Realtime Streams - Trigger.dev

Realtime Streams allow you to pipe streaming data from your Trigger.dev tasks to your frontend or backend applications in real-time. This is perfect for use cases like streaming AI completions, progress updates, or any continuous data flow.

Streams v2 requires SDK version 4.1.0 or later. Make sure to upgrade your @trigger.dev/sdk and @trigger.dev/react-hooks packages to use these features. If you’re on an earlier version, see the metadata.stream() documentation.

Overview

Streams v2 is a major upgrade that provides:

Unlimited stream length (previously capped at 2000 chunks)
Unlimited active streams per run (previously 5)
Improved reliability with automatic resumption on connection loss
28-day stream retention (previously 1 day)
Multiple client streams can pipe to a single stream
Enhanced dashboard visibility for viewing stream data in real-time

Enabling Streams v2

Streams v2 is automatically enabled when triggering runs from the SDK using 4.1.0 or later. If you aren’t triggering via the SDK, you’ll need to explicitly enable v2 streams via setting the x-trigger-realtime-streams-version=v2 header when triggering the task. If you’d like to opt-out of the v2 streams, you can see so in one of the following two ways:

Option 1: Configure the SDK

import { auth } from "@trigger.dev/sdk";

auth.configure({
  future: {
    v2RealtimeStreams: false,
  },
});

Option 2: Environment Variable

Set the TRIGGER_V2_REALTIME_STREAMS=0 environment variable in your backend code (where you trigger tasks).

Limits Comparison

Limit	Streams v1	Streams v2
Maximum stream length	2000	Unlimited
Number of active streams per run	5	Unlimited
Maximum streams per run	10	Unlimited
Maximum stream TTL	1 day	28 days
Maximum stream size	10MB	300 MiB

Quick Start

The recommended workflow for using Realtime Streams v2:

Define your streams in a shared location using streams.define()
Use the defined stream in your tasks with .pipe(), .append(), or .writer()
Read from the stream using .read() or the useRealtimeStream hook in React

This approach gives you full type safety, better code organization, and easier maintenance as your application grows.

Defining Typed Streams (Recommended)

The recommended way to work with streams is to define them once with streams.define(). This allows you to specify the chunk type and stream ID in one place, and then reuse that definition throughout your codebase with full type safety.

Creating a Defined Stream

Define your streams in a shared location (like app/streams.ts or trigger/streams.ts):

import { streams, InferStreamType } from "@trigger.dev/sdk";

// Define a stream with a specific type
export const aiStream = streams.define<string>({
  id: "ai-output",
});

// Export the type for use in frontend components
export type AIStreamPart = InferStreamType<typeof aiStream>;

You can define streams for any JSON-serializable type:

import { streams, InferStreamType } from "@trigger.dev/sdk";
import { UIMessageChunk } from "ai";

// Stream for AI UI message chunks
export const aiStream = streams.define<UIMessageChunk>({
  id: "ai",
});

// Stream for progress updates
export const progressStream = streams.define<{ step: string; percent: number }>({
  id: "progress",
});

// Stream for simple text
export const logStream = streams.define<string>({
  id: "logs",
});

// Export types
export type AIStreamPart = InferStreamType<typeof aiStream>;
export type ProgressStreamPart = InferStreamType<typeof progressStream>;
export type LogStreamPart = InferStreamType<typeof logStream>;

Using Defined Streams in Tasks

Once defined, you can use all stream methods on your defined stream:

import { task } from "@trigger.dev/sdk";
import { aiStream } from "./streams";

export const streamTask = task({
  id: "stream-task",
  run: async (payload: { prompt: string }) => {
    // Get a stream from an AI service, database, etc.
    const stream = await getAIStream(payload.prompt);

    // Pipe the stream using your defined stream
    const { stream: readableStream, waitUntilComplete } = aiStream.pipe(stream);

    // Option A: Iterate over the stream locally
    for await (const chunk of readableStream) {
      console.log("Received chunk:", chunk);
    }

    // Option B: Wait for the stream to complete
    await waitUntilComplete();

    return { message: "Stream completed" };
  },
});

Reading from a Stream

Use the defined stream’s read() method to consume data from anywhere (frontend, backend, or another task):

import { aiStream } from "./streams";

const stream = await aiStream.read(runId);

for await (const chunk of stream) {
  console.log(chunk); // chunk is typed as the stream's chunk type
}

With options:

const stream = await aiStream.read(runId, {
  timeoutInSeconds: 60, // Stop if no data for 60 seconds
  startIndex: 10, // Start from the 10th chunk
});

Appending to a Stream

Use the defined stream’s append() method to add a single chunk:

import { task } from "@trigger.dev/sdk";
import { aiStream, progressStream, logStream } from "./streams";

export const appendTask = task({
  id: "append-task",
  run: async (payload) => {
    // Append to different streams with full type safety
    await logStream.append("Processing started");
    await progressStream.append({ step: "Initialization", percent: 0 });

    // Do some work...

    await progressStream.append({ step: "Processing", percent: 50 });
    await logStream.append("Step 1 complete");

    // Do more work...

    await progressStream.append({ step: "Complete", percent: 100 });
    await logStream.append("All steps complete");
  },
});

Writing Multiple Chunks

Use the defined stream’s writer() method for more complex stream writing:

import { task } from "@trigger.dev/sdk";
import { logStream } from "./streams";

export const writerTask = task({
  id: "writer-task",
  run: async (payload) => {
    const { waitUntilComplete } = logStream.writer({
      execute: ({ write, merge }) => {
        // Write individual chunks
        write("Chunk 1");
        write("Chunk 2");

        // Merge another stream
        const additionalStream = ReadableStream.from(["Chunk 3", "Chunk 4", "Chunk 5"]);
        merge(additionalStream);
      },
    });

    await waitUntilComplete();
  },
});

Using Defined Streams in React

Defined streams work seamlessly with the useRealtimeStream hook:

"use client";

import { useRealtimeStream } from "@trigger.dev/react-hooks";
import { aiStream } from "@/app/streams";

export function StreamViewer({ accessToken, runId }: { accessToken: string; runId: string }) {
  // Pass the defined stream directly - full type safety!
  const { parts, error } = useRealtimeStream(aiStream, runId, {
    accessToken,
    timeoutInSeconds: 600,
  });

  if (error) return <div>Error: {error.message}</div>;
  if (!parts) return <div>Loading...</div>;

  return (
    <div>
      {parts.map((part, i) => (
        <span key={i}>{part}</span>
      ))}
    </div>
  );
}

Direct Stream Methods (Without Defining)

We strongly recommend using streams.define() instead of direct methods. Defined streams provide better organization, full type safety, and make it easier to maintain your codebase as it grows.

If you have a specific reason to avoid defined streams, you can use stream methods directly by specifying the stream key each time.

Direct Piping

import { streams, task } from "@trigger.dev/sdk";

export const directStreamTask = task({
  id: "direct-stream",
  run: async (payload: { prompt: string }) => {
    const stream = await getAIStream(payload.prompt);

    // Specify the stream key directly
    const { stream: readableStream, waitUntilComplete } = streams.pipe("ai-output", stream);

    await waitUntilComplete();
  },
});

Direct Reading

import { streams } from "@trigger.dev/sdk";

// Specify the stream key when reading
const stream = await streams.read(runId, "ai-output");

for await (const chunk of stream) {
  console.log(chunk);
}

Direct Appending

import { streams, task } from "@trigger.dev/sdk";

export const directAppendTask = task({
  id: "direct-append",
  run: async (payload) => {
    // Specify the stream key each time
    await streams.append("logs", "Processing started");
    await streams.append("progress", "50%");
    await streams.append("logs", "Complete");
  },
});

Direct Writing

import { streams, task } from "@trigger.dev/sdk";

export const directWriterTask = task({
  id: "direct-writer",
  run: async (payload) => {
    const { waitUntilComplete } = streams.writer("output", {
      execute: ({ write, merge }) => {
        write("Chunk 1");
        write("Chunk 2");
      },
    });

    await waitUntilComplete();
  },
});

Default Stream

Every run has a “default” stream, allowing you to skip the stream key entirely. This is useful for simple cases where you only need one stream per run. Using direct methods:

import { streams, task } from "@trigger.dev/sdk";

export const defaultStreamTask = task({
  id: "default-stream",
  run: async (payload) => {
    const stream = getDataStream();

    // No stream key needed - uses "default"
    const { waitUntilComplete } = streams.pipe(stream);

    await waitUntilComplete();
  },
});

// Reading from the default stream
const readStream = await streams.read(runId);

Targeting Different Runs

You can pipe streams to parent, root, or any other run using the target option. This works with both defined streams and direct methods.

With Defined Streams

import { task } from "@trigger.dev/sdk";
import { logStream } from "./streams";

export const childTask = task({
  id: "child-task",
  run: async (payload, { ctx }) => {
    const stream = getDataStream();

    // Pipe to parent run
    logStream.pipe(stream, { target: "parent" });

    // Pipe to root run
    logStream.pipe(stream, { target: "root" });

    // Pipe to self (default behavior)
    logStream.pipe(stream, { target: "self" });

    // Pipe to a specific run ID
    logStream.pipe(stream, { target: payload.otherRunId });
  },
});

With Direct Methods

import { streams, task } from "@trigger.dev/sdk";

export const childTask = task({
  id: "child-task",
  run: async (payload, { ctx }) => {
    const stream = getDataStream();

    // Pipe to parent run
    streams.pipe("output", stream, { target: "parent" });

    // Pipe to root run
    streams.pipe("output", stream, { target: "root" });

    // Pipe to a specific run ID
    streams.pipe("output", stream, { target: payload.otherRunId });
  },
});

Streaming from Outside a Task

If you specify a target run ID, you can pipe streams from anywhere (like a Next.js API route):

import { streams } from "@trigger.dev/sdk";
import { openai } from "@ai-sdk/openai";
import { streamText } from "ai";

export async function POST(req: Request) {
  const { messages, runId } = await req.json();

  const result = streamText({
    model: openai("gpt-4o"),
    messages,
  });

  // Pipe AI stream to a Trigger.dev run
  const { stream } = streams.pipe("ai-stream", result.toUIMessageStream(), {
    target: runId,
  });

  return new Response(stream as any, {
    headers: { "Content-Type": "text/event-stream" },
  });
}

React Hook

Use the useRealtimeStream hook to subscribe to streams in your React components.

With Defined Streams (Recommended)

"use client";

import { useRealtimeStream } from "@trigger.dev/react-hooks";
import { aiStream } from "@/app/streams";

export function StreamViewer({ accessToken, runId }: { accessToken: string; runId: string }) {
  // Pass the defined stream directly for full type safety
  const { parts, error } = useRealtimeStream(aiStream, runId, {
    accessToken,
    timeoutInSeconds: 600,
    onData: (chunk) => {
      console.log("New chunk:", chunk); // chunk is typed!
    },
  });

  if (error) return <div>Error: {error.message}</div>;
  if (!parts) return <div>Loading...</div>;

  return (
    <div>
      {parts.map((part, i) => (
        <span key={i}>{part}</span>
      ))}
    </div>
  );
}

With Direct Stream Keys

If you prefer not to use defined streams, you can specify the stream key directly:

"use client";

import { useRealtimeStream } from "@trigger.dev/react-hooks";

export function StreamViewer({ accessToken, runId }: { accessToken: string; runId: string }) {
  const { parts, error } = useRealtimeStream<string>(runId, "ai-output", {
    accessToken,
    timeoutInSeconds: 600,
  });

  if (error) return <div>Error: {error.message}</div>;
  if (!parts) return <div>Loading...</div>;

  return (
    <div>
      {parts.map((part, i) => (
        <span key={i}>{part}</span>
      ))}
    </div>
  );
}

Using Default Stream

// Omit stream key to use the default stream
const { parts, error } = useRealtimeStream<string>(runId, {
  accessToken,
});

Hook Options

const { parts, error } = useRealtimeStream(streamDef, runId, {
  accessToken: "pk_...", // Required: Public access token
  baseURL: "https://api.trigger.dev", // Optional: Custom API URL
  timeoutInSeconds: 60, // Optional: Timeout (default: 60)
  startIndex: 0, // Optional: Start from specific chunk
  throttleInMs: 16, // Optional: Throttle updates (default: 16ms)
  onData: (chunk) => {}, // Optional: Callback for each chunk
});

Complete Example: AI Streaming

Define the stream

// app/streams.ts
import { streams, InferStreamType } from "@trigger.dev/sdk";
import { UIMessageChunk } from "ai";

export const aiStream = streams.define<UIMessageChunk>({
  id: "ai",
});

export type AIStreamPart = InferStreamType<typeof aiStream>;

Create the task

// trigger/ai-task.ts
import { task } from "@trigger.dev/sdk";
import { openai } from "@ai-sdk/openai";
import { streamText } from "ai";
import { aiStream } from "@/app/streams";

export const generateAI = task({
  id: "generate-ai",
  run: async (payload: { prompt: string }) => {
    const result = streamText({
      model: openai("gpt-4o"),
      prompt: payload.prompt,
    });

    const { waitUntilComplete } = aiStream.pipe(result.toUIMessageStream());

    await waitUntilComplete();

    return { success: true };
  },
});

Frontend component

// components/ai-stream.tsx
"use client";

import { useRealtimeStream } from "@trigger.dev/react-hooks";
import { aiStream } from "@/app/streams";

export function AIStream({ accessToken, runId }: { accessToken: string; runId: string }) {
  const { parts, error } = useRealtimeStream(aiStream, runId, {
    accessToken,
    timeoutInSeconds: 300,
  });

  if (error) return <div>Error: {error.message}</div>;
  if (!parts) return <div>Loading...</div>;

  return (
    <div className="prose">
      {parts.map((part, i) => (
        <span key={i}>{part}</span>
      ))}
    </div>
  );
}

Migration from v1

If you’re using the old metadata.stream() API, here’s how to migrate to the recommended v2 approach:

Step 1: Define Your Streams

Create a shared streams definition file:

// app/streams.ts or trigger/streams.ts
import { streams, InferStreamType } from "@trigger.dev/sdk";

export const myStream = streams.define<string>({
  id: "my-stream",
});

export type MyStreamPart = InferStreamType<typeof myStream>;

Step 2: Update Your Tasks

Replace metadata.stream() with the defined stream’s pipe() method:

// Before (v1)
import { metadata, task } from "@trigger.dev/sdk";

export const myTask = task({
  id: "my-task",
  run: async (payload) => {
    const stream = getDataStream();
    await metadata.stream("my-stream", stream);
  },
});

// After (v2 - Recommended)
import { task } from "@trigger.dev/sdk";
import { myStream } from "./streams";

export const myTask = task({
  id: "my-task",
  run: async (payload) => {
    const stream = getDataStream();

    // Don't await - returns immediately
    const { waitUntilComplete } = myStream.pipe(stream);

    // Optionally wait for completion
    await waitUntilComplete();
  },
});

Step 3: Update Your Frontend

Use the defined stream with useRealtimeStream:

// Before
const { parts, error } = useRealtimeStream<string>(runId, "my-stream", {
  accessToken,
});

// After
import { myStream } from "@/app/streams";

const { parts, error } = useRealtimeStream(myStream, runId, {
  accessToken,
});

Alternative: Direct Methods (Not Recommended)

If you prefer not to use defined streams, you can use direct methods:

import { streams, task } from "@trigger.dev/sdk";

export const myTask = task({
  id: "my-task",
  run: async (payload) => {
    const stream = getDataStream();
    const { waitUntilComplete } = streams.pipe("my-stream", stream);
    await waitUntilComplete();
  },
});

Reliability Features

Streams v2 includes automatic reliability improvements:

Automatic resumption: If a connection is lost, both appending and reading will automatically resume from the last successful chunk
No data loss: Network issues won’t cause stream data to be lost
Idempotent operations: Duplicate chunks are automatically handled

These improvements happen automatically - no code changes needed.

Dashboard Integration

Streams are now visible in the Trigger.dev dashboard, allowing you to:

View stream data in real-time as it’s generated
Inspect historical stream data for completed runs
Debug streaming issues with full visibility into chunk delivery

Best Practices

Always use streams.define(): Define your streams in a shared location for better organization, type safety, and code reusability. This is the recommended approach for all streams.
Export stream types: Use InferStreamType to export types for your frontend components
Handle errors gracefully: Always check for errors when reading streams in your UI
Set appropriate timeouts: Adjust timeoutInSeconds based on your use case (AI completions may need longer timeouts)
Target parent runs: When orchestrating with child tasks, pipe to parent runs for easier consumption
Throttle frontend updates: Use throttleInMs in useRealtimeStream to prevent excessive re-renders
Use descriptive stream IDs: Choose clear, descriptive IDs like "ai-output" or "progress" instead of generic names

Troubleshooting

Stream not appearing in dashboard

Ensure you’ve enabled Streams v2 via the future flag or environment variable
Verify your task is actually writing to the stream
Check that the stream key matches between writing and reading

Stream timeout errors

Increase timeoutInSeconds in your read() or useRealtimeStream() calls
Ensure your stream source is actively producing data
Check network connectivity between your application and Trigger.dev

Missing chunks

With v2, chunks should never be lost due to automatic resumption
Verify you’re reading from the correct stream key
Check the startIndex option if you’re not seeing expected chunks

Getting started

Fundamentals

Writing tasks

Configuration

Development

Deployment

Realtime

CLI

MCP Server

Using the Dashboard

Troubleshooting

Self-hosting

Open source

Help

​Overview

​Enabling Streams v2

​Option 1: Configure the SDK

​Option 2: Environment Variable

​Limits Comparison

​Quick Start

​Defining Typed Streams (Recommended)

​Creating a Defined Stream

​Using Defined Streams in Tasks

​Reading from a Stream

​Appending to a Stream

​Writing Multiple Chunks

​Using Defined Streams in React

​Direct Stream Methods (Without Defining)

​Direct Piping

​Direct Reading

​Direct Appending

​Direct Writing

​Default Stream

​Targeting Different Runs

​With Defined Streams

​With Direct Methods

​Streaming from Outside a Task

​React Hook

​With Defined Streams (Recommended)

​With Direct Stream Keys

​Using Default Stream

​Hook Options

​Complete Example: AI Streaming

​Define the stream

​Create the task

​Frontend component

​Migration from v1

​Step 1: Define Your Streams

​Step 2: Update Your Tasks

​Step 3: Update Your Frontend

​Alternative: Direct Methods (Not Recommended)

​Reliability Features

​Dashboard Integration

​Best Practices

​Troubleshooting

​Stream not appearing in dashboard

​Stream timeout errors

​Missing chunks

Overview

Enabling Streams v2

Option 1: Configure the SDK

Option 2: Environment Variable

Limits Comparison

Quick Start

Defining Typed Streams (Recommended)

Creating a Defined Stream

Using Defined Streams in Tasks

Reading from a Stream

Appending to a Stream

Writing Multiple Chunks

Using Defined Streams in React

Direct Stream Methods (Without Defining)

Direct Piping

Direct Reading

Direct Appending

Direct Writing

Default Stream

Targeting Different Runs

With Defined Streams

With Direct Methods

Streaming from Outside a Task

React Hook

With Defined Streams (Recommended)

With Direct Stream Keys

Using Default Stream

Hook Options

Complete Example: AI Streaming

Define the stream

Create the task

Frontend component

Migration from v1

Step 1: Define Your Streams

Step 2: Update Your Tasks

Step 3: Update Your Frontend

Alternative: Direct Methods (Not Recommended)

Reliability Features

Dashboard Integration

Best Practices

Troubleshooting

Stream not appearing in dashboard

Stream timeout errors

Missing chunks