Plugin skills appear twice in system prompt skill list

Description

Every plugin skill/command is enumerated twice in the system-reminder skill list injected into the system prompt. This doubles the context window cost of having plugins enabled.

Steps to Reproduce

1. Enable multiple plugins in ~/.claude/settings.json
2. Start a new Claude Code session
3. Observe the system-reminder that lists available skills
4. Every plugin skill appears exactly twice in the list

Expected Behavior

Each plugin skill should appear once in the skill list.

Actual Behavior

The entire skill list is duplicated. For example:

- commit-commands:commit: Create a git commit
- feature-dev:feature-dev: Guided feature development...
- hookify:help: Get help with the hookify plugin
...
- commit-commands:commit: Create a git commit      ← duplicate
- feature-dev:feature-dev: Guided feature development...  ← duplicate
- hookify:help: Get help with the hookify plugin    ← duplicate
...

Impact

With 37 unique plugin skills, this results in 74 skill entries in the system prompt instead of 37. This wastes context window space and reduces available context for actual code, files, and conversation history — especially in longer sessions.

Environment

• macOS (Apple Silicon)
• Claude Code (latest as of 2026-02-28)
• Plugins installed at user scope only ("scope": "user")
• No project-level plugin settings

What I've Verified

• settings.json: each plugin listed once
• installed_plugins.json: each plugin has a single entry with "scope": "user"
• No project-level settings.json files exist
• No duplicate install paths in plugin cache
• The duplication appears to happen in the plugin loader's skill enumeration, not in user configuration