Custom marketplace plugins: Discover tab shows 'not installed' + updates don't sync

Bug Description

Two related issues with custom (user-created) marketplace plugins:

1. Discover tab doesn't reflect installed state: Plugins from a custom marketplace show as ✔ enabled in the Installed tab, but the Discover tab shows them as not installed (no checkmark, appear as if never installed).

1. Plugin updates don't propagate: After pushing updates to the custom marketplace GitHub repo, the cached version in ~/.claude/plugins/marketplaces/<name>/ doesn't pull the latest changes. The marketplace appears to fetch but not pull (related to #41885).

Environment

• Claude Code version: 2.1.92
• OS: macOS (Apple Silicon), Darwin 25.4.0
• Shell: zsh

Steps to Reproduce

Setup (custom marketplace)

1. Create a GitHub repo with .claude-plugin/marketplace.json defining plugins
2. Add the marketplace:

``
/plugins → Marketplaces → Add → github.com/username/repo-name
``

1. Install a plugin from the marketplace:

``
/plugins → Discover → find the plugin → Install
``

Bug 1: Discover tab inconsistency

1. Go to /plugins → Installed tab → Plugin shows ✔ enabled ✅
2. Go to /plugins → Discover tab → Same plugin shows as not installed ❌

Expected: Discover tab should show the plugin as installed (checkmark or "installed" badge).

Bug 2: Updates don't sync

1. Update SKILL.md in the marketplace repo, commit and push to GitHub
2. Restart Claude Code or wait for auto-sync
3. The plugin still uses the old cached version from ~/.claude/plugins/marketplaces/<name>/

Expected: After push to GitHub + restart, the plugin should reflect the latest version.

Workaround: Manually run cd ~/.claude/plugins/marketplaces/<name> && git pull to force update.

Screenshots

Installed tab — plugin shows as enabled:

Plugins  Discover   Installed   Marketplaces
  
  cyxj-obsidian-compiler Plugin · xiaochen-skills · ✔ enabled

Discover tab — same plugin not shown as installed:

Plugins  Discover   Installed   Marketplaces

  Discover plugins (1/130)
  ❯ ◯ frontend-design · claude-plugins-official · 455.6K installs
    ◯ superpowers · claude-plugins-official · 355.7K installs
    ...

(Custom marketplace plugins don't appear in Discover at all, or appear without installed indicator)

Additional Context

• The custom marketplace is registered in ~/.claude/settings.json under extraKnownMarketplaces
• Plugin files are cached in ~/.claude/plugins/marketplaces/<marketplace-name>/
• Related issues: #41885 (fetch but not pull), #42411 (plugin update reports "not found"), #36655 (marketplace add succeeds but not registered)