Cowork desktop: marketplace plugin listing cache stale post re-add

Summary

Cowork desktop BETA caches the plugin marketplace listing aggressively. After re-adding a marketplace whose .claude-plugin/marketplace.json references a plugin with a newer plugin.json version, Cowork continues showing the old version. UI shows only "Desinstalar" — no "Update" / "Reinstalar" button.

Reproduction

1. Install plugin v1.1.0 from marketplace admin431/PoWi-Mobile
2. In repo, bump plugin.json version to v1.5.0 (multiple commits, all merged to develop)
3. In Cowork: Marketplaces → remove admin431/PoWi-Mobile
4. Re-add marketplace with same URL https://github.com/admin431/PoWi-Mobile
5. Restart Cowork desktop multiple times

Expected

Cowork detects new plugin.json version (v1.5.0) and either:

• Shows "Update available" with button to apply, OR
• Refreshes listing automatically post re-add

Actual

Cowork keeps showing v1.1.0. UI offers only "Desinstalar". No way to update without uninstall+reinstall (which loses any local config).

Workaround

Uninstall plugin → Use zip flow (build zip from PowerShell with & scripts/build_powi_plugin_zip.ps1, then "+" → "Subir plugin" with the zip). Plugin installs fresh at v1.5.0. Loses marketplace tracking.

Why this matters

For organizations distributing private plugins via marketplace (our case: admin431/PoWi-Mobile with internal-only plugin), every plugin update requires this manual workaround. Defeats the purpose of marketplace-based distribution.

Environment

• Cowork desktop (Windows 11)
• Plugin: powi-claude-plugin private marketplace admin431/PoWi-Mobile
• Repo always has plugin.json version > marketplace.json version (per Anthropic doc: plugin.json value always wins silently)