diff --git a/.github/workflows/pg-diagnose.yml b/.github/workflows/pg-diagnose.yml
new file mode 100644
index 00000000..73c6a399
--- /dev/null
+++ b/.github/workflows/pg-diagnose.yml
@@ -0,0 +1,96 @@
+name: Diagnose PostgreSQL state on liderra.ru
+
+# Read-only diagnostic для incident "PG не принимает connections".
+# Запускается вручную: gh workflow run pg-diagnose.yml --ref <branch>
+# Ничего не меняет на проде — только читает systemctl/journalctl/df/free/uptime
+# + tail последних 200 строк postgresql-16-main.log.
+
+on:
+  workflow_dispatch:
+
+jobs:
+  diagnose:
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+
+    env:
+      LIDERRA_HOST: 111.88.246.137
+      LIDERRA_USER: ubuntu
+
+    steps:
+      - name: Setup SSH key
+        run: |
+          mkdir -p ~/.ssh
+          echo "${{ secrets.LIDERRA_SSH_KEY }}" > ~/.ssh/liderra_deploy
+          chmod 600 ~/.ssh/liderra_deploy
+          ssh-keyscan -H ${{ env.LIDERRA_HOST }} >> ~/.ssh/known_hosts 2>/dev/null
+
+      - name: Run PG diagnostic on prod
+        run: |
+          ssh -i ~/.ssh/liderra_deploy ${{ env.LIDERRA_USER }}@${{ env.LIDERRA_HOST }} \
+            "bash -s" <<'REMOTE' | tee /tmp/pg-diagnose.log
+          set +e
+          echo "=== 1. hostname + UTC time ==="
+          echo "host=$(hostname); utc=$(date -u)"
+          echo
+          echo "=== 2. uptime ==="
+          uptime
+          echo
+          echo "=== 3. last reboot ==="
+          who -b
+          last reboot --time-format=iso | head -5
+          echo
+          echo "=== 4. df -h / and /var ==="
+          df -h / /var /var/lib/postgresql 2>&1 | head -10
+          echo
+          echo "=== 5. free -h ==="
+          free -h
+          echo
+          echo "=== 6. systemctl status postgresql ==="
+          sudo systemctl status postgresql --no-pager 2>&1 | head -30
+          echo
+          echo "=== 7. systemctl status postgresql@16-main (cluster) ==="
+          sudo systemctl status postgresql@16-main --no-pager 2>&1 | head -30
+          echo
+          echo "=== 8. nginx + php-fpm status (one-line each) ==="
+          sudo systemctl is-active nginx php8.3-fpm liderra-queue 2>&1
+          echo
+          echo "=== 9. ps aux | postgres (top 15) ==="
+          ps auxf | grep -E "(postgres|recovery)" | grep -v grep | head -15
+          echo
+          echo "=== 10. journalctl postgresql last 80 lines ==="
+          sudo journalctl -u postgresql -n 80 --no-pager 2>&1 | tail -80
+          echo
+          echo "=== 11. journalctl postgresql@16-main last 80 lines ==="
+          sudo journalctl -u postgresql@16-main -n 80 --no-pager 2>&1 | tail -80
+          echo
+          echo "=== 12. tail -100 /var/log/postgresql/postgresql-16-main.log ==="
+          sudo tail -100 /var/log/postgresql/postgresql-16-main.log 2>&1
+          echo
+          echo "=== 13. WAL size and count ==="
+          sudo du -sh /var/lib/postgresql/16/main/pg_wal 2>&1
+          sudo ls /var/lib/postgresql/16/main/pg_wal 2>&1 | wc -l
+          echo
+          echo "=== 14. dmesg tail (kernel events, OOM, IO errors) ==="
+          sudo dmesg -T 2>&1 | tail -40
+          echo
+          echo "=== 15. liderra.ru HTTPS probe ==="
+          curl -sI -o /dev/null -w "HTTP %{http_code}\nTotal: %{time_total}s\n" https://liderra.ru/ --max-time 10
+          echo
+          echo "=== DONE ==="
+          REMOTE
+
+      - name: Print summary
+        if: always()
+        run: |
+          {
+            echo "## PG diagnostic on liderra.ru"
+            echo
+            echo '```'
+            cat /tmp/pg-diagnose.log 2>/dev/null || echo "(no log captured)"
+            echo '```'
+          } >> "$GITHUB_STEP_SUMMARY"
+
+      - name: Cleanup SSH key
+        if: always()
+        run: rm -f ~/.ssh/liderra_deploy