Batch push_events, RF path queries, and ETS tuning for hot paths

- Batch real-time packet push_events: collect marker data across the
  packet batch and send a single "new_packets" WebSocket message instead
  of one per packet. JS handler processes all live→historical conversions
  before adding new markers to avoid intra-batch conflicts.
- Batch RF path station queries: replace N+1 get_latest_packet_for_callsign
  calls with a single DISTINCT ON query selecting only callsign + lat/lng.
- Add read_concurrency: true to streaming_packets_subscribers and :aprsme
  ETS tables (read-heavy, rarely written).
- Remove dead GC code in PacketConsumer (threshold > 1000 unreachable with
  max batch_size of 100).

assets/js/map.ts

@@ -1125,6 +1125,89 @@ let MapAPRSMap = {
       }
     });
 
+    // Handle batched new packets from LiveView (performance optimization)
+    self.handleEvent(
+      "new_packets",
+      (payload: { packets: MarkerData[] }) => {
+        try {
+          if (!self || !self.map || self.isDestroyed) return;
+          if (!self.map.hasLayer) return;
+          if (self.heatLayer && self.map.hasLayer(self.heatLayer)) return;
+          if (!self.markerStates || !self.markers) return;
+
+          const packets = payload.packets;
+          if (!packets || packets.length === 0) return;
+
+          // Phase 1: Collect ALL markers to convert across the entire batch
+          // This prevents converting a marker that was just added by an earlier packet
+          const allNewCallsigns = new Set<string>();
+          const allNewIds = new Set<string>();
+          for (const data of packets) {
+            const cs = data.callsign_group || data.callsign || data.id;
+            if (cs) allNewCallsigns.add(cs);
+            if (data.id) allNewIds.add(String(data.id));
+          }
+
+          const markersToConvert: string[] = [];
+          self.markerStates.forEach((state, id) => {
+            const stateCallsign = state.callsign_group || state.callsign;
+            if (
+              stateCallsign &&
+              allNewCallsigns.has(stateCallsign) &&
+              (!state.historical || state.is_most_recent_for_callsign) &&
+              !allNewIds.has(String(id))
+            ) {
+              markersToConvert.push(String(id));
+            }
+          });
+
+          // Phase 2: Convert all existing live markers to historical dots
+          for (const id of markersToConvert) {
+            const existingMarker = self.markers.get(id);
+            const existingState = self.markerStates.get(id);
+            if (existingMarker && existingState) {
+              existingState.historical = true;
+              existingState.is_most_recent_for_callsign = false;
+              const incomingCallsign =
+                existingState.callsign_group || existingState.callsign;
+              const historicalIconData = {
+                id: String(id),
+                lat: existingState.lat,
+                lng: existingState.lng,
+                callsign: existingState.callsign || incomingCallsign,
+                callsign_group:
+                  existingState.callsign_group || incomingCallsign,
+                symbol_table_id: existingState.symbol_table,
+                symbol_code: existingState.symbol_code,
+                historical: true,
+                is_most_recent_for_callsign: false,
+                popup: existingState.popup,
+              };
+              existingMarker.setIcon(self.createMarkerIcon(historicalIconData));
+              (existingMarker as APRSMarker)._isHistorical = true;
+            }
+          }
+
+          // Phase 3: Add all new markers
+          for (const data of packets) {
+            const shouldOpenPopup = data.openPopup !== false;
+            const incomingCallsign =
+              data.callsign_group || data.callsign || data.id;
+            self.addMarker({
+              ...data,
+              historical: false,
+              is_most_recent_for_callsign: true,
+              callsign_group: incomingCallsign,
+              popup: data.popup || self.buildPopupContent(data),
+              openPopup: shouldOpenPopup,
+            });
+          }
+        } catch (error) {
+          console.error("Error in new_packets handler:", error);
+        }
+      },
+    );
+
     // Handle highlighting the latest packet (open its popup)
     self.currentPopupMarkerId = null;
     self.handleEvent("highlight_packet", (data: { id: string }) => {

lib/aprsme/application.ex

@@ -185,7 +185,7 @@ defmodule Aprsme.Application do
     :ets.new(:query_cache, [:set, :public, :named_table, read_concurrency: true])
     :ets.new(:device_cache, [:set, :public, :named_table, read_concurrency: true])
     :ets.new(:symbol_cache, [:set, :public, :named_table, read_concurrency: true])
-    :ets.new(:aprsme, [:set, :public, :named_table, write_concurrency: true])
+    :ets.new(:aprsme, [:set, :public, :named_table, read_concurrency: true])
     :ets.insert(:aprsme, {:message_number, 0})
 
     [

lib/aprsme/packet_consumer.ex

@@ -232,12 +232,6 @@ defmodule Aprsme.PacketConsumer do
       )
     end
 
-    # Only do minor GC after very large batches to prevent memory accumulation
-    # This should rarely trigger with batch_size of 100
-    if length(packets) > 1000 do
-      :erlang.garbage_collect(self(), type: :minor)
-    end
-
     :telemetry.execute(
       [
         :aprsme,

lib/aprsme/packets.ex

@@ -866,6 +866,15 @@ defmodule Aprsme.Packets do
     PreparedQueries.get_latest_packet_for_callsign(callsign)
   end
 
+  @doc """
+  Gets latest positions for multiple callsigns in a single batch query.
+  Returns a list of `%{callsign: String.t(), lat: float(), lng: float()}` maps.
+  """
+  @spec get_latest_positions_for_callsigns(list(String.t())) :: [map()]
+  def get_latest_positions_for_callsigns(callsigns) when is_list(callsigns) do
+    PreparedQueries.get_latest_positions_for_callsigns(callsigns)
+  end
+
   @doc """
   Gets the most recent weather packet for a callsign.
   Looks for any packet containing weather data fields.

lib/aprsme/packets/prepared_queries.ex

@@ -27,6 +27,28 @@ defmodule Aprsme.Packets.PreparedQueries do
     )
   end
 
+  @doc """
+  Get latest positions for multiple callsigns in a single query.
+  Returns a list of `%{callsign: String.t(), lat: float(), lng: float()}` maps.
+  Uses DISTINCT ON to get only the most recent packet per callsign.
+  """
+  @spec get_latest_positions_for_callsigns(list(String.t())) :: [map()]
+  def get_latest_positions_for_callsigns([]), do: []
+
+  def get_latest_positions_for_callsigns(callsigns) when is_list(callsigns) do
+    normalized = Enum.map(callsigns, &String.upcase(String.trim(&1)))
+
+    Repo.all(
+      from(p in Packet,
+        where: fragment("upper(?)", p.sender) in ^normalized,
+        where: not is_nil(p.location),
+        distinct: fragment("upper(?)", p.sender),
+        order_by: [asc: fragment("upper(?)", p.sender), desc: p.received_at],
+        select: %{callsign: p.sender, lat: fragment("ST_Y(?)", p.location), lng: fragment("ST_X(?)", p.location)}
+      )
+    )
+  end
+
   @doc """
   Get recent packets within bounds using prepared statement.
   """

lib/aprsme/streaming_packets_pubsub.ex

@@ -61,7 +61,7 @@ defmodule Aprsme.StreamingPacketsPubSub do
   @impl true
   def init(_opts) do
     # Create ETS table for fast lookups
-    :ets.new(@table_name, [:set, :protected, :named_table])
+    :ets.new(@table_name, [:set, :protected, :named_table, read_concurrency: true])
 
     # Monitor subscribers for cleanup
     Process.flag(:trap_exit, true)

lib/aprsme_web/live/map_live/index.ex

@@ -850,15 +850,38 @@ defmodule AprsmeWeb.MapLive.Index do
   end
 
   def handle_info({:packet_batch, packets}, socket) do
-    # Process batch of packets efficiently
-    socket =
-      Enum.reduce(packets, socket, fn packet, acc_socket ->
-        case handle_info_postgres_packet(packet, acc_socket) do
-          {:noreply, new_socket} -> new_socket
-          _ -> acc_socket
-        end
+    # Process batch: collect marker data without pushing events, then send one batch push
+    {socket, marker_data_list} =
+      Enum.reduce(packets, {socket, []}, fn packet, {acc_socket, markers} ->
+        {new_socket, marker_data} = process_packet_for_batch(packet, acc_socket)
+        markers = if marker_data, do: [marker_data | markers], else: markers
+        {new_socket, markers}
       end)
 
+    socket = assign(socket, :last_update_at, DateTime.utc_now())
+
+    # Send heat map update once if in heat map mode, otherwise batch markers
+    socket =
+      cond do
+        socket.assigns.map_zoom <= 8 and marker_data_list != [] ->
+          DisplayManager.send_heat_map_for_current_bounds(socket)
+
+        marker_data_list != [] ->
+          markers =
+            Enum.map(Enum.reverse(marker_data_list), fn data ->
+              if socket.assigns.station_popup_open do
+                Map.put(data, :openPopup, false)
+              else
+                data
+              end
+            end)
+
+          push_event(socket, "new_packets", %{packets: markers})
+
+        true ->
+          socket
+      end
+
     {:noreply, socket}
   end
 
@@ -1047,6 +1070,21 @@ defmodule AprsmeWeb.MapLive.Index do
     PacketProcessor.process_packet_for_display(packet, socket)
   end
 
+  defp process_packet_for_batch(packet, socket) do
+    if socket.assigns.tracked_callsign == "" do
+      PacketProcessor.process_packet_for_marker_data(packet, socket)
+    else
+      packet_sender = Map.get(packet, :sender, Map.get(packet, "sender", ""))
+
+      if String.upcase(packet_sender) == String.upcase(socket.assigns.tracked_callsign) do
+        socket = assign(socket, :tracked_callsign_latest_packet, packet)
+        PacketProcessor.process_packet_for_marker_data(packet, socket)
+      else
+        {socket, nil}
+      end
+    end
+  end
+
   # Handle replaying the next historical packet
 
   @impl true

lib/aprsme_web/live/map_live/packet_processor.ex

@@ -9,8 +9,8 @@ defmodule AprsmeWeb.MapLive.PacketProcessor do
   alias AprsmeWeb.Live.Shared.BoundsUtils
   alias AprsmeWeb.Live.Shared.CoordinateUtils
   alias AprsmeWeb.Live.Shared.PacketUtils, as: SharedPacketUtils
+  alias AprsmeWeb.MapLive.DataBuilder
   alias AprsmeWeb.MapLive.DisplayManager
-  alias AprsmeWeb.MapLive.PacketUtils
   alias Phoenix.LiveView
   alias Phoenix.LiveView.Socket
 
@@ -18,6 +18,7 @@ defmodule AprsmeWeb.MapLive.PacketProcessor do
 
   @doc """
   Process a packet for display on the map.
+  Pushes events directly to the socket (used for single-packet path).
   """
   @spec process_packet_for_display(map(), Socket.t()) :: {:noreply, Socket.t()}
   def process_packet_for_display(packet, socket) do
@@ -28,12 +29,24 @@ defmodule AprsmeWeb.MapLive.PacketProcessor do
     socket = handle_packet_visibility(packet, lat, lon, callsign_key, socket)
 
     # Update last update timestamp for real-time display in map sidebar
-    # This timestamp is shown to users to indicate when data was last refreshed
     socket = assign(socket, :last_update_at, DateTime.utc_now())
 
     {:noreply, socket}
   end
 
+  @doc """
+  Process a packet for batch display. Updates socket state but does NOT push
+  events. Returns `{socket, marker_data | nil}` where marker_data is the data
+  that should be included in a batched push_event, or nil if no marker needed.
+  """
+  @spec process_packet_for_marker_data(map(), Socket.t()) :: {Socket.t(), map() | nil}
+  def process_packet_for_marker_data(packet, socket) do
+    {lat, lon, _data_extended} = CoordinateUtils.get_coordinates(packet)
+    callsign_key = SharedPacketUtils.get_callsign_key(packet)
+
+    batch_visibility_action(packet, lat, lon, callsign_key, socket)
+  end
+
   @doc """
   Handle packet visibility logic based on bounds and existing markers.
   """
@@ -78,34 +91,17 @@ defmodule AprsmeWeb.MapLive.PacketProcessor do
   """
   @spec handle_valid_postgres_packet(map(), number() | nil, number() | nil, Socket.t()) :: Socket.t()
   def handle_valid_postgres_packet(packet, _lat, _lon, socket) do
-    # Add the packet to visible_packets and push a marker immediately
-    callsign_key = SharedPacketUtils.get_callsign_key(packet)
+    {socket, marker_data} = prepare_packet_state(packet, socket)
 
-    new_visible_packets = Map.put(socket.assigns.visible_packets, callsign_key, packet)
+    cond do
+      socket.assigns.map_zoom <= 8 ->
+        send_heat_map_for_current_bounds(socket)
 
-    # Enforce memory limits
-    new_visible_packets =
-      if map_size(new_visible_packets) > @max_visible_packets do
-        SharedPacketUtils.prune_oldest_packets(new_visible_packets, @max_visible_packets)
-      else
-        new_visible_packets
-      end
-
-    socket = assign(socket, :visible_packets, new_visible_packets)
-
-    # Check zoom level to decide how to display the packet
-    if socket.assigns.map_zoom <= 8 do
-      # We're in heat map mode - update the heat map with all current data
-      send_heat_map_for_current_bounds(socket)
-    else
-      # We're in marker mode - send individual marker
-      marker_data = PacketUtils.build_packet_data(packet, true, get_locale(socket))
-
-      if marker_data do
+      marker_data ->
         send_marker_with_popup_check(socket, marker_data)
-      else
+
+      true ->
         socket
-      end
     end
   end
 
@@ -119,14 +115,78 @@ defmodule AprsmeWeb.MapLive.PacketProcessor do
     assign(socket, :visible_packets, new_visible_packets)
   end
 
+  # Batch-mode visibility: same logic as visibility_action but returns
+  # {socket, marker_data | nil} without pushing events
+  defp batch_visibility_action(packet, lat, lon, callsign_key, socket) when not is_nil(lat) and not is_nil(lon) do
+    in_bounds = within_bounds?(%{lat: lat, lon: lon}, socket.assigns.map_bounds)
+    has_marker = Map.has_key?(socket.assigns.visible_packets, callsign_key)
+    batch_dispatch({in_bounds, has_marker}, packet, lat, lon, callsign_key, socket)
+  end
+
+  defp batch_visibility_action(_packet, _lat, _lon, _callsign_key, socket) do
+    {socket, nil}
+  end
+
+  # Out of bounds but has marker — remove it (still pushes remove_marker since
+  # removals are rare and don't benefit from batching)
+  defp batch_dispatch({false, true}, _packet, _lat, _lon, callsign_key, socket) do
+    socket = remove_marker_from_map(callsign_key, socket)
+    {socket, nil}
+  end
+
+  # In bounds, no existing marker — add it
+  defp batch_dispatch({true, false}, packet, _lat, _lon, _callsign_key, socket) do
+    prepare_packet_state(packet, socket)
+  end
+
+  # In bounds, existing marker — update if significant movement
+  defp batch_dispatch({true, true}, packet, lat, lon, callsign_key, socket) do
+    existing_packet = socket.assigns.visible_packets[callsign_key]
+    {existing_lat, existing_lon, _} = CoordinateUtils.get_coordinates(existing_packet)
+
+    if is_number(existing_lat) and is_number(existing_lon) and
+         GeoUtils.significant_movement?(existing_lat, existing_lon, lat, lon, 50) do
+      prepare_packet_state(packet, socket)
+    else
+      new_visible_packets = Map.put(socket.assigns.visible_packets, callsign_key, packet)
+      {assign(socket, :visible_packets, new_visible_packets), nil}
+    end
+  end
+
+  defp batch_dispatch(_, _packet, _lat, _lon, _callsign_key, socket) do
+    {socket, nil}
+  end
+
+  # Shared: updates visible_packets state and builds marker data.
+  # Returns {socket, marker_data | nil}. Does NOT push events.
+  defp prepare_packet_state(packet, socket) do
+    callsign_key = SharedPacketUtils.get_callsign_key(packet)
+
+    new_visible_packets = Map.put(socket.assigns.visible_packets, callsign_key, packet)
+
+    new_visible_packets =
+      if map_size(new_visible_packets) > @max_visible_packets do
+        SharedPacketUtils.prune_oldest_packets(new_visible_packets, @max_visible_packets)
+      else
+        new_visible_packets
+      end
+
+    socket = assign(socket, :visible_packets, new_visible_packets)
+
+    marker_data =
+      if socket.assigns.map_zoom > 8 do
+        DataBuilder.build_packet_data(packet, true, get_locale(socket))
+      end
+
+    {socket, marker_data}
+  end
+
   # Private helper functions
 
-  # Use shared bounds utility
   defp within_bounds?(coords, bounds) do
     BoundsUtils.within_bounds?(coords, bounds)
   end
 
-  # Helper to get locale from socket
   defp get_locale(socket) do
     Map.get(socket.assigns, :locale, "en")
   end
@@ -137,7 +197,6 @@ defmodule AprsmeWeb.MapLive.PacketProcessor do
 
   defp send_marker_with_popup_check(socket, marker_data) do
     if socket.assigns.station_popup_open do
-      # Send without opening popup to avoid interrupting user
       LiveView.push_event(socket, "new_packet", Map.put(marker_data, :openPopup, false))
     else
       LiveView.push_event(socket, "new_packet", marker_data)

lib/aprsme_web/live/map_live/rf_path.ex

@@ -46,12 +46,9 @@ defmodule AprsmeWeb.MapLive.RfPath do
   """
   @spec get_path_station_positions(list(binary()), Phoenix.LiveView.Socket.t()) :: list(map())
   def get_path_station_positions(path_stations, _socket) do
-    # Limit to prevent excessive database queries
-    limited_stations = Enum.take(path_stations, 10)
-
-    limited_stations
-    |> Enum.map(&get_station_position/1)
-    |> Enum.filter(& &1)
+    path_stations
+    |> Enum.take(10)
+    |> Packets.get_latest_positions_for_callsigns()
   end
 
   defp split_at_q_construct(elements) do
@@ -95,18 +92,4 @@ defmodule AprsmeWeb.MapLive.RfPath do
       ""
     end
   end
-
-  defp get_station_position(callsign) do
-    case Packets.get_latest_packet_for_callsign(callsign) do
-      %{lat: lat, lon: lon} when is_number(lat) and is_number(lon) ->
-        %{
-          callsign: callsign,
-          lat: lat,
-          lng: lon
-        }
-
-      _ ->
-        nil
-    end
-  end
 end

test/aprsme/packets/prepared_queries_test.exs

@@ -0,0 +1,113 @@
+defmodule Aprsme.Packets.PreparedQueriesTest do
+  use Aprsme.DataCase, async: false
+
+  alias Aprsme.Packet
+  alias Aprsme.Packets.PreparedQueries
+  alias Aprsme.Repo
+
+  defp create_positioned_packet(attrs) do
+    defaults = %{
+      sender: "TEST-1",
+      base_callsign: "TEST",
+      ssid: "1",
+      destination: "APRS",
+      data_type: "position",
+      lat: Decimal.new("33.0000"),
+      lon: Decimal.new("-96.0000"),
+      received_at: DateTime.truncate(DateTime.utc_now(), :second)
+    }
+
+    merged = Map.merge(defaults, attrs)
+
+    %Packet{}
+    |> Packet.changeset(Map.from_struct(Map.merge(%Packet{}, merged)))
+    |> Repo.insert()
+  end
+
+  describe "get_latest_positions_for_callsigns/1" do
+    test "returns positions for multiple callsigns" do
+      {:ok, _} =
+        create_positioned_packet(%{
+          sender: "K5GVL-10",
+          base_callsign: "K5GVL",
+          ssid: "10",
+          lat: Decimal.new("33.1000"),
+          lon: Decimal.new("-96.6000")
+        })
+
+      {:ok, _} =
+        create_positioned_packet(%{
+          sender: "N5TXZ-10",
+          base_callsign: "N5TXZ",
+          ssid: "10",
+          lat: Decimal.new("33.2000"),
+          lon: Decimal.new("-96.5000")
+        })
+
+      result = PreparedQueries.get_latest_positions_for_callsigns(["K5GVL-10", "N5TXZ-10"])
+
+      assert length(result) == 2
+      callsigns = Enum.map(result, & &1.callsign)
+      assert "K5GVL-10" in callsigns
+      assert "N5TXZ-10" in callsigns
+
+      k5gvl = Enum.find(result, &(&1.callsign == "K5GVL-10"))
+      assert_in_delta k5gvl.lat, 33.1, 0.01
+      assert_in_delta k5gvl.lng, -96.6, 0.01
+    end
+
+    test "returns empty list for empty input" do
+      assert PreparedQueries.get_latest_positions_for_callsigns([]) == []
+    end
+
+    test "returns empty list for nonexistent callsigns" do
+      result = PreparedQueries.get_latest_positions_for_callsigns(["NONEXIST-1", "FAKE-2"])
+      assert result == []
+    end
+
+    test "is case-insensitive" do
+      {:ok, _} =
+        create_positioned_packet(%{
+          sender: "K5GVL-10",
+          base_callsign: "K5GVL",
+          ssid: "10",
+          lat: Decimal.new("33.1000"),
+          lon: Decimal.new("-96.6000")
+        })
+
+      result = PreparedQueries.get_latest_positions_for_callsigns(["k5gvl-10"])
+
+      assert length(result) == 1
+      assert hd(result).callsign == "K5GVL-10"
+    end
+
+    test "returns latest position when multiple packets exist for a callsign" do
+      {:ok, _} =
+        create_positioned_packet(%{
+          sender: "K5GVL-10",
+          base_callsign: "K5GVL",
+          ssid: "10",
+          lat: Decimal.new("33.1000"),
+          lon: Decimal.new("-96.6000"),
+          received_at: DateTime.add(DateTime.utc_now(), -3600, :second)
+        })
+
+      {:ok, _} =
+        create_positioned_packet(%{
+          sender: "K5GVL-10",
+          base_callsign: "K5GVL",
+          ssid: "10",
+          lat: Decimal.new("34.0000"),
+          lon: Decimal.new("-97.0000"),
+          received_at: DateTime.truncate(DateTime.utc_now(), :second)
+        })
+
+      result = PreparedQueries.get_latest_positions_for_callsigns(["K5GVL-10"])
+
+      assert length(result) == 1
+      position = hd(result)
+      assert_in_delta position.lat, 34.0, 0.01
+      assert_in_delta position.lng, -97.0, 0.01
+    end
+  end
+end

test/aprsme_web/live/map_live/packet_processor_test.exs

@@ -0,0 +1,97 @@
+defmodule AprsmeWeb.MapLive.PacketProcessorTest do
+  use ExUnit.Case, async: true
+
+  alias AprsmeWeb.MapLive.PacketProcessor
+
+  defp build_socket(assigns \\ %{}) do
+    defaults = %{
+      map_bounds: %{north: 34.0, south: 32.0, east: -95.0, west: -97.0},
+      visible_packets: %{},
+      map_zoom: 10,
+      station_popup_open: false,
+      locale: "en"
+    }
+
+    merged = Map.merge(defaults, assigns)
+
+    socket = %Phoenix.LiveView.Socket{
+      assigns: Map.put(merged, :__changed__, %{})
+    }
+
+    socket
+  end
+
+  defp build_packet(overrides \\ %{}) do
+    Map.merge(
+      %{
+        id: "test-packet-1",
+        sender: "K5GVL-10",
+        base_callsign: "K5GVL",
+        ssid: "10",
+        lat: 33.1,
+        lon: -96.5,
+        symbol_table_id: "/",
+        symbol_code: "-",
+        comment: "Test station",
+        received_at: DateTime.utc_now()
+      },
+      overrides
+    )
+  end
+
+  describe "process_packet_for_marker_data/2" do
+    test "returns marker data for in-bounds packet at marker zoom level" do
+      socket = build_socket()
+      packet = build_packet()
+
+      {updated_socket, marker_data} = PacketProcessor.process_packet_for_marker_data(packet, socket)
+
+      assert marker_data
+      assert is_map(marker_data)
+      # Socket state should be updated
+      assert map_size(updated_socket.assigns.visible_packets) == 1
+    end
+
+    test "returns nil marker data for out-of-bounds packet" do
+      socket = build_socket()
+      # Packet outside the bounds (north: 34, south: 32, east: -95, west: -97)
+      packet = build_packet(%{lat: 40.0, lon: -80.0})
+
+      {updated_socket, marker_data} = PacketProcessor.process_packet_for_marker_data(packet, socket)
+
+      assert marker_data == nil
+      assert map_size(updated_socket.assigns.visible_packets) == 0
+    end
+
+    test "returns nil marker data for packet with nil coordinates" do
+      socket = build_socket()
+      packet = build_packet(%{lat: nil, lon: nil})
+
+      {updated_socket, marker_data} = PacketProcessor.process_packet_for_marker_data(packet, socket)
+
+      assert marker_data == nil
+      assert map_size(updated_socket.assigns.visible_packets) == 0
+    end
+
+    test "returns nil marker data in heat map mode (zoom <= 8)" do
+      socket = build_socket(%{map_zoom: 7})
+      packet = build_packet()
+
+      {_updated_socket, marker_data} = PacketProcessor.process_packet_for_marker_data(packet, socket)
+
+      assert marker_data == nil
+    end
+
+    test "does not push any events to socket" do
+      socket = build_socket()
+      packet = build_packet()
+
+      {updated_socket, _marker_data} = PacketProcessor.process_packet_for_marker_data(packet, socket)
+
+      # Socket should not have any push_events queued
+      # In LiveView, push_event adds to socket.private[:push_events]
+      push_events = get_in(updated_socket.private, [:push_events]) || []
+      assert push_events == []
+    end
+  end
+end