[FEATURE] Allow custom slash commands to invoke built-in CLI commands specifically /rename

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

Custom slash commands cannot programmatically invoke built-in CLI commands like /rename.

When a custom command instructs Claude to "Run /rename <name>", Claude cannot execute it because:

• The Skill tool only works for user-defined prompt-based skills
• Built-in CLI commands are not accessible to Claude during command execution

Proposed Solution

Allow slash commands to invoke the rename commands:

Example

---
description: Generate handoff prompt
allowed-tools: Bash(git:*), rename
---

# Handoff
1. Generate descriptive session name
2. Run `/rename <name>`  <!-- This should actually execute -->
3. Generate handoff prompt

Alternative Solutions

Current workaround: My /handoff command outputs a suggested /rename command for me to copy/paste manually - but this defeats the purpose of automation.

Priority

Low - Nice to have

Feature Category

CLI commands and flags

Use Case Example

I have a /handoff command that generates a session summary before ending work. I want it to automatically rename the session based on what was accomplished, so I can easily find it later.

Additional Context

_No response_