diff --git a/nix/host-modules/swarm-authelia.nix b/nix/host-modules/swarm-authelia.nix
index 7d4dfd6f..b3c9a027 100644
--- a/nix/host-modules/swarm-authelia.nix
+++ b/nix/host-modules/swarm-authelia.nix
@@ -43,6 +43,7 @@ let
   swarmDomain = hyperhiveCfg.swarm.domain;
   uiCfg = hyperhiveCfg.swarm.ui;
   forgeCfg = hyperhiveCfg.swarm.forge;
+  otelCfg = hyperhiveCfg.swarm.otel;
 
   # Group an account must hold to reach operator-only surfaces. Named
   # here because this module writes the rule that enforces it and
@@ -339,6 +340,36 @@ in
       '';
     };
 
+    metricsPort = lib.mkOption {
+      type = lib.types.port;
+      default = 9959;
+      description = ''
+        TCP port authelia serves its Prometheus metrics on, bound to
+        loopback. Upstream's default, kept so an operator reading
+        authelia's documentation finds what they expect.
+
+        A separate port from {option}`port` because it is a separate
+        listener with a different audience: the main one is proxied by
+        the gateway and reachable from the swarm, this one is scraped by
+        the collector on this host and by nothing else.
+
+        ⚠️ Every swarm container shares the host network namespace, so
+        two services defaulting to the same port do not conflict at build
+        time — one simply loses at runtime, with nothing in any log. Check
+        a new value against the others before changing this.
+
+        ::: {.note}
+        Loopback means this endpoint is only reachable by a collector on
+        the *same host*, so the scrape target is declared only when one is
+        enabled here. Run the swarm's collector elsewhere and authelia's
+        metrics are simply not collected — no error, and nothing in a log
+        to say so. Making them reachable across hosts is a different piece
+        of work: the endpoint would have to be published under a name,
+        with a certificate and an audience.
+        :::
+      '';
+    };
+
     domain = lib.mkOption {
       type = lib.types.str;
       # Under the SWARM domain, like the forge and matrix: a swarm has one
@@ -804,6 +835,26 @@ in
     # bridge at that wrong answer.
     services.hyperhive.gateway.localNames = [ cfg.domain ];
 
+    # Declared here rather than in the collector's module, per the option's
+    # own rule: an entry exists only where the service that named it runs.
+    #
+    # Gated on the collector's `enable` as well, and that second condition is
+    # what makes the loopback address honest. Both services default from
+    # `swarm.enableRequiredServices` — but `mkDefault` is an invitation to
+    # override, not a guarantee, so "they are on the same host" is a property
+    # of the auto-deployed topology rather than of the module. Without this
+    # gate, a host running authelia and no collector would declare a target
+    # nothing can read, and the absence would be silent: no error, no metrics,
+    # nothing to notice.
+    #
+    # It does not make authelia scrapeable from ANOTHER host — that needs the
+    # endpoint published under a name with a cert and an audience, which is a
+    # different piece of work. This only stops the config asserting a
+    # collection that is not happening.
+    services.hyperhive.swarm.otel.scrapeTargets = lib.mkIf otelCfg.enable {
+      authelia = "127.0.0.1:${toString cfg.metricsPort}";
+    };
+
     # This swarm-ui quick-links entry, same guard as the vhost/DNS name
     # above (only the host actually running the container claims it —
     # see `services.hyperhive.swarm.controller.links`'s description for
@@ -1110,6 +1161,16 @@ in
               };
               log.level = "info";
 
+              # Prometheus exposition for the swarm collector to scrape.
+              # Loopback only, like the main listener above and for a
+              # stronger reason: this endpoint has no authentication of its
+              # own, and it reports request volumes and outcomes for every
+              # SSO login on the swarm.
+              telemetry.metrics = {
+                enabled = true;
+                address = "tcp://127.0.0.1:${toString cfg.metricsPort}";
+              };
+
               # `watch` is load-bearing, not a convenience: authelia reads
               # this file once at startup, and `swarm-authelia-bridge` writes
               # it to create agent identities while being unable to restart