Idempotency Handling

This handles the tricky problem of ensuring operations don't run twice when requests get retried, which matters a lot for payments, order creation, or anything where duplicates cause real problems. The reference guides cover Redis-based storage, database implementations, and patterns modeled after Stripe's approach. You get middleware examples for Express and message queue handlers. The best practices are sensible: store the request body with the idempotency key so you can validate duplicates match, set TTLs so you're not storing this data forever, and use database constraints to handle concurrent requests atomically. If you're building any API that handles money or irreversible actions, you need something like this.

skills.sh installs: 467
GitHub stars: 379
last updated: Aug 21, 2026

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Install

$ npx -y skills add aj-geddes/useful-ai-prompts --skill idempotency-handling --agent claude-code

Installs into .claude/skills of the current project.

Files

Overview

Implement idempotency to ensure operations produce the same result regardless of how many times they're executed.

When to Use

Payment processing
API endpoints with retries
Webhooks and callbacks
Message queue consumers
Distributed transactions
Bank transfers
Order creation
Email sending
Resource creation

Quick Start

Minimal working example:

import express from "express";
import Redis from "ioredis";
import crypto from "crypto";

interface IdempotentRequest {
  key: string;
  status: "processing" | "completed" | "failed";
  response?: any;
  error?: string;
  createdAt: number;
  completedAt?: number;
}

class IdempotencyService {
  private redis: Redis;
  private ttl = 86400; // 24 hours

  constructor(redisUrl: string) {
    this.redis = new Redis(redisUrl);
  }

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