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/lib.rs

@@ -12,6 +12,7 @@ use codex_core::config::find_codex_home;
 use codex_core::config::load_config_as_toml_with_cli_overrides;
 use codex_core::protocol::AskForApproval;
 use codex_core::protocol::SandboxPolicy;
+use codex_login::AuthMode;
 use codex_login::CodexAuth;
 use codex_ollama::DEFAULT_OSS_MODEL;
 use codex_protocol::config_types::SandboxMode;
@@ -296,21 +297,27 @@ fn restore() {
     }
 }
 
-fn should_show_login_screen(config: &Config) -> bool {
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum LoginStatus {
+    AuthMode(AuthMode),
+    NotAuthenticated,
+}
+
+fn get_login_status(config: &Config) -> LoginStatus {
     if config.model_provider.requires_openai_auth {
         // Reading the OpenAI API key is an async operation because it may need
         // to refresh the token. Block on it.
         let codex_home = config.codex_home.clone();
-        match CodexAuth::from_codex_home(&codex_home) {
-            Ok(Some(_)) => false,
-            Ok(None) => true,
+        match CodexAuth::from_codex_home(&codex_home, config.preferred_auth_method) {
+            Ok(Some(auth)) => LoginStatus::AuthMode(auth.mode),
+            Ok(None) => LoginStatus::NotAuthenticated,
             Err(err) => {
                 error!("Failed to read auth.json: {err}");
-                true
+                LoginStatus::NotAuthenticated
             }
         }
     } else {
-        false
+        LoginStatus::NotAuthenticated
     }
 }