diff --git a/priv/static/changelog.txt b/priv/static/changelog.txt
index dd9dec89..87dcb18b 100644
--- a/priv/static/changelog.txt
+++ b/priv/static/changelog.txt
@@ -1,4 +1,5 @@
2026-05-09 — Smarter recommendations + AI-generated insight summaries
+* New recommendation: low optical Rx power on fiber transceivers, with the standard cleanup-then-replace troubleshooting ladder
* New recommendation: upstream degradation — when many of your APs at one site go bad at the same time, the system flags it as an upstream/backhaul problem so you don't waste time chasing per-AP RF symptoms
* New recommendation: device overheating — flags any device with a temperature sensor at or above 65 °C, with the linked QoE score so you can tell whether a slowdown is thermal vs RF before sending a truck
* New recommendation: same-channel conflicts within your own network — when two or more of your APs at the same site sit on the same channel, the system flags the conflict with a clickable evidence table showing noise floor, RF score, average CPE SNR, and client count per AP, and escalates to critical when the RF environment is also contaminated
diff --git a/test/towerops/recommendations/rules/optical_rx_low_test.exs b/test/towerops/recommendations/rules/optical_rx_low_test.exs
new file mode 100644
index 00000000..7f4a2390
--- /dev/null
+++ b/test/towerops/recommendations/rules/optical_rx_low_test.exs
@@ -0,0 +1,139 @@
+defmodule Towerops.Recommendations.Rules.OpticalRxLowTest do
+ @moduledoc """
+ Tests the rule that flags fiber transceivers whose latest received
+ optical power is below operator-actionable thresholds.
+ """
+ use Towerops.DataCase, async: true
+
+ import Towerops.AccountsFixtures
+ import Towerops.DevicesFixtures
+ import Towerops.OrganizationsFixtures
+
+ alias Towerops.Recommendations.Rules.OpticalRxLow
+ alias Towerops.Snmp.Device, as: SnmpDevice
+ alias Towerops.Snmp.Transceiver
+ alias Towerops.Snmp.TransceiverReading
+
+ setup do
+ user = user_fixture()
+ org = organization_fixture(user.id)
+ device = device_fixture(%{organization_id: org.id, name: "Switch-1"})
+
+ {:ok, snmp} =
+ %SnmpDevice{}
+ |> SnmpDevice.changeset(%{device_id: device.id, sys_name: "Switch-1"})
+ |> Repo.insert()
+
+ %{org: org, device: device, snmp: snmp}
+ end
+
+ defp insert_xcvr(snmp, opts \\ []) do
+ {:ok, xcvr} =
+ %Transceiver{}
+ |> Transceiver.changeset(%{
+ snmp_device_id: snmp.id,
+ port_index: Keyword.get(opts, :port, "Gi1/0/1"),
+ transceiver_type: "SFP+",
+ vendor_name: "Test",
+ wavelength_nm: 1310,
+ nominal_bitrate_mbps: 10_000,
+ supports_dom: true
+ })
+ |> Repo.insert()
+
+ xcvr
+ end
+
+ defp insert_reading(xcvr, rx_dbm, opts \\ []) do
+ measured_at = Keyword.get(opts, :measured_at, DateTime.truncate(DateTime.utc_now(), :second))
+
+ %TransceiverReading{}
+ |> TransceiverReading.changeset(%{
+ transceiver_id: xcvr.id,
+ rx_power_dbm: rx_dbm,
+ tx_power_dbm: Keyword.get(opts, :tx, -1.5),
+ temperature_celsius: 35.0,
+ measured_at: measured_at
+ })
+ |> Repo.insert!()
+ end
+
+ test "no insight when there are no transceivers", %{org: org} do
+ assert OpticalRxLow.evaluate(org.id) == []
+ end
+
+ test "no insight when rx_power is healthy", %{org: org, snmp: snmp} do
+ xcvr = insert_xcvr(snmp)
+ insert_reading(xcvr, -8.0)
+
+ assert OpticalRxLow.evaluate(org.id) == []
+ end
+
+ test "warning insight when rx_power is between -32 and -28 dBm",
+ %{org: org, device: device, snmp: snmp} do
+ xcvr = insert_xcvr(snmp, port: "Gi1/0/24")
+ insert_reading(xcvr, -29.5)
+
+ assert [insight] = OpticalRxLow.evaluate(org.id)
+ assert insight.type == "optical_rx_low"
+ assert insight.urgency == "warning"
+ assert insight.device_id == device.id
+ assert insight.metadata["rx_power_dbm"] == -29.5
+ assert insight.metadata["port"] == "Gi1/0/24"
+ assert insight.title =~ "Switch-1"
+ assert insight.title =~ "-29.5"
+ end
+
+ test "critical insight at <= -32 dBm", %{org: org, snmp: snmp} do
+ xcvr = insert_xcvr(snmp)
+ insert_reading(xcvr, -33.0)
+
+ assert [insight] = OpticalRxLow.evaluate(org.id)
+ assert insight.urgency == "critical"
+ end
+
+ test "uses the most recent reading per transceiver", %{org: org, snmp: snmp} do
+ xcvr = insert_xcvr(snmp)
+
+ insert_reading(xcvr, -29.0,
+ measured_at: DateTime.utc_now() |> DateTime.add(-3600, :second) |> DateTime.truncate(:second)
+ )
+
+ insert_reading(xcvr, -8.0)
+
+ assert OpticalRxLow.evaluate(org.id) == []
+ end
+
+ test "ignores readings older than 1 hour", %{org: org, snmp: snmp} do
+ xcvr = insert_xcvr(snmp)
+
+ insert_reading(xcvr, -29.0,
+ measured_at: DateTime.utc_now() |> DateTime.add(-2 * 3600, :second) |> DateTime.truncate(:second)
+ )
+
+ assert OpticalRxLow.evaluate(org.id) == []
+ end
+
+ test "produces one insight per (device, port) — distinct dedup", %{org: org, snmp: snmp} do
+ a = insert_xcvr(snmp, port: "Gi1/0/1")
+ b = insert_xcvr(snmp, port: "Gi1/0/2")
+
+ insert_reading(a, -29.0)
+ insert_reading(b, -30.0)
+
+ assert insights = OpticalRxLow.evaluate(org.id)
+ assert length(insights) == 2
+
+ keys = Enum.map(insights, & &1.metadata["dedup_key"])
+ assert Enum.uniq(keys) == keys
+ end
+
+ test "scopes to organization", %{snmp: snmp} do
+ xcvr = insert_xcvr(snmp)
+ insert_reading(xcvr, -33.0)
+
+ other_user = user_fixture()
+ other_org = organization_fixture(other_user.id)
+ assert OpticalRxLow.evaluate(other_org.id) == []
+ end
+end