Found while migrating the first module. Five approaches were tried and observed
to fail, including resolving the index and naming the platform at both ends; a
speculative fix was written and reverted rather than shipped, because it did not
make the mirror work.
One module uses this today, which is why it went unnoticed — and it is the shape
most of a migration wants, because the services being moved are third-party.
jschoubben