diff --git a/backend/src/infra.rs b/backend/src/infra.rs
index ecd5c3d..ff375a0 100644
--- a/backend/src/infra.rs
+++ b/backend/src/infra.rs
@@ -281,11 +281,7 @@ async fn try_sync_relay(relay: &Relay) -> Result<()> {
             .await?
             .is_none();
 
-    let host = if relay.custom_domain_verified == 1 && !relay.custom_domain.is_empty() {
-        relay.custom_domain.clone()
-    } else {
-        format!("{}.{}", relay.subdomain, env::get().relay_domain)
-    };
+    let host = relay.host();
 
     let mut body = serde_json::json!({
         "host": host,
diff --git a/backend/src/models.rs b/backend/src/models.rs
index 18bb64b..a451a9b 100644
--- a/backend/src/models.rs
+++ b/backend/src/models.rs
@@ -96,6 +96,18 @@ pub struct Relay {
     pub created_at: i64,
 }
 
+impl Relay {
+    /// The relay's effective public host: its verified custom domain when set,
+    /// otherwise its canonical `<subdomain>.<relay_domain>`.
+    pub fn host(&self) -> String {
+        if self.custom_domain_verified == 1 && !self.custom_domain.is_empty() {
+            self.custom_domain.clone()
+        } else {
+            format!("{}.{}", self.subdomain, crate::env::get().relay_domain)
+        }
+    }
+}
+
 impl Default for Relay {
     fn default() -> Self {
         Self {