[BUG] Multiple active CRONs kill telegram inbound messages

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?

Title: CronCreate degrades and breaks Telegram MCP inbound message handling after ~5
active crons

Description:

Summary

Creating multiple recurring crons progressively degrades and eventually kills
inbound MCP message handling (tested with the Telegram MCP plugin). Outbound
MCP calls continue to work.

Additional testing

• Creating all 7 crons in parallel (single message, 7 CronCreate calls) breaks

inbound immediately

• Creating crons sequentially delays the breakage but hits the same wall at ~5
• The issue appears to be total active cron count, not parallelism

Environment

• macOS (Darwin 25.3.0)
• MCP plugin: Telegram
• Model: Claude Opus 4.6

What Should Happen?

Claude Code should support many cron sessions without degrading telegram MCP performance

Error Messages/Logs

Steps to Reproduce

Reproduction

Start a session with an MCP plugin that receives inbound messages (e.g.,
Telegram)
Confirm inbound works
Create recurring crons one at a time, testing inbound between each
Observed behavior

Crons 1–4: Inbound works immediately
After cron 4: Inbound degrades (~30s delay)
After cron 5: Inbound stops entirely
Outbound: Continues working at all cron counts
Deleting crons does not restore inbound — requires a new session

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.97

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

iTerm2

Additional Information

_No response_