ci(pr-gate): wait for slow Backend CI instead of timing out at 40 min

.github/workflows/pr-gate.yml

@@ -59,7 +59,7 @@ jobs:
       actions: read
     name: "PR Gate: Backend"
     runs-on: ubuntu-latest
-    timeout-minutes: 45
+    timeout-minutes: 150
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v6
         with:
@@ -116,13 +116,15 @@ jobs:
           github-token: ${{ github.token }}
           # "Backend CI Status Gate" is the final aggregate job of
           # backend-ci.yml. It is not created until every other backend job
-          # finishes (~8 min on a green run), so we poll up to 40 minutes for it
-          # to appear and complete. The job's timeout-minutes: 45 remains the hard bound.
+          # finishes (up to 80 min under runner contention), so we poll up to
+          # 140 minutes for it to appear and complete. The job's 150-minute
+          # timeout remains the hard bound.
           script: |
             const { owner, repo } = context.repo;
             const sha = process.env.HEAD_SHA;
             const CHECK_NAME = process.env.CHECK_NAME;
-            const deadline = Date.now() + 40 * 60 * 1000;
+            const started = Date.now();
+            const deadline = started + 140 * 60 * 1000;
             const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));
 
             const callWithRetry = async (fn) => {
@@ -190,6 +192,7 @@ jobs:
             };
 
             let delay = 30000;
+            let completedWithoutGate = false;
             while (Date.now() < deadline) {
               const res = await callWithRetry(() =>
                 github.rest.checks.listForRef({
@@ -216,6 +219,36 @@ jobs:
                 return;
               }
 
+              const workflowRes = await callWithRetry(() =>
+                github.rest.actions.listWorkflowRuns({
+                  owner,
+                  repo,
+                  workflow_id: 'backend-ci.yml',
+                  head_sha: sha,
+                  event: 'pull_request',
+                  per_page: 20,
+                })
+              );
+              if (!workflowRes) {
+                break;
+              }
+              const workflowRuns = workflowRes.data?.workflow_runs || [];
+              if (workflowRuns.length === 0 && Date.now() - started >= 10 * 60 * 1000) {
+                core.setFailed('Backend paths changed but Backend CI was not triggered within 10 minutes; path lists in pr-gate.yml and backend-ci.yml may have drifted.');
+                return;
+              }
+              if (runs.length === 0 && workflowRuns.length > 0 && workflowRuns.every(r => r.status === 'completed')) {
+                if (completedWithoutGate) {
+                  core.setFailed(`Backend CI completed without ${CHECK_NAME} check run. Run conclusion: ${workflowRuns.map(r => r.conclusion || 'unknown').join(', ')}`);
+                  return;
+                }
+                completedWithoutGate = true;
+                core.info(`Backend CI completed (${workflowRuns.map(r => r.conclusion || 'unknown').join(', ')}); rechecking for ${CHECK_NAME}.`);
+              } else {
+                completedWithoutGate = false;
+                core.info(`Backend CI run status: ${workflowRuns.length ? workflowRuns.map(r => r.status).join(', ') : 'not triggered yet'}.`);
+              }
+
               const remaining = Math.max(0, deadline - Date.now());
               if (remaining === 0) {
                 break;