Port login server to rust (#2294)

Port the login server to rust.

---------

Co-authored-by: pakrym-oai <pakrym@openai.com>

codex-rs/tui/src/app.rs

@@ -522,6 +522,10 @@ impl App<'_> {
     }
 
     fn draw_next_frame(&mut self, terminal: &mut tui::Tui) -> Result<()> {
+        if matches!(self.app_state, AppState::Onboarding { .. }) {
+            terminal.clear()?;
+        }
+
         let screen_size = terminal.size()?;
         let last_known_screen_size = terminal.last_known_screen_size;
         if screen_size != last_known_screen_size {

codex-rs/tui/src/onboarding/auth.rs

@@ -44,11 +44,7 @@ pub(crate) struct ContinueInBrowserState {
 impl Drop for ContinueInBrowserState {
     fn drop(&mut self) {
         if let Some(child) = &self.login_child {
-            if let Ok(mut locked) = child.child.lock() {
-                // Best-effort terminate and reap the child to avoid zombies.
-                let _ = locked.kill();
-                let _ = locked.wait();
-            }
+            child.cancel();
         }
     }
 }
@@ -321,32 +317,16 @@ impl AuthModeWidget {
     }
 
     fn spawn_completion_poller(&self, child: codex_login::SpawnedLogin) {
-        let child_arc = child.child.clone();
-        let stderr_buf = child.stderr.clone();
         let event_tx = self.event_tx.clone();
         std::thread::spawn(move || {
             loop {
-                let done = {
-                    if let Ok(mut locked) = child_arc.lock() {
-                        match locked.try_wait() {
-                            Ok(Some(status)) => Some(status.success()),
-                            Ok(None) => None,
-                            Err(_) => Some(false),
-                        }
-                    } else {
-                        Some(false)
-                    }
-                };
-                if let Some(success) = done {
+                if let Some(success) = child.get_auth_result() {
                     if success {
                         event_tx.send(AppEvent::OnboardingAuthComplete(Ok(())));
                     } else {
-                        let err = stderr_buf
-                            .lock()
-                            .ok()
-                            .and_then(|b| String::from_utf8(b.clone()).ok())
-                            .unwrap_or_else(|| "login_with_chatgpt subprocess failed".to_string());
-                        event_tx.send(AppEvent::OnboardingAuthComplete(Err(err)));
+                        event_tx.send(AppEvent::OnboardingAuthComplete(Err(
+                            "login failed".to_string()
+                        )));
                     }
                     break;
                 }

codex-rs/tui/src/onboarding/onboarding_screen.rs

@@ -2,6 +2,8 @@ use codex_core::util::is_inside_git_repo;
 use crossterm::event::KeyEvent;
 use ratatui::buffer::Buffer;
 use ratatui::layout::Rect;
+use ratatui::prelude::Widget;
+use ratatui::widgets::Clear;
 use ratatui::widgets::WidgetRef;
 
 use codex_login::AuthMode;
@@ -113,6 +115,14 @@ impl OnboardingScreen {
                 Ok(()) => {
                     state.sign_in_state = SignInState::ChatGptSuccessMessage;
                     self.event_tx.send(AppEvent::RequestRedraw);
+                    let tx1 = self.event_tx.clone();
+                    let tx2 = self.event_tx.clone();
+                    std::thread::spawn(move || {
+                        std::thread::sleep(std::time::Duration::from_millis(150));
+                        tx1.send(AppEvent::RequestRedraw);
+                        std::thread::sleep(std::time::Duration::from_millis(200));
+                        tx2.send(AppEvent::RequestRedraw);
+                    });
                 }
                 Err(e) => {
                     state.sign_in_state = SignInState::PickMode;
@@ -171,6 +181,7 @@ impl KeyboardHandler for OnboardingScreen {
 
 impl WidgetRef for &OnboardingScreen {
     fn render_ref(&self, area: Rect, buf: &mut Buffer) {
+        Clear.render(area, buf);
         // Render steps top-to-bottom, measuring each step's height dynamically.
         let mut y = area.y;
         let bottom = area.y.saturating_add(area.height);
@@ -218,6 +229,7 @@ impl WidgetRef for &OnboardingScreen {
                     width,
                     height: h,
                 };
+                Clear.render(target, buf);
                 step.render_ref(target, buf);
                 y = y.saturating_add(h);
             }