote_reattach_program,
     remote_ssh_config_paths, set_default_plugin_pane_pwd, status_commands_supported,
-    StatusCommandGuard,
+    wait_client_stream_readable, StatusCommandGuard,
 };
 
 const WSL_MARKER_ENV_VARS: &[&str] = &["WSL_DISTRO_NAME", "WSL_INTEROP"];
diff --git a/src/platform/macos.rs b/src/platform/macos.rs
index 948468ac..8840c7ed 100644
--- a/src/platform/macos.rs
+++ b/src/platform/macos.rs
@@ -17,7 +17,7 @@ pub(crate) use super::unix_common::{
     create_remote_ssh_config_file, hostname, local_datetime, remote_bridge_endpoint_path,
     remote_private_temp_base, remote_reattach_argument, remote_reattach_program,
     remote_ssh_config_paths, set_default_plugin_pane_pwd, status_commands_supported,
-    StatusCommandGuard,
+    wait_client_stream_readable, StatusCommandGuard,
 };
 
 const PROC_PGRP_ONLY: u32 = 2;
diff --git a/src/platform/mod.rs b/src/platform/mod.rs
index 4b49b9f7..86a431aa 100644
--- a/src/platform/mod.rs
+++ b/src/platform/mod.rs
@@ -236,6 +236,9 @@ mod unix_common;
 #[cfg(unix)]
 pub(crate) use unix_common::{begin_cli_output, end_cli_output};
 
+mod client_state;
+pub(crate) use client_state::{create_private_state_file, replace_file, sync_parent_directory};
+
 #[cfg(not(unix))]
 pub(crate) fn begin_cli_output() {}
 
diff --git a/src/platform/unix_common.rs b/src/platform/unix_common.rs
index a7926c22..dff67357 100644
--- a/src/platform/unix_common.rs
+++ b/src/platform/unix_common.rs
@@ -1,5 +1,24 @@
 use std::path::{Path, PathBuf};
 
+pub(crate) fn wait_client_stream_readable(stream: &crate::ipc::LocalStream) -> std::io::Result<()> {
+    use std::os::fd::{AsFd as _, AsRawFd as _};
+    let crate::ipc::LocalStream::UdSocket(stream) = stream;
+    let mut descriptor = libc::pollfd {
+        fd: stream.as_fd().as_raw_fd(),
+        events: libc::POLLIN,
+        revents: 0,
+    };
+    // Bound cancellation latency without polling idle connections hundreds of times per second.
+    let result = unsafe { libc::poll(&mut descriptor, 1, 100) };
+    if result < 0 {
+        let error = std::io::Error::last_os_error();
+        if error.kind() != std::io::ErrorKind::Interrupted {
+            return Err(error);
+        }
+    }
+    Ok(())
+}
+
 pub(super) fn read_terminal_grid_size() -> std::io::Result<(u16, u16)> {
     crossterm::terminal::window_size().map(|size| (size.columns, size.rows))
 }
diff --git a/src/platform/windows.rs b/src/platform/windows.rs
index 1c5c4afb..ce0afedb 100644
--- a/src/platform/windows.rs
+++ b/src/platform/windows.rs
@@ -15,10 +15,52 @@ use std::{
 
 mod clipboard_image;
 
+pub(crate) fn wait_client_stream_readable(
+    _stream: &crate::ipc::LocalStream,
+) -> std::io::Result<()> {
+    // Sync named pipes have no read timeout. The caller peeks before each read and checks its
+    // cancellation flag between polls, including when a frame arrives in several fragments.
+    std::thread::sleep(Duration::from_millis(2));
+    Ok(())
+}
+
 pub(super) fn read_terminal_grid_size() -> std::io::Result<(u16, u16)> {
     crossterm::terminal::size()
 }
 
+pub(crate) fn replace_file(
+    source: &std::path::Path,
+    destination: &std::path::Path,
+) -> std::io::Result<()> {
+    use std::os::windows::ffi::OsStrExt;
+    use windows_sys::Win32::Storage::FileSystem::{
+        MoveFileExW, MOVEFILE_REPLACE_EXISTING, MOVEFILE_WRITE_THROUGH,
+    };
+
+    let source = source
+        .as_os_str()
+        .encode_wide()
+        .chain(std::iter::once(0))
+        .collect::<Vec<_>>();
+    let destination = destination
+        .as_os_str()
+        .encode_wide()
+        .chain(std::iter::once(0))
+        .collect::<Vec<_>>();
+    let moved = unsafe {
+        MoveFileExW(
+            source.as_ptr(),
+            destination.as_ptr(),
+            MOVEFILE_REPLACE_EXISTING | MOVEFILE_WRITE_THROUGH,
+        )
+    };
+    if moved == 0 {
+        Err(std::io::Error::last_os_error())
+    } else {
+        Ok(())
+    }
+}
+
 pub(crate) fn set_default_plugin_pane_pwd(
     _env: &mut Vec<(String, String)>,
     _cwd: &std::path::Path,