Inngest Steps

Build robust, durable workflows with Inngest's step methods. Each step is a separate HTTP request that can be independently retried and monitored.

These skills are focused on TypeScript. For Python or Go, refer to the Inngest documentation for language-specific guidance. Core concepts apply across all languages.

Core Concept

🔄 Critical: Each step re-runs your function from the beginning. Put ALL non-deterministic code (API calls, DB queries, randomness) inside steps, never outside.

📊 Step Limits: Every function has a maximum of 1,000 steps and 4MB total step data.

// ❌ WRONG - will run 4 times
export default inngest.createFunction(
  { id: "bad-example", triggers: [{ event: "test" }] },
  async ({ step }) => {
    console.log("This logs 4 times!"); // Outside step = bad
    await step.run("a", () => console.log("a"));
    await step.run("b", () => console.log("b"));
    await step.run("c", () => console.log("c"));
  }
);

// ✅ CORRECT - logs once each
export default inngest.createFunction(
  { id: "good-example", triggers: [{ event: "test" }] },
  async ({ step }) => {
    await step.run("log-hello", () => console.log("hello"));
    await step.run("a", () => console.log("a"));
    await step.run("b", () => console.log("b"));
    await step.run("c", () => console.log("c"));
  }
);

step.run()

Execute retriable code as a step. Each step ID can be reused - Inngest automatically handles counters.

// Basic usage
const result = await step.run("fetch-user", async () => {
  const user = await db.user.findById(userId);
  return user; // Always return useful data
});

// Synchronous code works too
const transformed = await step.run("transform-data", () => {
  return processData(result);
});

// Side effects (no return needed)
await step.run("send-notification", async () => {
  await sendEmail(user.email, "Welcome!");
});

✅ DO:

• Put ALL non-deterministic logic inside steps
• Return useful data for subsequent steps
• Reuse step IDs in loops (counters handled automatically)

❌ DON'T:

• Put deterministic logic in steps unnecessarily
• Forget that each step = separate HTTP request

step.sleep()

Pause execution without using compute time.

// Duration strings
await step.sleep("wait-24h", "24h");
await step.sleep("short-delay", "30s");
await step.sleep("weekly-pause", "7d");

// Use in workflows
await step.run("send-welcome", () => sendEmail(email));
await step.sleep("wait-for-engagement", "3d");
await step.run("send-followup", () => sendFollowupEmail(email));

step.sleepUntil()

Sleep until a specific datetime.

const reminderDate = new Date("2024-12-25T09:00:00Z");
await step.sleepUntil("wait-for-christmas", reminderDate);

// From event data
const scheduledTime = new Date(event.data.remind_at);
await step.sleepUntil("wait-for-scheduled-time", scheduledTime);

step.waitForEvent()

🚨 CRITICAL: waitForEvent ONLY catches events sent AFTER this step executes.

• ❌ Event sent before waitForEvent runs → will NOT be caught
• ✅ Event sent after waitForEvent runs → will be caught
• Always check for null return (means timeout, event never arrived)

// Basic event waiting with timeout
const approval = await step.waitForEvent("wait-for-approval", {
  event: "app/invoice.approved",
  timeout: "7d",
  match: "data.invoiceId" // Simple matching
});

// Expression-based matching (CEL syntax)
const subscription = await step.waitForEvent("wait-for-subscription", {
  event: "app/subscription.created",
  timeout: "30d",
  if: "event.data.userId == async.data.userId && async.data.plan == 'pro'"
});

// Handle timeout
if (!approval) {
  await step.run("handle-timeout", () => {
    // Approval never came
    return notifyAccountingTeam();
  });
}

✅ DO:

• Use unique IDs for matching (userId, sessionId, requestId)
• Always set reasonable timeouts
• Handle null return (timeout case)
• Use with Realtime for human-in-the-loop flows

❌ DON'T:

• Expect events sent before this step to be handled
• Use without timeouts in production

Expression Syntax

In expressions, event = the original triggering event, async = the new event being matched. See Expression Syntax Reference for full syntax, operators, and patterns.

step.waitForSignal()

Wait for unique signals (not events). Better for 1:1 matching.

const taskId = "task-"