enableStateless property
Opt-in for the 2026-07-28 stateless core (SEP-2577). Default false:
2026-07-28 is neither served nor advertised, and a request carrying
MCP-Protocol-Version: 2026-07-28 is rejected with an
UnsupportedProtocolVersionError (JSON-RPC -32022, HTTP 400) — so
there is ZERO behavior change from prior deployments.
When true, a POST carrying MCP-Protocol-Version: 2026-07-28 AND no
Mcp-Session-Id is routed down the stateless branch: no session is
created, client info/caps are read from the per-request _meta, and
server/discover is served. Legacy handshake requests (and any request
that carries a session id) keep the existing path unchanged, so one
endpoint answers both revisions (matches the spec's own SDK approach:
Go StreamableHTTPOptions.Stateless, Python "answers both revisions").
Implementation
final bool enableStateless;