[BUG] claude process leaks to 74 GB virtual memory, causing full system OOM freeze

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?

Version: 2.1.128
OS: Ubuntu 24.04, kernel 6.8.0-111-generic
RAM: 32 GB | Swap: 2 GB (swapfile)

## Description

The claude binary repeatedly grew to ~74 GB of virtual memory during normal use, eventually exhausting all RAM and swap. The system became completely unresponsive (no TTY switching)

Mai 05 16:54:02 kernel: Out of memory: Killed process 7595 (claude)
total-vm:74471564kB, anon-rss:163596kB

At time of kill:

• Free swap: 116 KB of 2 GB total
• Free RAM pages: ~197 MB

## Likely contributing factor: Codex plugin session loop

~/.claude/session-env/ contained 6,205 session directories, with 3,279
created on the day of the freeze — roughly one every 26 seconds. Each
directory is created by the Codex companion plugin's startup hook:

```sh
export CODEX_COMPANION_SESSION_ID='<uuid>'
export CLAUDE_PLUGIN_DATA='/home/laroy/.claude/plugins/data/codex-openai-codex'

This abnormal session-creation rate (codex-openai-codex plugin firing a
sessionstart hook in a loop) is likely feeding the memory growth in the
main claude process.

Active MCP servers at time of freeze

• contextpool (cxp 0.1.18, stdio) — 4.4 MB RSS, not the cause
• jina-ai (HTTP)
• Codex companion plugin

Impact

Complete system freeze, no interactive recovery possible. Required hard reboot.
Occurred multiple times in one day.

Workaround applied

• Installed earlyoom
• Cleaned up session-env directory (6,205 → 3,279 entries)

What Should Happen?

The claude process should maintain a stable memory footprint during normal use
and release memory after operations complete. It should not grow unbounded
regardless of session length or number of MCP/plugin calls. The Codex companion
plugin's sessionstart hook should fire once per session, not repeatedly in a loop.

Error Messages/Logs

Steps to Reproduce

. Install Claude Code 2.1.128 on Ubuntu 24.04 (32 GB RAM, 2 GB swap).

1. Install and enable the Codex companion plugin (codex-openai-codex).
2. Configure MCP servers: contextpool (cxp 0.1.18, stdio) and jina-ai (HTTP).
3. Use Claude Code normally across multiple sessions over several hours.
4. Observe ~/.claude/session-env/ accumulating thousands of directories

(3,279 in a single day), each containing a Codex sessionstart hook script.

1. Monitor claude process virtual memory — it grows unbounded over time.
2. System eventually exhausts RAM and swap; OOM killer fires and the system

freezes completely.

Note: Exact trigger for the session loop is unknown. The sessionstart hook
fires far more frequently than actual user-initiated sessions, suggesting the
Codex plugin is re-triggering it internally.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.128

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_