Fix toasts on Windows under WSL 2 (#7137)

Before this: no notifications or toasts when using Codex CLI in WSL 2.

After this: I get toasts from Codex

codex-rs/tui/src/notifications/mod.rs

@@ -0,0 +1,139 @@
+mod osc9;
+mod windows_toast;
+
+use std::env;
+use std::io;
+
+use codex_core::env::is_wsl;
+use osc9::Osc9Backend;
+use windows_toast::WindowsToastBackend;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum NotificationBackendKind {
+    Osc9,
+    WindowsToast,
+}
+
+#[derive(Debug)]
+pub enum DesktopNotificationBackend {
+    Osc9(Osc9Backend),
+    WindowsToast(WindowsToastBackend),
+}
+
+impl DesktopNotificationBackend {
+    pub fn osc9() -> Self {
+        Self::Osc9(Osc9Backend)
+    }
+
+    pub fn windows_toast() -> Self {
+        Self::WindowsToast(WindowsToastBackend::default())
+    }
+
+    pub fn kind(&self) -> NotificationBackendKind {
+        match self {
+            DesktopNotificationBackend::Osc9(_) => NotificationBackendKind::Osc9,
+            DesktopNotificationBackend::WindowsToast(_) => NotificationBackendKind::WindowsToast,
+        }
+    }
+
+    pub fn notify(&mut self, message: &str) -> io::Result<()> {
+        match self {
+            DesktopNotificationBackend::Osc9(backend) => backend.notify(message),
+            DesktopNotificationBackend::WindowsToast(backend) => backend.notify(message),
+        }
+    }
+}
+
+pub fn detect_backend() -> DesktopNotificationBackend {
+    if should_use_windows_toasts() {
+        tracing::info!(
+            "Windows Terminal session detected under WSL; using Windows toast notifications"
+        );
+        DesktopNotificationBackend::windows_toast()
+    } else {
+        DesktopNotificationBackend::osc9()
+    }
+}
+
+fn should_use_windows_toasts() -> bool {
+    is_wsl() && env::var_os("WT_SESSION").is_some()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::NotificationBackendKind;
+    use super::detect_backend;
+    use serial_test::serial;
+    use std::ffi::OsString;
+
+    struct EnvVarGuard {
+        key: &'static str,
+        original: Option<OsString>,
+    }
+
+    impl EnvVarGuard {
+        fn set(key: &'static str, value: &str) -> Self {
+            let original = std::env::var_os(key);
+            unsafe {
+                std::env::set_var(key, value);
+            }
+            Self { key, original }
+        }
+
+        fn remove(key: &'static str) -> Self {
+            let original = std::env::var_os(key);
+            unsafe {
+                std::env::remove_var(key);
+            }
+            Self { key, original }
+        }
+    }
+
+    impl Drop for EnvVarGuard {
+        fn drop(&mut self) {
+            unsafe {
+                match &self.original {
+                    Some(value) => std::env::set_var(self.key, value),
+                    None => std::env::remove_var(self.key),
+                }
+            }
+        }
+    }
+
+    #[test]
+    #[serial]
+    fn defaults_to_osc9_outside_wsl() {
+        let _wsl_guard = EnvVarGuard::remove("WSL_DISTRO_NAME");
+        let _wt_guard = EnvVarGuard::remove("WT_SESSION");
+        assert_eq!(detect_backend().kind(), NotificationBackendKind::Osc9);
+    }
+
+    #[test]
+    #[serial]
+    fn waits_for_windows_terminal() {
+        let _wsl_guard = EnvVarGuard::set("WSL_DISTRO_NAME", "Ubuntu");
+        let _wt_guard = EnvVarGuard::remove("WT_SESSION");
+        assert_eq!(detect_backend().kind(), NotificationBackendKind::Osc9);
+    }
+
+    #[cfg(target_os = "linux")]
+    #[test]
+    #[serial]
+    fn selects_windows_toast_in_wsl_windows_terminal() {
+        let _wsl_guard = EnvVarGuard::set("WSL_DISTRO_NAME", "Ubuntu");
+        let _wt_guard = EnvVarGuard::set("WT_SESSION", "abc");
+        assert_eq!(
+            detect_backend().kind(),
+            NotificationBackendKind::WindowsToast
+        );
+    }
+
+    #[cfg(not(target_os = "linux"))]
+    #[test]
+    #[serial]
+    fn stays_on_osc9_outside_linux_even_with_wsl_env() {
+        let _wsl_guard = EnvVarGuard::set("WSL_DISTRO_NAME", "Ubuntu");
+        let _wt_guard = EnvVarGuard::set("WT_SESSION", "abc");
+        assert_eq!(detect_backend().kind(), NotificationBackendKind::Osc9);
+    }
+}

codex-rs/tui/src/notifications/osc9.rs

@@ -0,0 +1,37 @@
+use std::fmt;
+use std::io;
+use std::io::stdout;
+
+use crossterm::Command;
+use ratatui::crossterm::execute;
+
+#[derive(Debug, Default)]
+pub struct Osc9Backend;
+
+impl Osc9Backend {
+    pub fn notify(&mut self, message: &str) -> io::Result<()> {
+        execute!(stdout(), PostNotification(message.to_string()))
+    }
+}
+
+/// Command that emits an OSC 9 desktop notification with a message.
+#[derive(Debug, Clone)]
+pub struct PostNotification(pub String);
+
+impl Command for PostNotification {
+    fn write_ansi(&self, f: &mut impl fmt::Write) -> fmt::Result {
+        write!(f, "\x1b]9;{}\x07", self.0)
+    }
+
+    #[cfg(windows)]
+    fn execute_winapi(&self) -> io::Result<()> {
+        Err(std::io::Error::other(
+            "tried to execute PostNotification using WinAPI; use ANSI instead",
+        ))
+    }
+
+    #[cfg(windows)]
+    fn is_ansi_code_supported(&self) -> bool {
+        true
+    }
+}

codex-rs/tui/src/notifications/windows_toast.rs

@@ -0,0 +1,128 @@
+use std::io;
+use std::process::Command;
+use std::process::Stdio;
+
+use base64::Engine as _;
+use base64::engine::general_purpose::STANDARD as BASE64;
+
+const APP_ID: &str = "Codex";
+const POWERSHELL_EXE: &str = "powershell.exe";
+
+#[derive(Debug)]
+pub struct WindowsToastBackend {
+    encoded_title: String,
+}
+
+impl WindowsToastBackend {
+    pub fn notify(&mut self, message: &str) -> io::Result<()> {
+        let encoded_body = encode_argument(message);
+        let encoded_command = build_encoded_command(&self.encoded_title, &encoded_body);
+        spawn_powershell(encoded_command)
+    }
+}
+
+impl Default for WindowsToastBackend {
+    fn default() -> Self {
+        WindowsToastBackend {
+            encoded_title: encode_argument(APP_ID),
+        }
+    }
+}
+
+fn spawn_powershell(encoded_command: String) -> io::Result<()> {
+    let mut command = Command::new(POWERSHELL_EXE);
+    command
+        .arg("-NoProfile")
+        .arg("-NoLogo")
+        .arg("-EncodedCommand")
+        .arg(encoded_command)
+        .stdin(Stdio::null())
+        .stdout(Stdio::null())
+        .stderr(Stdio::null());
+
+    let status = command.status()?;
+    if status.success() {
+        Ok(())
+    } else {
+        Err(io::Error::other(format!(
+            "{POWERSHELL_EXE} exited with status {status}"
+        )))
+    }
+}
+
+fn build_encoded_command(encoded_title: &str, encoded_body: &str) -> String {
+    let script = build_ps_script(encoded_title, encoded_body);
+    encode_script_for_powershell(&script)
+}
+
+fn build_ps_script(encoded_title: &str, encoded_body: &str) -> String {
+    format!(
+        r#"
+$encoding = [System.Text.Encoding]::UTF8
+$titleText = $encoding.GetString([System.Convert]::FromBase64String("{encoded_title}"))
+$bodyText = $encoding.GetString([System.Convert]::FromBase64String("{encoded_body}"))
+[Windows.UI.Notifications.ToastNotificationManager, Windows.UI.Notifications, ContentType = WindowsRuntime] | Out-Null
+$doc = [Windows.UI.Notifications.ToastNotificationManager]::GetTemplateContent([Windows.UI.Notifications.ToastTemplateType]::ToastText02)
+$textNodes = $doc.GetElementsByTagName("text")
+$textNodes.Item(0).AppendChild($doc.CreateTextNode($titleText)) | Out-Null
+$textNodes.Item(1).AppendChild($doc.CreateTextNode($bodyText)) | Out-Null
+$toast = [Windows.UI.Notifications.ToastNotification]::new($doc)
+[Windows.UI.Notifications.ToastNotificationManager]::CreateToastNotifier('Codex').Show($toast)
+"#,
+    )
+}
+
+fn encode_script_for_powershell(script: &str) -> String {
+    let mut wide: Vec<u8> = Vec::with_capacity((script.len() + 1) * 2);
+    for unit in script.encode_utf16() {
+        let bytes = unit.to_le_bytes();
+        wide.extend_from_slice(&bytes);
+    }
+    BASE64.encode(wide)
+}
+
+fn encode_argument(value: &str) -> String {
+    BASE64.encode(escape_for_xml(value))
+}
+
+pub fn escape_for_xml(input: &str) -> String {
+    let mut escaped = String::with_capacity(input.len());
+    for ch in input.chars() {
+        match ch {
+            '&' => escaped.push_str("&amp;"),
+            '<' => escaped.push_str("&lt;"),
+            '>' => escaped.push_str("&gt;"),
+            '"' => escaped.push_str("&quot;"),
+            '\'' => escaped.push_str("&apos;"),
+            _ => escaped.push(ch),
+        }
+    }
+    escaped
+}
+
+#[cfg(test)]
+mod tests {
+    use super::encode_script_for_powershell;
+    use super::escape_for_xml;
+    use pretty_assertions::assert_eq;
+
+    #[test]
+    fn escapes_xml_entities() {
+        assert_eq!(escape_for_xml("5 > 3"), "5 &gt; 3");
+        assert_eq!(escape_for_xml("a & b"), "a &amp; b");
+        assert_eq!(escape_for_xml("<tag>"), "&lt;tag&gt;");
+        assert_eq!(escape_for_xml("\"quoted\""), "&quot;quoted&quot;");
+        assert_eq!(escape_for_xml("single 'quote'"), "single &apos;quote&apos;");
+    }
+
+    #[test]
+    fn leaves_safe_text_unmodified() {
+        assert_eq!(escape_for_xml("codex"), "codex");
+        assert_eq!(escape_for_xml("multi word text"), "multi word text");
+    }
+
+    #[test]
+    fn encodes_utf16le_for_powershell() {
+        assert_eq!(encode_script_for_powershell("A"), "QQA=");
+    }
+}