Update init --codespaces to merge with existing devcontainer.json

[Copilot]

The init --codespaces command previously created devcontainer.json in a subfolder (.devcontainer/gh-aw/) to avoid conflicts. This required users to manually merge configurations when a devcontainer already existed at the default location.

Changes

• Modified ensureDevcontainerConfig() to check for existing devcontainer at .devcontainer/devcontainer.json first
• Merge strategy when existing file found:
  • Preserves: name, image, existing extensions, features, postCreateCommand
  • Adds: GitHub Copilot extensions, gh-aw features, Codespaces repository permissions
  • Appends: gh-aw installation to postCreateCommand (if not present)
  • Updates: old copilot-cli versions to :latest
• Creates at default location when no existing file found (not in subfolder)

Example

Existing devcontainer:

{
  "name": "Python Project",
  "image": "mcr.microsoft.com/devcontainers/python:3.11",
  "features": {
    "ghcr.io/devcontainers/features/docker-in-docker:2": {}
  }
}

After gh aw init --codespaces:

{
  "name": "Python Project",
  "image": "mcr.microsoft.com/devcontainers/python:3.11",
  "customizations": {
    "vscode": {
      "extensions": ["GitHub.copilot", "GitHub.copilot-chat"]
    },
    "codespaces": {
      "repositories": {
        "org/repo": { "permissions": { "workflows": "write", ... } }
      }
    }
  },
  "features": {
    "ghcr.io/devcontainers/features/docker-in-docker:2": {},
    "ghcr.io/devcontainers/features/github-cli:1": {},
    "ghcr.io/devcontainers/features/copilot-cli:latest": {}
  }
}

Helper Functions

• buildRepositoryPermissions() - constructs permissions map for current/additional repos
• mergeExtensions() - deduplicates extension arrays
• mergeFeatures() - merges feature maps, updates copilot-cli versions

Original prompt

The "init --codespaces" command should update an existing devcontainer file if it already exists instead of creating a new file in a subfolder. If it does not exist, create devcontainer file in default location

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[pelikhan]

@copilot add redhat yall extension