Integration Patterns

Covers the nuts and bolts of connecting financial systems: FIX protocol for order routing, ISO 20022 for SWIFT migrations, batch file processing for custodian feeds, and API design patterns that handle idempotency and retry logic. You'll want this when you're building integration pipelines between portfolio management systems, trading platforms, and custodians, or when you're debugging why reconciliation keeps breaking. The material is practical, covering things like cursor-based pagination for large position datasets, circuit breakers for flaky upstream systems, and mTLS for secure custodian connections. It won't teach you business logic, but it will help you design integrations that don't lose transactions or double-process trades.

skills.sh installs: 688
GitHub stars: 224
last updated: Aug 21, 2026

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Install

$ npx -y skills add joellewis/finance_skills --skill integration-patterns --agent claude-code

Installs into .claude/skills of the current project.

Files

Integration Patterns

Core Concepts

1. API Design for Financial Systems

Financial APIs serve position data, transaction history, account information, reference data, and order submission. Design conventions differ from general-purpose APIs due to the sensitivity, auditability, and volume of financial data.

REST conventions: Resource-oriented design with nouns for financial entities -- /accounts/{id}/positions, /transactions, /orders/{id}/executions. Use HTTP methods semantically: GET for reads (positions, balances), POST for actions (order submission, transfer initiation), PUT/PATCH for updates (account preferences, model assignments). Return standard HTTP status codes with domain-specific error bodies including error codes, human-readable messages, and correlation IDs for traceability. Financial APIs must distinguish between synchronous operations (position lookup returns immediately) and asynchronous operations (transfer initiation returns a 202 Accepted with a status polling URL or webhook callback). Long-running operations such as bulk rebalancing or batch trade submission should use the async pattern to avoid client-side timeouts.

SKILL.md on GitHub