[FEATURE] [VS Code] Allow .xlsx files in "Upload from computer"

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

Allow .xlsx files in "Upload from computer" (VS Code extension)

In the VS Code extension, the "Upload from computer" option doesn't accept Excel files (.xlsx). PDFs and images upload fine, but for spreadsheets I have to copy the file into a project folder and reference it with @ instead.

I often need Claude to review Excel files that live outside the project, like trading logs and AI-generated spreadsheets I want to compare. Copying them into the workspace first adds friction, and I then have to remember to delete them, especially when they hold personal data.

Request: please allow .xlsx (and ideally .xls/.csv) in the upload picker, the same way PDFs are supported.

Proposed Solution

In the VS Code extension, "Upload from computer" should accept Excel files (.xlsx, and ideally .xls and .csv) the same way it accepts PDFs and images.

Ideal experience:

1. I click the attach button and choose "Upload from computer".
2. In the file picker I select a .xlsx file from anywhere on my computer, not only inside the workspace.
3. The file shows up as an attachment in the prompt, like a PDF does, and Claude can read every sheet in it.

This way I wouldn't have to copy the file into a project folder and reference it with @, or remember to delete it afterwards. That matters when the spreadsheet holds personal or financial data that shouldn't stay in the project.

Alternative Solutions

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Priority

Medium - Would be very helpful

Feature Category

File operations

Use Case Example

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Additional Context

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