Inngest Setup

# Inngest Setup

This skill sets up Inngest in a TypeScript project from scratch, covering installation, client configuration, connection modes, and local development.

> **These skills are focused on TypeScript.** For Python or Go, refer to the [Inngest documentation](https://www.inngest.com/llms.txt) for language-specific guidance. Core concepts apply across all languages.

## Prerequisites

- Node.js 18+ (Node.js 22.4+ r ecommended for WebSocket support)
- TypeScript project
- Package manager (npm, yarn, pnpm, or bun)

## Step 1: Install the Inngest SDK

Install the `inngest` npm package in your project:

```bash
npm install inngest
# or
yarn add inngest
# or
pnpm add inngest
# or
bun add inngest
```

## Step 2: Create an Inngest Client

Create a shared client file that you'll import throughout your codebase:

```typescript
// src/inngest/client.ts
import { Inngest } from "inngest";

export const inngest = new Inngest({
  id: "my-app" // Unique identifier for your application (hyphenated slug)
});
// IMPORTANT: v4 defaults to Cloud mode. For local dev, set INNGEST_DEV=1 env var.
// Without it, your serve endpoint will return 500 ("In cloud mode but no signing key").
// In production, set INNGEST_SIGNING_KEY (required for Cloud mode).
```

### Key Configuration Options

- **`id`** (required): Unique identifier for your app. Use a hyphenated slug like `"my-app"` or `"user-service"`
- **`eventKey`**: Event key for sending events (prefer `INNGEST_EVENT_KEY` env var)
- **`env`**: Environment name for Branch Environments
- **`isDev`**: Force Dev mode (`true`) or Cloud mode (`false`). **v4 defaults to Cloud mode**, so set `INNGEST_DEV=1` env var for local development. **Never hardcode `isDev: true` in source code** — it will silently break in production. Always use the env var.
- **`signingKey`**: Signing key for production (prefer `INNGEST_SIGNING_KEY` env var). Moved from `serve()` to client in v4
- **`signingKeyFallback`**: Fallback signing key for key rotation (prefer `INNGEST_SIGNING_KEY_FALLBACK` env var)
- **`baseUrl`**: Custom Inngest API base URL (prefer `INNGEST_BASE_URL` env var)
- **`logger`**: Custom logger instance (e.g. winston, pino) — enables `logger` in function context
- **`middleware`**: Array of middleware (see **inngest-middleware** skill)

### Typed Events with eventType()

```typescript
import { Inngest, eventType } from "inngest";
import { z } from "zod";

const signupCompleted = eventType("user/signup.completed", {
  schema: z.object({
    userId: z.string(),
    email: z.string(),
    plan: z.enum(["free", "pro"])
  })
});

const orderPlaced = eventType("order/placed", {
  schema: z.object({
    orderId: z.string(),
    amount: z.number()
  })
});

export const inngest = new Inngest({ id: "my-app" });

// Use event types as triggers for full type safety:
inngest.createFunction(
  { id: "handle-signup", triggers: [signupCompleted] },
  async ({ event }) => {
    event.data.userId; /* typed as string */
  }
);

// Use event types when sending events:
await inngest.send(
  signupCompleted.create({
    userId: "user_123",
    email: "user@example.com",
    plan: "pro"
  })
);
```

### Environment Variables Setup

Set these environment variables in your `.env` file or deployment environment:

```env
# Required for production
INNGEST_EVENT_KEY=your-event-key-here
INNGEST_SIGNING_KEY=your-signing-key-here

# Force dev mode during local development
INNGEST_DEV=1

# Optional - custom dev server URL (default: http://localhost:8288)
INNGEST_BASE_URL=http://localhost:8288
```

**⚠️ Common Gotcha**: N