[BUG] Plugin skill tab completion: short name completes but qualified name is not discoverable

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?

When a plugin provides a skill (e.g., dev-tools:tfs-query), tab completion only works on the short name (/tfs-query), but after pressing Enter, it displays the fully qualified name (/dev-tools:tfs-query). The qualified name itself has no tab completion at all.

This creates three UX problems:

1. What you type doesn't match what executes. Typing /tfs-query + Enter shows /dev-tools:tfs-query in output — a "what just happened?" moment.
2. The qualified name is not discoverable. Typing /dev-tools yields no tab completions, so there's no way to discover skills by plugin prefix.
3. You can't reuse the displayed name. If a user copies the executed name /dev-tools:tfs-query and tries to type it next time, tab completion won't help — they have to remember to use the short name instead.

There is no path where the typed name matches the displayed name, which makes this confusing to explain to developers being onboarded to plugins.

Related: #17271 (plugin skills not visible in / command list at all)

What Should Happen?

At minimum, one of:

• Tab completion should also index on the plugin prefix (typing /dev-tools: should complete to available skills in that plugin)
• The displayed/executed name should match what was typed (if the short name is unambiguous, display the short name)

Ideally both.

Steps to Reproduce

1. Install a plugin that provides a skill (e.g., a plugin named dev-tools with a skill tfs-query)
2. Type /tfs and press Tab — completes to /tfs-query ✓
3. Press Enter — displays as /dev-tools:tfs-query (name mismatch)
4. Type /dev-tools: and press Tab — no completions offered
5. Type /dev-tools:tfs-query manually — no tab completion available at any point

Claude Model

Opus

Is this a regression?

I don't know

Claude Code Version

2.1.92

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

zsh (Ghostty)