load_metadata = function(filename)
	local mfile = metadata_file(filename)
	local mpath = full_path(mfile)
	if not App.file_info(mpath) then
		-- comments will always have metadata,
		-- so we only get here for top-level posts with no parent
		return {replies={}}
	end
	local contents, err = App.read_file(mpath)
	if not contents then
		error(err)
	end
	return json.decode(contents)
end