[BUG] /plugin command not recognized in v2.1.19 on macOS (regression from v2.1.18)

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 /plugin command is not recognized in Claude Code v2.1.19. When typing /plugin, it does not appear in the autocomplete menu, and pressing Enter shows "Defaulting" followed by a tip about creating skills.

This is a regression - the command worked on January 24, 2026 but stopped working on January 25, 2026.

What Should Happen?

According to the official documentation, the /plugin command should:

• Open the plugin manager with tabs for Discover, Installed, Marketplaces, and Errors
• Support subcommands like /plugin marketplace add, /plugin install, etc.

The documentation states: "If you don't see the /plugin command, update Claude Code to the latest version" - but v2.1.19 should definitely have this command (it was added in v1.0.33).

Error Messages/Logs

No error message - the command simply doesn't appear in autocomplete. When typing /plugin and pressing Enter:

• Shows "Defaulting" message
• Displays tip: "Create skills by making .md files to ./claude/skills/ in your project or ~/.claude/skills/ for skills that work in any project"

Steps to Reproduce

1. Install/update to Claude Code v2.1.19 on macOS
2. Launch Claude Code
3. Type /plugin
4. Observe: command does not appear in autocomplete dropdown
5. Press Enter
6. Observe: "Defaulting" message instead of plugin manager

Claude Model

Opus 4.5

Is this a regression?

Yes - the /plugin command worked on January 24, 2026 but not on January 25, 2026.

Last Working Version

v2.1.18 or earlier (worked on Jan 24, 2026)

Claude Code Version

2.1.19 (Claude Code)

Platform

Claude Max

Operating System

macOS 14.4 (Sonoma)

Terminal/Shell

Apple Terminal / iTerm2

Additional Information

• Installation method: Native binary (Claude Max subscription)
• Related issues: #16756, #9254 (similar issues on Windows, closed as duplicates)
• The autocomplete shows other commands like /init, /push-product, /claude-developer-docs, /docetl, /prd but NOT /plugin
• User has video evidence of the issue (screen recording showing the missing command)