BundleImporter.ApplyAsync opened a user-initiated transaction directly,
but the central ConfigurationDb context is configured with
EnableRetryOnFailure. SqlServerRetryingExecutionStrategy rejects
user-initiated transactions, so every bundle import threw on any real
SQL Server ('...does not support user-initiated transactions.'). The
whole Transport suite ran on the in-memory provider (no retrying
strategy, BeginTransaction is a no-op) so it never surfaced.
Extract the transactional apply into ApplyMergeAsync and drive it via
_dbContext.Database.CreateExecutionStrategy().ExecuteAsync, so the
strategy owns the BeginTransaction -> apply -> Commit unit as one
retriable block. The delegate resets per-attempt state (change tracker
+ ApplyMergeAsync rebuilds its own summary/resolution accumulators) so a
retried attempt cannot double-apply; a rollback failure is captured and
surfaced on the BundleImportFailed audit row exactly as before. Post-
commit side effects (ScriptArtifactsChanged publish, session zero/
remove) moved outside the retriable delegate so they run once.
Regression test: BundleImporterRetryingStrategyTests runs the import on
SQLite with a retrying execution strategy (RetriesOnFailure == true,
arming the same guard as production). It fails with the exact production
error on the pre-fix code and passes after. Existing rollback/apply
contracts unchanged (104 integration + 154 unit tests green).
Joseph Doherty