feat(devcontainer): install GitHub Copilot CLI

.devcontainer/devcontainer.json

@@ -49,6 +49,6 @@
             }
         }
     },
-    "updateContentCommand": "npm install -g opencode-ai",
+    "updateContentCommand": "npm install -g opencode-ai @github/copilot",
     "postCreateCommand": "opencode --version && echo 'Development environment ready'"
 }

.github/workflows/ci.yml

@@ -117,7 +117,7 @@ jobs:
           push: never
           runCmd: |
             set -eu
-            for cmd in python3 node npm gh opencode curl jq claude; do
+            for cmd in python3 node npm gh opencode copilot curl jq claude; do
               if ! command -v "$cmd" >/dev/null 2>&1; then
                 echo "::error::$cmd is missing"
                 exit 1

AGENTS.md

@@ -6,9 +6,9 @@ Guidance for AI agents and automated contributors working in this repository.
 
 This repository is a lean development container template for GitHub Codespaces
 and local VS Code Dev Containers. It defines a reproducible Ubuntu 26.04
-environment with Python 3, Node.js LTS, GitHub CLI, Claude Code CLI, and
-OpenCode TUI. The repository contains no application source code — all
-meaningful files are configuration.
+environment with Python 3, Node.js LTS, GitHub CLI, GitHub Copilot CLI, Claude
+Code CLI, and OpenCode TUI. The repository contains no application source code
+— all meaningful files are configuration.
 
 ## Repository layout
 
@@ -103,7 +103,7 @@ docker build --pull -t dev-template:local .devcontainer/
 npx -y @devcontainers/cli up --workspace-folder . --remove-existing-container
 npx @devcontainers/cli exec --workspace-folder . -- bash -c '
   set -eu
-  for cmd in python3 node npm gh opencode curl jq claude; do
+  for cmd in python3 node npm gh opencode copilot curl jq claude; do
     command -v "$cmd" || { echo "MISSING: $cmd"; exit 1; }
   done
   claude --version
@@ -131,7 +131,7 @@ npx @devcontainers/cli exec --workspace-folder . -- bash -c '
   re-run its `install.cjs`) to `updateContentCommand` — that step runs as user
   `vscode` and fails with `EACCES` trying to rename the root-owned package
   (this broke CI in PR #51). `updateContentCommand` should only install
-  user-writable packages (currently just `opencode-ai`).
+  user-writable packages (currently `opencode-ai` and `@github/copilot`).
 - **CI runs on Copilot/bot-authored PR branches often show `action_required`**
   and won't execute automatically. Approve them in the GitHub UI, or run
   `gh run rerun <run-id> --repo idvoretskyi/dev` to trigger them.

README.md

@@ -15,8 +15,10 @@ Codespaces and local VS Code Dev Containers.
   - Python 3 with `venv` and `pip`
   - Node.js LTS with `npm`
   - GitHub CLI
+  - GitHub Copilot CLI
   - Claude Code CLI (authenticated session persisted across rebuilds)
-  - OpenCode TUI installed via `updateContentCommand` (cached by prebuilds)
+  - OpenCode TUI and GitHub Copilot CLI installed via `updateContentCommand`
+    (cached by prebuilds)
   - Bash shell with common utilities
   - Build essentials (`gcc`, `make`, and related packages) via base image
 - VS Code extensions:
@@ -35,9 +37,9 @@ The devcontainer is tuned for fast Codespaces startup:
 - `common-utils` configured with zsh and Oh My Zsh disabled
 - `curl`, `wget`, `jq`, and `git` sourced from the base image — not
   re-installed in the Dockerfile
-- OpenCode TUI installed in `updateContentCommand` instead of
-  `postCreateCommand`, so it is cached during Codespaces prebuilds and not
-  re-run on every start
+- OpenCode TUI and GitHub Copilot CLI installed in `updateContentCommand`
+  instead of `postCreateCommand`, so they are cached during Codespaces
+  prebuilds and not re-run on every start
 - Claude Code authentication stored in a named volume
   (`claude-code-config-${devcontainerId}`) so sign-in survives container
   rebuilds
@@ -77,14 +79,16 @@ created from `main` will start in approximately **10–25 seconds**.
 1. Click "Code" button on the GitHub repository
 2. Select "Create codespace on main"
 3. Wait for the environment to build
-4. Run `claude` in the integrated terminal and follow the authentication prompt
+4. Run `copilot` or `claude` in the integrated terminal and follow the
+   authentication prompt
 
 ### VS Code Local Dev Containers
 
 1. Clone this repository
 2. Open in VS Code
 3. Click "Reopen in Container" when prompted
-4. Run `claude` in the integrated terminal and follow the authentication prompt
+4. Run `copilot` or `claude` in the integrated terminal and follow the
+   authentication prompt
 
 ## Repository Structure