Streamable HTTP client transport for MCP.

Sends JSON-RPC messages via HTTP POST and receives responses as either application/json or text/event-stream (SSE). Optionally opens a GET SSE stream for server-initiated messages.

Options

• :owner (required) — pid to receive {:mcp_message, map} and {:mcp_transport_closed, reason} messages
• :url (required) — the MCP endpoint URL (e.g., "http://localhost:8080/mcp")
• :headers — extra HTTP headers to include on all requests
• :protocol_version — MCP protocol version (default: "2025-11-25")

Session Management

The client automatically extracts the MCP-Session-Id header from the server's initialize response and includes it in all subsequent requests. On close, it sends an HTTP DELETE to terminate the session.