# Multi-hive swarms

A **swarm** is a collection of agents that share an identity and
coordinate across one or more hives. A single hyperhive instance
running on one host is already a swarm (one hive). This doc covers
the additional config needed when the swarm spans multiple hosts.

## Terminology

- **hive** — a single hyperhive installation on one host. Has its
  own `services.hyperhive.domain` DNS name and its own set of agent
  containers.
- **swarm** — one or more hives whose operators have declared them
  as peers. Agents can be qualified as `agent@hive-domain`.
- **peer hive** — a remote hive declared under
  `services.hyperhive.swarm.peers` on the local host.

## Hive identity config

```nix
services.hyperhive = {
  domain   = "pr1ma.example.com";   # machine-addressable DNS domain
  hiveName  = "pr1ma";              # human display name (optional)
  swarmName = "constellat1on";      # shared swarm display name (optional)
};
```

`domain` is required when matrix federation is on (`matrix.enable`);
it drives `HYPERHIVE_HIVE_DOMAIN` in every container so agents can
form qualified labels (`iris@pr1ma.example.com`). `hiveName` and
`swarmName` are purely display — they surface in the dashboard chrome
header and per-agent system prompts. Federated hives at different
domains can share a `swarmName`.

See `docs/conventions.md` § Hive identity for the env-var chain
and `qualify()` / `qualified_label()` semantics.

## Declaring peer hives

```nix
services.hyperhive.swarm.peers = {
  "lab.example.com"  = { };                               # CA-trusted (Let's Encrypt etc.)
  "edge.corp"        = { certFingerprint = "sha256:…"; }; # self-signed TLS
};
```

The attrset key is the peer's DNS domain. `certFingerprint` is
optional:

- **Omitted / null** — the system CA bundle validates the peer's TLS
  cert. Correct for peers with Let's Encrypt or any standard CA cert.
- **Set** (`"sha256:…"`) — pin a specific cert fingerprint. Use this
  for peers whose self-signed TLS cert doesn't chain to a CA your
  host trusts.

The nix module serialises the attrset to a `HYPERHIVE_PEERS` JSON
array (`[{ domain, cert_fingerprint }]`) injected into the c0re
environment and forwarded to agent containers.

## What the config does at runtime

1. **Dashboard P33RS tab** — `parse_peer_hives()` in `dashboard.rs`
   reads `HYPERHIVE_PEERS` and includes
   `peer_hives: Vec<{ name, url }>` in `/api/state`. The dashboard
   shows a P33RS tab (hidden when the list is empty) with a card per
   peer linking to `https://{domain}/`. See
   `docs/web-ui/dashboard.md` § P33RS tab.

2. **Agent identity** — the same `HYPERHIVE_PEERS` env var is
   forwarded to agent containers by `meta.rs`; agent code can call
   `identity::peers()` to discover peer hives and address them with
   qualified names (`agent@domain`).

3. **Matrix federation** — when `matrix.enable` is on, tuwunel
   federates with the peer's matrix server at
   `matrix.{peer-domain}:8448`. No extra config needed; federation
   works as soon as the domains are reachable and TLS validates.
   See `docs/matrix.md` for federation firewall requirements.

## Bilateral setup

Each hive must declare the other. If hive A lists hive B as a peer,
B must also list A for agents on B to see A in their peer list:

```
# hive A (pr1ma.example.com)
services.hyperhive.swarm.peers."edge.corp" = { };

# hive B (edge.corp)
services.hyperhive.swarm.peers."pr1ma.example.com" = { certFingerprint = "sha256:…"; };
```

Mixed trust is fine: A trusts B via CA bundle (no fingerprint), B
pins A's self-signed cert.

## WireGuard inter-hive mesh (optional)

The peer config above uses public HTTPS for all inter-hive traffic.
For private deployments — or to reduce latency and TLS overhead on
intra-swarm traffic — hive-c0re can configure a host-to-host
WireGuard mesh.

### Generating keys

On each hive host:

```bash
wg genkey | install -m 0400 /dev/stdin /etc/wireguard/hive.key
wg pubkey < /etc/wireguard/hive.key   # → share this with peer operators
```

### Config example (two hives)

```nix
# hive A (pr1ma.example.com, mesh IP 10.100.0.1)
services.hyperhive = {
  swarm.wireguard = {
    enable        = true;
    privateKeyFile = "/etc/wireguard/hive.key";
    address        = "10.100.0.1/24";
    listenPort     = 51820;          # optional, default 51820
  };

  swarm.peers."edge.corp" = {
    certFingerprint    = "sha256:…";   # TLS trust (unchanged)
    wireguardPublicKey = "base64key="; # peer's wg pubkey
    wireguardEndpoint  = "203.0.113.42:51820"; # peer's public IP:port
    wireguardAddress   = "10.100.0.2/32";      # peer's mesh IP
  };
};

# hive B (edge.corp, mesh IP 10.100.0.2)
services.hyperhive = {
  swarm.wireguard = {
    enable        = true;
    privateKeyFile = "/etc/wireguard/hive.key";
    address        = "10.100.0.2/24";
  };

  swarm.peers."pr1ma.example.com" = {
    wireguardPublicKey = "base64key="; # hive A's wg pubkey
    wireguardEndpoint  = "198.51.100.1:51820";
    wireguardAddress   = "10.100.0.1/32";
  };
};
```

### What the mesh does

- `networking.wireguard.interfaces.wg-hive` is configured on the host
  (not inside agent containers; containers reach peers via the host's
  routing table).
- UDP port 51820 (or `listenPort`) is opened on the host firewall.
- `HYPERHIVE_PEERS` gains a `wireguard_address` field for each mesh
  peer so hive-c0re can reach intra-swarm services without a public
  DNS round-trip.
- `persistentKeepalive = 25` is set by default; override or null to
  disable (not needed when both sides have public IPs and no NAT).

### NAT / one-sided endpoints

If one host is behind NAT and can't accept incoming connections, only
that host needs a null `wireguardEndpoint` on the peer config — the
other side initiates. With keepalive on, the NAT hole stays open.

If both hosts are behind NAT, a STUN relay or a third host (exit node)
is required. Out of scope for v0.

## Cross-references

- `docs/conventions.md` § Hive identity — env vars, qualified labels
- `docs/matrix.md` — matrix federation, TLS cert auto-generation,
  firewall posture
- `docs/web-ui/dashboard.md` § P33RS tab — dashboard surface
- `docs/gateway.md` — nginx vhosts and the `.well-known/matrix/`
  auto-discovery scheme