fix(ci): enqueue merge queue as seahaven-bot (PLAT-108) (#38)

* fix(ci): enqueue merge queue as seahaven-bot

* fix(ci): limit seahaven-bot enqueue to PRs targeting main

.github/workflows/auto-merge.yaml

@@ -4,41 +4,65 @@ on:
   pull_request:
     types: [opened, ready_for_review, reopened, synchronize]
     branches: [main]
+  pull_request_review:
+    types: [submitted]
 
 concurrency:
   group: enable-auto-merge-${{ github.event.pull_request.number }}
   cancel-in-progress: true
 
 permissions:
-  contents: write
+  contents: read
-  pull-requests: write
 
 jobs:
   enable:
     if: >-
       github.event.pull_request.draft == false
+      && github.event.pull_request.base.ref == 'main'
       && github.event.pull_request.head.repo.full_name == github.repository
       && github.event.pull_request.user.login != 'dependabot[bot]'
       && github.event.pull_request.user.login != 'renovate[bot]'
+      && (github.event_name != 'pull_request_review' || github.event.review.state == 'approved')
     runs-on: ubuntu-latest
     steps:
-      - name: Enable squash auto-merge
+      - name: Mint seahaven-bot token
+        id: app-token
+        uses: actions/create-github-app-token@bcd2ba49218906704ab6c1aa796996da409d3eb1 # v3.2.0
+        with:
+          app-id: ${{ secrets.SEAHAVEN_BOT_APP_ID }}
+          private-key: ${{ secrets.SEAHAVEN_BOT_PRIVATE_KEY }}
+          owner: Sea-Haven-Industries
+          repositories: ${{ github.event.repository.name }}
+
+      - name: Enqueue or arm auto-merge
         env:
-          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GH_TOKEN: ${{ steps.app-token.outputs.token }}
           PR: ${{ github.event.pull_request.number }}
           REPO: ${{ github.repository }}
+          PR_NODE_ID: ${{ github.event.pull_request.node_id }}
         run: |
           set -euo pipefail
-          if [ "$(gh pr view "$PR" --repo "$REPO" --json autoMergeRequest --jq '.autoMergeRequest != null')" = "true" ]; then
+          in_queue="$(gh api graphql -f query='query($id:ID!) { node(id:$id) { ... on PullRequest { isInMergeQueue } } }' -f id="$PR_NODE_ID" --jq '.data.node.isInMergeQueue')"
-            echo "auto-merge already enabled"
+          if [ "$in_queue" = "true" ]; then
+            echo "already in merge queue"
             exit 0
           fi
-          if ! out=$(gh pr merge "$PR" --repo "$REPO" --auto 2>&1); then
+          set +e
-            echo "$out"
+          out="$(gh api graphql -f query='mutation($id:ID!) { enqueuePullRequest(input:{pullRequestId:$id}) { mergeQueueEntry { state } } }' -f id="$PR_NODE_ID" 2>&1)"
+          status=$?
+          set -e
+          if [ "$status" -eq 0 ]; then
+            printf '%s\n' "$out"
+            exit 0
+          fi
+          echo "$out"
+          # Re-arm as seahaven-bot. A leftover GITHUB_TOKEN auto-merge would
+          # enqueue without starting merge_group.
+          gh pr merge "$PR" --repo "$REPO" --disable-auto || true
+          if ! gh pr merge "$PR" --repo "$REPO" --auto; then
             if [ "$(gh pr view "$PR" --repo "$REPO" --json autoMergeRequest --jq '.autoMergeRequest != null')" = "true" ]; then
               echo "auto-merge already enabled"
               exit 0
             fi
             exit 1
           fi
-          printf '%s\n' "$out"