Inngest Setup - My Crypto Server

Inngest runs the durable workflows that power the payment lifecycle. Instead of cron jobs or long-running workers, Inngest provides event-driven step functions that survive server restarts, network failures, and cold starts.

Why Inngest

Without Inngest, you’d need:

A polling cron to check pending sessions
A background worker for payment verification
A retry queue for webhook delivery

Inngest replaces all of these. The app defines 5 functions; Inngest manages their execution.

The 5 functions

Function	Trigger	What it does
`sessionLifecycle`	`session/created`	Subscribes address to Alchemy, sleeps until expiry
`paymentVerify`	`payment/detected`	Waits for confirmations, finalizes the session, runs sweep
`webhookDeliver`	`session.paid` etc.	POSTs event to merchant webhook endpoint, retries on failure
`reconcileAlchemy`	Hourly cron	Re-syncs Alchemy watchlists; catches missed webhooks
`cleanupIdempotency`	Daily cron	Removes expired idempotency cache entries

Getting started

Create a free account at app.inngest.com.
Create a new project.
Go to Manage → Event Keys and copy your Event Key.
Go to Manage → Signing Keys and copy your Signing Key.

Environment variables

INNGEST_EVENT_KEY=your-event-key
INNGEST_SIGNING_KEY=your-signing-key

Without these, the app runs in local dev mode (uses pnpm inngest:dev) and won’t connect to Inngest Cloud.

Registering the app

After your first Vercel deployment:

In the Inngest dashboard, click Add app.
Enter your app URL: https://your-app.vercel.app/api/inngest
Inngest will discover all 5 functions automatically.

Every subsequent Vercel deployment re-registers the functions — no manual step needed.

Pricing

Inngest charges per step. One complete payment flow uses approximately 4 steps:

1 step in sessionLifecycle (subscribe address + sleep)
1–2 steps in paymentVerify (verify + finalize)
1 step in webhookDeliver (deliver event)

The free tier includes ~50,000 steps/month — enough for roughly 12,000 payments.

Local development

For local development, start the Inngest dev server alongside the web app:

# Both together (recommended)
pnpm dev:all

# Separate terminals
pnpm dev          # web app on :8256
pnpm inngest:dev  # Inngest UI on :8288

Visit http://localhost:8288 to see function runs, replay events, and debug workflows.

Recovery after an outage

If Inngest is unavailable during active sessions, re-emit lifecycle events after it recovers:

pnpm inngest:resync

This re-emits session/created events for all in-flight sessions. Each event is deduplicated by session-{id} so running it multiple times is safe.

​Why Inngest

​The 5 functions

​Getting started

​Environment variables

​Registering the app

​Pricing

​Local development

​Recovery after an outage