Migration dry run failed on 4% of customer records

What happened — the dry run rejected 7,200 of 180,000 records. Failures cluster on accounts created before the 2019 billing change, which carry a field format the new schema does not accept.

Impact — 4% of customers would land in the new portal with broken billing history. Not a launch-blocker in volume, absolutely a launch-blocker in visibility.

Next step — write a transformation rule for the pre-2019 format rather than repairing records by hand. Re-run the dry run to confirm.

Related — this is the consequence of assumption A-01 turning out to be false.