Cowork panel auto-opens every session and shows broken preview for local MCP extension file

Description

Every time Claude Code Desktop is opened, the Cowork panel activates automatically and shows a broken file preview dialog.

Steps to reproduce

1. Have the Kapture MCP extension installed in Claude Code Desktop (ant.dir.gh.williamkapke.kapture)
2. Open Claude Code Desktop (any project)
3. The Cowork panel opens automatically

Expected behavior

Cowork panel should not auto-open on every session unless explicitly triggered by the user.

Actual behavior

• The Cowork panel opens showing "Vamos a completar algo de tu lista" (onboarding/checklist UI)
• A dialog appears saying "La vista previa no está disponible para C:\Users\...\Claude Extensions\ant.dir.gh.williamkapke.kapture\dist\index.js" with a "Descargar" (Download) button
• This happens on every single Claude Code session open

Environment

• OS: Windows 10 Pro 10.0.19045
• Claude Code: Desktop app
• MCP extension installed: ant.dir.gh.williamkapke.kapture (Kapture browser automation)

Additional context

No user-configured hooks, scheduled tasks, or settings are triggering this — it appears to be behavior of the Claude Code Desktop app itself opening the Cowork panel on startup when the Kapture extension is installed.

The preview dialog for index.js (a compiled Node.js file) suggests the Cowork panel is trying to render a file that cannot be previewed in the UI.