feat(ntfy): dispatch gateway_online/gateway_offline from model

app/models/gateway.rb

@@ -1,4 +1,6 @@
 class Gateway < ApplicationRecord
+  include NtfyDispatchable
+
   # Normalize metadata to always be a Hash
   attribute :metadata, :jsonb, default: {}
 
@@ -35,12 +37,31 @@ class Gateway < ApplicationRecord
 
   # Update heartbeat timestamp and status
   def heartbeat!
+    was_offline = status == "offline"
     update!(status: "online", last_heartbeat_at: Time.current)
+
+    if was_offline
+      self.class.dispatch_ntfy("gateway_online",
+        title: "Gateway online",
+        message: "#{name} (#{device_id}) came back online",
+        priority: 3,
+        tags: ["white_check_mark"],
+        click: nil)
+    end
   end
 
   # Mark gateway as offline
   def mark_offline!
+    was_online = status == "online"
     update!(status: "offline")
+
+    if was_online
+      self.class.dispatch_ntfy("gateway_offline",
+        title: "Gateway offline",
+        message: "#{name} (#{device_id}) went offline",
+        priority: 4,
+        tags: ["rotating_light"])
+    end
   end
 
   # Increment message counters

test/models/gateway_test.rb

@@ -0,0 +1,51 @@
+require "test_helper"
+
+class GatewayTest < ActiveSupport::TestCase
+  include ActiveJob::TestHelper
+
+  setup do
+    ActiveJob::Base.queue_adapter = :test
+    @admin = AdminUser.create!(
+      name: "GW Admin", email: "gw@example.com",
+      password: "password123",
+      ntfy_topic: "gw-topic", ntfy_token: "tk_gw",
+      ntfy_enabled: true, ntfy_server_url: "https://ntfy.example.com"
+    )
+    stub_request(:post, "https://ntfy.example.com/gw-topic").to_return(status: 200)
+  end
+
+  test "heartbeat! dispatches gateway_online notification when transitioning from offline" do
+    gateway = Gateway.create!(
+      device_id: "dev-online", name: "GW",
+      api_key_digest: "x" * 64, status: "offline"
+    )
+
+    assert_enqueued_jobs 1 do
+      gateway.heartbeat!
+    end
+  end
+
+  test "heartbeat! does not dispatch if already online" do
+    gateway = Gateway.create!(
+      device_id: "dev-stay", name: "GW",
+      api_key_digest: "y" * 64, status: "online",
+      last_heartbeat_at: 1.minute.ago
+    )
+
+    assert_enqueued_jobs 0 do
+      gateway.heartbeat!
+    end
+  end
+
+  test "mark_offline! dispatches gateway_offline notification when transitioning from online" do
+    gateway = Gateway.create!(
+      device_id: "dev-off", name: "GW",
+      api_key_digest: "z" * 64, status: "online",
+      last_heartbeat_at: 1.minute.ago
+    )
+
+    assert_enqueued_jobs 1 do
+      gateway.mark_offline!
+    end
+  end
+end