event() :: event_load_attempt_started() | event_load_attempt_dismissed().

event_load_attempt_dismissed() :: {load_attempt_dismissed, source()}.

event_load_attempt_started() :: {load_attempt_started, source()}.

msg() ::
    {event, event()} |
    {finished, {success, success()}} |
    {finished, dismissed} |
    {finished, {error, not_found}} |
    {finished, {error, term()}}.

path() :: nonempty_string().

source() :: {cache | filesystem, path()}.

state() :: #state{}.

success() :: #{modified_on := calendar:datetime(), content := binary()}.