State Streaming Setup - Copilotkit

<Steps> <Step> ### Install the ADK + AG-UI bridge

```bash
pip install ag-ui-adk
```

</Step> <Step> ### Declare the predicted state mapping

ADK state streaming uses `PredictStateMapping` to map the streaming
`write_document` tool argument into `state["document"]`. Add
`AGUIToolset()` to the agent so CopilotKit can forward the state deltas to
the UI.

<DemoCode file="src/agents/shared_state_streaming_agent.py" region="state-streaming-middleware" />

</Step> </Steps>