fix(server): prevent stdio transport from closing original stdio handles#2424
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goingforstudying-ctrl wants to merge 1 commit intomodelcontextprotocol:mainfrom
Open
fix(server): prevent stdio transport from closing original stdio handles#2424goingforstudying-ctrl wants to merge 1 commit intomodelcontextprotocol:mainfrom
goingforstudying-ctrl wants to merge 1 commit intomodelcontextprotocol:mainfrom
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When using transport='stdio', the stdio_server context manager wraps sys.stdin.buffer and sys.stdout.buffer in TextIOWrapper. When these wrappers are closed (either explicitly or when exiting the context), they also close the underlying buffers, causing subsequent stdio operations to fail with ValueError. This fix duplicates the file descriptors before wrapping them, so that the original stdin/stdout remain open after the transport is closed. Fixes modelcontextprotocol#1933
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Description
When using , the context manager wraps and in . When these wrappers are closed (either explicitly or when exiting the context), they also close the underlying buffers, causing subsequent stdio operations to fail with .
Changes
This PR duplicates the file descriptors before wrapping them using , so that the original stdin/stdout remain open after the transport is closed.
Before (problem):
After (fixed):
Technical Details
Fixes #1933
/cc @maintainers