Copilot CLI: Fix Initializing Connections#3618
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alexweininger
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Feb 10, 2026
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Pull request overview
Fixes Copilot CLI MCP session routing by aligning the MCP SDK session ID with the client-provided CLI session ID, so follow-up requests can reliably resolve the correct in-proc HTTP transport.
Changes:
- Use the client’s session ID as the MCP transport session ID (via
sessionIdGenerator) and register transports under that ID. - Reject duplicate
initializerequests for an already-connected session ID with an explicit conflict response.
rebornix
approved these changes
Feb 10, 2026
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Fix session ID mismatch in MCP transport registration. The transport was registered under the client's
x-copilot-session-id, but the MCP SDK generated a differentmcp-session-idviasessionIdGenerator. Follow-up requests using the SDK-assigned ID couldn't find the transport, causing"Bad Request: No valid session ID provided"errors. Fixed by using the client's session ID as the MCP session ID.Also, added code to not allow multiple clients to connect for the same CLI session ID.