dbos-typescript

---
name: dbos-typescript
description: DBOS TypeScript SDK for building reliable, fault-tolerant applications with durable workflows. Use this skill when writing TypeScript code with DBOS, creating workflows and steps, using queues, using DBOSClient from external applications, or building applications that need to be resilient to failures.
license: MIT
---

# DBOS TypeScript Best Practices

Guide for building reliable, fault-tolerant TypeScript applications with DBOS durable workflows.

## When to Apply

Reference these guidelines when:
- Adding DBOS to existing TypeScript code
- Creating workflows and steps
- Using queues for concurrency control
- Implementing workflow communication (events, messages, streams)
- Configuring and launching DBOS applications
- Using DBOSClient from external applications
- Testing DBOS applications

## Rule Categories by Priority

| Priority | Category | Impact | Prefix |
|----------|----------|--------|--------|
| 1 | Lifecycle | CRITICAL | `lifecycle-` |
| 2 | Workflow | CRITICAL | `workflow-` |
| 3 | Step | HIGH | `step-` |
| 4 | Queue | HIGH | `queue-` |
| 5 | Communication | MEDIUM | `comm-` |
| 6 | Pattern | MEDIUM | `pattern-` |
| 7 | Testing | LOW-MEDIUM | `test-` |
| 8 | Client | MEDIUM | `client-` |
| 9 | Advanced | LOW | `advanced-` |

## Critical Rules

### Installation

Always install the latest version of DBOS:

```bash
npm install @dbos-inc/dbos-sdk@latest
```

### DBOS Configuration and Launch

A DBOS application MUST configure and launch DBOS before running any workflows:

```typescript
import { DBOS } from "@dbos-inc/dbos-sdk";

async function main() {
  DBOS.setConfig({
    name: "my-app",
    applicationVersion: "0.1.0",
    systemDatabaseUrl: process.env.DBOS_SYSTEM_DATABASE_URL,
  });
  await DBOS.launch();
  await myWorkflow();
}

main().catch(console.log);
```

When creating a new application, set `applicationVersion` to `"0.1.0"`. If omitted, DBOS derives an opaque hash from workflow source code. When editing an existing application, leave its configured version alone — changing it is a deployment decision (see `references/advanced-versioning.md`).

### Workflow and Step Structure

Workflows are comprised of steps. Any function performing complex operations or accessing external services must be run as a step using `DBOS.runStep`:

```typescript
import { DBOS } from "@dbos-inc/dbos-sdk";

async function fetchData() {
  return await fetch("https://api.example.com").then(r => r.json());
}

async function myWorkflowFn() {
  const result = await DBOS.runStep(fetchData, { name: "fetchData" });
  return result;
}
const myWorkflow = DBOS.registerWorkflow(myWorkflowFn);
```

### Key Constraints

- Do NOT call, start, or enqueue workflows from within steps
- Do NOT use threads or uncontrolled concurrency to start workflows - use `DBOS.startWorkflow` or queues
- Workflows MUST be deterministic - non-deterministic operations go in steps
- Do NOT modify global variables from workflows or steps

## How to Use

Read individual rule files for detailed explanations and examples:

```
references/lifecycle-config.md
references/workflow-determinism.md
references/queue-concurrency.md
```

## References

- https://docs.dbos.dev/
- https://github.com/dbos-inc/dbos-transact-ts