From e8813b86eb31c0a4c5f7060b0345413f25eba46c Mon Sep 17 00:00:00 2001
From: atlas <atlas@pr1ma.darkest.space>
Date: Sun, 30 Aug 2026 15:08:27 +0200
Subject: [PATCH] matrix: forward the homeserver URL from client hives too
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HIVE_MATRIX_URL was conditioned on this host deploying the homeserver,
so a hive that is a client of the swarm's matrix forwarded nothing and
every agent's hive-matrix-daemon no-opped. hive-c0re already provisions
those agents' accounts against a remote homeserver through
HIVE_MATRIX_API_URL three lines below, whose gate is `apiUrl != null` —
it registered the users and then never told them where to log in.

gatewayHost is swarm-scoped and defaults to chat.<swarm-domain>, so it
names the swarm's one homeserver from any member hive. Its being set is
the real question, and a null swarm domain is already caught by the
assertion in hive-network.nix rather than by this expression.
---
 nix/host-modules/hive-c0re/environment.nix | 42 +++++++++++-----------
 1 file changed, 20 insertions(+), 22 deletions(-)

diff --git a/nix/host-modules/hive-c0re/environment.nix b/nix/host-modules/hive-c0re/environment.nix
index 11088fc3..ffe9ba18 100644
--- a/nix/host-modules/hive-c0re/environment.nix
+++ b/nix/host-modules/hive-c0re/environment.nix
@@ -159,28 +159,26 @@ in
   # a reading no correctly-built hive should ever have to make.
   HIVE_RESERVED_NAMES = lib.concatStringsSep " " (import ../../reserved-names.nix);
 }
-//
-  lib.optionalAttrs
-    (
-      config.services.hyperhive.deploy.matrix.enable
-      && config.services.hyperhive.swarm.matrix.gatewayHost != null
-    )
-    {
-      # In-cluster matrix homeserver URL for each agent's
-      # hive-matrix-daemon — the gateway vhost (`matrix.<domain>`).
-      # Forwarded to agents by meta.rs alongside HIVE_FORGE_URL; shares the
-      # same env-forwarding ordering caveat (value baked at
-      # config-generation time).
-      #
-      # A domain-less config forwards nothing rather than falling back to
-      # loopback. The old fallback read as harmless because hive-c0re shares
-      # the host netns — but the value it produced was handed to *agents*,
-      # which do not, so `127.0.0.1` there names the agent itself. An absent
-      # forward leaves `hyperhive.matrix.url` null and the daemon no-ops;
-      # that is the honest answer when the hive has no matrix vhost to point
-      # at.
-      HIVE_MATRIX_URL = "http://${config.services.hyperhive.swarm.matrix.gatewayHost}";
-    }
+// lib.optionalAttrs (config.services.hyperhive.swarm.matrix.gatewayHost != null) {
+  # Matrix homeserver URL for each agent's hive-matrix-daemon — the
+  # gateway vhost (`chat.<swarm-domain>`). Forwarded to agents by meta.rs
+  # alongside HIVE_FORGE_URL; shares the same env-forwarding ordering
+  # caveat (value baked at config-generation time).
+  #
+  # Deliberately NOT conditioned on this host running the homeserver. A
+  # swarm has one matrix, and every hive's agents talk to it — the hive
+  # that hosts it is not the only hive whose agents need its address.
+  # `gatewayHost` is swarm-scoped and names that one homeserver from any
+  # member hive, so its being set is the whole question.
+  #
+  # Null forwards nothing rather than falling back to loopback. That
+  # fallback reads as harmless because hive-c0re shares the host netns —
+  # but the value is handed to *agents*, which do not, so `127.0.0.1`
+  # there names the agent itself. An absent forward leaves
+  # `hyperhive.matrix.url` null and the daemon no-ops; that is the honest
+  # answer when there is no matrix vhost to point at.
+  HIVE_MATRIX_URL = "http://${config.services.hyperhive.swarm.matrix.gatewayHost}";
+}
 // lib.optionalAttrs (config.services.hyperhive.swarm.matrix.apiUrl != null) {
   # Client-server API base hive-c0re uses to provision matrix (register
   # agent users, create the hive space + chat room, invite members).