hyperhive/docs/integrations/matrix.md

hive-matrix

Private Matrix homeserver (matrix-tuwunel — the conduwuit successor) wrapped in a nixos-container, plus optional fluffychat-web client at chat.<swarm-domain>/ (the gatewayHost vhost). Configured via services.hyperhive.swarm.matrix.*; vhost routing lives in gateway.md.

Container shape

Same shape as gateway.md::hive-forge container shape:

• Container name hive-matrix (not h-*) so c0re's lifecycle scanner ignores it; operator manages via the standard nixos-container CLI.
• Keeps hive-matrix from fighting any services.matrix-* the operator already runs on the host — separate systemd namespace, separate state dir.
• Container shares the host network namespace (privateNetwork = false) for state + systemd-unit isolation. Agents reach the homeserver at chat.<swarm-domain> via the gateway (agents run in private netns and can't access host loopback directly).
• Persistent state at /var/lib/nixos-containers/hive-matrix/var/lib/matrix-tuwunel/ survives container restart / host reboot. To wipe, destroy the container.

Identity vs API listener: serverName vs gatewayHost

Two distinct hostnames:

• serverName — matrix-spec server_name, embedded irrevocably in every @user:<server_name> and !room:<server_name> identifier minted on this homeserver. can't be changed later without abandoning every account and chat history. Defaults to the bare services.hyperhive.swarm.domain; clients autodiscover the actual API endpoint via the .well-known/matrix/{client,server} routes the gateway serves at that domain.
• gatewayHost — the API listener hostname, where the gateway's matrix vhost proxies /_matrix/* to tuwunel. Defaults to chat.<services.hyperhive.swarm.domain>. Set to null to skip the gateway vhost (tuwunel stays direct on httpPort).

Both default under the swarm domain, because a swarm runs one homeserver: tying its identity to a single hive's domain would make relocating the container between hives look like a different homeserver.

⚠️ they're still not interchangeable, and the difference is the cost of changing one. gatewayHost is a routing detail clients rediscover through .well-known, so it's safe to move on a running deployment. The matrix id format bakes serverName into every user and room id, so adopting a new one does not rename the existing users and rooms — it strands them, because their ids still name a homeserver that no longer answers.

Upgrading a homeserver that already has ids

serverName's default has changed across releases. A homeserver that has already minted ids under an older default must pin the value it actually minted them under, not adopt the new default — see above for why adopting a new one strands existing users and rooms:

services.hyperhive.swarm.matrix = {
  # whichever this deployment already uses
  serverName = config.services.hyperhive.domain;
  gatewayHost = "matrix.${config.services.hyperhive.domain}";
};

A rebuild on a host that already has a homeserver prints a hive-matrix: WARNING — … serverName is unset line when this is missing, naming the value it's about to default to. That warning is why this section exists; it never fails the rebuild, so it's on you to act on it before the ids are minted.

Default-closed firewall

openFirewall defaults to false (secure-by-default): the host reaches the homeserver on loopback, and agent containers reach it at chat.<swarm-domain> via the gateway — so the firewall hole only matters for access from outside the host. Flip to true when announcing the homeserver to other hives or when an external matrix client needs to reach the client-server API directly.

Federation port 8448 is intentionally not opened here — tuwunel serves the federation API on the same httpPort as client-server by default. Reaching it on 8448 needs either an explicit tuwunel bind to that port OR a reverse-proxy + .well-known/matrix/server delegation (the latter lives in gateway.md::Discovery flow).

Provisioning flow (registration token)

Token-gated registration: hive-c0re holds the token, agents never see it. The agent only receives the resulting access_token.

1. System activation writes a 32-byte random hex token (64 chars) to cfg.registrationTokenFile (/var/lib/hyperhive/matrix-register-token by default), mode 0600 root:root, before any container start. Idempotent — only writes when the file is missing or empty; always re-applies 0600 (normalises any 0640 / world-readable carry-over from pre-LoadCredential deployments). This runs at activation time (not first container start) to dodge a race where nspawn creates an empty file when the bind-mount target is missing and tuwunel reads registration_token_file="", rejecting every registration until next restart.
2. Read-only bind-mount maps the host file into the tuwunel container at the same path.
3. systemd LoadCredential= inside the container copies the bind-mounted file into /run/credentials/tuwunel.service/registration_token, owned by tuwunel's dynamic user with mode 0400, at service start. The host file stays root:root 0600 — no chown :tuwunel / chmod 0640 / GID-pin gymnastics required. Keeps DynamicUser = true + PrivateUsers = true intact.
4. tuwunel's registration_token_file points at the credentials path, not the original bind-mount path.
5. hive-c0re uses the token to register each agent account via the matrix-spec UIAA registration flow, persists the returned access_token to <agent-state>/matrix-token. The agent's matrix MCP client authenticates with that access_token and never touches the shared registration token.
6. hive-c0re restarts hive-matrix-daemon for the agent immediately after writing the token so the daemon picks up the new credential without waiting for a full container restart. If the restart fails (for example daemon not yet running on first boot) hive-c0re logs the error as a warning and the .path-trigger sibling (hive-matrix-daemon.path watching for matrix-token appearance) brings the daemon up on the same boot cycle anyway.

Initial rollout settings:

• allow_federation = true at the protocol level so swarms can be wired up later by extending trustedServers without a homeserver restart. trusted_servers = [] keeps it effectively closed until you list peers.
• allow_registration = true (required for the token flow to engage). The absent yes_i_am_very_very_sure_…_open_registration_… flag keeps the server closed to anyone without the token.
• allow_encryption — server-side E2EE switch, sourced from services.hyperhive.swarm.matrix.allowEncryption (default false, opt-in). Off by default because on the hive-internal homeserver the operator already controls the transport; turn it on for encrypted rooms on external / federated homeservers or to keep contents opaque to the homeserver admin. The agent matrix client always supports decryption regardless of this flag — it uses the e2e-encryption feature of matrix-sdk so it can read encrypted rooms it's invited to even when this homeserver doesn't permit room encryption. matrix-sdk stores crypto keys in the per-agent sqlite store under the state dir; they persist across restarts (lost on --purge). read_room decrypts via room.messages() — UTD events surface as event_type = "m.room.encrypted" with body = "[unable to decrypt]". Cross-signing and automatic key backup aren't enabled for the first pass: static bearer-token bot accounts can't bootstrap cross-signing without MSC3967.

Hive Matrix Space

On first boot, after hive-c0re provisions all agent accounts, it creates a private Matrix Space named "hive" using the admin account (@hive:<server_name>) and invites every provisioned agent into it. This gives the operator a single Space in FluffyChat or any Matrix client that groups all agent-to-agent + operator rooms in one place.

The sweep also provisions a default hive-chat room as an m.space.child of the Space. Joining a Space doesn't autojoin child rooms — the explicit room entry ensures the operator and every agent can find a common chat room without manual setup. Room join is restricted (any Space member including the operator can join; agents are explicitly invited). Room version pinned to 10 for the restricted join floor.

State: hive-c0re persists both room IDs to /var/lib/hyperhive/matrix/ (mode 0600, owned by the hive-c0re service user):

• space-room-id — the Space itself
• chat-room-id — the hive-chat room

These paths are outside every agent state dir and are NOT deleted by nixos-container destroy --purge — both survive full agent purges, and hive-c0re reuses them on re-provision.

Idempotent: if the files exist and are non-empty, hive-c0re considers the Space and room already created. Delete the files to force re-creation (for example after a homeserver wipe).

Configuration tuning

services.hyperhive.swarm.matrix = {
  trustedServers  = [ "matrix.org" "example.com" ];   # default: []
  maxRequestSize  = 20000000;                          # default: 20 MB
};

trustedServers (default []) — list of peer homeserver names whose signing keys tuwunel will fetch and trust. Federation is enabled at the protocol level from first boot (allow_federation = true) but no remote homeserver is trusted until listed here. For a closed single-hive deployment the default empty list is correct — add peer hive domains here when connecting hives into a swarm (see docs/swarm/).

maxRequestSize (default 20_000_000 bytes = 20 MB) — maximum size of a single matrix client request body. Matches the matrix-spec recommendation for media uploads and the upstream tuwunel default. Raise for deployments that need large file transfers; lower for resource-constrained hosts where a 20 MB request is unexpectedly large.

Assertion rationale

config.assertions in this module fail eval early rather than ship surprising behaviour:

• cfg.gatewayHost != "" — same footgun as forge.domain: empty string renders .<hive>-shaped garbage in both nginx server_name (treated as wildcard catch-all, surprising) and /etc/hosts (invalid entry). null is the right opt-out shape; a config assertion rejects empty string explicitly. SSO is unconditional, so the three below are requirements of running a homeserver at all rather than of a setting:

• sso.clientSecretFile is required — fails at eval, not at boot: tuwunel reads its identity providers from the config file, so a half-configured one can stop the homeserver from starting outright rather than merely hiding a login button. On a host that also runs the swarm's authelia it's wired up for you.

• swarm.authelia.url is required — without a provider URL there is nothing to discover against.

• gatewayHost != null is required — the SSO callback URL is format-locked to <homeserver>/_matrix/client/unstable/login/sso/callback/<client_id>, and the identity provider needs a public name to redirect the browser to.

server_name's own bogus-value guard lives in hive-network.nix (services.hyperhive.domain != null), not here — see docs/networking/network.md.

fluffychat-web build fixes

pkgs.fluffychat-web ships from flutter341.buildFlutterApplication, which has two upstream gaps for fluffychat's web target:

• The dart web-worker entry point (web/native_executor.dart) isn't compiled — buildFlutterApplication only runs flutter build web on the main entry.
• native_imaging's C source isn't built — emscripten isn't a flutter-builder native build input.

Both fixed in nix/host-modules/hive-matrix.nix via two derivations:

• fluffychat-web-imaging builds Imaging.{js,wasm} from the native_imaging C source via pkgs.emscripten. Source comes from pkgs.fluffychat-web.passthru.pubspecLock.dependencySources.native_imaging — already in the build closure of the flutter app, so no parallel hash pin and version autosyncs with nixpkgs bumps. Build closure is ~3.6 GiB (emscripten LLVM); runtime closure is just the two output files. dontConfigure = true because cmake runs inside js/Makefile via emcmake cmake, not at the package root. The build script needs HOME + EM_CACHE writable for emscripten's on-demand sysroot build (libc, libc++ → wasm).
• fluffychat-web-fixed is pkgs.fluffychat-web plus a postInstall patch that (a) compiles web/native_executor.dart via dart compile js (dart from the flutter341 closure, no incremental cost) and (b) installs fluffychat-web-imaging's outputs into $out.

Two subtle details worth knowing before touching either derivation:

• make -C js instead of cd js; make — keeps the build-phase pwd at the source root so installPhase doesn't have to know about the cd. Robust against future reorders / dontBuild.
• web/native_executor.dart as a build-CWD-relative path, not $src/web/... — dart's package_config.json walk-up needs to hit buildFlutterApplication's pub-get output (.dart_tool/ in the build CWD). Walking up from a read-only $src/ store path finds no .dart_tool/ and errors with "Couldn't resolve the package 'matrix'."

Drop both derivations when nixpkgs's flutter builder grows worker

• emcc support upstream.

Mount point is chat.<swarm-domain>/ (the gatewayHost vhost); upstream --base-href "/" is correct at sub-domain root, no override.