[[!comment format=mdwn
 username="joey"
 subject="""comment 1"""
 date="2018-09-11T16:56:14Z"
 content="""
What you're looking for is the [[design/external_special_remote_protocol]].
When you build your own special remote using that protocol,
it can use SETSTATE and GETSTATE to store and retrieve
the immutable IDs.

It should not be hard to write your own special remote. See
[[this page|special_remotes/external]].

The Datalad project has a bunch of special remotes doing things like this
BTW.
"""]]
