Plugin installs from personal marketplaces don't persist across Cowork sessions #157
Description
I built a plugin marketplace at github.com/benjaroy/personal-writing as a set of skills to help people write with Claude. I followed the structure documented at code.claude.com/docs/en/plugin-marketplaces and made sure to match the pattern in anthropics/knowledge-work-plugins such that marketplace.json at the root is pointing to a plugin subdirectory with its own plugin.json and skills.
The Cowork installation flow works correctly: Customize → Add marketplace → paste URL → Sync. That finds the marketplace and displays the plugin. Then after clicking Install it shows "Personal writing is installed and ready to use." All the skills load and function within that session, but the issue is that the installation doesn't persist, so when I open another Cowork session, Claude is unaware of the plugin and the plugin entry is gone from .remote-plugins/manifest.json. Only cowork-plugin-management survives across sessions. I've reproduced this multiple times where the install succeeds each time, but the manifest reverts when I restart the session.
I've verified the plugin structure against this repo's conventions and the official docs. The issue appears to be in how Cowork installs from personal (non-Anthropic) marketplaces specifically.
Steps to reproduce:
-In Cowork, go to Customize → Add marketplace
-Paste https://github.com/benjaroy/personal-writing and click Sync
-Click Install on the Personal writing plugin
-Confirm skills are available in that session
-Start a new Cowork session
-Check .remote-plugins/manifest.json and you'll see the plugin entry is gone (or ask Claude what skills/plugins it has access to and it doesn't reference the plugin)
I don't know if this is a design choice for non-Anthropic marketplaces, but I would love to just be able to install this once and have access to it for good (as well as send it to people and have them be able to install once as well). Thank you.