lewiswigmore/agent-skills

VS Code Extension Guide

Create, develop, and publish VS Code extensions.

When to Use

• VS Code extension, extension development, vscode plugin
• Creating a new VS Code extension from scratch
• Adding commands, keybindings, or settings to an extension
• Publishing to VS Code Marketplace

Quick Start

# Scaffold new extension (recommended)
npm install -g yo generator-code
yo code

# Or minimal manual setup
mkdir my-extension && cd my-extension
npm init -y && npm install -D typescript @types/vscode

Project Structure

my-extension/
├── package.json          # Extension manifest (CRITICAL)
├── src/extension.ts      # Entry point
├── out/                  # Compiled JS (gitignore)
├── images/icon.png       # 128x128 PNG for Marketplace
└── .vscodeignore         # Exclude files from VSIX

Building & Packaging

npm run compile      # Build once
npm run watch        # Watch mode (F5 to launch debug)
npx @vscode/vsce package   # Creates .vsix

Done Criteria

• Extension activates without errors
• All commands registered and working
• Package size < 5MB (use .vscodeignore)
• README.md includes Marketplace/GitHub links

Quick Troubleshooting

Symptom	Fix
Extension not loading	Check activationEvents (auto-detected since VS Code 1.74 for contributed commands/views)
Command not found	Match command ID in package.json/code
Shortcut not working	Remove when clause, check conflicts

Topic	Reference
AI Customization	references/ai-customization.md
Code Review Prompts	references/code-review-prompts.md
Code Samples	references/code-samples.md
TreeView	references/treeview.md
Webview	references/webview.md
Testing	references/testing.md
Publishing	references/publishing.md
Troubleshooting	references/troubleshooting.md

Best Practices

Naming Consistency

Unify package name, setting keys, command IDs, and view IDs before publishing:

Item	Example
Package name	copilot-scheduler
Setting key	copilotScheduler.enabled
Command ID	copilotScheduler.createTask
View ID	copilotSchedulerTasks

Centralised Notification Handling

type NotificationMode = "sound" | "silentToast" | "silentStatus";

function getNotificationMode(): NotificationMode {
  const config = vscode.workspace.getConfiguration("myExtension");
  return config.get<NotificationMode>("notificationMode", "sound");
}

function notifyInfo(message: string, timeoutMs = 4000): void {
  const mode = getNotificationMode();
  switch (mode) {
    case "silentStatus":
      vscode.window.setStatusBarMessage(message, timeoutMs);
      break;
    case "silentToast":
      void vscode.window.withProgress(
        { location: vscode.ProgressLocation.Notification, title: message },
        async () => {},
      );
      break;
    default:
      void vscode.window.showInformationMessage(message);
  }
}

function notifyError(message: string, timeoutMs = 6000): void {
  const mode = getNotificationMode();
  if (mode === "silentStatus") {
    vscode.window.setStatusBarMessage(`⚠ ${message}`, timeoutMs);
    console.error(message);
    return;
  }
  void vscode.window.showErrorMessage(message);
}

Expose a notificationMode setting so users can control how notifications are delivered.