Open an MCP server-to-client SSE stream

GET 
/v1/mcp

Legacy-era only (2025-11-25 and earlier). Open a long-lived server-to-client SSE stream for an MCP session created via POST /v1/mcp. 2026-07-28 clients do not use GET; they POST subscriptions/listen instead. The Mcp-Session-Id header must identify an existing legacy session.

Request

Responses

200

SSE stream (text/event-stream) of server-originated MCP messages.

401

Unauthorized. The /v1/mcp endpoint requires runtime.auth to be configured. Configure an API key provider in your Spicepod and retry with credentials.

403

Forbidden. The Host header value is not in the runtime.mcp.allowed_hosts list, or the Origin header is not in runtime.cors.allowed_origins. Host ["*"] disables the Host check. Origin ["*"] expands to localhost defaults — it does not accept every Origin.

404

Unknown or expired Mcp-Session-Id.