[BUG] Plugin shows installed in config files but not in /plugin UI — Claude falsely claims to use it!

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 frontend-design@claude-plugins-official plugin appears as installed in both config files (installed_plugins.json and settings.json) but does NOT appear in the /plugin → Installed tab, which shows "No plugins or MCP servers installed."

More critically, when asked whether the plugin was used during a session, Claude falsely confirmed it had used the plugin to perform UI improvements. When confronted with evidence that the plugin wasn't actually loaded, Claude initially doubled down on the claim before admitting it had never been used.

<img width="983" height="738" alt="Image" src="https://github.com/user-attachments/assets/b5476ad1-38b5-4a47-9342-0ce73680417c" />

What Should Happen?

1. Plugins installed via marketplace should appear in /plugin → Installed tab. If installation is incomplete (version: "unknown"), an error state should be shown instead of silently hiding the plugin.

1. When asked whether a plugin/tool was used, Claude should verify it was actually loaded in the session — not just check config files and assume. If uncertain, Claude should say "I'm not sure" instead of falsely confirming.

Error Messages/Logs

Steps to Reproduce

Technical Bug (Plugin not visible)

1. Install frontend-design plugin from the official marketplace
2. Verify ~/.claude/plugins/installed_plugins.json contains the entry:

{
"frontend-design@claude-plugins-official": [{
"scope": "user",
"version": "unknown",
"installedAt": "2026-04-07T13:38:28.685Z"
}]
}

1. Verify ~/.claude/settings.json contains:

{
"enabledPlugins": {
"frontend-design@claude-plugins-official": true
}
}

1. Open /plugin → Installed tab
2. Expected: Plugin appears in the list
3. Actual: "No plugins or MCP servers installed."

Note: The plugin version field is "unknown" — this may be the root cause.

Behavioral Bug (False confirmation)

1. Ask Claude "Did you use the frontend-design plugin for the UI changes?"
2. Claude checks config files, sees the plugin entry, and confirms it used the plugin — without verifying whether the plugin was

actually loaded/active in the session

1. When confronted with the /plugin UI showing nothing installed, Claude admits it never actually used the plugin

Expected Behavior

1. Technical: If a plugin is in installed_plugins.json and enabledPlugins, it should appear in the /plugin → Installed UI. If

installation is broken/incomplete (e.g., version: "unknown"), it should show an error state rather than being silently invisible.

1. Behavioral: Claude should never confirm that a tool/plugin was used unless it can verify it was actually loaded and invoked in the

session. If uncertain, it should say "I'm not sure, let me check" rather than fabricating a confirmation.

Environment

• Claude Code v2.1.96
• Model: Claude Opus 4.6 (1M context)
• OS: macOS Darwin 25.3.0
• Plugin: frontend-design@claude-plugins-official
• Node.js: 20

Impact

• Trust: User pays for the service and was misled about plugin functionality being used. Claude only admitted the truth after being

directly confronted with contradictory evidence. This is a significant trust violation.

• Functional: Plugin installed but not usable — user cannot leverage paid plugin functionality.

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.96

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_