PRS-2025-003
Ledger Cutover
Month-end reconciliation fell from 3 h 10 min to 14 min, with no downtime in the close window.
14 weeks · 4 people · −93%
6 steps · 1 trapdoor
Discipline
Backend
1 case study · 1 trapdoor
Related trapdoor entries
The cohort that posted twice
- What
- Cohort 3 posted 212 ledger lines twice for nine minutes during the cutover.
- Cause
- A consumer replayed an offset after a partition rebalance, and the posting call was not idempotent.
- Cost
- Three hours of cleanup and reconciliation. No money moved: payments were still gated by the batch.
- Changed
- Every posting carries an idempotency key. Each cohort starts with a replay drill on a copy.
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