Workflows

A workflow is a script with a name and a typed interface: JSON Schemas for its input, its output and each signal it accepts. Your harness registers workflows, and so does the model, with the agent tool save_workflow: a procedure it wrote once becomes a building block of its later scripts.

Typed end to end

Registering a workflow checks its script against its toolset and its own schemas: main must accept the input and return the output, and signal() only takes a declared name and returns that signal’s type. A script that starts the workflow is checked against the same schemas before it runs.

A script that uses the workflow repo_check

import { repo_check } from "rewind:workflows";

export default async function main(input: { repos: string[] }) {
  const runs = await Promise.all(input.repos.map((repo) => repo_check.start({ repo })));
  await Promise.all(runs.map((run) => run.signal("acknowledge", { by: "check-all" })));
  const results = await Promise.all(runs.map((run) => run.result()));
  return results.sort((a, b) => b.stars - a.stars);
}

Call	Does
`repo_check.start(input, opts?)`	Starts a run of the workflow and returns its handle once it exists. `opts`: `detached`, `labels` (added to the parent’s), `ttl`
`run.signal(name, payload)`	Sends one of the workflow’s signals. Resolves once the signal is in the run’s mailbox
`run.result()`, `run.result({ timeout })`	The run’s output. Rejects with `WorkflowError` if it failed, was cancelled or aborted
`repo_check.get(runId)`	A handle on an existing run of the workflow, to signal it

Versions

Each registration is a new immutable version, identified by its digest (repo_check@9fbd13f4bb9b). A toolset that names a workflow pins its latest version when it is registered, as it pins the schemas of MCP tools. Runs that are already going keep their version: changing a workflow never breaks a run in flight.

Attached and detached runs

A run started by a script is attached to it: the parent does not end before its attached children, and a parent that fails, is cancelled or aborted cancels the children still running. A forgotten result() is harmless. A run started with detached: true lives on its own: start a long workflow and move on.

Started by your harness

Your harness starts runs of a workflow too, by name (its latest version) or by version, and signals them:

const run = await rewind.namespace(user.id).runs.start({ workflow: "repo_check", input: { repo: "acme/api" } });
await rewind.runs.signal(run.id, "acknowledge", { by: "the harness" });

A run of a workflow accepts only the signals its workflow declares, with a payload that matches their schema; anything else is refused (422), whoever sends it. In the dashboard, a run of a workflow shows its workflow and version, the run that started it, and the runs it started in Runs started. See Workflows in the SDK.

Get started

How it works

Run Rewind

Typed end to end

Versions

Attached and detached runs

Started by your harness