Fintech Patterns

Purpose

This skill defines the architectural standards, state management strategies, and security best practices for developing highly resilient, high-throughput fintech backend systems. It covers the implementation of strict double-entry accounting ledgers, robust idempotency controls, and stringent adherence to PCI-DSS compliance requirements, ensuring financial data integrity at all times.

Core Principles

Double-Entry Consistency: Total debits must always strictly equal total credits within a single atomic transaction.
Strict Idempotency: All financial operations must process requests exactly once regardless of network retries.
Immutability: Ledgers are append-only; state changes are never mutated or deleted, only compensated.
Security by Design: All PII and PAN data must be tokenized and encrypted at rest and in transit.
High Availability: Systems must be designed with CQRS, Event Sourcing, and sharding to sustain high read/write throughput without downtime.

Agent Protocol

Triggers

Designing new financial ledgers
Implementing payment gateway integrations
Auditing existing systems for PCI-DSS compliance