home / skills / kevinslin / llm / dev.code-extension

dev.code-extension skill

safe

This skill installs VS Code or Cursor extensions from a local .vsix file using the appropriate CLI, then verifies installation.

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---
name: dev.code-extension
description: Install VS Code/Cursor extensions from a local .vsix via CLI (code, code-insiders, cursor, cursor-nightly). Use whenever asked to install an extension programmatically.
version: 1.0.0
---

# dev.code-extension

Use this skill when the user asks to install a VS Code-compatible extension into **VS Code** or **Cursor** (stable or nightly).

## Input contract

- Expect a **local filesystem path** to a `.vsix` file.
- If the user provides a Marketplace ID instead of a path, ask for the `.vsix` path (unless they explicitly want Marketplace install).

## Install commands (local `.vsix`)

### VS Code (stable)

```bash
code --install-extension "/path/to/extension.vsix" --force
code --list-extensions --show-versions
```

### VS Code Insiders

```bash
code-insiders --install-extension "/path/to/extension.vsix" --force
code-insiders --list-extensions --show-versions
```

### Cursor (stable)

```bash
cursor --install-extension "/path/to/extension.vsix" --force
cursor --list-extensions --show-versions
```

### Cursor Nightly

Prefer `cursor-nightly` if it’s on PATH. If not (macOS default), call it from the app bundle:

```bash
"/Applications/Cursor Nightly.app/Contents/Resources/app/bin/cursor-nightly" --install-extension "/path/to/extension.vsix" --force
"/Applications/Cursor Nightly.app/Contents/Resources/app/bin/cursor-nightly" --list-extensions --show-versions
```

## Verification

- After install, verify by grepping the extension list:
  - `cursor --list-extensions --show-versions | rg -n "<publisher>\\.<name>|<name>"`

## Automation/CI option (avoid touching a developer profile)

If the user wants isolated installs (recommended for scripts/CI), add:

- `--user-data-dir <dir>`
- `--extensions-dir <dir>`

Example:

```bash
cursor --user-data-dir /tmp/cursor-user --extensions-dir /tmp/cursor-ext --install-extension "/path/to/extension.vsix" --force
```

## Sandbox note (Codex CLI)

Installing extensions writes to user/application support directories (outside the repo).
In sandboxed runs, request escalated permissions for these commands.

Overview

This skill installs VS Code-compatible extensions from a local .vsix file into VS Code or Cursor (stable or nightly) via CLI. It targets code, code-insiders, cursor, and cursor-nightly binaries and provides the exact install and verification commands. Use it whenever you need a programmatic, reproducible local install of an extension. It also supports isolated installs for CI or scripts.

How this skill works

Provide a local filesystem path to a .vsix file and the skill returns the appropriate CLI commands to install that package into the chosen editor binary. It supports code, code-insiders, cursor, and cursor-nightly, including a macOS fallback path for Cursor Nightly. The skill also supplies verification commands to confirm installation and optional user-data/extensions directory flags for isolated installs.

When to use it

You have a local .vsix file and need to install it into VS Code or Cursor programmatically.
Automating extension installs in scripts, CI, or reproducible developer environments.
Testing an extension build locally before publishing to the Marketplace.
Installing an extension in a sandbox or isolated profile to avoid touching a developer profile.
When asked explicitly to install an extension via CLI rather than using the Marketplace UI.

Best practices

Always pass the full path to the .vsix file and use --force to overwrite existing installs if needed.
Verify installation with --list-extensions --show-versions and grep for publisher.name or name.
For CI or automation, use --user-data-dir and --extensions-dir to avoid modifying a personal profile.
Prefer cursor-nightly on PATH; on macOS call the app bundle binary if the CLI is not available.
In sandboxed environments, request elevated permissions because installs write to user/app support directories.

Example use cases

Install a locally built extension into VS Code stable: code --install-extension "/path/to/ext.vsix" --force
Add an extension to VS Code Insiders during a test run: code-insiders --install-extension "/path/to/ext.vsix" --force
Install into Cursor Nightly on macOS using the app bundle path if cursor-nightly is not on PATH
Run isolated installs in CI: cursor --user-data-dir /tmp/user --extensions-dir /tmp/ext --install-extension "/path/to/ext.vsix" --force
Verify installation with: cursor --list-extensions --show-versions | rg -n "publisher\.name|name"

FAQ

What if I only have a Marketplace ID?

If you provide a Marketplace ID, ask for the .vsix path unless you explicitly want a Marketplace install; this skill focuses on local .vsix installs.

Can I install without affecting my main profile?

Yes. Use --user-data-dir and --extensions-dir to install into isolated directories suitable for CI or scripting.