Now I have the full picture. Here's my analysis:

What 2.1.81 is: Claude Code v2.1.81. You had 5 Claude Code instances running at shutdown time.

Shutdown timeline:

• 01:36:33 — Force shutdown initiated
• 01:36:36 — Shutdown stall captured (162 processes still running, 21 of them Python)
• 01:37:11 — System booted

Process tree at shutdown:

Normal Claude Code MCP servers (2 instances):

Claude Code [82193] → python3.13 [88842] → node [88854] (416MB)
Claude Code [35621] → python3.13 [45088] → node [45091] (228MB)

These are MCP server bridges — Python wraps a Node.js MCP server. Normal behavior.

A uv run chain:

zsh → uv [74172] (deadlocked) → python3.13 [74174] (running a .py file)
→ python3.13 [74180] (python -c "...", reading pipe)
→ python3.13 [86263] (running .py file, sleeping + os.stat)
→ python3.13 [86264] (python -c "...", reading pipe)

14 orphaned python -c processes (two batches of 7):

• PIDs 89759-89765 (~38 hours old)
• PIDs 67956-67962 (different age)
• All running _PyRun_SimpleStringFlagsWithName — this is python -c "exec(base64.b64decode(...))"
• All orphaned (parent died, reparented to launchd)
• All stuck reading from a dead pipe

What likely happened:

The exec(base64.b64decode('...')) pattern is not malware — it's how Python tooling (including Claude Code's Bash tool) passes code snippets to python -c while avoiding shell escaping issues. The base64 encoding is just a safe transport mechanism.

The 11k process storm was likely a runaway spawning loop from one of these sources:

1. A Claude Code tool/agent interaction that got stuck in a loop spawning python -c processes
2. A uv run script (the 74174 chain) that had a subprocess spawning bug

Good news:

• No persistence mechanisms found — no suspicious crontabs, launch agents, or launchd jobs
• No suspicious Python processes running now — clean after reboot
• All processes used your local uv Python — nothing from unknown paths
• No malicious indicators — all parents trace back to Claude Code, uv, or zsh

Recommendations:

1. Check if you had a Claude Code agent running in a loop before the incident
2. If it happens again, try killall python3.13 before force-shutting down
3. Consider setting a process limit: ulimit -u 2048 in your .zshrc to prevent fork bombs