//! Caller-supplied additional MCP server for an agent-completion run.
//!
//! `extra_mcp_servers` lets a caller attach extra MCP upstreams onto a
//! single `create_streaming` call without baking those URLs into the
//! agent's own content-hashed configuration. Each entry pairs a URL with an
//! optional per-server header set; both flow through to the proxy as
//! one URL in `X-MCP-Servers` and one entry in `X-MCP-Headers`'s
//! per-URL header map (merged on top of any orchestrator-wide
//! `extra_mcp_headers`, with the per-server values winning on conflict).
use IndexMap;
/// One extra MCP upstream to attach to an agent-completion request.