Integrate Serverless Background Jobs with Inngest

This skill covers Inngest, a serverless-first platform for background jobs, event-driven workflows, and durable execution without managing queues or workers. Its principles set the model: events are the primitive everything triggers from (not queues); each step's result is durably stored as a checkpoint; sleeps are real durable waits, not blocking threads; retries are automatic but the policy is yours to configure; functions are just HTTP handlers deployable anywhere that serves HTTP; concurrency limits are a first-class way to protect downstream services; idempotency keys prevent duplicate execution on critical operations; and fan-out (one event triggering many functions) is built in.

Five patterns are covered with working TypeScript: basic function setup in Next.js (a typed Inngest client, a function triggered by an event, step.run for durable steps, step.sleep for a real 24-hour wait between steps, and the serve() handler wired into an API route); a multi-step order-processing workflow combining parallel step.run calls, a fan-out step.sendEvent instead of a direct function call, and a concurrency: { limit: 10 } cap; scheduled/cron functions for recurring tasks; a webhook handler pattern built around idempotency; and an AI pipeline pattern for long-running processing.

Use it for serverless background jobs, event-driven workflows, step functions, durable sleeps, fan-out patterns, concurrency control, and scheduled functions on Next.js, Express, Hono, Remix, or SvelteKit, deployed to Vercel, Cloudflare Workers, Netlify, Railway, or Fly.io. The skill's scope section explicitly routes elsewhere for adjacent needs: Redis-based queues to a BullMQ-specific skill, serverless queues to Upstash QStash, general workflow orchestration to a Temporal-focused skill, and message streaming to an event-architecture skill.

Don't skip idempotency keys on payment or other critical-operation functions - the validation checks explicitly flag their absence, since Inngest's automatic retries can otherwise re-execute a side effect more than once.

Ten validation checks catch common mistakes mechanically: a missing Inngest serve handler, functions not actually registered with serve, a step.run call lacking a descriptive name, waitForEvent without a timeout, a function without a concurrency limit, undefined event types, a function without a unique id, sleep not using a duration string, no retry policy configured, and a missing idempotency key on payment functions.

Core tooling is the inngest package and inngest-cli. It integrates with Next.js, Express, Hono, Remix, and SvelteKit, and deploys to Vercel, Cloudflare Workers, Netlify, Railway, or Fly.io.

Developers building serverless background jobs, multi-step workflows, or AI pipelines who want durable step-by-step execution and built-in fan-out without standing up and operating their own queue infrastructure.