[FEATURE] Support virtual filesystems (non-file:// URI schemes) in VSCode extension

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

The Claude Code VSCode extension currently only reads files from the local filesystem (file:// URIs). When working with virtual filesystem extensions, Claude Code cannot access file contents even when they are open and visible in the editor.

This creates a major gap for enterprise developers using remote filesystem extensions like:

• ABAP Remote Filesystem (SAP development)
• Remote SSH/WSL/Container development
• Cloud storage extensions (Azure, AWS, GCP)
• Database code editors
• GitHub Gists and other virtual file providers

Currently, when I have an ABAP file open via the ABAP Remote Filesystem extension, Claude Code cannot:

• Read the file with the Read tool
• See selected code in the conversation context
• Navigate to definitions or references
• Work with the code at all

This forces me to copy-paste code manually or use workarounds, breaking the seamless workflow that Claude Code otherwise provides.

Proposed Solution

The VSCode extension should use VSCode's FileSystem API (vscode.workspace.fs.readFile(uri)) instead of Node.js filesystem APIs. This would enable Claude Code to read any file from any registered filesystem provider, regardless of URI scheme.

Ideal user experience:

1. I open a file from a virtual filesystem (e.g., adt://sap/bc/adt/oo/classes/zcl_example)
2. I select code or ask Claude to explain/modify it
3. Claude Code reads the file content seamlessly, just like it does with local files
4. All features (Read, Edit, navigation, etc.) work identically for virtual files

Technical implementation:

• Replace fs.readFile() with vscode.workspace.fs.readFile(uri)
• Handle any URI scheme that VSCode supports
• Maintain backward compatibility with local files

Alternative Solutions

Current workarounds I'm using:

1. Copy-paste code from virtual files into the chat (tedious and breaks workflow)
2. Use MCP server tools to access SAP directly (works but bypasses VSCode's filesystem entirely)
3. Save temporary local copies of files (creates sync issues and clutter)

How other tools handle this:

• GitHub Copilot successfully reads virtual filesystem files using VSCode's FileSystem API
• Other VSCode extensions (linters, formatters) work seamlessly with virtual files
• This is a solved problem in the VSCode ecosystem

Priority

Critical - Blocking my work

Feature Category

File operations

Use Case Example

Scenario: SAP ABAP Development

1. I'm an enterprise developer working on SAP ABAP code
2. I connect to SAP using the ABAP Remote Filesystem extension (adt:// protocol)
3. I browse ABAP classes, programs, and interfaces in VSCode's file explorer
4. I open ZCL_ORDER_PROCESSOR (a class streaming from SAP as a virtual file)
5. I select a method and ask Claude Code: "Explain this code and suggest optimizations"
6. Current behavior: Claude responds "I don't see any selected code in the context"
7. Expected behavior: Claude reads the virtual file and provides analysis

Impact:

• Without this feature, I cannot use Claude Code for my daily SAP development work
• Affects thousands of enterprise developers using virtual filesystem extensions
• Makes Claude Code incompatible with modern remote/cloud development workflows

Time saved with this feature:

• Eliminates 10-20 copy-paste operations per hour
• Enables seamless AI assistance for enterprise codebases
• Brings Claude Code to parity with competing tools that already support this

Additional Context

Similar features in other tools:

• GitHub Copilot reads virtual files using vscode.workspace.fs API
• VSCode's built-in features (search, intellisense) work with virtual files

Technical reference:

• VSCode FileSystem API
• ABAP Remote Filesystem Extension

Affected URI schemes (examples):

• adt:// - ABAP Development Tools (SAP)
• vscode-vfs:// - Remote SSH/WSL/Container
• gist:// - GitHub Gists
• azurerepos:// - Azure Repos
• Any custom filesystem provider

This feature would significantly expand Claude Code's applicability to enterprise and cloud development scenarios.