A site.standard publication changes platform by editing its own record —
the url names the host that serves it. Two things broke when a
publication arrived from, or left for, another platform.
Importing: a record already pointing at <name>.leaflet.pub had nowhere
to register that subdomain. addDomain refuses leaflet.pub to everyone
but four hardcoded staff emails, and createPublication only registers a
subdomain for a record it is creating itself. The publication indexed and
appeared in the dashboard, but its address resolved to nothing.
claimPublicationSubdomain does what createPublication already does at
the end — Vercel project domain, custom_domains, publication_domains —
for a publication that exists. It reads the subdomain off the caller's own
publication record rather than taking it as input, so it can't be used to
reserve arbitrary leaflet.pub names, and it's idempotent against a domain
half-registered by an earlier attempt. The publication's domain settings
surface it as a "set up" row.
Exporting: isLeafletPublication inferred ownership from the theme.
An absent theme now no longer reads as "made here":
ownership follows the record's url, which is what the middleware routes on
and what an author edits to move. Publications on an author's own domain
still count, via the domains registered against them here.
Covers both record formats — site.standard's url and pub.leaflet's
base_path — and leaves legacy records without either untouched.
