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# Run.timeTravelStream()

`.timeTravelStream()` 方法会从任意指定步骤开始重新执行 Workflow，并流式传输事件。你可以在时间旅行执行期间接收实时更新，同时完整了解每个步骤的进度。

## 用法示例

```typescript
const run = await workflow.createRun()

const output = run.timeTravelStream({
  step: 'step2',
  inputData: { value: 10 },
})

// Process events as they arrive
for await (const event of output.fullStream) {
  console.log(event.type, event.payload)
}

// Get the final result
const result = await output.result
```

## 参数

所有参数都与 [`Run.timeTravel()`](https://mastra.zisheng.pro/reference/workflows/run-methods/timeTravel) 相同。有关详细的参数文档，请参阅 [timeTravel 参考](https://mastra.zisheng.pro/reference/workflows/run-methods/timeTravel)。

## 返回值

**output** (`WorkflowRunOutput<WorkflowResult<TState, TInput, TOutput, TSteps>>`): 同时包含 Stream 和结果 Promise 的对象

**output.fullStream** (`ReadableStream<WorkflowStreamEvent>`): 随着执行推进发出 Workflow 事件的可读 Stream

**output.result** (`Promise<WorkflowResult<TState, TInput, TOutput, TSteps>>`): 解析为最终 Workflow 执行结果的 Promise

**output.traceId** (`string`): 启用 Tracing 时与本次执行关联的 Trace ID

## Stream 事件

Stream 会在执行期间发出 Workflow 事件：

- `workflow-step-start`：步骤开始执行时发出
- `workflow-step-finish`：步骤成功完成时发出
- `workflow-step-error`：步骤遇到错误时发出
- `workflow-step-suspended`：步骤暂停时发出
- 其他事件取决于步骤类型（Agent、Tool 等）

## 扩展用法示例

### 在时间旅行期间处理事件

```typescript
const run = await workflow.createRun()

const output = run.timeTravelStream({
  step: 'step2',
  inputData: { value: 10 },
})

for await (const event of output.fullStream) {
  switch (event.type) {
    case 'workflow-step-start':
      console.log(`Starting step: ${event.payload.stepName}`)
      break
    case 'workflow-step-finish':
      console.log(`Completed step: ${event.payload.stepName}`)
      break
    case 'workflow-step-error':
      console.error(`Error in step: ${event.payload.stepName}`, event.payload.error)
      break
  }
}

const result = await output.result
console.log('Time travel completed:', result)
```

### 带上下文的时间旅行 Stream

```typescript
const output = run.timeTravelStream({
  step: 'step2',
  context: {
    step1: {
      status: 'success',
      payload: { value: 0 },
      output: { step1Result: 2 },
      startedAt: Date.now(),
      endedAt: Date.now(),
    },
  },
})

for await (const event of output.fullStream) {
  // Handle events
  console.log(event)
}

const result = await output.result
```

### 带嵌套 Workflow 的时间旅行 Stream

```typescript
const output = run.timeTravelStream({
  step: ['nestedWorkflow', 'step3'],
  inputData: { value: 10 },
  nestedStepsContext: {
    nestedWorkflow: {
      step2: {
        status: 'success',
        payload: { step1Result: 2 },
        output: { step2Result: 3 },
        startedAt: Date.now(),
        endedAt: Date.now(),
      },
    },
  },
})

for await (const event of output.fullStream) {
  console.log(event.type, event.payload)
}

const result = await output.result
```

## 注意事项

- 时间旅行执行完成或遇到错误时，Stream 会自动关闭
- 可以在 Workflow 仍在执行时处理 Stream 中的事件
- `result` Promise 仅在所有步骤完成后才会解析
- Stream 事件采用与常规 Workflow Streaming 相同的格式
- 时间旅行 Streaming 依赖持久化的 Workflow 快照，因此需要配置存储

## 相关内容

- [Run.timeTravel()](https://mastra.zisheng.pro/reference/workflows/run-methods/timeTravel)
- [时间旅行](https://mastra.zisheng.pro/docs/workflows/time-travel)
- [Workflow Streaming](https://mastra.zisheng.pro/docs/workflows/overview)
- [Run.stream()](https://mastra.zisheng.pro/reference/streaming/workflows/stream)
- [Run.resumeStream()](https://mastra.zisheng.pro/reference/streaming/workflows/resumeStream)