function on_torrent_finished(event)
    print("torrent " .. event.torrent_id .. " finished")
end

function on_file_complete(event)
    -- Labels surface to Lua as a plain array of strings; use the first to route.
    local labels = naut.get_labels(event.torrent_id)
    local suffix = labels[1] or "moved"
    naut.move_file(event.torrent_id, event.index, event.path .. "." .. suffix)
end