Cowork: third-party private-repo marketplaces permanently stale per-account — version label frozen at first-add value, re-add doesn't refresh, releases not picked up

Summary

On one Claude account, third-party plugin marketplaces (private GitHub repos) in Cowork are permanently stale per-account. The version label shown in the plugin UI stays frozen at whatever marketplace.json declared when the marketplace was first added to the account, and newer GitHub releases are not picked up. Removing the plugin, removing the marketplace, fully quitting the app, and re-adding always comes back at the frozen version. After the latest remove/re-add cycle, the plugin stopped being delivered to new sessions entirely (skills absent from the session's available-skills list) even though the UI shows it installed.

The same marketplaces on a second Claude account (same machine, added fresh) show the current versions. The same marketplaces in Claude Code CLI on the same machine update correctly. This points to per-account server-side registration state that is never refreshed and survives remove/re-add.

Environment

• Claude desktop app 1.11847.5 (Cowork, local sessions), macOS (Darwin 25.5.0)
• Two third-party marketplaces, both private GitHub repos, added via "Add marketplace" with the repo URL
• Marketplace layout: .claude-plugin/marketplace.json at repo root, plugin in ./plugin (relative source)

Evidence / timeline

• Marketplace A first added ~May 29 when its marketplace.json declared 0.1.0. Repo is now at 0.6.1 (tags + GitHub releases published, marketplace.json and plugin.json in sync on the default branch). Cowork UI still shows 0.1.0.
• Marketplace B shows 0.2.2 while its repo is at 0.4.0 — same account, same pattern.
• Inspecting local session records (local-agent-mode-sessions/.../audit.jsonl), the skill set actually delivered to sessions matched an intermediate release (the one published the previous day) — so plugin content syncs with lag, while the version label appears to read registration-time metadata. After the most recent uninstall/re-add cycle, new sessions list no skills at all from that plugin.
• Multiple new GitHub releases were published across several days; none changed what account A receives.
• Account B, same machine, same repo URLs, fresh "Add marketplace": current version label and content.

What was tried (no effect)

Uninstall plugin → reinstall · remove marketplace → re-add (same URL) · full quit (Cmd+Q) → reopen · clearing local plugin caches. Host-side ~/.claude/plugins/ (CLI) was confirmed clean and current — Cowork does not appear to read it.

Expected

Re-adding a marketplace (or an explicit refresh action) should re-fetch marketplace.json and plugin content from the source repo, and the displayed version should reflect what is actually installed/delivered.

Actual

Version label frozen at first-add value per account; releases not picked up; remove/re-add returns the stale registration; in the worst state the plugin is shown as installed but no skills reach sessions.

Possibly related

#45834 (version metadata not updated on plugin update) · #56678 (Cowork serves stale cached skill content) · #38185 (Cowork: cannot update third-party plugins / Personal tab) · #40475 / #38429 (RemotePluginManager removing 3rd-party plugins on sync) · #37670 (stale marketplace metadata on install)

I can share the marketplace/repo identifiers and the affected account email privately if useful for tracing the server-side registration.