Caught live 2026-08-01 importing a bundle into the empty env2 cluster: a
create-missing Site has Id == 0 until SaveChanges on a relational provider,
and ApplyDataConnectionsAsync stamps DataConnection.SiteId as a raw scalar
(no navigation, no EF fix-up), so the insert violated
FK_DataConnections_Sites_SiteId. Every importer integration test runs on
the EF in-memory provider, which assigns ids eagerly on AddAsync — the
exact masking the in-code comment predicted. Fix: one SaveChangesAsync
between the site pass and the connection pass, riding the same outer
transaction (all-or-nothing preserved; the failed live import rolled back
cleanly). Regression test runs the create-missing path on SQLite
(CreateMissingSiteRelationalTests) — red without the fix, green with it.
Joseph Doherty