chore: move top-level load_auth() to CodexAuth::from_codex_home() (#1966)

There are two valid ways to create an instance of `CodexAuth`:
`from_api_key()` and `from_codex_home()`. Now both are static methods of
`CodexAuth` and are listed first in the implementation.

---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/openai/codex/pull/1966).
* #1971
* #1970
* __->__ #1966
* #1965
* #1962

codex-rs/chatgpt/src/chatgpt_token.rs

@@ -1,3 +1,4 @@
+use codex_login::CodexAuth;
 use std::path::Path;
 use std::sync::LazyLock;
 use std::sync::RwLock;
@@ -18,7 +19,7 @@ pub fn set_chatgpt_token_data(value: TokenData) {
 
 /// Initialize the ChatGPT token from auth.json file
 pub async fn init_chatgpt_token_from_auth(codex_home: &Path) -> std::io::Result<()> {
-    let auth = codex_login::load_auth(codex_home)?;
+    let auth = CodexAuth::from_codex_home(codex_home)?;
     if let Some(auth) = auth {
         let token_data = auth.get_token_data().await?;
         set_chatgpt_token_data(token_data);

codex-rs/cli/src/login.rs

@@ -4,8 +4,8 @@ use codex_common::CliConfigOverrides;
 use codex_core::config::Config;
 use codex_core::config::ConfigOverrides;
 use codex_login::AuthMode;
+use codex_login::CodexAuth;
 use codex_login::OPENAI_API_KEY_ENV_VAR;
-use codex_login::load_auth;
 use codex_login::login_with_api_key;
 use codex_login::login_with_chatgpt;
 use codex_login::logout;
@@ -47,7 +47,7 @@ pub async fn run_login_with_api_key(
 pub async fn run_login_status(cli_config_overrides: CliConfigOverrides) -> ! {
     let config = load_config_or_exit(cli_config_overrides);
 
-    match load_auth(&config.codex_home) {
+    match CodexAuth::from_codex_home(&config.codex_home) {
         Ok(Some(auth)) => match auth.mode {
             AuthMode::ApiKey => match auth.get_token().await {
                 Ok(api_key) => {

codex-rs/cli/src/proto.rs

@@ -9,7 +9,7 @@ use codex_core::config::Config;
 use codex_core::config::ConfigOverrides;
 use codex_core::protocol::Submission;
 use codex_core::util::notify_on_sigint;
-use codex_login::load_auth;
+use codex_login::CodexAuth;
 use tokio::io::AsyncBufReadExt;
 use tokio::io::BufReader;
 use tracing::error;
@@ -36,7 +36,7 @@ pub async fn run_main(opts: ProtoCli) -> anyhow::Result<()> {
         .map_err(anyhow::Error::msg)?;
 
     let config = Config::load_with_cli_overrides(overrides_vec, ConfigOverrides::default())?;
-    let auth = load_auth(&config.codex_home)?;
+    let auth = CodexAuth::from_codex_home(&config.codex_home)?;
     let ctrl_c = notify_on_sigint();
     let CodexSpawnOk { codex, .. } = Codex::spawn(config, auth, ctrl_c.clone()).await?;
     let codex = Arc::new(codex);

codex-rs/core/src/codex_wrapper.rs

@@ -6,7 +6,7 @@ use crate::config::Config;
 use crate::protocol::Event;
 use crate::protocol::EventMsg;
 use crate::util::notify_on_sigint;
-use codex_login::load_auth;
+use codex_login::CodexAuth;
 use tokio::sync::Notify;
 use uuid::Uuid;
 
@@ -26,7 +26,7 @@ pub struct CodexConversation {
 /// that callers can surface the information to the UI.
 pub async fn init_codex(config: Config) -> anyhow::Result<CodexConversation> {
     let ctrl_c = notify_on_sigint();
-    let auth = load_auth(&config.codex_home)?;
+    let auth = CodexAuth::from_codex_home(&config.codex_home)?;
     let CodexSpawnOk {
         codex,
         init_id,

codex-rs/login/src/lib.rs

@@ -61,6 +61,12 @@ impl CodexAuth {
         }
     }
 
+    /// Loads the available auth information from the auth.json or
+    /// OPENAI_API_KEY environment variable.
+    pub fn from_codex_home(codex_home: &Path) -> std::io::Result<Option<CodexAuth>> {
+        load_auth(codex_home, true)
+    }
+
     pub async fn get_token_data(&self) -> Result<TokenData, std::io::Error> {
         #[expect(clippy::unwrap_used)]
         let auth_dot_json = self.auth_dot_json.lock().unwrap().clone();
@@ -152,12 +158,7 @@ impl CodexAuth {
     }
 }
 
-// Loads the available auth information from the auth.json or OPENAI_API_KEY environment variable.
-pub fn load_auth(codex_home: &Path) -> std::io::Result<Option<CodexAuth>> {
-    _load_auth(codex_home, true)
-}
-
-fn _load_auth(codex_home: &Path, include_env_var: bool) -> std::io::Result<Option<CodexAuth>> {
+fn load_auth(codex_home: &Path, include_env_var: bool) -> std::io::Result<Option<CodexAuth>> {
     let auth_file = get_auth_file(codex_home);
 
     let auth_dot_json = try_read_auth_json(&auth_file).ok();
@@ -433,7 +434,7 @@ mod tests {
     fn writes_api_key_and_loads_auth() {
         let dir = tempdir().unwrap();
         login_with_api_key(dir.path(), "sk-test-key").unwrap();
-        let auth = _load_auth(dir.path(), false).unwrap().unwrap();
+        let auth = load_auth(dir.path(), false).unwrap().unwrap();
         assert_eq!(auth.mode, AuthMode::ApiKey);
         assert_eq!(auth.api_key.as_deref(), Some("sk-test-key"));
     }
@@ -446,7 +447,7 @@ mod tests {
         let env_var = std::env::var(OPENAI_API_KEY_ENV_VAR);
 
         if let Ok(env_var) = env_var {
-            let auth = _load_auth(dir.path(), true).unwrap().unwrap();
+            let auth = load_auth(dir.path(), true).unwrap().unwrap();
             assert_eq!(auth.mode, AuthMode::ApiKey);
             assert_eq!(auth.api_key, Some(env_var));
         }
@@ -505,7 +506,7 @@ mod tests {
             mode,
             auth_dot_json,
             auth_file,
-        } = _load_auth(dir.path(), false).unwrap().unwrap();
+        } = load_auth(dir.path(), false).unwrap().unwrap();
         assert_eq!(None, api_key);
         assert_eq!(AuthMode::ChatGPT, mode);
         assert_eq!(dir.path().join("auth.json"), auth_file);
@@ -570,7 +571,7 @@ mod tests {
         )
         .unwrap();
 
-        let auth = _load_auth(dir.path(), false).unwrap().unwrap();
+        let auth = load_auth(dir.path(), false).unwrap().unwrap();
         assert_eq!(auth.mode, AuthMode::ApiKey);
         assert_eq!(auth.api_key, Some("sk-test-key".to_string()));
 

codex-rs/tui/src/lib.rs

@@ -12,7 +12,7 @@ use codex_core::config::load_config_as_toml_with_cli_overrides;
 use codex_core::config_types::SandboxMode;
 use codex_core::protocol::AskForApproval;
 use codex_core::protocol::SandboxPolicy;
-use codex_login::load_auth;
+use codex_login::CodexAuth;
 use codex_ollama::DEFAULT_OSS_MODEL;
 use log_layer::TuiLogLayer;
 use std::fs::OpenOptions;
@@ -304,7 +304,7 @@ fn should_show_login_screen(config: &Config) -> bool {
         // 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 load_auth(&codex_home) {
+        match CodexAuth::from_codex_home(&codex_home) {
             Ok(Some(_)) => false,
             Ok(None) => true,
             Err(err) => {