Fix #3267: everything sever response with an extra empty SSE event caus#3376
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danielalanbates wants to merge 1 commit intomodelcontextprotocol:mainfrom
Open
Fix #3267: everything sever response with an extra empty SSE event caus#3376danielalanbates wants to merge 1 commit intomodelcontextprotocol:mainfrom
danielalanbates wants to merge 1 commit intomodelcontextprotocol:mainfrom
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… work around empty SSE event parsing issues When connecting with protocol version 2025-11-25+, the everything server sends an empty SSE priming event as required by SEP-1699 for resumability support. However, some clients (like the Java MCP client) don't properly handle empty SSE data events per the SSE specification, causing deserialization failures. This commit adds a DISABLE_SSE_RESUMABILITY environment variable that allows users to disable the eventStore, preventing the priming event from being sent. This is a workaround for clients that don't properly handle empty SSE events. Users can now disable resumability with: DISABLE_SSE_RESUMABILITY=true npx @modelcontextprotocol/server-everything streamableHttp Changes: - Modified streamableHttp.ts to check DISABLE_SSE_RESUMABILITY env var - Only create eventStore if resumability is enabled - Updated README.md with documentation and usage examples The proper fix is still to update affected clients to handle empty SSE events correctly per the SSE standard.
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Fixes #3267
Summary
This PR fixes: everything sever response with an extra empty SSE event causing the java mcp client to fail deserialization
Changes
Testing
Please review the changes carefully. The fix was verified against the existing test suite.
This PR was created with the assistance of Claude Haiku 4.5 by Anthropic | effort: low. Happy to make any adjustments!
By submitting this pull request, I confirm that my contribution is made under the terms of the project's license (contributor license agreement).