diff --git a/src/gateway/config-reload.test.ts b/src/gateway/config-reload.test.ts
index 8eee9df30..ad36dcc75 100644
--- a/src/gateway/config-reload.test.ts
+++ b/src/gateway/config-reload.test.ts
@@ -147,6 +147,18 @@ describe("buildGatewayReloadPlan", () => {
     expect(plan.restartChannels).toEqual(expected);
   });
 
+  it("restarts heartbeat when model-related config changes", () => {
+    const plan = buildGatewayReloadPlan([
+      "models.providers.openai.models",
+      "agents.defaults.model",
+    ]);
+    expect(plan.restartGateway).toBe(false);
+    expect(plan.restartHeartbeat).toBe(true);
+    expect(plan.hotReasons).toEqual(
+      expect.arrayContaining(["models.providers.openai.models", "agents.defaults.model"]),
+    );
+  });
+
   it("treats gateway.remote as no-op", () => {
     const plan = buildGatewayReloadPlan(["gateway.remote.url"]);
     expect(plan.restartGateway).toBe(false);
diff --git a/src/gateway/config-reload.ts b/src/gateway/config-reload.ts
index a1a89717a..ff2eebc1f 100644
--- a/src/gateway/config-reload.ts
+++ b/src/gateway/config-reload.ts
@@ -59,6 +59,16 @@ const BASE_RELOAD_RULES: ReloadRule[] = [
     kind: "hot",
     actions: ["restart-heartbeat"],
   },
+  {
+    prefix: "agents.defaults.model",
+    kind: "hot",
+    actions: ["restart-heartbeat"],
+  },
+  {
+    prefix: "models",
+    kind: "hot",
+    actions: ["restart-heartbeat"],
+  },
   { prefix: "agent.heartbeat", kind: "hot", actions: ["restart-heartbeat"] },
   { prefix: "cron", kind: "hot", actions: ["restart-cron"] },
   {
@@ -73,7 +83,6 @@ const BASE_RELOAD_RULES_TAIL: ReloadRule[] = [
   { prefix: "identity", kind: "none" },
   { prefix: "wizard", kind: "none" },
   { prefix: "logging", kind: "none" },
-  { prefix: "models", kind: "none" },
   { prefix: "agents", kind: "none" },
   { prefix: "tools", kind: "none" },
   { prefix: "bindings", kind: "none" },