# ag-ui-protocol Python SDK for the **Agent-User Interaction (AG-UI) Protocol**. `ag-ui-protocol` provides Python developers with strongly-typed data structures and event encoding for building AG-UI compatible agent servers. Built on Pydantic for robust validation and automatic camelCase serialization for seamless frontend integration. ## Installation ```bash pip install ag-ui-protocol poetry add ag-ui-protocol pipenv install ag-ui-protocol ``` ## Features - 🐍 **Python-native** – Idiomatic Python APIs with full type hints and validation - 📋 **Pydantic models** – Runtime validation and automatic JSON serialization - 🔄 **Streaming events** – 16 core event types for real-time agent communication - ⚡ **High performance** – Efficient event encoding for Server-Sent Events ## Quick example ```python from ag_ui.core import TextMessageContentEvent, EventType from ag_ui.encoder import EventEncoder # Create a streaming text event event = TextMessageContentEvent( type=EventType.TEXT_MESSAGE_CONTENT, message_id="msg_123", delta="Hello from Python!" ) # Encode for HTTP streaming encoder = EventEncoder() sse_data = encoder.encode(event) # Output: data: {"type":"TEXT_MESSAGE_CONTENT","messageId":"msg_123","delta":"Hello from Python!"}\n\n ``` ### Multimodal user message ```python from ag_ui.core import UserMessage, TextInputContent, ImageInputPart, InputContentUrlSource message = UserMessage( id="user-123", content=[ TextInputContent(text="Please describe this image"), ImageInputPart( source=InputContentUrlSource( value="https://example.com/cat.png", mime_type="image/png", ) ), ], ) payload = message.model_dump(by_alias=True) # {"id": "user-123", "role": "user", "content": [...]} ``` > `BinaryInputContent` is deprecated. Use modality-specific input parts (`ImageInputPart`, `AudioInputPart`, `VideoInputPart`, `DocumentInputPart`) with `InputContentDataSource` or `InputContentUrlSource`. ### Optional fields with no value are left out Serializing an AG-UI type omits every optional field that has no value instead of writing it as `null` — matching what a TypeScript producer puts on the wire. This is built into the base model, so it holds on every path (`model_dump`, `model_dump_json`, nesting inside another model, the `EventEncoder`) and you do not need to pass `exclude_none=True`: ```python from ag_ui.core import ToolCallStartEvent ToolCallStartEvent(tool_call_id="tc_1", tool_call_name="search").model_dump_json(by_alias=True) # {"type":"TOOL_CALL_START","toolCallId":"tc_1","toolCallName":"search"} # note: no "parentMessageId": null ``` `null` as an actual value is untouched: a required field holding `None`, a `None` inside a `dict` or `list` (an individual metadata value, a JSON Patch `replace` with `null`), and any extra field all serialize as `null`. ## Packages - **`ag_ui.core`** – Types, events, and data models for AG-UI protocol - **`ag_ui.encoder`** – Event encoding utilities for HTTP streaming ## Documentation - Concepts & architecture: [`docs/concepts`](https://docs.ag-ui.com/concepts/architecture) - Full API reference: [`docs/sdk/python`](https://docs.ag-ui.com/sdk/python/core/overview) ## Contributing Bug reports and pull requests are welcome! Please read our [contributing guide](https://docs.ag-ui.com/development/contributing) first. ## License MIT © 2025 AG-UI Protocol Contributors