LangGraph4j AG-UI Spring Boot

Spring Boot web and SSE integration for langgraph4j-ag-ui-sdk.

Classes overview

AGUISSEController

Spring Boot @Controller exposing a POST /sse/{agentId} Server-Sent Events endpoint compliant with the AG-UI protocol. It resolves the target AGUIAgent from an injected AGUIAgentRegistry, deserializes the request body into an AGUIRunAgentInput, starts the agent run and streams back every produced AG-UI Event as an SSE message, completing the connection when the run finishes or fails.

Sample: reference implementations (test sources)

The test sources of this module provide a runnable, end-to-end reference implementation showing how to expose a LangGraph4j AgentExecutor (built with spring-ai) as an AG-UI agent, supporting both the CopilotKit HITL (Human-In-The-Loop) approval flow and a custom interruption flow based on the AG-UI Interrupt/Resume model.

AGUIApplication

The Spring Boot application entry point. It wires the AGUIJacksonSerializer bean and an AGUIAgentRegistry bean registering the two reference agents below (AGUIAgentExecutorINTERRUPT under id "INTERRUPT", AGUIAgentExecutorHITL under id "HITL"), so they are both served through AGUISSEController.

AGUIAgentExecutorHITL

AGUIAgentBase implementation showing the CopilotKit HITL pattern: it builds an AgentExecutorEx graph with an approvalOn("sendEmail", ...) interruptionn point, and, when the graph interrupts, overrides onCompleteEvents(...) to emit the pending tool call together with a StateDeltaEvent that flips a resume flag in the shared state (the convention expected by CopilotKit's HITL UI). On the next run, graphInput(...) detects that resume flag in the incoming state to resume the graph with the user's approval decision.

AGUIAgentExecutorINTERRUPT

AGUIAgentBase implementation showing a custom interruption pattern based on AG-UI's native Interrupt/Resume messages: on interruption, it overrides onCompleteEvents(...) to emit an InterruptOutcome (via RunFinishedEvent) carrying one AG-UI Interrupt per pending tool call; graphInput(...) resumes the graph by reading the approval result from the resume payload of the incoming RunAgentInput, without relying on any extra state flag.