Cowork: personal marketplace never re-syncs — "Update" reports latest version while repo is 3 versions ahead

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?

Related to #38185 (locked). Personal marketplace added via "Add from a repository" (public GitHub repo). Repo's plugin was updated 0.1.0 → 0.4.0 across several pushes (plugin.json and marketplace.json versions both bumped, verified live on GitHub via raw at commit hash). Installed plugin still shows 0.1.0; hovering "Update" says I have the latest version. Removing the plugin and reinstalling from the still-registered marketplace reinstalls the stale version — the marketplace's cached copy appears never to refresh. Workaround that appears required: remove the marketplace itself, restart the app, re-add. Desktop app on Windows, repo: github.com/CThomas-PO/cthomas-plugins.

What Should Happen?

Plugin users should be able to easily update one or all of their plugins. Better yet, there should be a setting that initiates automatic updates.

Error Messages/Logs

Steps to Reproduce

Related: #38185 (locked), #40600
Environment: Claude desktop app on Windows 11, Cowork mode, personal (non-organization) account.
Steps to reproduce:

Create a public GitHub repo containing a plugin marketplace: .claude-plugin/marketplace.json at root, plugin source under plugins/<name>/ with its own .claude-plugin/plugin.json, both version fields set to 0.1.0.
In the desktop app: Customize → Plugins → + → Add from a repository → paste the repo URL. Install the plugin. Card correctly shows version 0.1.0.
Push updates to the repo: change a skill's SKILL.md and bump the version to 0.4.0 in both plugins/<name>/.claude-plugin/plugin.json and the plugin's entry in .claude-plugin/marketplace.json. Verify the changes are live on GitHub (raw fetch at the new commit hash shows 0.4.0).
In the app, hover/click Update on the installed plugin.
Uninstall the plugin, then reinstall it from the still-registered marketplace.

Claude Model

Opus

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

N/A — issue occurs in Claude desktop app (Cowork mode), app version <X.Y.Z>. No standalone CLI installed.

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_