Clarify that idempotency precedence is domain-specific: Person/Tag scalar fields
preserve human edits, while document sender/receivers/tags are canonical-authoritative
(cleared and re-populated on re-import so a shrunk set prunes stale links). Pin the
cross-loader provisional precedence. Record that runImport() is non-transactional
(per-loader transactions only) and the partial-failure-then-retry recovery is safe
because the import is idempotent.
Refs #669
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>