Workflow Automation - Rivet

Durable workflows that survive crashes and restarts
Multi-step orchestration with sessions, file operations, and process execution
Error handling and retry via ctx.step() for each operation
Agent chaining where output of one session feeds into the next

Basic workflow

Use the actor workflow() primitive to orchestrate a multi-step agent task. Each step is durable and will resume from where it left off after a restart.

Session creation and prompting must happen within the same step because sessions are ephemeral and won't survive a replay.

<CodeGroup stacked> ```ts @nocheck server.ts import { agentOs } from "rivetkit/agent-os"; import common from "@rivet-dev/agent-os-common"; import pi from "@rivet-dev/agent-os-pi"; import { actor, setup, workflow } from "rivetkit";

  // Step 1: Clone the repo
  await c.step("clone-repo", async () => {
    return agentHandle.exec(`git clone ${repo} /home/user/repo`);
  });

  // Step 2: Agent fixes the bug (session lives within this step)
  await c.step("fix-bug", async () => {
    const session = await agentHandle.createSession("pi", {
      env: { ANTHROPIC_API_KEY: process.env.ANTHROPIC_API_KEY! },
    });
    await agentHandle.sendPrompt(
      session.sessionId,
      `Fix the bug described in issue: ${issue}`,
    );
    await agentHandle.closeSession(session.sessionId);
  });

  // Step 3: Run tests
  const tests = await c.step("run-tests", async () => {
    return agentHandle.exec("cd /home/user/repo && npm test");
  });

  console.log("Tests exit code:", tests.exitCode);
  await message.complete();
}

}, });

const vm = agentOs({ options: { software: [common, pi] }, });

export const registry = setup({ use: { automator, vm } }); registry.start();


```ts @nocheck client.ts
import { createClient } from "rivetkit/client";
import type { registry } from "./server";

const client = createClient<typeof registry>("http://localhost:6420");
const handle = client.automator.getOrCreate(["main"]);

// Trigger the workflow
await handle.send("fixBug", {
  repo: "https://github.com/example/repo.git",
  issue: "Fix the login redirect bug",
});

</CodeGroup>

Agent chaining

Output of one agent session feeds into the next. Each session is created and completed within its own step.

const pipeline = actor({ workflows: { codeReview: workflow<{ filePath: string }>(), }, run: async (c) => { for await (const message of c.workflow.iter("codeReview")) { const agentHandle = c.actors.vm.getOrCreate([review-${Date.now()}]);

  // Step 1: Agent reviews code and writes findings to a file
  await c.step("review", async () => {
    const session = await agentHandle.createSession("pi", {
      env: { ANTHROPIC_API_KEY: process.env.ANTHROPIC_API_KEY! },
    });
    await agentHandle.sendPrompt(
      session.sessionId,
      `Review the code at ${message.body.filePath} and write your findings to /home/user/review.md`,
    );
    await agentHandle.closeSession(session.sessionId);
  });

  // Step 2: Read the review from the filesystem
  const review = await c.step("read-review", async () => {
    const content = await agentHandle.readFile("/home/user/review.md");
    return new TextDecoder().decode(content);
  });

  // Step 3: Second session applies fixes based on the review
  await c.step("fix", async () => {
    const session = await agentHandle.createSession("pi", {
      env: { ANTHROPIC_API_KEY: process.env.ANTHROPIC_API_KEY! },
    });
    await agentHandle.sendPrompt(
      session.sessionId,
      `Apply the following review feedback:\n\n${review}`,
    );
    await agentHandle.closeSession(session.sessionId);
  });

  await message.complete();
}

}, });

const vm = agentOs({ options: { software: [common, pi] }, });

export const registry = setup({ use: { pipeline, vm } }); registry.start();


```ts @nocheck client.ts
import { createClient } from "rivetkit/client";
import type { registry } from "./server";

const client = createClient<typeof registry>("http://localhost:6420");
const handle = client.pipeline.getOrCreate(["main"]);

await handle.send("codeReview", { filePath: "/home/user/src/auth.ts" });

</CodeGroup>

Recommendations

Create and close sessions within the same step. Sessions are ephemeral and won't exist after a workflow replays.
Pass data between steps via the filesystem or step return values, not session state.
Keep step names stable across code changes. Renaming a step breaks replay for in-progress workflows.
Use separate actors for the workflow orchestrator and the agentOS VM.
See Workflows for the full workflow API reference including timers, joins, and races.