Function prune_orphan_keeping_history 

fn prune_orphan_keeping_history(
    dir: &Path,
    root: &Path,
) -> Result<PruneOutcome, String>

Removes an orphaned account dir (<root>/<account_id>/), only if it resolves strictly inside root (the same escape guard cleanup_oauth_dir uses), except that each provider subdir’s conversation history is kept, the same rule account delete follows (remove_credentials_keep_history). Without this, the sweep would delete, a few minutes later, the history that deleting the account kept.