Shell snapshot captures set -o onecmd — breaks shell after one command (recurring)

Bug Description

Shell snapshots at ~/.claude/shell-snapshots/snapshot-bash-*.sh incorrectly capture set -o onecmd. When Claude Code loads these snapshots, bash exits after executing a single command, breaking all subsequent operations.

Evidence

• set -o onecmd is NOT present in ~/.bashrc, ~/.bash_profile, or /etc/profile
• Running set -o | grep onecmd shows onecmd off
• Despite this, Claude Code snapshots contain set -o onecmd (observed at line 45)
• This has occurred 5 times over multiple months

Reproduction Pattern

1. Start Claude Code
2. Shell snapshot is created/loaded
3. Snapshot contains set -o onecmd
4. Shell breaks (exits after one command)
5. Workaround: delete corrupted snapshots (rm -f ~/.claude/shell-snapshots/*.sh)
6. Next session: new snapshot created with the same bug

Proposed Fix

Add a blocklist to the snapshot capture logic to filter out destructive shell options:

onecmd    — exits shell after one command
errexit   — exits on any error
nounset   — exits on undefined variable
pipefail  — changes pipeline error handling

These options should never be persisted in snapshots as they fundamentally change shell behavior in destructive ways.

Environment

• OS: macOS (Darwin)
• Shell: bash 3.2.57
• Claude Code: installed via Homebrew