The ✨ **Generate Commit Message** action is not available when a workspace is backed by a virtual file system

### Description

The ✨ **Generate Commit Message** action is not available when a workspace is
backed by a virtual file system, such as one opened with the **GitHub
Repositories** extension (`vscode-vfs://github//`).

### Repro

1. Open any repo via **GitHub Repositories: Open Repository...**
2. Ensure Copilot Chat is installed, enabled, and signed in with an active subscription
3. Edit a file so there are pending changes
4. Open the Source Control view

**Expected:** the Generate Commit Message action appears in the SCM input box
toolbar, as it does in a local clone.

**Actual:** the action is absent. "Commit & Push" works normally, so the SCM
provider itself is functional — only the AI commit message action is missing.

No Copilot configuration changes this. It remains absent with Copilot Chat
enabled, signed in, and `github.copilot.enable` at defaults.

### Analysis

In a virtual workspace the SCM input box is owned by the GitHub Repositories
provider rather than the built-in Git extension, and the action appears to be
contributed only against the built-in Git provider. Confirmed via **Developer:
Inspect Context Keys** on the commit input — `scmProvider` is not `git` here.

### Why it matters

The GitHub Repositories extension is positioned for quick edits and reviews
without cloning — exactly the small, one-or-two-file commits where a generated
message saves the most effort. Today those are the only commits that can't have
one.

### Related

- #313051 — extensions cannot programmatically commit or invalidate the GitHub
Repositories provider's SCM cache (same provider, adjacent integration gap)

### Issue Details

Item|Value
---|---
Issue Category|Feature Request
Target|Visual Studio Code
VS Code Version|Code 1.137.0 (645f29cc3176500b4b5762ba887cf2a7f0ffdf2c, 2026-09-08T13:43:59-07:00)
OS Version|Windows_NT x64 10.0.26200

### Additional Issue Data

[issue-data.md](https://github.com/user-attachments/files/32121112/issue-data.md)

### Attachments