diff --git a/test/towerops/workers/device_poller_worker_branches_test.exs b/test/towerops/workers/device_poller_worker_branches_test.exs
new file mode 100644
index 00000000..476dde42
--- /dev/null
+++ b/test/towerops/workers/device_poller_worker_branches_test.exs
@@ -0,0 +1,660 @@
+defmodule Towerops.Workers.DevicePollerWorkerBranchesTest do
+  @moduledoc """
+  Branch coverage for `Towerops.Workers.DevicePollerWorker` focusing on:
+    * sensor error log clauses (`:no_such_object`, `:no_such_instance`, `:end_of_mib_view`)
+    * unknown processor type
+    * UCD CPU error path
+    * state sensor change broadcast (value change between polls)
+    * interface change events (oper status, admin status, speed, MAC)
+    * storage / mempool error paths
+  """
+  use Towerops.DataCase, async: false
+
+  import Mox
+  import Towerops.AccountsFixtures
+
+  alias Towerops.Devices
+  alias Towerops.Organizations
+  alias Towerops.Repo
+  alias Towerops.Sites
+  alias Towerops.Snmp.Device, as: SnmpDevice
+  alias Towerops.Snmp.Interface
+  alias Towerops.Snmp.Mempool
+  alias Towerops.Snmp.Processor
+  alias Towerops.Snmp.ProcessorReading
+  alias Towerops.Snmp.Sensor
+  alias Towerops.Snmp.SensorReading
+  alias Towerops.Snmp.SnmpMock
+  alias Towerops.Snmp.StateSensor
+  alias Towerops.Snmp.Storage
+  alias Towerops.Workers.DevicePollerWorker
+
+  setup :verify_on_exit!
+
+  setup do
+    old_adapter = Application.get_env(:towerops, :snmp_adapter)
+    Application.put_env(:towerops, :snmp_adapter, SnmpMock)
+
+    on_exit(fn ->
+      if old_adapter do
+        Application.put_env(:towerops, :snmp_adapter, old_adapter)
+      else
+        Application.delete_env(:towerops, :snmp_adapter)
+      end
+    end)
+
+    user = user_fixture()
+    {:ok, organization} = Organizations.create_organization(%{name: "Branches Org"}, user.id)
+    {:ok, site} = Sites.create_site(%{name: "Branches Site", organization_id: organization.id})
+
+    %{organization: organization, site: site}
+  end
+
+  defp create_polled_device(site, attrs \\ %{}) do
+    base = %{
+      name: "Dev #{System.unique_integer([:positive])}",
+      ip_address: "10.0.0.#{Enum.random(1..250)}",
+      site_id: site.id,
+      organization_id: site.organization_id,
+      snmp_enabled: true,
+      snmp_version: "2c",
+      snmp_community: "public",
+      check_interval_seconds: 600
+    }
+
+    {:ok, device} = Devices.create_device(Map.merge(base, attrs))
+    Repo.delete_all(Oban.Job)
+    device
+  end
+
+  defp create_snmp_device(device, attrs \\ %{}) do
+    %SnmpDevice{}
+    |> SnmpDevice.changeset(Map.merge(%{device_id: device.id, sys_name: "host", sys_descr: "Test"}, attrs))
+    |> Repo.insert!()
+  end
+
+  defp insert_dummy_sensor(snmp) do
+    %Sensor{}
+    |> Sensor.changeset(%{
+      snmp_device_id: snmp.id,
+      sensor_type: "temperature",
+      sensor_index: "999",
+      sensor_oid: "1.3.6.1.99.99.99.999",
+      sensor_descr: "Gate Sensor"
+    })
+    |> Repo.insert!()
+  end
+
+  defp stub_walks_empty do
+    stub(SnmpMock, :walk, fn _, _, _ -> {:ok, []} end)
+  end
+
+  defp run_perform(device) do
+    DevicePollerWorker.perform(%Oban.Job{args: %{"device_id" => device.id}})
+  end
+
+  describe "sensor error logging branches" do
+    test ":no_such_object error path", %{site: site} do
+      device = create_polled_device(site)
+      snmp = create_snmp_device(device)
+
+      sensor =
+        %Sensor{}
+        |> Sensor.changeset(%{
+          snmp_device_id: snmp.id,
+          sensor_type: "temperature",
+          sensor_index: "1",
+          sensor_oid: "1.3.6.1.2.1.99.1.1.1.4.1",
+          sensor_descr: "NSO Sensor"
+        })
+        |> Repo.insert!()
+
+      stub(SnmpMock, :get, fn _, _, _ -> {:error, :no_such_object} end)
+      stub(SnmpMock, :get_multiple, fn _, _, _ -> {:error, :timeout} end)
+      stub_walks_empty()
+
+      assert :ok = run_perform(device)
+
+      reading = Repo.one(Ecto.Query.where(SensorReading, sensor_id: ^sensor.id))
+      assert reading.status == "error"
+    end
+
+    test ":no_such_instance error path", %{site: site} do
+      device = create_polled_device(site)
+      snmp = create_snmp_device(device)
+
+      sensor =
+        %Sensor{}
+        |> Sensor.changeset(%{
+          snmp_device_id: snmp.id,
+          sensor_type: "temperature",
+          sensor_index: "1",
+          sensor_oid: "1.3.6.1.2.1.99.1.1.1.4.1",
+          sensor_descr: "NSI Sensor"
+        })
+        |> Repo.insert!()
+
+      stub(SnmpMock, :get, fn _, _, _ -> {:error, :no_such_instance} end)
+      stub(SnmpMock, :get_multiple, fn _, _, _ -> {:error, :timeout} end)
+      stub_walks_empty()
+
+      assert :ok = run_perform(device)
+
+      reading = Repo.one(Ecto.Query.where(SensorReading, sensor_id: ^sensor.id))
+      assert reading.status == "error"
+    end
+
+    test ":end_of_mib_view error path", %{site: site} do
+      device = create_polled_device(site)
+      snmp = create_snmp_device(device)
+
+      sensor =
+        %Sensor{}
+        |> Sensor.changeset(%{
+          snmp_device_id: snmp.id,
+          sensor_type: "temperature",
+          sensor_index: "1",
+          sensor_oid: "1.3.6.1.2.1.99.1.1.1.4.1",
+          sensor_descr: "EoM Sensor"
+        })
+        |> Repo.insert!()
+
+      stub(SnmpMock, :get, fn _, _, _ -> {:error, :end_of_mib_view} end)
+      stub(SnmpMock, :get_multiple, fn _, _, _ -> {:error, :timeout} end)
+      stub_walks_empty()
+
+      assert :ok = run_perform(device)
+
+      reading = Repo.one(Ecto.Query.where(SensorReading, sensor_id: ^sensor.id))
+      assert reading.status == "error"
+    end
+  end
+
+  describe "processor branches" do
+    test "ucd_cpu with one OID failing falls into error branch", %{site: site} do
+      device = create_polled_device(site)
+      snmp = create_snmp_device(device)
+      insert_dummy_sensor(snmp)
+
+      proc =
+        %Processor{}
+        |> Processor.changeset(%{
+          snmp_device_id: snmp.id,
+          processor_index: "ucd_1",
+          processor_type: "ucd_cpu",
+          description: "UCD CPU partial"
+        })
+        |> Repo.insert!()
+
+      stub(SnmpMock, :get, fn _, oid, _ ->
+        case oid do
+          # user OK
+          "1.3.6.1.4.1.2021.11.9.0" -> {:ok, 10}
+          # system fails
+          "1.3.6.1.4.1.2021.11.10.0" -> {:error, :timeout}
+          _ -> {:error, :no_such_object}
+        end
+      end)
+
+      stub(SnmpMock, :get_multiple, fn _, _, _ -> {:error, :timeout} end)
+      stub_walks_empty()
+
+      assert :ok = run_perform(device)
+
+      reading = Repo.one(Ecto.Query.where(ProcessorReading, processor_id: ^proc.id))
+      assert reading.status == "error"
+    end
+
+    test "hr_processor with non-integer SNMP value gives error", %{site: site} do
+      device = create_polled_device(site)
+      snmp = create_snmp_device(device)
+      insert_dummy_sensor(snmp)
+
+      proc =
+        %Processor{}
+        |> Processor.changeset(%{
+          snmp_device_id: snmp.id,
+          processor_index: "hr_1",
+          processor_type: "hr_processor",
+          description: "HR partial"
+        })
+        |> Repo.insert!()
+
+      stub(SnmpMock, :get, fn _, oid, _ ->
+        case oid do
+          "1.3.6.1.2.1.25.3.3.1.2.1" -> {:ok, "not-an-int"}
+          _ -> {:error, :no_such_object}
+        end
+      end)
+
+      stub(SnmpMock, :get_multiple, fn _, _, _ -> {:error, :timeout} end)
+      stub_walks_empty()
+
+      assert :ok = run_perform(device)
+
+      reading = Repo.one(Ecto.Query.where(ProcessorReading, processor_id: ^proc.id))
+      assert reading.status == "error"
+    end
+  end
+
+  describe "state sensor change broadcasting" do
+    test "broadcasts state change when state_value changes between polls", %{site: site} do
+      device = create_polled_device(site)
+      snmp = create_snmp_device(device)
+      insert_dummy_sensor(snmp)
+
+      # State sensor with previous value=2 (ok / enabled), now changing to 3
+      # (warning / disabled). The broadcast_state_sensor_change branch fires
+      # because old_state_value != nil && old_state_value != new_state_value.
+      ss =
+        %StateSensor{}
+        |> StateSensor.changeset(%{
+          snmp_device_id: snmp.id,
+          sensor_descr: "Power Supply 1",
+          sensor_oid: "1.3.6.1.2.1.47.1.1.1.1.5.1",
+          sensor_index: "1",
+          state_value: 2,
+          state_descr: "enabled",
+          status: "ok"
+        })
+        |> Repo.insert!()
+
+      Phoenix.PubSub.subscribe(Towerops.PubSub, "device:#{device.id}")
+      Phoenix.PubSub.subscribe(Towerops.PubSub, "device:events")
+      Phoenix.PubSub.subscribe(Towerops.PubSub, "device_events:org:#{device.organization_id}")
+
+      stub(SnmpMock, :get, fn _, oid, _ ->
+        case oid do
+          "1.3.6.1.2.1.47.1.1.1.1.5.1" -> {:ok, 3}
+          _ -> {:error, :no_such_object}
+        end
+      end)
+
+      stub(SnmpMock, :get_multiple, fn _, _, _ -> {:error, :timeout} end)
+      stub_walks_empty()
+
+      assert :ok = run_perform(device)
+
+      updated = Repo.get!(StateSensor, ss.id)
+      assert updated.state_value == 3
+      assert updated.status == "warning"
+      assert updated.state_descr == "disabled"
+
+      # We expect at least one device_event broadcast describing the change
+      assert_receive {:device_event, %{message: msg}}, 2_000
+      assert msg =~ "Power Supply 1"
+      assert msg =~ "enabled"
+      assert msg =~ "disabled"
+    end
+
+    test "broadcasts state change for ok→critical (severity = critical)", %{site: site} do
+      device = create_polled_device(site)
+      snmp = create_snmp_device(device)
+      insert_dummy_sensor(snmp)
+
+      # Previous: state_value=2, status=ok. New: an unknown state value (5)
+      # that maps to status="unknown". We can't drive critical from
+      # entity_state_to_status which only outputs ok/warning/unknown, but
+      # broadcast_state_sensor_change does run for ok→unknown transitions.
+      ss =
+        %StateSensor{}
+        |> StateSensor.changeset(%{
+          snmp_device_id: snmp.id,
+          sensor_descr: "Fan 1",
+          sensor_oid: "1.3.6.1.2.1.47.1.1.1.1.5.2",
+          sensor_index: "2",
+          state_value: 2,
+          state_descr: "enabled",
+          status: "ok"
+        })
+        |> Repo.insert!()
+
+      Phoenix.PubSub.subscribe(Towerops.PubSub, "device:events")
+
+      stub(SnmpMock, :get, fn _, oid, _ ->
+        case oid do
+          "1.3.6.1.2.1.47.1.1.1.1.5.2" -> {:ok, 5}
+          _ -> {:error, :no_such_object}
+        end
+      end)
+
+      stub(SnmpMock, :get_multiple, fn _, _, _ -> {:error, :timeout} end)
+      stub_walks_empty()
+
+      assert :ok = run_perform(device)
+
+      updated = Repo.get!(StateSensor, ss.id)
+      assert updated.state_value == 5
+
+      assert_receive {:device_event, _event}, 2_000
+    end
+
+    test "no broadcast when state_value is unchanged", %{site: site} do
+      device = create_polled_device(site)
+      snmp = create_snmp_device(device)
+      insert_dummy_sensor(snmp)
+
+      ss =
+        %StateSensor{}
+        |> StateSensor.changeset(%{
+          snmp_device_id: snmp.id,
+          sensor_descr: "Steady",
+          sensor_oid: "1.3.6.1.2.1.47.1.1.1.1.5.3",
+          sensor_index: "3",
+          state_value: 2,
+          state_descr: "enabled",
+          status: "ok"
+        })
+        |> Repo.insert!()
+
+      stub(SnmpMock, :get, fn _, oid, _ ->
+        case oid do
+          "1.3.6.1.2.1.47.1.1.1.1.5.3" -> {:ok, 2}
+          _ -> {:error, :no_such_object}
+        end
+      end)
+
+      stub(SnmpMock, :get_multiple, fn _, _, _ -> {:error, :timeout} end)
+      stub_walks_empty()
+
+      assert :ok = run_perform(device)
+
+      updated = Repo.get!(StateSensor, ss.id)
+      assert updated.state_value == 2
+    end
+  end
+
+  describe "interface change detection events" do
+    test "speed change generates a speed_change event", %{site: site} do
+      device = create_polled_device(site)
+      snmp = create_snmp_device(device)
+
+      _interface =
+        %Interface{}
+        |> Interface.changeset(%{
+          snmp_device_id: snmp.id,
+          if_index: 7,
+          if_name: "eth7",
+          if_descr: "ethernet",
+          if_type: 6,
+          if_speed: 1_000_000_000,
+          if_phys_address: "00:11:22:33:44:55",
+          if_admin_status: "up",
+          if_oper_status: "up",
+          monitored: true
+        })
+        |> Repo.insert!()
+
+      Phoenix.PubSub.subscribe(Towerops.PubSub, "device:#{device.id}")
+
+      # Speed dropped to 100Mbps (warning), MAC and admin/oper unchanged.
+      stub(SnmpMock, :get, fn _, oid, _ ->
+        case oid do
+          "1.3.6.1.2.1.31.1.1.1.6.7" -> {:ok, 1_000}
+          "1.3.6.1.2.1.31.1.1.1.10.7" -> {:ok, 2_000}
+          "1.3.6.1.2.1.2.2.1.14.7" -> {:ok, 0}
+          "1.3.6.1.2.1.2.2.1.20.7" -> {:ok, 0}
+          "1.3.6.1.2.1.2.2.1.13.7" -> {:ok, 0}
+          "1.3.6.1.2.1.2.2.1.19.7" -> {:ok, 0}
+          _ -> {:error, :no_such_object}
+        end
+      end)
+
+      stub(SnmpMock, :get_multiple, fn _, _oids, _ ->
+        {:ok,
+         %{
+           # speed changed
+           "1.3.6.1.2.1.2.2.1.5.7" => {:integer, 100_000_000},
+           "1.3.6.1.2.1.2.2.1.6.7" => {:"OCTET STRING", <<0, 17, 34, 51, 68, 85>>},
+           "1.3.6.1.2.1.2.2.1.7.7" => {:integer, 1},
+           "1.3.6.1.2.1.2.2.1.8.7" => {:integer, 1}
+         }}
+      end)
+
+      stub_walks_empty()
+
+      assert :ok = run_perform(device)
+
+      received_events = collect_events([], 1_500)
+
+      assert Enum.any?(received_events, fn e ->
+               Map.get(e, :event_type) == "interface_speed_change"
+             end)
+    end
+
+    test "MAC change generates a mac_change event", %{site: site} do
+      device = create_polled_device(site)
+      snmp = create_snmp_device(device)
+
+      _interface =
+        %Interface{}
+        |> Interface.changeset(%{
+          snmp_device_id: snmp.id,
+          if_index: 8,
+          if_name: "eth8",
+          if_descr: "ethernet",
+          if_type: 6,
+          if_speed: 100_000_000,
+          if_phys_address: "00:11:22:33:44:55",
+          if_admin_status: "up",
+          if_oper_status: "up",
+          monitored: true
+        })
+        |> Repo.insert!()
+
+      Phoenix.PubSub.subscribe(Towerops.PubSub, "device:#{device.id}")
+
+      stub(SnmpMock, :get, fn _, oid, _ ->
+        case oid do
+          "1.3.6.1.2.1.31.1.1.1.6.8" -> {:ok, 1_000}
+          "1.3.6.1.2.1.31.1.1.1.10.8" -> {:ok, 2_000}
+          "1.3.6.1.2.1.2.2.1.14.8" -> {:ok, 0}
+          "1.3.6.1.2.1.2.2.1.20.8" -> {:ok, 0}
+          "1.3.6.1.2.1.2.2.1.13.8" -> {:ok, 0}
+          "1.3.6.1.2.1.2.2.1.19.8" -> {:ok, 0}
+          _ -> {:error, :no_such_object}
+        end
+      end)
+
+      stub(SnmpMock, :get_multiple, fn _, _, _ ->
+        {:ok,
+         %{
+           "1.3.6.1.2.1.2.2.1.5.8" => {:integer, 100_000_000},
+           # changed MAC
+           "1.3.6.1.2.1.2.2.1.6.8" => {:"OCTET STRING", <<0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF>>},
+           "1.3.6.1.2.1.2.2.1.7.8" => {:integer, 1},
+           "1.3.6.1.2.1.2.2.1.8.8" => {:integer, 1}
+         }}
+      end)
+
+      stub_walks_empty()
+
+      assert :ok = run_perform(device)
+
+      received_events = collect_events([], 1_500)
+
+      assert Enum.any?(received_events, fn e ->
+               Map.get(e, :event_type) == "interface_mac_change"
+             end)
+    end
+
+    test "oper_status change down→up generates interface_up event", %{site: site} do
+      device = create_polled_device(site)
+      snmp = create_snmp_device(device)
+
+      _interface =
+        %Interface{}
+        |> Interface.changeset(%{
+          snmp_device_id: snmp.id,
+          if_index: 9,
+          if_name: "eth9",
+          if_descr: "ethernet",
+          if_type: 6,
+          if_speed: 100_000_000,
+          if_phys_address: "00:11:22:33:44:55",
+          if_admin_status: "up",
+          if_oper_status: "down",
+          monitored: true
+        })
+        |> Repo.insert!()
+
+      Phoenix.PubSub.subscribe(Towerops.PubSub, "device:#{device.id}")
+
+      stub(SnmpMock, :get, fn _, oid, _ ->
+        case oid do
+          "1.3.6.1.2.1.31.1.1.1.6.9" -> {:ok, 1_000}
+          "1.3.6.1.2.1.31.1.1.1.10.9" -> {:ok, 2_000}
+          "1.3.6.1.2.1.2.2.1.14.9" -> {:ok, 0}
+          "1.3.6.1.2.1.2.2.1.20.9" -> {:ok, 0}
+          "1.3.6.1.2.1.2.2.1.13.9" -> {:ok, 0}
+          "1.3.6.1.2.1.2.2.1.19.9" -> {:ok, 0}
+          _ -> {:error, :no_such_object}
+        end
+      end)
+
+      stub(SnmpMock, :get_multiple, fn _, _, _ ->
+        {:ok,
+         %{
+           "1.3.6.1.2.1.2.2.1.5.9" => {:integer, 100_000_000},
+           "1.3.6.1.2.1.2.2.1.6.9" => {:"OCTET STRING", <<0, 17, 34, 51, 68, 85>>},
+           "1.3.6.1.2.1.2.2.1.7.9" => {:integer, 1},
+           # now up
+           "1.3.6.1.2.1.2.2.1.8.9" => {:integer, 1}
+         }}
+      end)
+
+      stub_walks_empty()
+
+      assert :ok = run_perform(device)
+
+      events = collect_events([], 1_500)
+
+      assert Enum.any?(events, fn e ->
+               Map.get(e, :event_type) == "interface_up"
+             end)
+    end
+  end
+
+  describe "storage and mempool error paths" do
+    test "storage SNMP error skips reading and does not raise", %{site: site} do
+      device = create_polled_device(site)
+      snmp = create_snmp_device(device)
+      insert_dummy_sensor(snmp)
+
+      _storage =
+        %Storage{}
+        |> Storage.changeset(%{
+          snmp_device_id: snmp.id,
+          storage_index: 11,
+          storage_type: "ram",
+          description: "Mem"
+        })
+        |> Repo.insert!()
+
+      stub(SnmpMock, :get, fn _, _, _ -> {:error, :timeout} end)
+      stub(SnmpMock, :get_multiple, fn _, _, _ -> {:error, :timeout} end)
+      stub_walks_empty()
+
+      assert :ok = run_perform(device)
+    end
+
+    test "mempool SNMP error skips reading and does not raise", %{site: site} do
+      device = create_polled_device(site)
+      snmp = create_snmp_device(device)
+      insert_dummy_sensor(snmp)
+
+      _mempool =
+        %Mempool{}
+        |> Mempool.changeset(%{
+          snmp_device_id: snmp.id,
+          mempool_index: "12",
+          mempool_type: "hr_memory",
+          description: "Bad"
+        })
+        |> Repo.insert!()
+
+      stub(SnmpMock, :get, fn _, _, _ -> {:error, :timeout} end)
+      stub(SnmpMock, :get_multiple, fn _, _, _ -> {:error, :timeout} end)
+      stub_walks_empty()
+
+      assert :ok = run_perform(device)
+    end
+
+    test "storage with non-integer values triggers invalid_values branch", %{site: site} do
+      device = create_polled_device(site)
+      snmp = create_snmp_device(device)
+      insert_dummy_sensor(snmp)
+
+      _storage =
+        %Storage{}
+        |> Storage.changeset(%{
+          snmp_device_id: snmp.id,
+          storage_index: 13,
+          storage_type: "fixed_disk",
+          description: "Strange"
+        })
+        |> Repo.insert!()
+
+      stub(SnmpMock, :get, fn _, oid, _ ->
+        case oid do
+          "1.3.6.1.2.1.25.2.3.1.6.13" -> {:ok, "not-int"}
+          "1.3.6.1.2.1.25.2.3.1.5.13" -> {:ok, "not-int"}
+          "1.3.6.1.2.1.25.2.3.1.4.13" -> {:ok, "not-int"}
+          _ -> {:error, :no_such_object}
+        end
+      end)
+
+      stub(SnmpMock, :get_multiple, fn _, _, _ -> {:error, :timeout} end)
+      stub_walks_empty()
+
+      assert :ok = run_perform(device)
+    end
+
+    test "mempool with non-integer values triggers invalid_values branch", %{site: site} do
+      device = create_polled_device(site)
+      snmp = create_snmp_device(device)
+      insert_dummy_sensor(snmp)
+
+      _mempool =
+        %Mempool{}
+        |> Mempool.changeset(%{
+          snmp_device_id: snmp.id,
+          mempool_index: "14",
+          mempool_type: "hr_memory",
+          description: "Strange"
+        })
+        |> Repo.insert!()
+
+      stub(SnmpMock, :get, fn _, oid, _ ->
+        case oid do
+          "1.3.6.1.2.1.25.2.3.1.6.14" -> {:ok, "not-int"}
+          "1.3.6.1.2.1.25.2.3.1.5.14" -> {:ok, "not-int"}
+          "1.3.6.1.2.1.25.2.3.1.4.14" -> {:ok, "not-int"}
+          _ -> {:error, :no_such_object}
+        end
+      end)
+
+      stub(SnmpMock, :get_multiple, fn _, _, _ -> {:error, :timeout} end)
+      stub_walks_empty()
+
+      assert :ok = run_perform(device)
+    end
+  end
+
+  describe "decode_snmp_value larger sizes" do
+    test "decodes binary larger than 16 bytes (s > 8 fallback offset path)" do
+      # 12-byte binary: prefix 4 zero bytes, then 8-byte counter
+      bin = <<0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7>>
+      assert 7 == DevicePollerWorker.decode_snmp_value(bin)
+    end
+  end
+
+  # Walks message queue collecting :device_event payloads up to a deadline.
+  defp collect_events(acc, ms_remaining) do
+    receive do
+      {:device_event, e} -> collect_events([e | acc], ms_remaining)
+    after
+      ms_remaining -> Enum.reverse(acc)
+    end
+  end
+end