Plugin safety: third-party plugins can silently disable auto_memory via env vars

Summary

A third-party plugin (claude-mem by thedotmack) silently disables Claude Code's built-in auto_memory system during installation by writing CLAUDE_CODE_DISABLE_AUTO_MEMORY=1 to ~/.claude/settings.json env block. There is no user confirmation, no warning, and no protection against this.

This caused a power user with 75+ accumulated memory files to experience complete apparent memory loss on their next session.

The Problem

1. CLAUDE_CODE_DISABLE_AUTO_MEMORY is an official env var toggle (per #23544)
2. Any plugin installer can write to ~/.claude/settings.json freely
3. There is no mechanism to:

• Warn users when a plugin modifies core behavior settings
• Require user consent before disabling built-in features
• Sandbox plugin installers from modifying global settings
• Show what settings changed after plugin installation

What Happened

• User had 75 memory files (user profile, 25+ behavioral rules, 20+ active projects) in memory/MEMORY.md
• Installed claude-mem plugin
• Plugin's install.ts → disableClaudeAutoMemory() wrote CLAUDE_CODE_DISABLE_AUTO_MEMORY=1
• Next session: Claude had zero memory, didn't recognize the user
• Memory files were intact on disk but not loaded
• User spent ~30 minutes diagnosing what appeared to be catastrophic data loss

Suggestion

1. Protected settings: Core behavior toggles like auto_memory should require explicit user action (e.g. claude config set auto_memory false), not be silently writable by plugin installers
2. Settings change audit: After plugin installation, show a diff of what changed in settings.json
3. Plugin manifest declarations: Require plugins to declare in their manifest what settings they modify, and surface this to users before installation
4. Sandboxing: Plugin installers should not have unrestricted write access to ~/.claude/settings.json

Environment

• Claude Code: latest (Opus 4.6)
• Plugin: claude-mem v13.4.0 (thedotmack)
• OS: Windows 11
• Related issue on plugin repo: https://github.com/thedotmack/claude-mem/issues/2836

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Reported via Claude Code session 2026-06-08.