[BUG] Skills with prefix name relationships - shorter name not loaded

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?

Summary

When two skills exist where one skill's name is a prefix of another's name, the shorter-named skill is not loaded into the available skills list.

Evidence

This is affecting real skills:

• using-jj (missing) and using-jj-workspaces (present)

Both skills have identical directory structure, valid frontmatter, and correct permissions. The only commonality is the prefix relationship.

What Should Happen?

Expected Behavior

Both test-prefix and test-prefix-extended appear in the available skills list.

Actual Behavior

Only test-prefix-extended appears. test-prefix is missing.

Error Messages/Logs

Steps to Reproduce

Reproduction Steps

1. Create two skills with a prefix relationship:

~/.claude/skills/
├── test-prefix/SKILL.md
└── test-prefix-extended/SKILL.md

1. test-prefix/SKILL.md:

---
name: test-prefix
description: Test skill for reproducing prefix bug - the shorter name
---

# Test Prefix Skill
This is the shorter-named skill.

1. test-prefix-extended/SKILL.md:

---
name: test-prefix-extended
description: Test skill for reproducing prefix bug - the longer name
---

# Test Prefix Extended Skill
This is the longer-named skill.

1. Start a new Claude Code session
2. Check available skills list

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.7 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

• Invoking the missing skill directly with the Skill tool does work - the skill loads and executes correctly
• The issue is specifically with the skill discovery/listing at session start
• Workaround: rename skills to avoid prefix relationships (e.g., jj-basics instead of using-jj)