From ff84ca947db98819c9c6de3e414c685f1a13307f Mon Sep 17 00:00:00 2001
From: atlas <atlas@pr1ma.darkest.space>
Date: Wed, 5 Aug 2026 22:46:13 +0200
Subject: [PATCH] feat(nix): the matrix gateway host moves to
 chat.<swarm.domain>
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Both halves change: the parent, because a swarm runs one homeserver and
every hive reaches it; and the label, because `chat` names the service
people use rather than the protocol it speaks.

⚠️ `serverName` is deliberately NOT touched, and the two are now
documented as the different things they are. `gatewayHost` is a routing
detail -- the API listener nginx proxies `/_matrix/*` to, which clients
rediscover through `.well-known`. `serverName` is the matrix identifier
baked into every user and room id: changing it is a different
homeserver, not a rename, so it still falls back to the bare hive
domain. A note at the fallback says so, since that binding is where a
future edit would most plausibly "fix" the inconsistency.

Old deployments pin `matrix.<hive domain>` -- exactly what the old
default rendered -- and dnsmasq already lists `gatewayHost` explicitly,
so a pinned or moved name stays routed either way.
---
 nix/host-modules/hive-matrix.nix | 44 +++++++++++++++++++++++---------
 1 file changed, 32 insertions(+), 12 deletions(-)

diff --git a/nix/host-modules/hive-matrix.nix b/nix/host-modules/hive-matrix.nix
index 96aca15e..fef052f5 100644
--- a/nix/host-modules/hive-matrix.nix
+++ b/nix/host-modules/hive-matrix.nix
@@ -8,6 +8,12 @@ let
   cfg = config.services.hyperhive.swarm.matrix;
   networkCfg = config.services.hyperhive.network;
   hyperhiveDomain = config.services.hyperhive.domain;
+  swarmDomain = config.services.hyperhive.swarm.domain;
+  # ⚠️ Falls back to the HIVE domain, and must keep doing so even though
+  # `gatewayHost` moved to the swarm's: `serverName` is the matrix
+  # identifier baked into every user and room id, so changing it is a
+  # different homeserver rather than a rename. The two are independent on
+  # purpose — see the `gatewayHost` description below.
   effectiveServerName = if cfg.serverName != null then cfg.serverName else hyperhiveDomain;
 
   # fluffychat-web build fixes: nixpkgs's `flutter341.buildFlutterApplication`
@@ -194,23 +200,37 @@ in
 
     gatewayHost = lib.mkOption {
       type = lib.types.nullOr lib.types.str;
-      # Total on a null hive domain so the required-domain assertion in
+      # `chat.` under the SWARM domain — both halves change: a swarm runs
+      # one homeserver, and the label follows the service rather than the
+      # protocol.
+      #
+      # Total on a null swarm domain so the required-domain assertion in
       # hive-network.nix is the thing that fires; see the comment there.
-      default = if hyperhiveDomain == null then "matrix.invalid" else "matrix.${hyperhiveDomain}";
-      defaultText = lib.literalExpression ''"matrix.''${services.hyperhive.domain}"'';
+      default = if swarmDomain == null then "chat.invalid" else "chat.${swarmDomain}";
+      defaultText = lib.literalExpression ''"chat.''${services.hyperhive.swarm.domain}"'';
       example = "matrix.example.com";
       description = ''
         Public hostname for the matrix homeserver behind the gateway.
-        Defaults to `matrix.''${services.hyperhive.domain}` (sub-domain
-        shape — see `docs/gateway.md`). Set to `null` to skip the
-        gateway vhost (tuwunel stays direct on `httpPort`). See
-        `docs/gateway.md` for the vhost map + matrix discovery flow,
-        and the federation port-8448 caveat at the bottom of that doc.
+        Defaults to `chat.''${services.hyperhive.swarm.domain}` — the
+        swarm's domain, because a swarm runs **one** homeserver. Set to
+        `null` to skip the gateway vhost (tuwunel stays direct on
+        `httpPort`). See `docs/gateway.md` for the vhost map + matrix
+        discovery flow, and the federation port-8448 caveat at the
+        bottom of that doc.
 
-        Note: `gatewayHost` is the API listener hostname (where nginx
-        proxies `/_matrix/*`); `serverName` is the matrix-identifier
-        domain embedded irrevocably in user/room IDs (default = bare
-        hive-domain). The two are distinct.
+        ⚠️ **`gatewayHost` and `serverName` are different things, and
+        only this one moved.** `gatewayHost` is the API listener
+        hostname (where nginx proxies `/_matrix/*`) and is free to
+        change: it is a routing detail clients rediscover through
+        `.well-known`. `serverName` is the matrix-identifier domain
+        embedded **irrevocably** in every user and room id — changing
+        that is a different homeserver, not a rename, so it still
+        defaults to the bare hive domain and is untouched here.
+
+        A deployment that was running before this moved keeps its
+        current name by pinning
+        `matrix.''${services.hyperhive.domain}` here — exactly what the
+        old default rendered.
       '';
     };