Show login options when not signed in with ChatGPT (#2440)

Motivation: we have users who uses their API key although they want to
use ChatGPT account. We want to give them the chance to always login
with their account.

This PR displays login options when the user is not signed in with
ChatGPT. Even if you have set an OpenAI API key as an environment
variable, you will still be prompted to log in with ChatGPT.

We’ve also added a new flag, `always_use_api_key_signing` false by
default, which ensures you are never asked to log in with ChatGPT and
always defaults to using your API key.



https://github.com/user-attachments/assets/b61ebfa9-3c5e-4ab7-bf94-395c23a0e0af

After ChatGPT sign in:


https://github.com/user-attachments/assets/d58b366b-c46a-428f-a22f-2ac230f991c0

codex-rs/tui/src/app.rs

@@ -1,12 +1,13 @@
+use crate::LoginStatus;
 use crate::app_event::AppEvent;
 use crate::app_event_sender::AppEventSender;
 use crate::chatwidget::ChatWidget;
 use crate::file_search::FileSearchManager;
 use crate::get_git_diff::get_git_diff;
+use crate::get_login_status;
 use crate::onboarding::onboarding_screen::KeyboardHandler;
 use crate::onboarding::onboarding_screen::OnboardingScreen;
 use crate::onboarding::onboarding_screen::OnboardingScreenArgs;
-use crate::should_show_login_screen;
 use crate::slash_command::SlashCommand;
 use crate::tui;
 use codex_core::ConversationManager;
@@ -137,8 +138,11 @@ impl App<'_> {
             });
         }
 
-        let show_login_screen = should_show_login_screen(&config);
-        let app_state = if show_login_screen || show_trust_screen {
+        let login_status = get_login_status(&config);
+        let should_show_onboarding =
+            should_show_onboarding(login_status, &config, show_trust_screen);
+        let app_state = if should_show_onboarding {
+            let show_login_screen = should_show_login_screen(login_status, &config);
             let chat_widget_args = ChatWidgetArgs {
                 config: config.clone(),
                 initial_prompt,
@@ -150,9 +154,10 @@ impl App<'_> {
                     event_tx: app_event_tx.clone(),
                     codex_home: config.codex_home.clone(),
                     cwd: config.cwd.clone(),
-                    show_login_screen,
                     show_trust_screen,
+                    show_login_screen,
                     chat_widget_args,
+                    login_status,
                 }),
             }
         } else {
@@ -613,3 +618,77 @@ impl App<'_> {
         }
     }
 }
+
+fn should_show_onboarding(
+    login_status: LoginStatus,
+    config: &Config,
+    show_trust_screen: bool,
+) -> bool {
+    if show_trust_screen {
+        return true;
+    }
+
+    should_show_login_screen(login_status, config)
+}
+
+fn should_show_login_screen(login_status: LoginStatus, config: &Config) -> bool {
+    match login_status {
+        LoginStatus::NotAuthenticated => true,
+        LoginStatus::AuthMode(method) => method != config.preferred_auth_method,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use codex_core::config::ConfigOverrides;
+    use codex_core::config::ConfigToml;
+    use codex_login::AuthMode;
+
+    fn make_config(preferred: AuthMode) -> Config {
+        let mut cfg = Config::load_from_base_config_with_overrides(
+            ConfigToml::default(),
+            ConfigOverrides::default(),
+            std::env::temp_dir(),
+        )
+        .expect("load default config");
+        cfg.preferred_auth_method = preferred;
+        cfg
+    }
+
+    #[test]
+    fn shows_login_when_not_authenticated() {
+        let cfg = make_config(AuthMode::ChatGPT);
+        assert!(should_show_login_screen(
+            LoginStatus::NotAuthenticated,
+            &cfg
+        ));
+    }
+
+    #[test]
+    fn shows_login_when_api_key_but_prefers_chatgpt() {
+        let cfg = make_config(AuthMode::ChatGPT);
+        assert!(should_show_login_screen(
+            LoginStatus::AuthMode(AuthMode::ApiKey),
+            &cfg
+        ))
+    }
+
+    #[test]
+    fn hides_login_when_api_key_and_prefers_api_key() {
+        let cfg = make_config(AuthMode::ApiKey);
+        assert!(!should_show_login_screen(
+            LoginStatus::AuthMode(AuthMode::ApiKey),
+            &cfg
+        ))
+    }
+
+    #[test]
+    fn hides_login_when_chatgpt_and_prefers_chatgpt() {
+        let cfg = make_config(AuthMode::ChatGPT);
+        assert!(!should_show_login_screen(
+            LoginStatus::AuthMode(AuthMode::ChatGPT),
+            &cfg
+        ))
+    }
+}