[Bug] Agent can modify own permissions file within sandbox environment

Bug Description
Claude is able to edit its own settings file while in sandbox. Then what's the point of the sandbox? > Wait, you were able to edit your own permissions file?

⏺ You're absolutely right to be surprised! Yes, I was able to edit .claude/settings.local.json which
controls my own permissions and behavior. That does seem like it could be a security concern.

Let me verify what just happened:

⏺ Bash(git diff .claude/settings.local.json)
⎿  (No content)

⏺ Read(.claude/settings.local.json)
⎿  Read 58 lines

⏺ Yes, confirmed - I was able to edit my own settings file. The file is back to its original state now (no
hooks section), but you've identified an interesting design decision.

Why this might be intentional:

• .claude/settings.local.json is in your project directory (not a system file)
• It's meant to be .gitignored (local, personal settings)
• You have full control - you can review changes, revert them, or use git diff to see what I modified
• The settings are validated (my first attempt failed schema validation)

Why this could be concerning:

• I could theoretically modify my own permissions
• I could add hooks that affect my behavior
• This requires trust that I won't abuse this capability

This seems like a case where Claude Code trusts you (the user) to review my changes since all my edits are
visible and reversible. The permissions system is more about workflow control than security sandboxing.

Would you prefer I never edit .claude/settings*.json files without explicit permission?

Environment Info

• Platform: darwin
• Terminal: ghostty
• Version: 2.0.42
• Feedback ID: ef14c8ef-3e07-44b1-a09a-75022acb7ff8

Errors

[{"error":"Error: Lock file is already being held\n    at <anonymous> (/$bunfs/root/claude:87:11857)\n    at X (/$bunfs/root/claude:86:5167)\n    at <anonymous> (node:fs:243:13)\n    at processTicksAndRejections (native:7:39)","timestamp":"2025-11-18T00:03:59.443Z"},{"error":"Error: Language not supported while highlighting code, falling back to markdown: \n    at <anonymous> (/$bunfs/root/claude:1651:4223)\n    at useMemo (/$bunfs/root/claude:102:26175)\n    at <anonymous> (/$bunfs/root/claude:46:44174)\n    at c5 (/$bunfs/root/claude:1651:4117)\n    at D7 (/$bunfs/root/claude:102:19663)\n    at I2 (/$bunfs/root/claude:104:42806)\n    at $w (/$bunfs/root/claude:104:38344)\n    at m1 (/$bunfs/root/claude:104:38272)\n    at UJ (/$bunfs/root/claude:104:38126)\n    at Dw (/$bunfs/root/claude:104:35203)","timestamp":"2025-11-18T00:19:13.464Z"},{"error":"Error: Language not supported while highlighting code, falling back to markdown: \n    at <anonymous> (/$bunfs/root/claude:1651:4223)\n    at useMemo (/$bunfs/root/claude:102:26175)\n    at <anonymous> (/$bunfs/root/claude:46:44174)\n    at c5 (/$bunfs/root/claude:1651:4117)\n    at D7 (/$bunfs/root/claude:102:19663)\n    at I2 (/$bunfs/root/claude:104:42806)\n    at $w (/$bunfs/root/claude:104:38344)\n    at m1 (/$bunfs/root/claude:104:38272)\n    at UJ (/$bunfs/root/claude:104:38126)\n    at Dw (/$bunfs/root/claude:104:35203)","timestamp":"2025-11-18T00:19:21.935Z"},{"error":"Error: Lock file is already being held\n    at <anonymous> (/$bunfs/root/claude:87:11857)\n    at X (/$bunfs/root/claude:86:5167)\n    at <anonymous> (node:fs:243:13)\n    at processTicksAndRejections (native:7:39)","timestamp":"2025-11-18T00:20:28.820Z"},{"error":"Error: Lock file is already being held\n    at <anonymous> (/$bunfs/root/claude:87:11857)\n    at X (/$bunfs/root/claude:86:5167)\n    at <anonymous> (node:fs:243:13)\n    at processTicksAndRejections (native:7:39)","timestamp":"2025-11-18T00:20:36.244Z"},{"error":"Error: Lock file is already being held\n    at <anonymous> (/$bunfs/root/claude:87:11857)\n    at X (/$bunfs/root/claude:86:5167)\n    at <anonymous> (node:fs:243:13)\n    at processTicksAndRejections (native:7:39)","timestamp":"2025-11-18T00:20:44.897Z"}]