> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cascadeflow.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Streaming

> TypeScript streaming API with StreamEvent, StreamEventType, and async iterators for real-time cascade output.

# Streaming

`CascadeAgent` supports streaming via `streamEvents()` and `stream()` async iterators.

## streamEvents()

```typescript theme={null}
import { CascadeAgent, StreamEventType } from '@cascadeflow/core';

const agent = new CascadeAgent({
  models: [
    { name: 'gpt-4o-mini', provider: 'openai', cost: 0.00015 },
    { name: 'gpt-4o', provider: 'openai', cost: 0.0025 },
  ],
});

for await (const event of agent.streamEvents('Explain TypeScript')) {
  switch (event.type) {
    case StreamEventType.ROUTING:
      console.log(`Routing: ${event.data.strategy}`);
      break;
    case StreamEventType.CHUNK:
      process.stdout.write(event.content);
      break;
    case StreamEventType.DRAFT_DECISION:
      console.log(`Draft ${event.data.accepted ? 'accepted' : 'rejected'}`);
      break;
    case StreamEventType.COMPLETE:
      console.log(`\nModel: ${event.data.result?.modelUsed}`);
      console.log(`Cost: $${event.data.result?.totalCost ?? 0}`);
      break;
  }
}
```

## StreamEvent

```typescript theme={null}
interface StreamEvent {
  type: StreamEventType;
  content: string;
  data: StreamEventData;
}
```

| Field | Type | Description |
| - | - | - |
| `type` | `StreamEventType` | Event type |
| `content` | `string` | Content chunk (for `CHUNK` events) |
| `data` | `StreamEventData` | Event metadata |

## StreamEventType

| Value | Description |
| - | - |
| `ROUTING` | Routing decision made |
| `CHUNK` | Content chunk received |
| `DRAFT_DECISION` | Draft quality validation result |
| `SWITCH` | Switching from drafter to verifier |
| `COMPLETE` | Streaming complete |
| `ERROR` | Error occurred |

## StreamEventData

| Field | Type | Description |
| - | - | - |
| `model` | `string` | Current model name |
| `phase` | `string` | Current phase (`draft`, `verifier`, or `direct`) |
| `strategy` | `string` | Routing strategy used |
| `accepted` | `boolean` | Whether draft was accepted (on `DRAFT_DECISION`) |
| `result` | `CascadeResult` | Final result on `COMPLETE` |
| `reason` | `string` | Routing or validation reason |
| `score` | `number` | Quality score when available |
| `from_model` / `to_model` | `string` | Model transition on `SWITCH` |

## StreamEventsOptions

Streaming options include the shared generation, knowledge, tool, routing, and provider options from `agent.run()`.

```typescript theme={null}
for await (const event of agent.streamEvents('Query', {
  maxTokens: 500,
  temperature: 0.7,
  systemPrompt: 'You are a helpful assistant.',
})) {
  // ...
}
```


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