feat: accept calibration readings only from a chosen tag

lib/localiser/rssi_buffer.ex

@@ -35,26 +35,27 @@ defmodule Localiser.RSSI.Buffer do
 
   defp flush_batches(batches) do
     Enum.each(batches, fn {tag_id, readings} ->
-      case Registry.lookup(Localiser.Registry, {:filter, tag_id}) do
-        [{_pid, _}] ->
-          measurements = Enum.flat_map(readings, &resolve_measurement/1)
-          if measurements != [], do: TagFilter.ingest(tag_id, measurements)
+      # Calibration routing runs regardless of whether the tag has a filter registered,
+      # so scan-mode readings from unknown tags still reach the sensor server.
+      normal = Enum.flat_map(readings, &route_reading(tag_id, &1))
 
-        [] ->
-          :ok
+      if normal != [] do
+        case Registry.lookup(Localiser.Registry, {:filter, tag_id}) do
+          [{_pid, _}] -> TagFilter.ingest(tag_id, normal)
+          [] -> :ok
+        end
       end
     end)
   end
 
-  # Resolves a raw RSSI reading to a measurement with sensor location and distance.
-  # If the sensor is in calibration mode, feeds the reading to Sensor.Server instead
-  # and returns [] so the sample is excluded from Tag.Filter measurements.
-  # If the sensor server isn't running, returns [].
-  defp resolve_measurement(%{sensor_id: sensor_id, rssi: rssi, tx_power: tx_power}) do
+  # Routes one reading. If the sensor is in any calibration state, forwards to Sensor.Server
+  # (with tag_id so scan-mode can advertise it) and returns [] to exclude from Tag.Filter.
+  # Otherwise returns a normal measurement map.
+  defp route_reading(tag_id, %{sensor_id: sensor_id, rssi: rssi, tx_power: tx_power}) do
     case Registry.lookup(Localiser.Registry, {:sensor, sensor_id}) do
       [{_pid, _}] ->
-        if SensorServer.calibrating?(sensor_id) do
-          SensorServer.calibration_reading(sensor_id, rssi)
+        if SensorServer.in_calibration_mode?(sensor_id) do
+          SensorServer.calibration_reading(sensor_id, tag_id, rssi)
           []
         else
           [SensorServer.measure(sensor_id, rssi, tx_power)]