# 3. Central Verae NATS.IO 3-server cluster

All durable messaging for this product is **NATS JetStream**, not Zapier queues and not a public TCP API.

## Cluster

Three `nats-server -js` nodes form the Verae cluster (routes between them, JetStream replication). Clients (middleware, poller, aggregator, WORM, tree nodes, account-balance, zappier-edge billing, CS/sales/accounting, and any new process cloned from `verae-nats-process`) connect with a **cluster URL list**, for example:

```text
nats://127.0.0.1:4222,nats://127.0.0.1:4223,nats://127.0.0.1:4224
```

On a given machine the listener stays on **loopback** (or a private interface). Operators reach it with `scripts/nats-tunnel.sh` / `ssh -L 14222:127.0.0.1:4222`. **Do not bind 4222 on `0.0.0.0` without auth.**

Today’s NS1 box (`NS1.GEORGELAMBERT.ORG`, `70.88.205.138`) already runs JetStream on `127.0.0.1:4222`. The **target** is three clustered nodes so losing one server does not lose the stream. Fleet SSH hosts (`ns1`, later `lan-134`) run **workers**, not extra public NATS listeners.

![NATS cluster](diagrams/nats-cluster.svg)

## Who may connect

| Allowed | Forbidden |
|---------|-----------|
| access-authz, access-leaf (after token), middleware, fleet workers, WORM, tree, account-balance, access planes, CS/sales | Zapier cloud, customer browsers (HTTPS to access-web / access-api / access-zapier only) |

## Address families already in use

| Address | Kind | Notes |
|---------|------|--------|
| `verae.zapier.jobs.watch` | work queue | poller |
| `verae.zapier.jobs.events` | events | wait + webhooks |
| `verae.zapier.webhooks.deliver` | work queue | HTTPS to Zapier REST Hook |
| `verae.zapier.usage` | optional | metering |
| `verae.billing.statement.get` | request-reply | portal, CS, sales, admin |
| `verae.billing.balance.adjust` | request-reply | CS credits, portal reload |
| `verae.billing.usage.recorded` | pub | zappier-edge meter |
| `verae.archive.put` | JetStream | splitter / merkle builder |
| `verae.archive.query` | **broadcast** (no queue group) | every WORM and tree node |
| `verae.archive.reply.<correlationId>` | replies | **only on bloom hit** |

New functions get new `verae.<area>.<resource>.<action>` addresses — see [06-address-routing.md](06-address-routing.md).