diff --git a/nix/modules/hive-gateway.nix b/nix/modules/hive-gateway.nix
index aeaf6e72..d38e05de 100644
--- a/nix/modules/hive-gateway.nix
+++ b/nix/modules/hive-gateway.nix
@@ -326,48 +326,21 @@ in
                   # (https://spec.matrix.org/v1.15/client-server-api/#getwell-knownmatrixclient).
                   # No-op until the operator turns matrix on; until then
                   # there's no homeserver to advertise.
-                  lib.optionalAttrs (matrixCfg.enable && hyperhiveDomain != null) (
-                    let
-                      # `.well-known/matrix/{client,server}` advertise where
-                      # the actual matrix API lives. When `matrixCfg.gatewayHost`
-                      # is set (default `matrix.<hive-domain>`, #747), point
-                      # at the sub-domain — no port suffix when the gateway
-                      # is on the canonical port 80, transparent to clients
-                      # (mara on #749:9609 sub-domain verdict, "not user-
-                      # visible because the .well-known redirect routes
-                      # clients through automatically"). When `gatewayHost`
-                      # is unset (no hive-domain, or operator nulled it),
-                      # fall back to the direct `host:port` shape — clients
-                      # reach tuwunel without going through the gateway,
-                      # no sub-domain delegation.
-                      portSuffix = if cfg.port == 80 then "" else ":${toString cfg.port}";
-                      clientBaseUrl =
-                        if matrixCfg.gatewayHost != null then
-                          "http://${matrixCfg.gatewayHost}${portSuffix}"
-                        else
-                          "http://${hyperhiveDomain}:${toString matrixCfg.httpPort}";
-                      serverHostPort =
-                        if matrixCfg.gatewayHost != null then
-                          "${matrixCfg.gatewayHost}${portSuffix}"
-                        else
-                          "${hyperhiveDomain}:${toString matrixCfg.httpPort}";
-                    in
-                    {
-                      "= /.well-known/matrix/client" = {
-                        extraConfig = ''
-                          default_type application/json;
-                          add_header Access-Control-Allow-Origin *;
-                          return 200 '{"m.homeserver":{"base_url":"${clientBaseUrl}"}}';
-                        '';
-                      };
-                      "= /.well-known/matrix/server" = {
-                        extraConfig = ''
-                          default_type application/json;
-                          return 200 '{"m.server":"${serverHostPort}"}';
-                        '';
-                      };
-                    }
-                  )
+                  lib.optionalAttrs (matrixCfg.enable && hyperhiveDomain != null) {
+                    "= /.well-known/matrix/client" = {
+                      extraConfig = ''
+                        default_type application/json;
+                        add_header Access-Control-Allow-Origin *;
+                        return 200 '{"m.homeserver":{"base_url":"http://${hyperhiveDomain}:${toString matrixCfg.httpPort}"}}';
+                      '';
+                    };
+                    "= /.well-known/matrix/server" = {
+                      extraConfig = ''
+                        default_type application/json;
+                        return 200 '{"m.server":"${hyperhiveDomain}:${toString matrixCfg.httpPort}"}';
+                      '';
+                    };
+                  }
                 //
                   # Per-agent UIs (#15 v0). One `/agent/<name>/`
                   # block per `<name>: <port>` entry in
@@ -469,61 +442,6 @@ in
                     '';
                   };
                 };
-              }
-              //
-              # Matrix homeserver vhost (#747, mara verdict on #749:9609 —
-              # sub-domain over sub-path for matrix; "not user-visible"
-              # because clients discover the sub-domain via the
-              # `.well-known/matrix/{client,server}` delegation served
-              # above on the bare hive-domain).
-              #
-              # `server { server_name = matrixCfg.gatewayHost; }` proxies
-              # `/_matrix/...` → `http://127.0.0.1:''${matrixCfg.httpPort}/_matrix/...`.
-              # Tuwunel listens on `:''${httpPort}` (default 8008); the
-              # gateway terminates on `:''${cfg.port}` (80) so external
-              # clients speak matrix over the canonical web port without
-              # operators having to open the tuwunel port through firewalls.
-              #
-              # `/` returns 404 — nothing else lives at the matrix vhost;
-              # the matrix client-server API is entirely under `/_matrix/`,
-              # and federation under `/_matrix/federation/...`.
-              #
-              # CORS `*` on the matrix vhost per the matrix spec —
-              # federation + client requests come from any origin.
-              #
-              # `client_max_body_size 50M` covers typical media uploads
-              # (matrix-spec media size cap default); operators with bigger
-              # uploads override via the matrix module's own cap when that
-              # lands.
-              #
-              # `proxy_read_timeout 1h` for long-poll `/sync`; the default
-              # 60s would abort `/sync?timeout=30000` legitimately when
-              # tuwunel's keepalive exceeds that.
-              lib.optionalAttrs (matrixCfg.enable && matrixCfg.gatewayHost != null) {
-                "${matrixCfg.gatewayHost}" = {
-                  listen = [
-                    {
-                      addr = "0.0.0.0";
-                      port = cfg.port;
-                    }
-                  ];
-                  locations = {
-                    "/_matrix/" = {
-                      proxyPass = "http://127.0.0.1:${toString matrixCfg.httpPort}";
-                      proxyWebsockets = true;
-                      extraConfig = ''
-                        proxy_buffering off;
-                        client_max_body_size 50M;
-                        proxy_read_timeout 1h;
-                        proxy_send_timeout 1h;
-                        add_header Access-Control-Allow-Origin *;
-                      '';
-                    };
-                    "/" = {
-                      return = "404";
-                    };
-                  };
-                };
               };
           };
         };
@@ -534,16 +452,16 @@ in
     };
 
     # `/etc/hosts` entries for local dev: the bare hive domain plus
-    # any sub-domain modules (forge via #749/#754, matrix via #747)
-    # that are on. All map to `127.0.0.1` since the gateway shares
-    # host netns. Operators with real DNS leave `localHostsEntry =
-    # false`; this is the dev-loop shortcut for `http://<hive-domain>/`
-    # + `http://forge.<hive-domain>/` + `http://matrix.<hive-domain>/`
-    # resolving locally.
+    # any sub-domain modules (forge, matrix-via-#751) that are on.
+    # All map to `127.0.0.1` since the gateway shares host netns.
+    # Operators with real DNS leave `localHostsEntry = false`; this
+    # is the dev-loop shortcut for `http://<hive-domain>/` +
+    # `http://forge.<hive-domain>/` resolving locally.
     #
-    # `lib.unique` collapses any duplicate (e.g. if forge.domain
-    # happens to equal hyperhiveDomain or matrixCfg.gatewayHost) so
-    # `/etc/hosts` doesn't carry the same entry twice.
+    # Forge's `cfg.domain` may equal `hyperhiveDomain` (e.g. operator
+    # set `forge.domain = "darkest.space"` matching the hive domain)
+    # — `lib.unique` collapses the duplicate so `/etc/hosts` doesn't
+    # carry the same entry twice.
     networking.hosts = lib.mkIf (cfg.localHostsEntry && hyperhiveDomain != null) {
       "127.0.0.1" = lib.unique (
         [ hyperhiveDomain ]
@@ -551,7 +469,6 @@ in
           (config.services.hyperhive.forge.enable or false)
           && (config.services.hyperhive.forge.behindGateway or false)
         ) config.services.hyperhive.forge.domain
-        ++ lib.optional (matrixCfg.enable && matrixCfg.gatewayHost != null) matrixCfg.gatewayHost
       );
     };
   };
diff --git a/nix/modules/hive-matrix.nix b/nix/modules/hive-matrix.nix
index 05b97925..907312aa 100644
--- a/nix/modules/hive-matrix.nix
+++ b/nix/modules/hive-matrix.nix
@@ -252,63 +252,6 @@ in
       '';
     };
 
-    gatewayHost = lib.mkOption {
-      type = lib.types.nullOr lib.types.str;
-      default = if hyperhiveDomain != null then "matrix.${hyperhiveDomain}" else null;
-      defaultText = lib.literalExpression ''
-        if services.hyperhive.domain != null then
-          "matrix.''${services.hyperhive.domain}"
-        else
-          null
-      '';
-      example = "matrix.example.com";
-      description = ''
-        Public hostname for the matrix homeserver behind the
-        hive-gateway nginx (#747, mara verdict on #749:9609 — sub-domain
-        over sub-path for matrix, but **not user-visible** because the
-        `.well-known/matrix/{client,server}` redirect routes clients
-        through automatically).
-
-        When set + gateway is on, the gateway adds a `server { server_name
-        = gatewayHost; }` block that proxies `/_matrix/...` →
-        `http://127.0.0.1:''${httpPort}/_matrix/...`. The
-        `.well-known/matrix/{client,server}` endpoints (served by the
-        gateway at the bare hive-domain) then point at
-        `http(s)://''${gatewayHost}/` — matrix clients automatically
-        discover + follow that delegation.
-
-        Defaults to `matrix.''${services.hyperhive.domain}` when the
-        hive-domain is set (idiomatic matrix-spec shape — `matrix`
-        labelled under the hive's bare server_name domain). Defaults to
-        `null` when the hive-domain is unset (gateway vhost not added;
-        clients reach tuwunel directly on `httpPort`).
-
-        Set to a full hostname (`matrix.example.com`,
-        `homeserver.internal.lan`) for a bespoke vhost shape. Set to
-        `null` to disable the gateway vhost entirely (tuwunel stays
-        direct on `httpPort`).
-
-        **server_name vs gatewayHost**: `serverName` is the matrix
-        identifier domain embedded in user/room IDs irrevocably (per
-        #660 default = bare hive-domain). `gatewayHost` is just where
-        the API listens behind nginx. The two are different — see the
-        matrix-spec server-discovery flow.
-
-        **Federation port caveat**: the `.well-known/matrix/server`
-        delegation advertises `''${gatewayHost}` with no port suffix
-        when the gateway listens on 80. Per the matrix federation
-        spec, peers fall back to port 8448 when no explicit port is
-        present — but the gateway only listens on the configured
-        `services.hyperhive.gateway.port`. Cross-hive federation
-        therefore needs either:
-        - a DNS SRV record (`_matrix._tcp.''${gatewayHost}` → port 80),
-        - or `services.hyperhive.matrix.openFirewall = true` so peers
-          can reach tuwunel's federation port directly.
-        Hyperhive is mostly closed/internal, so this rarely bites in
-        practice — but flagging for the federation-curious operator.
-      '';
-    };
-
     openFirewall = lib.mkOption {
       type = lib.types.bool;
       default = false;
@@ -452,22 +395,6 @@ in
           stable hostname before enabling.
         '';
       }
-      {
-        # Same footgun as forge.domain (#754): empty string renders
-        # `.<hive>` shaped garbage in both nginx server_name (treated
-        # as wildcard catch-all, surprising) and /etc/hosts (invalid
-        # entry). Argus 🟡 on #764 — fail loud here rather than ship
-        # the surprising behaviour.
-        assertion = cfg.gatewayHost == null || cfg.gatewayHost != "";
-        message = ''
-          services.hyperhive.matrix.gatewayHost = "" is rejected. The
-          rendered URLs would be invalid (nginx wildcard catch-all for
-          an empty server_name, /etc/hosts rejects empty entries).
-          Use `null` to disable the gateway vhost entirely (tuwunel
-          stays direct on httpPort), or set a non-empty hostname like
-          "matrix.example.com" or "homeserver.internal".
-        '';
-      }
     ];
 
     # Generate the registration token at system activation time, BEFORE