Done.

[Download the HAProxy auto-update bundle](sandbox:/mnt/data/haproxy_auto_update_bundle.zip)

Included:

* `scripts/cluster-node-haproxy.sh`
* `README.md`

What it does:

* auto-adds a DB node to HAProxy backend
* auto-removes a DB node from HAProxy backend
* validates config
* reloads/restarts HAProxy

Example:

```bash
chmod +x scripts/cluster-node-haproxy.sh
./scripts/cluster-node-haproxy.sh add-replica db4 10.20.0.14 root@db4.example.com root@proxy1.example.com
```

Next I’ll do **backup + WAL archiving setup**.