Add OpenAI Codex Multiplexer service

service/ocm/credential_darwin.go

@@ -0,0 +1,25 @@
+//go:build darwin
+
+package ocm
+
+func platformReadCredentials(customPath string) (*oauthCredentials, error) {
+	if customPath == "" {
+		var err error
+		customPath, err = getDefaultCredentialsPath()
+		if err != nil {
+			return nil, err
+		}
+	}
+	return readCredentialsFromFile(customPath)
+}
+
+func platformWriteCredentials(credentials *oauthCredentials, customPath string) error {
+	if customPath == "" {
+		var err error
+		customPath, err = getDefaultCredentialsPath()
+		if err != nil {
+			return err
+		}
+	}
+	return writeCredentialsToFile(credentials, customPath)
+}