🚀 Feature Request: Support extension version pinning in devcontainer.json

まず devcontainer.json スキーマと、customizations.vscode.extensions の既存の処理を見つけます。提案されている文字列構文とオプションのオブジェクト構文を比較し、そのうえで、固定されたバージョンに必要な検証およびインストールの動作を判断します。対応済みとは、サポートされ文書化された構文によって、固定されていない宣言を壊すことなく、要求された拡張機能のバージョンを確実にインストールできることです。

Problem

Currently, when defining extensions in devcontainer.json:

{
  "customizations": {
    "vscode": {
      "extensions": [
        "ms-dotnettools.csharp"
      ]
    }
  }
}

The latest version of the extension is always installed.

This creates issues in team environments because:

• Extension updates can introduce breaking changes
• Developers may end up with inconsistent environments
• Builds and development workflows become less predictable

---

Proposed Solution

Allow specifying a version when declaring extensions, for example:

{
  "customizations": {
    "vscode": {
      "extensions": [
        "ms-dotnettools.csharp@1.25.0"
      ]
    }
  }
}

---

Alternative Syntax (optional)

Another possible approach could be:

{
  "customizations": {
    "vscode": {
      "extensions": [
        {
          "id": "ms-dotnettools.csharp",
          "version": "1.25.0"
        }
      ]
    }
  }
}

---

Benefits

• Reproducible development environments
• Better stability for teams and CI/CD workflows
• Alignment with other ecosystems (e.g., npm, pip, Docker image tags)
• Eliminates need for manual .vsix workarounds

---

Current Workarounds

• Manually downloading .vsix files and installing them via scripts
• Using postCreateCommand to install specific versions (not always reliable)
• Maintaining custom Docker images with pre-installed extensions

These approaches add complexity and reduce maintainability.

---

Additional Context

This feature would significantly improve Dev Container usability in professional environments, especially for teams working with strict version control and reproducibility requirements.

---

Thank you 🙏

Thanks for the amazing work on Dev Containers! This feature would make it even more powerful for team-based development.