[BUG] Initialization delay causes resources/list and prompts/list timeout

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

A delay in notifications/initialized request handling causes successful initialization, but following resources/list and prompts/list requests are getting notifications/cancelled with McpError: MCP error -32001: Request timed out, even if they respond instantly. tools/list is not affected.

What Should Happen?

Either initialization should fail, or the following processing should work fine.

Error Messages/Logs

Steps to Reproduce

1. Create a remote MCP server, that

• Has 3s delay before sending 202 response to notifications/initialized
• Responds to */list instantly

1. Configure it as a custom connector in Claude Desktop / claude.ai
2. Try to connect

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude 0.13.37 (bfd4ed) 2025-09-24T22:18:50.000Z

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_