Conversation
Treat session-era initialize requests as legacy based on params.protocolVersion even when optional request metadata is present. This prevents MCP Python SDK 2.x initialization from being rejected as modern traffic. Signed-off-by: lucarlig <luca.carlig@ibm.com>
lucarlig
marked this pull request as ready for review
September 18, 2026 17:48
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Summary
initializerequests fromparams.protocolVersionbefore the harness's modern-era routingRequestParams._meta, including the empty metadata object emitted by MCP Python SDK 2.xThis is the harness-side fix for the failure seen in IBM/mcp-context-forge#6868. The same root fix is proposed upstream in modelcontextprotocol/conformance#507; keeping it in the pinned fixture patch unblocks ContextForge without waiting for a new upstream conformance release.
Validation
docker/mcp-conformance-server.Dockerfilefrom the pinned alpha.11 revisionlegacymode and received HTTP 200 plusMcp-Session-Idfor aninitializerequest containing_meta: {}cargo test --locked(431 tests)git diff --check