fix: default to credits from ChatGPT auth, when possible

codex-rs/login/src/lib.rs

@@ -160,46 +160,72 @@ impl 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();
-
-    let auth_json_api_key = auth_dot_json
-        .as_ref()
-        .and_then(|a| a.openai_api_key.clone())
-        .filter(|s| !s.is_empty());
-
-    let openai_api_key = if include_env_var {
-        env::var(OPENAI_API_KEY_ENV_VAR)
-            .ok()
-            .filter(|s| !s.is_empty())
-            .or(auth_json_api_key)
-    } else {
-        auth_json_api_key
+    let auth_dot_json = match try_read_auth_json(&auth_file) {
+        Ok(auth) => auth,
+        // If auth.json does not exist, try to read the OPENAI_API_KEY from the
+        // environment variable.
+        Err(e) if e.kind() == std::io::ErrorKind::NotFound && include_env_var => {
+            return match read_openai_api_key_from_env() {
+                Some(api_key) => Ok(Some(CodexAuth::from_api_key(&api_key))),
+                None => Ok(None),
+            };
+        }
+        // Though if auth.json exists but is malformed, do not fall back to the
+        // env var because the user may be expecting to use AuthMode::ChatGPT.
+        Err(e) => {
+            return Err(e);
+        }
     };
 
-    let has_tokens = auth_dot_json
-        .as_ref()
-        .and_then(|a| a.tokens.as_ref())
-        .is_some();
+    let AuthDotJson {
+        openai_api_key: auth_json_api_key,
+        tokens,
+        last_refresh,
+    } = auth_dot_json;
 
-    if openai_api_key.is_none() && !has_tokens {
-        return Ok(None);
+    // If the auth.json has an API key AND does not appear to be on a plan that
+    // should use prefer AuthMode::ChatGPT, use AuthMode::ApiKey.
+    if let Some(api_key) = &auth_json_api_key {
+        // Should any of these by AuthMode::ChatGPT with the api_key set?
+        // Does AuthMode::ChatGPT indicate that there is an auth.json that is
+        // "refreshable" even if we are using the API key for auth?
+        match &tokens {
+            Some(tokens) => {
+                if tokens.is_plan_that_should_use_api_key() {
+                    return Ok(Some(CodexAuth::from_api_key(api_key)));
+                } else {
+                    // Ignore the API key and fall through to ChatGPT auth.
+                }
+            }
+            None => {
+                // This is a bit suspicious because we have an API key but no
+                // tokens. Perhaps the user updated auth.json by hand, so let's
+                // assume they are trying to use their API key.
+                return Ok(Some(CodexAuth::from_api_key(api_key)));
+            }
+        }
     }
 
-    let mode = if openai_api_key.is_some() {
-        AuthMode::ApiKey
-    } else {
-        AuthMode::ChatGPT
-    };
-
+    // For the AuthMode::ChatGPT variant, perhaps neither api_key should not
+    // exist?
     Ok(Some(CodexAuth {
-        api_key: openai_api_key,
-        mode,
+        api_key: None,
+        mode: AuthMode::ChatGPT,
         auth_file,
-        auth_dot_json: Arc::new(Mutex::new(auth_dot_json)),
+        auth_dot_json: Arc::new(Mutex::new(Some(AuthDotJson {
+            openai_api_key: None,
+            tokens,
+            last_refresh,
+        }))),
     }))
 }
 
+fn read_openai_api_key_from_env() -> Option<String> {
+    env::var(OPENAI_API_KEY_ENV_VAR)
+        .ok()
+        .filter(|s| !s.is_empty())
+}
+
 pub fn get_auth_file(codex_home: &Path) -> PathBuf {
     codex_home.join("auth.json")
 }

codex-rs/login/src/token_data.rs

@@ -17,6 +17,19 @@ pub struct TokenData {
     pub account_id: Option<String>,
 }
 
+impl TokenData {
+    /// Returns true if this is a plan that should use the traditional
+    /// "metered" billing via an API key.
+    pub(crate) fn is_plan_that_should_use_api_key(&self) -> bool {
+        match self.id_token.chatgpt_plan_type.as_deref() {
+            // TODO: Verify this is a comprehensive list of plans that
+            // should NOT use the API key.
+            Some("free") | Some("plus") | Some("pro") | Some("team") => false,
+            _ => true,
+        }
+    }
+}
+
 /// Flat subset of useful claims in id_token from auth.json.
 #[derive(Debug, Clone, PartialEq, Eq, Default, Serialize)]
 pub struct IdTokenInfo {