Add git-constraint-helper

Author: rkunjappan

.github/scripts/create-multidev.sh

@@ -1,10 +1,13 @@
 #!/bin/bash
 set -euo pipefail
 
+# Source the constraint helper to auto-detect the right Composer version.
+. "$(dirname "${BASH_SOURCE[0]}")/git-constraint-helper"
+
 MULTIDEV_NAME="$1"
 TERMINUS_SITE="$2"
 GITHUB_ENV_FILE="${3:-${GITHUB_ENV:-}}"
-GIT_REF="${4:-dev-1.0.x}"
+CONSTRAINT=$(get_current_constraint)
 
 # Limit multidev name to 11 characters
 MULTIDEV="${MULTIDEV_NAME:0:11}"
@@ -32,9 +35,12 @@ cd pantheon-site
 echo "Checking out branch $MULTIDEV..."
 git checkout "$MULTIDEV"
 
-# Add pantheon_content_publisher module via composer
+# Add pantheon_content_publisher module via composer.
+# The VCS repo is needed so Composer can resolve dev branch constraints
+# (packages.drupal.org only serves tagged releases).
 composer config repositories.pantheon_content_publisher '{"type": "vcs", "url": "git@github.com:pantheon-systems/pantheon-content-publisher-drupal.git", "canonical": false}'
-composer require drupal/pantheon_content_publisher:"${GIT_REF}"
+echo "Installing drupal/pantheon_content_publisher:${CONSTRAINT}"
+composer require drupal/pantheon_content_publisher:"${CONSTRAINT}"
 
 # Show where the module was installed for diagnostics.
 echo "Module installed at:"

.github/scripts/git-constraint-helper

@@ -0,0 +1,55 @@
+#!/bin/bash
+#
+# @file Git Constraint Helper
+# Determines the correct Composer version constraint based on the current
+# Git state (branch, tag, or PR context).
+#
+# Usage:
+#   . "$(dirname "${BASH_SOURCE[0]}")/git-constraint-helper"
+#   CONSTRAINT=$(get_current_constraint)
+#   composer require drupal/pantheon_content_publisher:"$CONSTRAINT"
+
+# Format a branch name as a Composer dev constraint.
+# Composer uses two formats:
+#   - Version-like branches (1.0.x, 2.x) → "1.0.x-dev" (suffix)
+#   - Non-version branches (main, feature/foo) → "dev-main" (prefix)
+_branch_to_constraint() {
+  local branch="$1"
+  if [[ "$branch" =~ ^v?[0-9]+(\.[0-9x]+)+ ]]; then
+    echo "${branch}-dev"
+  else
+    echo "dev-${branch}"
+  fi
+}
+
+get_current_constraint() {
+  # 1. On a named branch?
+  local branch
+  branch=$(git rev-parse --abbrev-ref HEAD | tr -d '[:space:]')
+  if [ "$branch" != "HEAD" ]; then
+    _branch_to_constraint "$branch"
+    return
+  fi
+
+  # 2. On an exact tag (detached HEAD at a release)?
+  local tag
+  tag=$(git describe --exact-match --tags "$(git log -n1 --pretty='%h')" 2>/dev/null | tr -d '[:space:]')
+  if [ -n "$tag" ]; then
+    echo "$tag"
+    return
+  fi
+
+  # 3. In a GitHub Actions PR (detached HEAD)? Use GITHUB_HEAD_REF.
+  if [ -n "$GITHUB_HEAD_REF" ]; then
+    local pr_branch
+    IFS='/' read -ra parts <<< "$GITHUB_HEAD_REF"
+    pr_branch="${parts[-1]}"
+    if [ -n "$pr_branch" ]; then
+      _branch_to_constraint "$pr_branch"
+      return
+    fi
+  fi
+
+  # 4. Fallback to latest stable.
+  echo "^1"
+}

.github/workflows/pull_request.yml

@@ -107,7 +107,7 @@ jobs:
           ssh-private-key: ${{ secrets.PANTHEON_CI_SSH_KEY }}
 
       - name: Create multidev environment
-        run: .github/scripts/create-multidev.sh "$MULTIDEV_NAME" "$TERMINUS_SITE" "$GITHUB_ENV" "dev-${{ github.head_ref || github.ref_name }}"
+        run: .github/scripts/create-multidev.sh "$MULTIDEV_NAME" "$TERMINUS_SITE" "$GITHUB_ENV"
 
       - name: Clear cache
         run: |