feat: Add installation script for GitHub Copilot CLI and update README with environment variable options

Author: glav

.devcontainer/install-copilot-cli.sh

@@ -0,0 +1,74 @@
+#!/usr/bin/env bash
+
+set -e
+set -o pipefail
+
+## Optional Environment Variables:
+
+SKIP_INSTALL_COPILOT_CLI="${SKIP_INSTALL_COPILOT_CLI:-}" # Set to 'true' to skip installing Copilot CLI
+COPILOT_CLI_VERSION="${COPILOT_CLI_VERSION:-}"           # Optional version (ex. 'v0.0.369'); defaults to latest when unset
+COPILOT_CLI_PREFIX="${COPILOT_CLI_PREFIX:-}"             # Optional install prefix; defaults per official installer
+
+log() {
+	printf "========== %s ==========%s" "$1" $'\n'
+}
+
+err() {
+	printf "[ ERROR ]: %s%s" "$1" $'\n' >&2
+	exit 1
+}
+
+require_downloader() {
+	if command -v curl &>/dev/null; then
+		echo "curl"
+		return 0
+	fi
+
+	if command -v wget &>/dev/null; then
+		echo "wget"
+		return 0
+	fi
+
+	err "Either 'curl' or 'wget' is required to install Copilot CLI"
+}
+
+install_copilot_cli() {
+	if [[ ${SKIP_INSTALL_COPILOT_CLI,,} == "true" ]]; then
+		log "Skipping Copilot CLI install"
+		return 0
+	fi
+
+	local downloader
+	downloader="$(require_downloader)"
+
+	log "Installing Copilot CLI (standalone)"
+
+	if [[ $downloader == "curl" ]]; then
+		if [[ $COPILOT_CLI_VERSION || $COPILOT_CLI_PREFIX ]]; then
+			VERSION="$COPILOT_CLI_VERSION" PREFIX="$COPILOT_CLI_PREFIX" curl -fsSL https://gh.io/copilot-install | bash
+		else
+			curl -fsSL https://gh.io/copilot-install | bash
+		fi
+	else
+		if [[ $COPILOT_CLI_VERSION || $COPILOT_CLI_PREFIX ]]; then
+			VERSION="$COPILOT_CLI_VERSION" PREFIX="$COPILOT_CLI_PREFIX" wget -qO- https://gh.io/copilot-install | bash
+		else
+			wget -qO- https://gh.io/copilot-install | bash
+		fi
+	fi
+
+	if [[ ! $COPILOT_CLI_PREFIX ]]; then
+		export PATH="$HOME/.local/bin:$PATH"
+	else
+		export PATH="$COPILOT_CLI_PREFIX/bin:$PATH"
+	fi
+
+	if ! command -v copilot &>/dev/null; then
+		err "Copilot CLI install completed but 'copilot' is not on PATH"
+	fi
+
+	copilot --version || true
+	log "Copilot CLI is available via 'copilot'"
+}
+
+install_copilot_cli

.devcontainer/post-script.sh

@@ -3,6 +3,12 @@
 set -e
 set -o pipefail
 
+## Optional Environment Variables:
+
+SKIP_INSTALL_COPILOT_CLI="${SKIP_INSTALL_COPILOT_CLI:-}" # Set to 'true' to skip installing Copilot CLI
+COPILOT_CLI_VERSION="${COPILOT_CLI_VERSION:-}"           # Optional version (ex. 'v0.0.369'); defaults to latest when unset
+COPILOT_CLI_PREFIX="${COPILOT_CLI_PREFIX:-}"             # Optional install prefix; defaults per official installer
+
 log() {
 	printf "========== %s ==========%s" "$1" $'\n'
 }
@@ -37,6 +43,8 @@ install_uv() {
 
 install_uv
 
+bash .devcontainer/install-copilot-cli.sh
+
 echo ----------------------------------------------
 echo If you want help using the prompt library or list
 echo of available prompts, simply type:

README.md

@@ -66,3 +66,13 @@ This template includes an `.agent/` directory containing reusable prompt “comm
 - `.agent/instructions/`: “apply-to” instructions that guide how agents write certain file types (e.g. Bash and Bicep)
 
 If you base a new repository on this template, treat `.agent/` as a starting library: keep what helps your team, remove what doesn’t, and add org-specific workflows over time.
+
+## Copilot CLI (devcontainer)
+
+The devcontainer runs a post-create script that installs GitHub Copilot CLI using the official installer (`https://gh.io/copilot-install`).
+
+Optional environment variables:
+
+- `SKIP_INSTALL_COPILOT_CLI=true`: skip installing Copilot CLI
+- `COPILOT_CLI_VERSION=vX.Y.Z`: install a specific version tag (defaults to latest)
+- `COPILOT_CLI_PREFIX=/some/path`: install to a custom prefix (defaults per installer)