ag_ui library

AG-UI Dart SDK - Standardizing agent-user interactions

This library provides strongly-typed Dart models for the AG-UI protocol, enabling agent-user interaction through a standardized event-based system.

Features

Core Protocol Support: Full implementation of AG-UI event types
HTTP Client: Production-ready client with SSE streaming support
Event Streaming: Real-time event processing with backpressure handling
Tool Interactions: Support for tool calls with generative UI
State Management: Handle snapshots and deltas (JSON Patch RFC 6902)
Type Safety: Strongly-typed models for all protocol entities

Getting Started

import 'package:ag_ui/ag_ui.dart';

final client = AgUiClient(
  config: AgUiClientConfig(
    baseUrl: 'http://localhost:8000',
  ),
);

final input = SimpleRunAgentInput(
  messages: [
    UserMessage(
      id: 'msg_1',
      content: 'Hello, world!',
    ),
  ],
);

await for (final event in client.runAgent('agent', input)) {
  print('Event: ${event.type}');
}

Classes

ActivityDeltaEvent: Event containing a JSON Patch (RFC 6902) delta for an activity message
ActivityMessage: Activity message embedded in a MESSAGES_SNAPSHOT payload.
ActivitySnapshotEvent: Event containing a snapshot of an activity message.
AgUiClient: Main client for interacting with AG-UI servers.
AgUiClientConfig: Configuration for AgUiClient.
AGUIModel: Base class for all AG-UI models with JSON serialization support.
AssistantMessage: Assistant message with optional content and tool calls.
AudioInputContent: Audio part of a multimodal message.
BackoffStrategy: Abstract interface for backoff strategies.
BaseEvent: Base event for all AG-UI protocol events.
BinaryInputContent: Legacy binary content part.
CancelToken: Cancel token for request cancellation.
ClientToolResult: ToolResult model for submitting tool execution results to the server.
ConstantBackoff: Simple constant backoff strategy that returns the same delay every time.
Context: Additional context for the agent
CustomEvent: Event containing a custom event
DataSource: Inline content source carrying a data payload (e.g. base64-encoded bytes).
Decoder: Decoder extensions for client operations
DeveloperMessage: Developer message with required content.
DocumentInputContent: Document part of a multimodal message.
Encoder: Encoder extensions for client operations
EventDecoder: Decoder for AG-UI events.
EventEncoder: Encoder for AG-UI events.
EventStreamAdapter: Adapter for converting streams of SSE messages to typed AG-UI events.
ExponentialBackoff: Implements exponential backoff with jitter for reconnection attempts.
FunctionCall: Represents a function call within a tool call.
ImageInputContent: Image part of a multimodal message.
InputContent: A single typed part of a multimodal UserMessage.
InputContentSource: The source of a multimodal InputContent part.
JsonDecoder: Utility for tolerant JSON decoding that ignores unknown fields.
LegacyBackoffStrategy: Legacy class for backward compatibility - maintains state internally
Message: Base message class for all message types.
MessagesSnapshotEvent: Event containing a snapshot of messages
MultimodalContent: Multimodal user message content. Serializes to a JSON List.
RawEvent: Event wrapping a raw, uninterpreted upstream event payload.
ReasoningEncryptedValueEvent: Event containing an encrypted value for a message or tool call.
ReasoningEndEvent: Event indicating the end of a reasoning phase.
ReasoningMessage: Reasoning message emitted by models that expose their chain-of-thought.
ReasoningMessageChunkEvent: Event containing a chunk of reasoning message content.
ReasoningMessageContentEvent: Event containing a piece of reasoning message content.
ReasoningMessageEndEvent: Event indicating the end of a reasoning message.
ReasoningMessageStartEvent: Event indicating the start of a reasoning message.
ReasoningStartEvent: Event indicating the start of a reasoning phase.
Run: Represents a run in the AG-UI protocol
RunAgentInput: Input for running an agent.
RunErrorEvent: Event indicating that a run has encountered an error
RunFinishedEvent: Event indicating that a run has finished
RunStartedEvent: Event indicating that a run has started
SimpleRunAgentInput: Simplified input for running an agent via HTTP endpoint
SseClient: A client for Server-Sent Events (SSE) with automatic reconnection.
SseMessage: Represents a Server-Sent Event message.
StateDeltaEvent: Event containing a delta of the state (JSON Patch RFC 6902)
StateSnapshotEvent: Event containing a snapshot of the state
StepFinishedEvent: Event indicating that a step has finished
StepStartedEvent: Event indicating that a step has started
SystemMessage: System message with required content.
TextContent: Plain-text user message content. Serializes to a JSON String.
TextInputContent: Plain text part of a multimodal message.
TextMessageChunkEvent: Event containing a chunk of text message content
TextMessageContentEvent: Event containing text message content
TextMessageEndEvent: Event indicating the end of a text message
TextMessageStartEvent: Event indicating the start of a text message
ThinkingContentEvent: Event containing thinking content.
ThinkingEndEvent: Event indicating the end of a thinking section
ThinkingStartEvent: Event indicating the start of a thinking section
ThinkingTextMessageContentEvent: Event containing thinking text message content.
ThinkingTextMessageEndEvent: Event indicating the end of a thinking text message.
ThinkingTextMessageStartEvent: Event indicating the start of a thinking text message.
Tool: Represents a tool definition.
ToolCall: Represents a tool call made by the assistant.
ToolCallArgsEvent: Event containing tool call arguments
ToolCallChunkEvent: Event containing a chunk of tool call content
ToolCallEndEvent: Event indicating the end of a tool call
ToolCallResultEvent: Event containing the result of a tool call
ToolCallStartEvent: Event indicating the start of a tool call
ToolMessage: Tool message with tool call result.
ToolResult: Represents the result of a tool call
UrlSource: Remote content source referenced by URL.
UserMessage: User message with text or multimodal content.
UserMessageContent: The content union for a UserMessage: plain text or multimodal parts.
Validators: Validation utilities for AG-UI SDK
VideoInputContent: Video part of a multimodal message.

Enums

EventType: Enumeration of all AG-UI event types
MessageRole: Role types for messages in the AG-UI protocol.
ReasoningEncryptedValueSubtype: Subtype for ReasoningEncryptedValueEvent.
ReasoningMessageRole: Role for reasoning messages (aligned with the AG-UI protocol).
TextMessageRole: Text message roles that can be used in text message events.
ToolCallResultRole: Role for tool-call result messages (aligned with the AG-UI protocol).

Mixins

TypeDiscriminator: Mixin for models with type discriminators.

Constants

aguiMediaType → const String: The AG-UI protobuf media type constant.
agUiVersion → const String: SDK version
kUnsetSentinel → const _CopyWithSentinel: Single shared sentinel instance used across all AG-UI copyWith methods.

Functions

camelToSnake(String camel) → String: Converts camelCase to snake_case
initAgUI() → void: Initialize the AG-UI SDK
snakeToCamel(String snake) → String: Converts snake_case to camelCase

Typedefs

AgUiClientException = AgUiError
AgUiConnectionException = TransportError
AgUiHttpException = TransportError
AgUiTimeoutException = AGUITimeoutError
AgUiValidationException = ValidationError
State = dynamic: Type alias for state (can be any type)
TimeoutError = AGUITimeoutError: Deprecated alias for AGUITimeoutError.

Exceptions / Errors

AGUIError: Base exception for AG-UI protocol errors.
AgUiError: Base class for runtime / transport / decoding AG-UI errors.
AGUITimeoutError: Error when operation times out.
AGUIValidationError: Represents a validation error during JSON decoding.
CancellationError: Error when operation is cancelled
DecodeError: Error thrown when decoding fails.
DecodingError: Error decoding JSON or event data
EncodeError: Error thrown when encoding fails.
EncoderError: Base error for encoder/decoder operations.
ProtocolViolationError: Error when protocol rules are violated
ServerError: Server-side application error
TransportError: Error during HTTP/SSE transport operations
ValidationError: Error validating input or output data.

ag_ui library

Features

Getting Started

Classes

Enums

Mixins

Constants

Functions

Typedefs

Exceptions / Errors

ag_ui package

ag_ui library