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Related Issues

This appears to be a regression that worsened #7880. See also #7719 and #3507.

Issue description

After updating home-manager past commit b59376563943ce163b2553aeb63d0c170967d74e (Feb 1, 2026 - "vscode: fix extension path for antigravity"), extensions defined under profiles.default.extensions are no longer recognized by VS Code, even though they are correctly symlinked.

Before the update (home-manager d055b309... from Jan 23): Extensions worked
After the update (home-manager 436b2774... from Feb 21, includes the commit): Extensions not loaded

Steps to Reproduce

1. Use profiles.default.extensions in vscode config
2. Run darwin-rebuild switch (or home-manager switch)
3. Open VS Code
4. Run code --list-extensions - shows only manually installed extensions

Actual Output

$ code --list-extensions
github.copilot-chat  # Only 1 of 9 declared extensions

$ ls ~/.vscode/extensions/
.extensions-immutable.json -> /nix/store/...  # Correctly symlinked
Ionide.Ionide-fsharp -> /nix/store/...        # Correctly symlinked
ms-vscode.PowerShell -> /nix/store/...        # Correctly symlinked
# ... all 9 extensions present as symlinks

$ cat ~/.vscode/extensions/.obsolete
{"ionide.ionide-fsharp-7.31.1":true,"ms-vscode.powershell-2025.4.0":true,...}
# VS Code marks them all obsolete

Symptoms

1. Extensions are correctly symlinked in ~/.vscode/extensions/
2. .extensions-immutable.json is correctly generated with all extensions
3. VS Code's extensions.json only recognizes manually installed extensions
4. .obsolete file marks all Nix-managed extensions as obsolete
5. code --list-extensions shows only manually installed extensions

Configuration

programs.vscode = {
  enable = true;
  profiles.default.userSettings = { ... };
  profiles.default.extensions = with pkgs; [
    vscode-extensions.ionide.ionide-fsharp
    vscode-extensions.ms-dotnettools.csdevkit
    vscode-extensions.jnoortheen.nix-ide
    vscode-extensions.ms-vscode.powershell
    vscode-extensions.github.copilot-chat
    # ... more extensions
  ];
};

Root Cause Analysis

The commit b59376563943ce163b2553aeb63d0c170967d74e changed extension path handling:

• Removed the sharePrefix variable
• Changed paths from "${sharePrefix}/extensions" to hardcoded "/share/vscode/extensions"
• Modified how .extensions-immutable.json is generated

This change, intended to fix antigravity support, appears to have broken the extension loading mechanism for regular VS Code on Darwin when using profiles.default.extensions.

Workarounds

Workaround 1 (from #7880): Use legacy extensions option with mutableExtensionsDir = false:

programs.vscode = {
  enable = true;
  mutableExtensionsDir = false;
  extensions = [ ... ];  # Instead of profiles.default.extensions
  profiles.default.userSettings = { ... };
};

Workaround 2 (from #7719): Delete VS Code state and rebuild (temporary fix, breaks again on next rebuild):

rm -rf ~/.vscode ~/Library/Application\ Support/Code
darwin-rebuild switch  # or home-manager switch

System information

- system: `"aarch64-darwin"`
- host os: `Darwin 25.3.0, macOS 26.3`
- multi-user?: `yes`
- sandbox: `no`
- nixpkgs: `d1c15b7d5806069da59e819999d70e1cec0760bf`
- home-manager: `436b27742c996b75e2baf8e835e3b3eae0c9fbd4`