fix(CI): cancel a PR's CI when the PR closes (#26719)

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-authored-by: CodeRabbit <coderabbitai[bot]@users.noreply.github.com>

.github/workflows/cancel-pr-runs-on-close.yml

@@ -0,0 +1,48 @@
+name: cancel-pr-runs-on-close
+on:
+  # pull_request_target, not pull_request: for a PR from a fork the GITHUB_TOKEN
+  # of a pull_request run is read-only, so the cancel would 403. This workflow
+  # never checks out or runs PR code, so the elevated token is not exposed to it.
+  pull_request_target:
+    types:
+      - closed
+
+permissions:
+  actions: write
+
+jobs:
+  cancel:
+    runs-on: ubuntu-latest
+    name: cancel CI still running for the closed PR
+    if: github.repository == 'azerothcore/azerothcore-wotlk'
+    steps:
+      - name: Cancel workflow runs for this PR
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GH_REPO: ${{ github.repository }}
+          PR_SHA: ${{ github.event.pull_request.head.sha }}
+          PR_REPO: ${{ github.event.pull_request.head.repo.full_name }}
+        run: |
+          set -euo pipefail
+
+          # head_sha alone would let anyone cancel another PR's CI: push that
+          # PR's head commit to your own fork, open a PR and close it, and every
+          # run for the commit matches. So the run must also come from this PR's
+          # head repository. `gh run list` exposes neither head_repository nor
+          # the (fork-empty) pull_requests field, hence the raw API call.
+          gh api "repos/${GH_REPO}/actions/runs?event=pull_request&head_sha=${PR_SHA}&per_page=100" \
+            --jq '.workflow_runs[]
+                  | select(.head_repository.full_name == env.PR_REPO and .status != "completed")
+                  | .id' \
+          | while read -r id; do
+              # gh has no bulk cancel. A run that finishes between the listing
+              # and the cancel returns 409, which is not worth failing over.
+              if ! err=$(gh run cancel "$id" 2>&1); then
+                if echo "$err" | grep -Fq "HTTP 409"; then
+                  echo "::warning::run $id was already finished"
+                else
+                  echo "::error::Failed to cancel run $id: $err"
+                  exit 1
+                fi
+              fi
+            done

.github/workflows/core-build-nopch.yml

@@ -20,8 +20,9 @@ concurrency:
   #
   # - PRs use `refs/pull/<PR_NUMBER>/merge`, so new commits cancel older
   #   in-progress runs for the same PR.
-  # - When a PR is merged, a push to the target branch starts a new group,
-  #   canceling any still-running PR CI.
+  # - A merge does NOT cancel the PR's own runs: this group is keyed on
+  #   refs/pull/<N>/merge and the master push on refs/heads/master, so they
+  #   never share a group. See the cancel-pr-runs-on-close workflow.
   # - Branch pushes are isolated by ref.
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true

.github/workflows/core-build-pch.yml

@@ -20,8 +20,9 @@ concurrency:
   #
   # - PRs use `refs/pull/<PR_NUMBER>/merge`, so new commits cancel older
   #   in-progress runs for the same PR.
-  # - When a PR is merged, a push to the target branch starts a new group,
-  #   canceling any still-running PR CI.
+  # - A merge does NOT cancel the PR's own runs: this group is keyed on
+  #   refs/pull/<N>/merge and the master push on refs/heads/master, so they
+  #   never share a group. See the cancel-pr-runs-on-close workflow.
   # - Branch pushes are isolated by ref.
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true

.github/workflows/core_modules_build.yml

@@ -28,8 +28,9 @@ concurrency:
   #
   # - PRs use `refs/pull/<PR_NUMBER>/merge`, so new commits cancel older
   #   in-progress runs for the same PR.
-  # - When a PR is merged, a push to the target branch starts a new group,
-  #   canceling any still-running PR CI.
+  # - A merge does NOT cancel the PR's own runs: this group is keyed on
+  #   refs/pull/<N>/merge and the master push on refs/heads/master, so they
+  #   never share a group. See the cancel-pr-runs-on-close workflow.
   # - Branch pushes are isolated by ref.
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true

.github/workflows/docker_build.yml

@@ -13,8 +13,9 @@ concurrency:
   #
   # - PRs use `refs/pull/<PR_NUMBER>/merge`, so new commits cancel older
   #   in-progress runs for the same PR.
-  # - When a PR is merged, a push to the target branch starts a new group,
-  #   canceling any still-running PR CI.
+  # - A merge does NOT cancel the PR's own runs: this group is keyed on
+  #   refs/pull/<N>/merge and the master push on refs/heads/master, so they
+  #   never share a group. See the cancel-pr-runs-on-close workflow.
   # - Branch pushes are isolated by ref.
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true

.github/workflows/tools_build.yml

@@ -13,8 +13,9 @@ concurrency:
   #
   # - PRs use `refs/pull/<PR_NUMBER>/merge`, so new commits cancel older
   #   in-progress runs for the same PR.
-  # - When a PR is merged, a push to the target branch starts a new group,
-  #   canceling any still-running PR CI.
+  # - A merge does NOT cancel the PR's own runs: this group is keyed on
+  #   refs/pull/<N>/merge and the master push on refs/heads/master, so they
+  #   never share a group. See the cancel-pr-runs-on-close workflow.
   # - Branch pushes are isolated by ref.
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true

.github/workflows/windows_build.yml

@@ -13,8 +13,9 @@ concurrency:
   #
   # - PRs use `refs/pull/<PR_NUMBER>/merge`, so new commits cancel older
   #   in-progress runs for the same PR.
-  # - When a PR is merged, a push to the target branch starts a new group,
-  #   canceling any still-running PR CI.
+  # - A merge does NOT cancel the PR's own runs: this group is keyed on
+  #   refs/pull/<N>/merge and the master push on refs/heads/master, so they
+  #   never share a group. See the cancel-pr-runs-on-close workflow.
   # - Branch pushes are isolated by ref.
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true