Pranay Prakash
6cc851c342
The only thing a World does with `eventCount` is bump-and-report: when the write lands above the position named, it reads the events in between and returns them so the writer can merge them without a second round-trip. The replay loop and the suspension handler merge that page into their loaded log. The step executor has no log to merge into, so it took the page's highest position and discarded the rest. In production that discarded read fell on a third of all `step_started` writes (10.8M of 13.4M skipped-slot report reads per day were on executor event types), each a strongly consistent DynamoDB query on the run partition with resolved refs, on the response path. This removes the executor's `knownSlot` / `observeSlot` machinery, the `slotSnapshot` executor param, and the `batchCommittedSlotCeiling` the suspension handler computed only to seed it. The loop's and the suspension handler's own snapshots are unchanged; they consume their reports. The World contract already describes omitting the count for a caller with no loaded log to be stale against; the executor now matches it. Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>
Workflow SDK
Workflow SDK makes TypeScript and JavaScript functions durable. It persists workflow progress, retries failed steps, and provides built-in observability. Workflows can suspend without using compute while they wait.
Quick start
Install the SDK in an existing project:
npm install workflow
Configure the integration for your framework. For example, with Next.js:
// next.config.ts
import { withWorkflow } from 'workflow/next';
export default withWorkflow({});
Then start a workflow from an API route, Server Action, or other server-side code:
import { start } from 'workflow/api';
import { onboardUser } from './workflows/onboard-user';
await start(onboardUser, ['hello@example.com']);
Run your app, then open the local observability UI in another terminal:
npm run dev
npx workflow web
Choose your framework in the getting-started guides.
Note
The
workflowpackage includes its full documentation, so coding agents can read version-matched guides locally fromnode_modules/workflow/docs.
Run anywhere
Local development uses the bundled backend with no configuration. Deploy to Vercel for managed storage, queuing, scaling, and observability. To self-host, use the Postgres backend or implement a custom World.
The Worlds page lists maintainer-curated third-party Worlds, including self-hosted and managed options. Submit your World by updating the Worlds Manifest.
Community
The Workflow SDK community lives on GitHub Discussions, where you can ask questions, share ideas, and show what you have built.
Contributing
Contributions are welcome. Use issues and discussions to collaborate with the team and wider community. By participating, you agree to our Code of Conduct.
Security
If you find a security vulnerability in Workflow SDK, disclose it responsibly instead of opening a public issue.
To participate in our Open Source Software Bug Bounty program, please email responsible.disclosure@vercel.com. We will add you to the program and provide further instructions for submitting your report.