payment-trading-extension

What problem does it solve?

This Skill prevents payment and trading changes from causing double charges, silent ledger drift, incorrect state transitions, and regulatory or PCI compliance failures by enforcing server-authoritative confirmation, idempotency, immutable double-entry accounting, and replay-safe webhook processing.

Core Features & Use Cases

It defines an end-to-end domain discipline for payments, subscriptions, refunds, disputes, trading orders/settlement, and reconciliation workflows that must be correct even under retries, timeouts, and webhook replays. It provides non-negotiable guardrails for payment state machines, idempotency for every payment-mutating operation, immutable ledger writes with double-entry invariants, fixed-point financial arithmetic, and webhook signature verification and deduplication. It is used when implementing or changing checkout/payment intent flows, billing proration and renewals, refund/chargeback handling, ledger and balance logic, webhook endpoints for providers (e.g., Stripe), and reconciliation reporting that must match provider settlement.

Quick Start

Ask the agent to assess a proposed payment, billing, or trading change and produce a pass/block decision based on state machine completeness, idempotency coverage, immutable ledger and double-entry correctness, webhook signature verification with replay protection, fixed-point arithmetic, PCI-safe card-data handling, and daily reconciliation requirements.