AgentCoreRuntimeHost exposes the AgentCore Runtime-shaped endpoints:

• POST /invocations accepts exactly one of { "prompt": "..." } or { "content": <Core-serialized MultimodalContent> }; input remains an ingress-only compatibility alias for older TPipe-AgentCore callers.
• GET /ping returns a health response with the last update timestamp.
• GET /ws accepts the same invocation objects over WebSocket.
• stream: true on /invocations returns chunk, final, and error SSE events. WebSocket streaming uses the same JSON event objects.

Successful responses use { "output": <Core-serialized MultimodalContent> }. Errors use type, errorType, message, and retryable. Runtime session correlation is carried by x-amzn-bedrock-agentcore-runtime-session-id, not by the canonical request body.

The host maps input to the existing P2PRequest and maps the output back to the existing P2PResponse shape. It does not change Core’s Transport enum.

The default ISOLATED mode creates one TPipe root per session id. A per-session mutex serializes requests for that root, while different session mutexes allow concurrency. SHARED is available for applications that intentionally want a single root, but it should be selected only when cross-session state sharing is acceptable.

AgentCoreRuntimeAgent is the inverse adapter: it implements generic P2PInterface and invokes an external Runtime endpoint. AgentCoreHarnessAgent uses the same P2P boundary for an external Harness worker.