chore(ci): diagnostic v2 — capture headers to attribute the 500s

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.gitea/workflows/diag-staging.yml

@@ -15,12 +15,14 @@ jobs:
         env:
           BASE: ${{ secrets.STAGING_BASE_URL }}
         run: |
-          echo "== /api/filters years =="
-          curl -s --max-time 15 "$BASE/api/filters" -o /tmp/f.json -w "status %{http_code}\n"
-          python3 -c "import json; print(json.load(open('/tmp/f.json')).get('years'))" || head -c 300 /tmp/f.json
-          echo "== /api/rankings probes (metric=rwm_expected_pct, limit=3) =="
-          for Q in "" "&year=202425" "&year=201819" "&year=2024"; do
-            CODE=$(curl -s --max-time 15 -o /tmp/r.json -w "%{http_code}" "$BASE/api/rankings?metric=rwm_expected_pct&limit=3$Q")
-            echo "query [$Q] -> status $CODE"
-            python3 -c "import json; d=json.load(open('/tmp/r.json')); print('  year:', d.get('year'), 'total:', d.get('total'), 'rows:', len(d.get('rankings', [])))" || head -c 300 /tmp/r.json
-          done
+          probe() {
+            echo "== $1 =="
+            curl -s --max-time 15 -D /tmp/h.txt -o /tmp/b.txt "$BASE$1"
+            echo "--- headers:"; cat /tmp/h.txt
+            echo "--- body (first 400 bytes):"; head -c 400 /tmp/b.txt; echo
+          }
+          probe "/api/data-info"
+          probe "/api/filters"
+          probe "/api/rankings?metric=rwm_expected_pct&limit=3"
+          probe "/api/rankings?metric=rwm_expected_pct&limit=3&year=202425"
+          probe "/"