feat: expose negotiated protocol version on stdio transports#1660
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rechedev9 wants to merge 2 commits intomodelcontextprotocol:mainfrom
Open
feat: expose negotiated protocol version on stdio transports#1660rechedev9 wants to merge 2 commits intomodelcontextprotocol:mainfrom
rechedev9 wants to merge 2 commits intomodelcontextprotocol:mainfrom
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Add setProtocolVersion() method and protocolVersion getter to both StdioServerTransport and StdioClientTransport, so callers can inspect the MCP protocol version negotiated during the initialize handshake. - Client already calls transport.setProtocolVersion() after handshake, so StdioClientTransport now surfaces that value. - Server._oninitialize() now calls transport.setProtocolVersion?() so StdioServerTransport is populated on the server side as well. Closes modelcontextprotocol#1468
🦋 Changeset detectedLatest commit: 1c1cc4e The changes in this PR will be included in the next version bump. This PR includes changesets to release 5 packages
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Summary
Closes #1468
setProtocolVersion(version: string): voidandprotocolVersiongetter toStdioServerTransportandStdioClientTransportClientalready callstransport.setProtocolVersion()after the initialize handshake —StdioClientTransportnow stores and exposes that valueServer._oninitialize()now callstransport.setProtocolVersion?.()soStdioServerTransportis also populated after the handshake — matching behaviour for HTTP transportsPreviously the negotiated MCP protocol version was only observable on HTTP-based transports (where it is needed for request headers). After this change it is accessible on stdio transports too, which is useful for debugging clients/servers and for tools like mcpc.
Test plan
packages/server/test/server/stdio.test.ts— verifiesStdioServerTransport.protocolVersiongetterpackages/client/test/client/stdio.test.ts— verifiesStdioClientTransport.protocolVersiongettertest/integration/test/issues/test1468.stdio-protocol-version.test.ts— verifies that both client and server transports havesetProtocolVersioncalled withLATEST_PROTOCOL_VERSIONafter a full MCP handshakepnpm typecheck:allpassespnpm lint:fix:allpasses