Fix "Missing session ID" by making the MCP transport stateless - #161
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Cloud Run logs (after the 421 fix deployed) showed several container instances each starting their own independent StreamableHTTP session manager -- confirms the default session manager's in-memory, per-instance session tracking doesn't survive a follow-up request landing on a different instance than the one that created the session (maxScale=15, no session affinity configured). Both tools (get_day, search_saints) are stateless reads with no need for server-side session state in the first place, so stateless_http=True is the correct fix rather than trying to force session affinity: it makes every request self-contained instead. Verified locally: a tools/call with no prior initialize on the connection and no session ID at all now succeeds. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Hf6j2xXQXywHVh3HAVRxB3
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Summary
/mcpstarted returning "Bad Request: Missing session ID."StreamableHTTP session managerin short succession -- confirms the SDK's default session manager tracks each session's transport in that process's own memory, but this service scales to multiple instances (maxScale=15, no session affinity configured), with no guarantee a session's follow-up request lands back on the instance that created it.get_day,search_saints) are stateless reads with no need for server-side session state in the first place, sostateless_http=Trueis the correct fix rather than trying to force session affinity: it makes every request self-contained instead.Test plan
docker compose run --rm tests— 135/135 passingtools/callwith no priorinitializeon the connection and no session ID at all now succeeds (200 OK, correct data) -- confirms statelessness, not just that the old flow still happens to work🤖 Generated with Claude Code
https://claude.ai/code/session_01Hf6j2xXQXywHVh3HAVRxB3