Open Scaffold

Build AI workflows you can test like software.

The Problem

AI workflows are hard to test. Every run is different. Costs add up during development. CI pipelines can't rely on non-deterministic API calls. When something breaks in production, you can't reproduce it.

The Solution

Capability	What it does
Build	Define agents with typed outputs, compose into phases, wire into workflows
Debug	VCR-style recording: run once with real APIs, replay infinitely in tests
Evaluate	Compare workflow variants, score outputs, A/B test prompts

Quick Example

import { agent, workflow, phase, run } from "@open-scaffold/core"
import { AnthropicProvider } from "@open-scaffold/server"
import { z } from "zod"

// 1. Define an agent with typed output
const researcher = agent({
  name: "researcher",
  model: "claude-sonnet-4-5",
  output: z.object({ findings: z.array(z.string()) }),
  prompt: (state) => `Research: ${state.topic}`,
  update: (output, draft) => { draft.findings = output.findings }
})

// 2. Compose into a workflow
const researchFlow = workflow({
  name: "research-flow",
  initialState: { topic: "", findings: [] as string[] },
  start: (input: string, draft) => { draft.topic = input },
  phases: {
    research: { run: researcher, next: "done" },
    done: phase.terminal()
  }
})

// 3. Run with observer callbacks
const result = await run(researchFlow, {
  input: "quantum computing",
  runtime: {
    providers: { "claude-sonnet-4-5": AnthropicProvider() },
    mode: "live"  // Switch to "playback" for tests
  },
  observer: {
    onStateChanged: (state) => console.log("State:", state),
    onTextDelta: ({ agent, delta }) => process.stdout.write(delta),
    onAgentCompleted: ({ agent, output, durationMs }) => {
      console.log(`${agent} finished in ${durationMs}ms`)
    }
  }
})

How It Works

Every action in a workflow is recorded as an immutable event. In live mode, API calls are made and responses are saved. In playback mode, saved responses are replayed exactly -- no API calls, no costs, deterministic every time. This means you can develop against real APIs, then run tests in CI with perfect reproducibility.

Packages

Package	Description
@open-scaffold/core	Agents, phases, workflows, and execution runtime
@open-scaffold/server	HTTP/SSE server, providers (Anthropic), port 42069
@open-scaffold/client	HTTP client + React hooks (18 hooks)
@open-scaffold/testing	Shared recordings database for deterministic tests

Get Started

bun add @open-scaffold/core

See the documentation for full guides.

License

MIT