fix(deploy): migrate after stop and shrink DB pool

Stage migrate hit ER_CON_COUNT_ERROR while live still held the pool. Build in stage with DATABASE_POOL_SIZE=5, run db:migrate only after stopping the service (with retries), and lower the default pool from 40 to 10.

Co-authored-by: Cursor <[email protected]>

.gitea/workflows/deploy.yaml

@@ -293,9 +293,13 @@ jobs:
           find . -maxdepth 3 -name '*.tsbuildinfo' -delete 2>/dev/null || true
           rm -rf .output dist .next .next/types .next/dev
 
+          # Stage shares MySQL with the live app + emulator. Keep the stage pool
+          # tiny so install/test/build cannot exhaust max_connections.
+          export DATABASE_POOL_SIZE="${DEPLOY_DATABASE_POOL_SIZE:-5}"
+          echo "STAGE DATABASE_POOL_SIZE=${DATABASE_POOL_SIZE}"
+
           pnpm install --frozen-lockfile
-          # Additive migrations while the old build still serves traffic.
-          pnpm db:migrate
+          # prisma generate does not need a live DB connection.
           pnpm prisma:generate
           pnpm typecheck
           pnpm test
@@ -308,10 +312,29 @@ jobs:
             exit 1
           fi
 
-          echo "Cutover: stop service, sync code, swap .next artifact..."
+          echo "Cutover: stop service (free DB connections), migrate, swap .next..."
           CUTOVER_STARTED=1
           sudo systemctl stop atom-nexst.service || true
           pkill -f 'next-server' || true
+          # Give MariaDB a moment to reclaim the live pool.
+          sleep 2
+
+          # Migrate only after live is stopped — avoids ER_CON_COUNT_ERROR while
+          # the old process still holds DATABASE_POOL_SIZE connections.
+          cd "${STAGE}"
+          MIGRATE_OK=0
+          for i in 1 2 3 4 5; do
+            if pnpm db:migrate; then
+              MIGRATE_OK=1
+              break
+            fi
+            echo "migrate attempt ${i}/5 failed (likely DB connections), retrying..."
+            sleep 3
+          done
+          if [ "${MIGRATE_OK}" != "1" ]; then
+            echo "ERROR: db:migrate failed after retries" >&2
+            exit 1
+          fi
 
           cd "${LIVE}"
           echo "Hard reset live tree to origin/main (no nuclear src wipe)..."