ci(sync): auto-open main to develop PR after main checks

Author: deeleeramone

.github/workflows/sync-main-to-develop.yml

@@ -0,0 +1,80 @@
+name: Sync main to develop
+
+on:
+  workflow_run:
+    workflows:
+      - Deploy Documentation
+    types:
+      - completed
+
+permissions:
+  contents: read
+  pull-requests: write
+
+concurrency:
+  group: sync-main-to-develop
+  cancel-in-progress: false
+
+jobs:
+  open-sync-pr:
+    name: Open main -> develop sync PR
+    if: >-
+      github.event.workflow_run.conclusion == 'success' &&
+      github.event.workflow_run.event == 'push' &&
+      github.event.workflow_run.head_branch == 'main'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Create or reuse sync PR
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const owner = context.repo.owner;
+            const repo = context.repo.repo;
+            const base = "develop";
+            const head = "main";
+
+            // Only open a PR when main is ahead of develop.
+            const compare = await github.rest.repos.compareCommitsWithBasehead({
+              owner,
+              repo,
+              basehead: `${base}...${head}`,
+            });
+
+            if (compare.data.ahead_by === 0) {
+              core.info("main is not ahead of develop; no sync PR needed.");
+              return;
+            }
+
+            const existing = await github.rest.pulls.list({
+              owner,
+              repo,
+              state: "open",
+              base,
+              head: `${owner}:${head}`,
+              per_page: 10,
+            });
+
+            if (existing.data.length > 0) {
+              core.info(`Sync PR already open: #${existing.data[0].number}`);
+              return;
+            }
+
+            const run = context.payload.workflow_run;
+            const body = [
+              "Automated branch sync after successful post-merge checks on main.",
+              "",
+              `Source commit: ${run.head_sha}`,
+              `Source workflow run: ${run.html_url}`,
+            ].join("\n");
+
+            const created = await github.rest.pulls.create({
+              owner,
+              repo,
+              title: "chore(sync): merge main into develop",
+              head,
+              base,
+              body,
+              maintainer_can_modify: true,
+            });
+
+            core.info(`Created sync PR #${created.data.number}`);