[BUG] /permissions UI accepts and hides invalid permission entries without validation

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?

The /permissions UI (Add a new rule) accepts permission entries that lack the required tool wrapper (e.g., say * instead of Bash(say *)). It writes them to settings.json without any validation or warning. Then, when viewing permissions again via /permissions, the invalid entry is silently hidden -- it does not appear in the list.

This creates a confusing situation where:

1. User adds a permission rule via the UI
2. The rule appears to be accepted (no error)
3. The rule is written to settings.json
4. The permission does not actually work (tool still prompts for approval)
5. Going back to /permissions shows no trace of the entry
6. The only way to discover the orphaned entry is to manually inspect settings.json

What Should Happen?

Either:

• Validate on input: Reject entries without a valid tool wrapper, or auto-complete/suggest the correct format (e.g., prompt the user to wrap say * as Bash(say *))
• Display invalid entries: Show all entries from the file in the /permissions UI, even if invalid, with a warning indicator so the user can fix or remove them

Error Messages/Logs

No error messages are shown -- that is the problem. The entry is silently accepted and silently hidden.

Steps to Reproduce

1. Run /permissions then Add a new rule then Allow
2. Type say * (without the Bash() wrapper)
3. Entry is accepted, written to settings.json
4. Ask Claude to run say "hello" -- it still prompts for permission
5. Run /permissions again -- the say * entry is not visible in the list
6. Open settings.json manually -- "say *" is there in the allow array

Claude Model

Opus

Is this a regression?

I don't know

Claude Code Version

Claude Code 2.1.50

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

iTerm2

Additional Information

Related but distinct from #27686 (which is about the UI mangling valid input). This issue is specifically about:

1. No input validation when adding permission rules via /permissions
2. Invalid entries being silently hidden from the UI on subsequent views