[BUG] MCP connection failure session poisoning

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?

When an MCP connection fails, rather than handling it gracefully Claude Code seems to be poisoning sessions somehow, resulting in that session being unresumable after erroneously giving connection errors (when there are definitely no network problems).

What Should Happen?

CC should gracefully report MCP connection failures without poisoning sessions.

Error Messages/Logs

Steps to Reproduce

Have more than 3 local MCP servers active. Do a complex task under system load (not even high load) & the connection failure time is low enough on most default configurations for MCP servers to bring this bug out.

Claude Model

Not sure / Multiple models

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.5 (Claude Code)

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

_No response_