pub fn save_credential(
cred: &CredentialRef,
creds: &OAuthCredentials,
) -> Result<(), String>Expand description
Persist a credential into exactly one account slot. Other slots (including
the provider’s default slot) and any non-secret metadata already stored in
this slot are preserved. A corrupt store is an error — the account path
never resets the file (that would wipe every other slot); the legacy
single-credential save_provider_auth resets only an empty file.