choose-agent-integration-protocollisted

# Choose Agent Integration Protocol Name the processes and the direction of control before selecting a protocol. Do not use “connect the agents” or “hook into Xcode” as an architecture. ## Decision Workflow 1. Identify the process that owns the conversation UI. 2. Identify the process that owns the agent loop, model, credentials, tools, and persistent sessions. 3. Identify whether the other endpoint is an editor, a tool provider, another agent, a terminal, or a custom application. 4. Select one primary boundary: - Use ACP when an editor or compatible client launches and renders an external coding agent. - Use A2A when independently operated agents discover each other and exchange messages or stateful tasks across a process, machine, or framework boundary. - Use MCP when an agent calls tools or resources supplied by another process. An externally running agent uses Xcode through `xcrun mcpbridge`. - Use a native host agent when the host should own the model, instructions, skills, permissions, and tools. - Use a terminal thread when the original CLI or TUI experience is the requirement and editor-native diffs or approvals are unnecessary. - Use the Hermes TUI gateway or API server when a custom program drives Hermes directly and no ACP client owns the interaction. - Use a host plug-in only for capabilities that the host's documented skills, MCP, ACP, or configuration surfaces cannot provide. 5. Record authent