Add McpClientOptions.InitializeMeta to set _meta on the initialize request#1599
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adityasingh2400 wants to merge 1 commit into
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Add McpClientOptions.InitializeMeta to set _meta on the initialize request#1599adityasingh2400 wants to merge 1 commit into
adityasingh2400 wants to merge 1 commit into
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InitializeRequestParams already inherits Meta (_meta) from RequestParams, but McpClientImpl.ConnectAsync built the params without reading from McpClientOptions, so callers had no way to populate it. Add an InitializeMeta property on McpClientOptions and thread it through the handshake. Fixes modelcontextprotocol#1593
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Fixes #1593.
Problem
InitializeRequestParamsinheritsMeta([JsonPropertyName("_meta")]) fromRequestParams, in line with the 2025-11-25 schema, butMcpClientImpl.ConnectAsyncconstructs the params without reading fromMcpClientOptions. So the type supports_metaoninitializewhile the public client API offers no way to populate it. The current workaround is a customIClientTransportthat writes out-of-band data before the handshake, which couples the mechanism to the transport layer the SDK is meant to abstract.Fix
Add an
InitializeMetaproperty toMcpClientOptionsand pass it asMetawhen building theInitializeRequestParams. The protocol layer already models the field, so this is options-to-params plumbing only. WhenInitializeMetais null, no_metais sent, so existing behavior is unchanged.Testing
Added two tests to
McpClientMetaTeststhat use a server-side incoming message filter to capture theinitializerequest:InitializeMeta_IsSentToServer_WhenSetasserts the value set onMcpClientOptionsarrives in the server'sinitialize_meta.InitializeMeta_IsOmitted_WhenNotSetasserts no_metais sent by default.dotnet buildofModelContextProtocol.Coreis clean (warnings-as-errors). The fullMcpClientMetaTestsclass passes (5/5) on net10.0.