Matt Aitken
e2d3b8388c
## Summary
Two ergonomic additions for custom chat-agent loops that own the turn
loop (`chat.customAgent`, `chat.createSession`, and the hand-rolled
primitives).
`chat.writeTurnComplete()` now resolves to `{ lastEventId }`, the resume
cursor for the start of the next turn. A custom loop can persist it
straight from the task instead of round-tripping it back from the client
after the turn ends. The value was already produced internally by the
turn-complete write; the public wrapper simply discarded it.
`chat.pipeAndCapture()` no longer throws when a stream is stopped or
fails. It now resolves to a `PipeAndCaptureResult` carrying any partial
`message` captured before the stop or failure, a typed `status`
(`"complete" | "aborted" | "error"`), and the `error` on failure.
Previously a failed stream threw and the partial was lost, and an abort
was captured only when the AI SDK happened to fire `onFinish` in time.
```ts
const { message, status, error } = await chat.pipeAndCapture(result, { signal });
if (message) conversation.addResponse(message);
if (status === "error") logger.error("turn failed", { error });
const { lastEventId } = await chat.writeTurnComplete();
await db.chats.update(chatId, { lastEventId });
```
## Design
`pipeAndCapture` wraps the pipe in a `try/catch` and classifies the
outcome from the abort signal (a stop drains the source stream cleanly
rather than throwing) versus a thrown error. It also races the
`onFinish` capture against a timeout so a hard stop that prevents
`onFinish` from firing can't hang the caller. This mirrors the capture
path `chat.agent` already uses internally.
The `finishReason` from `onFinish` is surfaced too, since it was already
captured on the built-in path.
The internal `turn.complete()` helper keeps its existing contract: it
still returns `UIMessage | undefined`, still throws on a genuine stream
failure, and still discards output on a full run cancel.
## Breaking change
`chat.pipeAndCapture` previously resolved to `UIMessage | undefined`.
Call sites now read `.message` off the result. This is a young,
low-level API; the docs examples are updated in this PR.
Official TypeScript SDK for Trigger.dev
The Trigger.dev SDK is a TypeScript/JavaScript library that allows you to define and trigger tasks in your projects.
About Trigger.dev
Trigger.dev is an open source platform for building and deploying fully-managed AI agents and workflows. Write workflows in normal async TypeScript for everything from simple tasks to long-running AI agents, heavy media processing, complex real-time systems and more. Complete with full observability, managed queues, and elastic infrastructure which handles the horizontal scaling.
Core features
- Task creation and execution
- CLI for development and deployment
- Build system with extensions
- Management API for runs, schedules, and environment variables
Key Components:
- Tasks: Background jobs written in TypeScript/JavaScript
- CLI: Commands for login, init, dev, deploy
- Build Extensions: Customize builds (Prisma, Python, FFmpeg, etc.)
- Management API: Programmatic control over runs and resources
Getting started
There are two ways to get started:
- Create an account in our web app, create a new project and follow the instructions in the onboarding. Build and deploy your first task in minutes.
- Manual setup in your existing project.
SDK documentation
For more information on our SDK, refer to our docs.
Support
If you have any questions, please reach out to us on Discord and we'll be happy to help.