git:20260914.a98e723 to git:20260914.887c127

4 added, 1 removed. Audit A to A.

---

name: vscode-extension-guide

description: "Guide for creating VS Code extensions and plugins from scratch through Marketplace publication. Use when developing a VS Code extension/plugin, adding commands or keybindings, building TreeView or Webview UI, publishing to Marketplace, or troubleshooting activation and packaging issues."

argument-hint: "作りたい拡張機能、追加したい機能、困っている点"

user-invocable: true

license: CC BY-NC-SA 4.0

metadata:

author: yamapan (https://github.com/aktsmm)

---

# VS Code Extension Guide

Create, develop, and publish VS Code extensions.

For extensions with a management UI, default to a dedicated Activity Bar icon

and sidebar unless another entry point is explicitly chosen. A Marketplace

`icon` alone does not create that navigation; use the TreeView reference below.

## 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

```bash

# 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)

├── artifacts/vsix/ # Keep local VSIX archives out of the repo root

├── images/icon.png # 128x128 PNG for Marketplace

└── .vscodeignore # Exclude files from VSIX

```

## Building & Packaging

```bash

npm run compile # Build once

npm run watch # Watch mode (F5 to launch debug)

mkdir -p artifacts/vsix

npx @vscode/vsce package --out artifacts/vsix/my-extension-1.0.0.vsix

```

Keep local `.vsix` archives under `artifacts/vsix/` instead of the repository root, and prune old local builds on a schedule so release artifacts do not pile up.

## Done Criteria

- [ ] Extension activates without errors

- [ ] Primary sidebar entry and commands work; referenced icons are present in the VSIX

- [ ] Package size < 5MB (use `.vscodeignore`)

- [ ] README.md includes Marketplace/GitHub links

- [ ] Local VSIX artifacts stored outside the repo root and pruned regularly

## Quick Troubleshooting

| Symptom | Fix |

| --------------------- | -------------------------------------- |

| Extension not loading | Add `activationEvents` to package.json |

| Command not found | Match command ID in package.json/code |

| Shortcut not working | Remove `when` clause, check conflicts |

## Reference Map

| Topic | Reference |

| ------------------- | ------------------------------------------------------------------------------------------------------------------- |

| AI Customization | [references/ai-customization.md](references/ai-customization.md) |

| Code Review Prompts | [references/code-review-prompts.md](references/code-review-prompts.md) |

| Code Samples | [references/ai-customization.md](references/ai-customization.md) and [references/webview.md](references/webview.md) |

| TreeView | [references/treeview.md](references/treeview.md) |

| Webview | [references/webview.md](references/webview.md) |

| Testing | [references/testing.md](references/testing.md) |

| Publishing | [references/publishing.md](references/publishing.md) |

| Troubleshooting | [references/troubleshooting.md](references/troubleshooting.md) |

| Notifications | [references/notification-normalization.md](references/notification-normalization.md) |

## Best Practices

### Extension Host 境界

- Extension Host 上で動く scanner / provider / TreeView は、同じことができるなら Node 固有の `path` / `Buffer` / 生 `fs` より VS Code API を優先する。Problems と実ビルドの環境差を避けやすい。

- 自分の拡張に同梱したリソースは、ユーザーのホーム配下や VS Code のインストール先を推測せず、`context.extensionUri` と `vscode.Uri.joinPath` など extension context から解決する。

- Runtime の診断ログは `console.log` に散らさず、Output Channel ベースの logger に集約する。ユーザーがログを開ける導線も command / notification / README のどこかに用意する。

- 大きい入力の parse や集計を Extension Host スレッドで同期実行しない。上限付きの bytes を `node:worker_threads` へ渡し、cancel / opt-out では `await worker.terminate()` と listener 解除を済ませ、世代 ID が一致する結果だけで cache / UI を更新する。

- transfer するのは専有した非 `SharedArrayBuffer` だけにし、transfer 後は送信側の view を使わない（同じ backing store の view はすべて detach される）。`Buffer` は pool を共有し得るので、offset 付き view や所有が曖昧な buffer は必要範囲だけを別 buffer へ copy して渡す。

- worker や別プロセスから受け取った結果をそのまま cache / 表示しない。許可キー検査は `Reflect.ownKeys`、必須キーの存在確認は `Object.hasOwn` で行う（`Object.keys` は非列挙の own property を見逃し、`in` や素の property 参照は継承値を通す）。

- 例外の `Error.name` や `FileSystemError.code` をそのままログ / UI へ出さない。既知 code の allowlist へ正規化し、未知は単一の汎用 code に落とす。path や token が名前に混ざるケースを防げる。

### Manifest / Docs / Localization

- `package.json` の commands、views、configuration、menus を変えたら、コード上の command ID / setting key と同時に確認する。

- Marketplace 表示や設定説明をローカライズしている拡張では、`package.nls.json` と対象言語の `package.nls.*.json` を同じ変更で更新する。

- 設定の並び順や説明を変えたら README の設定表、manifest consistency test、release notes の必要有無までまとめて見る。

### Language Model Tools

- Extension-provided LM Tools need strong `modelDescription` intent phrases. Prefer `Use when the user asks to ...` plus natural-language verbs for create/update/delete/toggle paths, and add a manifest/doc guard so future wording changes do not silently weaken agent-mode tool selection.

- - Treat `prepareInvocation().confirmationMessages` as extension custom confirmation text, not a complete approval bypass. VS Code / Copilot Chat can still show generic approval or Always Allow UI, so docs/settings should say they control custom confirmations only.

+ - For configuration from VS Code Chat, prefer native LM Tools when no external client is required; do not call them an external MCP server. Share validated domain operations with the GUI, expose only necessary actions, and use explicit enable/disable values rather than retry-sensitive toggles.

+ - Keep `prepareInvocation` side-effect free and request confirmation for mutations or sensitive disclosure. Revalidate input, cancellation, trust and the queried revision inside the locked write after confirmation. Host approval UI/policies still apply; custom confirmation text is not a bypass. Never accept secret values through tool arguments or silently widen execution permissions.

+ - Page query results and omit prompt, environment and raw-output payloads by default. Make sensitive detail retrieval explicit with disclosure confirmation; describe which metadata reaches the model and treat stored strings as data, not instructions.

+ - Return typed outcomes from shared operations; a GUI handler that catches errors and returns nothing cannot prove a tool succeeded. Keep committed IDs/success when only presentation fails, return a sanitized warning and tell the caller to query rather than repeat the mutation. Configuration saved is not work executed.

- Before publishing an extension with LM Tools, inspect the packaged VSIX rather than trusting source files: confirm `extension/package.json` has the intended version, expected `contributes.languageModelTools` count, and no `src/`, test payloads, or sourcemaps unless intentionally shipped.

### Generated Sections

- `START` / `END` marker で囲む generated section は単一の SSOT として扱う。

- 重複した marker pair を見つけたら、両方を残して追記せず、内容を統合して marker pair を1つに戻す。

### 命名の一貫性

公開前にパッケージ名・設定キー・コマンド名を統一：

| 項目 | 例 |

| ------------ | ----------------------------- |

| パッケージ名 | `copilot-scheduler` |

| 設定キー | `copilotScheduler.enabled` |

| コマンドID | `copilotScheduler.createTask` |

| ビューID | `copilotSchedulerTasks` |

### 通知の一元管理

通知は共通helperへ集約し、設定値をruntimeで既知enumへ正規化する。重複抑止、ログとの分離、action、securityの設計は [Notification Normalization](references/notification-normalization.md) を参照する。