typescript-sdk/.changeset/no-cancel-notification-for-initialize.md

@modelcontextprotocol/core-internal	@modelcontextprotocol/client	@modelcontextprotocol/server
patch	patch	patch

Stop sending notifications/cancelled for the initialize handshake. The spec is explicit that a client MUST NOT attempt to cancel its initialize request, but the outbound cancel path fired for any in-flight request: aborting the AbortSignal passed to connect(), or letting the handshake hit its timeout, put a forbidden cancellation on the wire naming the initialize request id.

The local behaviour is unchanged — the caller's promise still rejects with the same abort/timeout error, and connect() still tears the connection down. Only the wire notification is suppressed. Every other method keeps the existing cancellation path.