feat(client)!: support stateful streamable-HTTP servers - #18
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mcpInitialize now sends notifications/initialized and returns an McpSession whose Mcp-Session-Id and MCP-Protocol-Version later requests carry. Discovery, mcpTools and the sidecar bundle pass it on, and reopen it after a failed call. A protocolVersion that is not printable ASCII is refused before it is echoed into a header, and a timed-out notification is an McpError. Non-JSON data frames are skipped, and only a message with result or error and no method counts as the response. e2e covers the official SDK's stateless and stateful server transports; the SDK is a devDependency only. BREAKING CHANGE: mcpInitialize returns McpSession instead of McpServerInfo.
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The client ignored
Mcp-Session-Idand never sentnotifications/initializedorMCP-Protocol-Version. Against the official SDK's stateful transport,initializeworked buttools/listand every sidecartools/callfailed with a 400. A non-JSONdata:frame threw a rawSyntaxError, and a server request reusing our id was taken as the response.Changes
mcpInitializesendsinitialize, thennotifications/initialized, and returns anMcpSession(protocolVersion,sessionId?,serverInfo?).McpClientOptions.sessionsendsMcp-Session-IdandMCP-Protocol-Versionon later requests.McpSessionis exported.mcpToolsand the sidecar bundle carry the session totools/listandtools/call.mcpToolsand the bundle open one session per server on first use and reopen it after a failed call, in case the server expired it. The discovery route'sserverInforesponse is unchanged.mcpInitializerefuses a serverprotocolVersionthat is not printable ASCII before echoing it intoMCP-Protocol-Version, and a timed-outnotifications/initializedis anMcpError. Both are tested and fail before the fix.data:frames are skipped. Only a message withresultorerrorand nomethodcounts as the response, for both SSE and JSON bodies.e2e/sdk-transport.test.tsruns discovery, the sidecar bundle andmcpToolsagainst@modelcontextprotocol/sdk's stateless and stateful streamable-HTTP server transports. The stateful cases fail before the fix. The SDK andzodare devDependencies only. Newtest:e2escript, run in CI.mcpInitializereturn type.Breaking
Yes, marked
!:mcpInitializereturnsMcpSessioninstead ofMcpServerInfo. It is part of the pending 0.2.0 release, so there is no extra version bump.Checks
bun run check,bun run test:e2e,bun run buildand the Node pack smoke pass locally.Closes CL-9454