This pattern deploys a real-time streaming chat service using AWS AppSync Events with a two-phase Lambda architecture to invoke a Strands agent running on Amazon Bedrock AgentCore Runtime.

The client publishes messages to an inbound channel via HTTP. AppSync Events triggers an agent invoker Lambda via direct Lambda integration (synchronous only), which asynchronously invokes a separate stream relay Lambda function, then returns immediately. Two Lambda functions are needed because AppSync Events requires a synchronous function invocation, so the invoker must return quickly. The stream relay calls the AgentCore Runtime, consumes the Server-Sent Events (SSE) stream, and publishes response chunks back to a separate response channel.

The client receives agent response tokens in real time via a WebSocket subscription. Separate channel namespaces for inbound and outbound traffic prevent re-invocation loops.