typescript-sdk/.changeset/bound-resumability-version-gates.md

@modelcontextprotocol/server
patch

Bound the protocol-version checks gating SSE resumability behavior (priming events and closeSSEStream callbacks) in the Streamable HTTP server transport. Previously an open-ended >= '2025-11-25' comparison let unknown future protocol version strings from an initialize request body enable this behavior; the version must now also be one of the transport's supported protocol versions. Behavior for all currently supported protocol versions is unchanged.