Claude Desktop's fileTypeAssociation manifest invalidates existing UserChoice defaults for Office/dev file types on Windows

Preflight Checklist

• I have searched existing issues and this hasn't been reported yet
• This is a single bug report (please file separate reports for different bugs)
• I am using the latest version of Claude Code

What's Wrong?

Description:
After installing/updating Claude Desktop (Windows, MSIX package Claude_2.2553.1.0_x64), Explorer's "Type" column started showing raw ProgId strings (e.g. Excel.Sheet.12 instead of "Microsoft Excel Worksheet") and generic/broken icons for .docx, .xlsx, .pptx and other files.

Root cause found: AppxManifest.xml declares a windows.fileTypeAssociation extension (Name="documents") listing a very broad set of SupportedFileTypes, including .docx, .doc, .xlsx, .xlsm, .xls, .pptx, .ppt, .csv, .json, .xml, .md, .txt, .pdf, .png, .jpg, etc. Registering a new app as a candidate opener for these extensions causes Windows to invalidate the per-user UserChoice registry key for each one (documented Windows anti-hijack behavior). The HKCR default ProgId itself stays correct (files still open in the right app), but the friendly type name/icon resolution breaks until the user manually reconfirms the default app via "Open With" or Settings for every affected extension.

This is very confusing for end users — it looks exactly like a file-association hijack, even though it isn't one. In my case it was severe enough to previously cause a full Windows reformat, mistakenly believing it was a hijack/malware-style issue, before the actual cause (this manifest's broad file type registration) was identified.

Suggestion: Either scope SupportedFileTypes down to types Claude Desktop actually needs to claim "Open with Claude" for (rather than common productivity formats like Office documents), or make this file type association registration opt-in/configurable, to avoid silently resetting users' existing default-app choices on install/update.

Environment: Windows 11 Pro 10.0.26200, Claude Desktop 2.2553.1.0 (MSIX/AppX), Microsoft Office Click-to-Run.

What Should Happen?

Não sobrepor a associação de programas padrão;

Error Messages/Logs

Steps to Reproduce

Após atualizar ou instalar o Claude Desktop sobre o Windows 11.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

No response

Claude Code Version

2.2553.1

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

No response

Start by locating the Windows AppX packaging manifest, specifically AppxManifest.xml and its windows.fileTypeAssociation extension. Review the SupportedFileTypes entries against the file types Claude Desktop actually needs, then test installation or update behavior on Windows 11 with existing Office associations. Done means affected UserChoice defaults, friendly type names, and icons remain intact after installation or update.