install: use GITHUB_TOKEN for authenticated GitHub requests

When the GITHUB_TOKEN environment variable is set, pass it as an
Authorization header on curl/wget downloads and embed it in the git
remote URL for ls-remote. This helps avoid rate limits and enables
installation from private repositories.

When GITHUB_TOKEN is unset, behavior is unchanged — the auth arrays
expand to nothing and the git remote URL stays unauthenticated.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: devm33

install.sh

@@ -34,6 +34,16 @@ case "$(uname -m)" in
   *) echo "Error: Unsupported architecture $(uname -m)" >&2 ; exit 1 ;;
 esac
 
+# Set up authentication for GitHub requests if GITHUB_TOKEN is available
+CURL_AUTH=()
+WGET_AUTH=()
+GIT_REMOTE="https://github.com/github/copilot-cli"
+if [ -n "$GITHUB_TOKEN" ]; then
+  CURL_AUTH=(-H "Authorization: token $GITHUB_TOKEN")
+  WGET_AUTH=(--header="Authorization: token $GITHUB_TOKEN")
+  GIT_REMOTE="https://x-access-token:${GITHUB_TOKEN}@github.com/github/copilot-cli"
+fi
+
 # Determine download URL based on VERSION
 if [ "${VERSION}" = "latest" ] || [ -z "$VERSION" ]; then
   DOWNLOAD_URL="https://github.com/github/copilot-cli/releases/latest/download/copilot-${PLATFORM}-${ARCH}.tar.gz"
@@ -44,7 +54,7 @@ elif [ "${VERSION}" = "prerelease" ]; then
     echo "Error: git is required to install prerelease versions" >&2
     exit 1
   fi
-  VERSION="$(git ls-remote --tags https://github.com/github/copilot-cli | tail -1 | awk -F/ '{print $NF}')"
+  VERSION="$(git ls-remote --tags "$GIT_REMOTE" | tail -1 | awk -F/ '{print $NF}')"
   if [ -z "$VERSION" ]; then
     echo "Error: Could not determine prerelease version" >&2
     exit 1
@@ -67,9 +77,9 @@ echo "Downloading from: $DOWNLOAD_URL"
 TMP_DIR="$(mktemp -d)"
 TMP_TARBALL="$TMP_DIR/copilot-${PLATFORM}-${ARCH}.tar.gz"
 if command -v curl >/dev/null 2>&1; then
-  curl -fsSL "$DOWNLOAD_URL" -o "$TMP_TARBALL"
+  curl -fsSL "${CURL_AUTH[@]}" "$DOWNLOAD_URL" -o "$TMP_TARBALL"
 elif command -v wget >/dev/null 2>&1; then
-  wget -qO "$TMP_TARBALL" "$DOWNLOAD_URL"
+  wget -qO "$TMP_TARBALL" "${WGET_AUTH[@]}" "$DOWNLOAD_URL"
 else
   echo "Error: Neither curl nor wget found. Please install one of them."
   rm -rf "$TMP_DIR"
@@ -80,9 +90,9 @@ fi
 TMP_CHECKSUMS="$TMP_DIR/SHA256SUMS.txt"
 CHECKSUMS_AVAILABLE=false
 if command -v curl >/dev/null 2>&1; then
-  curl -fsSL "$CHECKSUMS_URL" -o "$TMP_CHECKSUMS" 2>/dev/null && CHECKSUMS_AVAILABLE=true
+  curl -fsSL "${CURL_AUTH[@]}" "$CHECKSUMS_URL" -o "$TMP_CHECKSUMS" 2>/dev/null && CHECKSUMS_AVAILABLE=true
 elif command -v wget >/dev/null 2>&1; then
-  wget -qO "$TMP_CHECKSUMS" "$CHECKSUMS_URL" 2>/dev/null && CHECKSUMS_AVAILABLE=true
+  wget -qO "$TMP_CHECKSUMS" "${WGET_AUTH[@]}" "$CHECKSUMS_URL" 2>/dev/null && CHECKSUMS_AVAILABLE=true
 fi
 
 if [ "$CHECKSUMS_AVAILABLE" = true ]; then