cNGN Stablecoin Settlement Hub

A production-grade, bare-metal C++23 clearing-and-settlement engine, purpose-built to run an institutional cNGN regional settlement hub. It clears high-value B2B stablecoin obligations between members instantly and internally, then settles only the net position on-chain and over Nigerian bank rails — the model central banks and CLS use for fiat, brought to stablecoin settlement.

At its core is a deterministic, single-writer, event-sourced state machine: money is integer minor units, every transaction passes an inline invariant gauntlet before any balance changes, and state is a pure fold over an append-only, SHA-256 hash-chained event log — tamper-evident, replay-bit-identical, RPO-0 recoverable. A clearing decision runs in ~0.17µs median, ~3.5M/sec on a single core. Around the core sit a fail-closed compliance plane (KYB, sanctions, AML, FATF Travel Rule) and a settlement plane with multilateral netting, continuous reserve reconciliation, threshold custody, and a CCP-style default-management waterfall.

The differentiation is determinism and speed together, paired with risk machinery banks recognise. Delivered as source with formal TLA+ specifications, ~190 tests, an independent forensic security review with all findings remediated, and 12 architecture decision records.