Validate the HTTP MCP-Protocol-Version header for a request. Per the
2025-06-18 / 2025-11-25 transport ("Protocol Version Header"): if the header
is present but carries an invalid or unsupported version, the server MUST
respond with 400 Bad Request. Returns an UnsupportedProtocolVersionError
(-32004, which the transport maps to HTTP 400) in that case, else null.
An absent header is permitted: older clients omit it, and the request then
proceeds under the previously negotiated version.
Validate the HTTP MCP-Protocol-Version header for a request. Per the 2025-06-18 / 2025-11-25 transport ("Protocol Version Header"): if the header is present but carries an invalid or unsupported version, the server MUST respond with 400 Bad Request. Returns an UnsupportedProtocolVersionError (-32004, which the transport maps to HTTP 400) in that case, else null.
An absent header is permitted: older clients omit it, and the request then proceeds under the previously negotiated version.