Design a Scalable Idempotent Ledger Service

Scalable Internal Double-Entry Ledger 1. Core Requirements Build an internal ledger that records every money movement as an immutable, append-only double-entry transaction. The system must support: Debits and credits that always balance. Retried writes without duplicate postings. Balance reads that indicate how fresh the balance is. Atomic commit of all legs of a transaction. High throughput on popular accounts. Sharding across many accounts without breaking atomicity.…