fix(snmp): scale agent-polled temperatures + quiet two info logs

- ToweropsWeb.AgentChannel now runs sensor readings through
  Towerops.Snmp.SensorScale.normalize/2 in both resolve_sensor_value/2
  and the GraphQL publisher. Without this, MikroTik mtxrHl* deci-degree
  readings (e.g. Culleoka reporting 294 -> 29.4°C) were stored and
  alerted on at 294°C. The DevicePollerWorker path already did this;
  only the agent path was missing it.
- Demote "Received SNMP result from agent" and "Processing polling
  result for X" from info to debug — they fire every poll cycle on
  every device and were dominating prod logs.

CHANGELOG.txt

@@ -1,3 +1,20 @@
+2026-05-10
+fix(snmp): apply SensorScale on the agent-polled path
+  ToweropsWeb.AgentChannel.resolve_sensor_value/2 and the GraphQL
+  publisher now run readings through Towerops.Snmp.SensorScale.normalize/2
+  before storing/publishing. Previously only the direct DevicePollerWorker
+  path normalized values, so MikroTik mtxrHl* deci-degree readings (e.g.
+  Culleoka router reporting 294 → expected 29.4 °C) were stored and
+  alerted on as 294 °C.
+  Test: agent_channel_test.exs gains "poll result rescales implausibly
+  hot temperature readings" — pushing 294 lands as 29.4 in last_value.
+
+chore(logs): demote two noisy info → debug
+  AgentChannel "Received SNMP result from agent" and
+  "Processing polling result for X" now log at debug. They fire on
+  every successful agent poll cycle and were dominating production
+  log volume.
+
 2026-05-10
 feat(insights): superuser "Regenerate insights" button on /insights
   ToweropsWeb.InsightsLive.Index — new handle_event("regenerate_insights")

lib/towerops_web/channels/agent_channel.ex

@@ -52,6 +52,7 @@ defmodule ToweropsWeb.AgentChannel do
   alias Towerops.Snmp.AgentDiscovery
   alias Towerops.Snmp.Discovery
   alias Towerops.Snmp.SensorChangeDetector
+  alias Towerops.Snmp.SensorScale
   alias Towerops.Topology
   alias ToweropsWeb.GraphQL.Subscriptions
   alias ToweropsWeb.RemoteIp
@@ -705,7 +706,7 @@ defmodule ToweropsWeb.AgentChannel do
   # Private helpers
 
   defp process_snmp_result_message(binary_b64, socket) do
-    Logger.info("Received SNMP result from agent (binary size: #{byte_size(binary_b64)})")
+    Logger.debug("Received SNMP result from agent (binary size: #{byte_size(binary_b64)})")
 
     with {:ok, binary} <- safe_base64_decode(binary_b64),
          {:ok, result} <- SnmpResult.decode(binary) do
@@ -1932,7 +1933,7 @@ defmodule ToweropsWeb.AgentChannel do
     # Use server time to avoid clock drift issues between agents
     timestamp = Towerops.Time.now()
 
-    Logger.info(
+    Logger.debug(
       "Processing polling result for #{device.name}: #{map_size(oid_values)} OIDs, #{length(snmp_device.sensors)} sensors, #{length(snmp_device.interfaces)} interfaces"
     )
 
@@ -2140,7 +2141,13 @@ defmodule ToweropsWeb.AgentChannel do
         normalized_oid = String.trim_leading(sensor.sensor_oid, ".")
         raw_value = Map.get(oid_values, normalized_oid)
         parsed = parse_float(raw_value)
-        value = if parsed, do: Float.round(parsed / sensor.sensor_divisor, 1)
+
+        value =
+          if parsed do
+            divided = parsed / sensor.sensor_divisor
+            scaled = SensorScale.normalize(sensor.sensor_type, divided)
+            Float.round(scaled / 1.0, 2)
+          end
 
         %{
           sensor_id: sensor.id,
@@ -2168,7 +2175,9 @@ defmodule ToweropsWeb.AgentChannel do
 
     with value when not is_nil(value) <- Map.get(oid_values, normalized_oid),
          parsed when not is_nil(parsed) <- parse_float(value) do
-      Float.round(parsed / sensor.sensor_divisor, 1)
+      divided = parsed / sensor.sensor_divisor
+      normalized = SensorScale.normalize(sensor.sensor_type, divided)
+      Float.round(normalized / 1.0, 2)
     else
       _ -> nil
     end

test/towerops_web/channels/agent_channel_test.exs

@@ -993,6 +993,36 @@ defmodule ToweropsWeb.AgentChannelTest do
       assert updated_sensor.last_value == 45.0
     end
 
+    test "poll result rescales implausibly hot temperature readings", %{
+      socket: socket,
+      device: device,
+      sensor: sensor
+    } do
+      # Some MikroTik models (e.g. RB-series with mtxrHl* OIDs) report
+      # temperature in deci-degrees so a "29.4°C" reading lands on the
+      # wire as 294. SensorScale.normalize/2 must run on the agent path
+      # so it doesn't store 294°C.
+      result = %SnmpResult{
+        device_id: device.id,
+        job_type: :POLL,
+        job_id: "poll:#{device.id}",
+        timestamp: DateTime.to_unix(DateTime.utc_now()),
+        oid_values: %{
+          sensor.sensor_oid => "294"
+        }
+      }
+
+      push(socket, "result", encode_payload(result))
+
+      updated_sensor =
+        poll_until(fn ->
+          s = Towerops.Repo.get!(Sensor, sensor.id)
+          if s.last_value && s.last_value < 100.0, do: s
+        end)
+
+      assert_in_delta updated_sensor.last_value, 29.4, 0.01
+    end
+
     test "poll result stores interface stats", %{
       socket: socket,
       device: device,