feat(ntfy): dispatch gateway_offline from CheckGatewayHealthJob after bulk update

app/jobs/check_gateway_health_job.rb

@@ -2,13 +2,24 @@ class CheckGatewayHealthJob < ApplicationJob
   queue_as :default
 
   def perform
-    # Mark gateways as offline if no heartbeat in last 2 minutes
-    offline_count = Gateway.where("last_heartbeat_at < ?", 2.minutes.ago)
-                          .where.not(status: "offline")
-                          .update_all(status: "offline")
+    # Capture stale gateway details BEFORE update_all (update_all bypasses callbacks
+    # and would change the scope, so we snapshot the rows first)
+    stale_gateway_details = Gateway.where("last_heartbeat_at < ?", 2.minutes.ago)
+                                   .where.not(status: "offline")
+                                   .pluck(:id, :name, :device_id)
+
+    offline_count = Gateway.where(id: stale_gateway_details.map(&:first)).update_all(status: "offline")
 
     if offline_count > 0
       Rails.logger.warn("Marked #{offline_count} gateways as offline due to missing heartbeat")
+
+      stale_gateway_details.each do |_id, name, device_id|
+        Gateway.dispatch_ntfy("gateway_offline",
+          title: "Gateway offline",
+          message: "#{name} (#{device_id}) went offline — no heartbeat for 2+ minutes",
+          priority: 4,
+          tags: ["rotating_light"])
+      end
     end
   end
 end

test/jobs/check_gateway_health_job_test.rb

@@ -0,0 +1,45 @@
+require "test_helper"
+
+class CheckGatewayHealthJobTest < ActiveJob::TestCase
+  setup do
+    ActiveJob::Base.queue_adapter = :test
+    @admin = AdminUser.create!(
+      name: "Health Admin", email: "health@example.com",
+      password: "password123",
+      ntfy_topic: "health-topic", ntfy_token: "tk_health",
+      ntfy_enabled: true, ntfy_server_url: "https://ntfy.example.com"
+    )
+    stub_request(:post, "https://ntfy.example.com/health-topic").to_return(status: 200)
+  end
+
+  test "dispatches gateway_offline for each stale gateway marked offline" do
+    stale_gw = Gateway.create!(
+      device_id: "stale-1", name: "Stale One",
+      api_key_digest: "a" * 64, status: "online",
+      last_heartbeat_at: 5.minutes.ago
+    )
+    Gateway.create!(
+      device_id: "fresh-1", name: "Fresh",
+      api_key_digest: "b" * 64, status: "online",
+      last_heartbeat_at: 30.seconds.ago
+    )
+
+    assert_enqueued_jobs 1 do
+      CheckGatewayHealthJob.perform_now
+    end
+
+    assert_equal "offline", stale_gw.reload.status
+  end
+
+  test "does not dispatch when no gateways go stale" do
+    Gateway.create!(
+      device_id: "fresh-2", name: "Fresh Two",
+      api_key_digest: "c" * 64, status: "online",
+      last_heartbeat_at: 10.seconds.ago
+    )
+
+    assert_enqueued_jobs 0 do
+      CheckGatewayHealthJob.perform_now
+    end
+  end
+end