A ledger cutover that held
Northledger moved posting off a weekend batch. The boring parts are the ones that mattered.
Northledger posted on a weekend batch that nobody wanted to own. The cutover was not a rewrite. It was a dual-write, a week of shadowed totals, and a Monday when the batch job was allowed to fail because nothing read it.
The platform team sat with finance for the shadow week. That is the whole story. Tools were ordinary. The room was not.
When a ledger moves, the CMS has to carry the write-up: what changed, who signed, what we will not do again. This is that write-up.