yaak-mountain-loop/MCP_CLIENT_PLAN.md

MCP Client Plan

Goal

Add an MCP client mode to Yaak so users can connect to and debug MCP servers.

Core Design

• Protocol layer: Implement JSON‑RPC framing, message IDs, and notifications as the common core.
• Transport interface: Define an async trait with connect, send, receive, and close methods.
• Transports:
  • Start with Standard I/O for local development.
  • Reuse the existing HTTP stack for HTTP streaming next.
  • Leave hooks for WebSocket support later.

Integration

• Register MCP as a new request type alongside REST, GraphQL, gRPC, and WebSocket.
• Allow per‑request transport selection (stdio or HTTP).
• Map inbound messages into a new MCP response model that feeds existing timeline and debug views.

Testing and Dog‑fooding

• Convert Yaak's own MCP server to Standard I/O for local testing.
• Use it internally to validate protocol behavior and message flow.
• Add unit and integration tests for JSON‑RPC messaging and transport abstractions.

Future Refinements

• Add WebSocket transport support once core paths are stable.
• Extend timelines for protocol‑level visualization layered over raw transport events.
• Implement version and capability negotiation between client and server.