diff --git a/lib/microwaveprop/rover.ex b/lib/microwaveprop/rover.ex
new file mode 100644
index 00000000..7742dec5
--- /dev/null
+++ b/lib/microwaveprop/rover.ex
@@ -0,0 +1,139 @@
+defmodule Microwaveprop.Rover do
+  @moduledoc """
+  Context for managing a user's fixed stations and providing the
+  rover-planning defaults.
+
+  All mutations are scoped to a user — `update_station/3`, `delete_station/2`,
+  and `toggle_selected/2` return `{:error, :not_found}` when invoked on
+  a station belonging to a different user.
+  """
+
+  import Ecto.Query
+
+  alias Microwaveprop.Accounts.User
+  alias Microwaveprop.Radio.Maidenhead
+  alias Microwaveprop.Repo
+  alias Microwaveprop.Rover.FixedStation
+
+  @default_stations [
+    %{callsign: "W5LUA", grid: "EM13qc"},
+    %{callsign: "W5HN", grid: "EM13nf"},
+    %{callsign: "N5XU", grid: "EM10cl"}
+  ]
+
+  @spec list_stations(User.t()) :: [FixedStation.t()]
+  def list_stations(%User{id: user_id}) do
+    FixedStation
+    |> where([s], s.user_id == ^user_id)
+    |> order_by([s], asc: s.position, asc: s.inserted_at)
+    |> Repo.all()
+  end
+
+  @spec create_station(User.t(), map()) :: {:ok, FixedStation.t()} | {:error, Ecto.Changeset.t()}
+  def create_station(%User{} = user, attrs) do
+    attrs_with_position = Map.put_new(attrs, :position, next_position(user))
+
+    %FixedStation{user_id: user.id}
+    |> FixedStation.changeset(attrs_with_position)
+    |> Repo.insert()
+    |> maybe_enqueue_elevation()
+  end
+
+  @spec update_station(User.t(), Ecto.UUID.t(), map()) ::
+          {:ok, FixedStation.t()} | {:error, :not_found | Ecto.Changeset.t()}
+  def update_station(%User{} = user, id, attrs) do
+    case fetch_owned(user, id) do
+      {:ok, station} ->
+        station
+        |> FixedStation.changeset(attrs)
+        |> Repo.update()
+
+      {:error, :not_found} ->
+        {:error, :not_found}
+    end
+  end
+
+  @spec delete_station(User.t(), Ecto.UUID.t()) ::
+          {:ok, FixedStation.t()} | {:error, :not_found}
+  def delete_station(%User{} = user, id) do
+    case fetch_owned(user, id) do
+      {:ok, station} ->
+        Repo.delete(station)
+
+      {:error, :not_found} ->
+        {:error, :not_found}
+    end
+  end
+
+  @spec toggle_selected(User.t(), Ecto.UUID.t()) ::
+          {:ok, FixedStation.t()} | {:error, :not_found | Ecto.Changeset.t()}
+  def toggle_selected(%User{} = user, id) do
+    case fetch_owned(user, id) do
+      {:ok, station} ->
+        station
+        |> Ecto.Changeset.change(selected: not station.selected)
+        |> Repo.update()
+
+      {:error, :not_found} ->
+        {:error, :not_found}
+    end
+  end
+
+  @doc """
+  Three hardcoded NTMS stations used as the anonymous-user fallback in
+  the rover planner. Plain maps shaped like `FixedStation`, with lat/lon
+  derived from each grid via `Maidenhead.to_latlon/1`.
+  """
+  @spec default_stations() :: [map()]
+  def default_stations do
+    @default_stations
+    |> Enum.with_index()
+    |> Enum.map(fn {%{callsign: callsign, grid: grid}, index} ->
+      {:ok, {lat, lon}} = Maidenhead.to_latlon(grid)
+
+      %{
+        callsign: callsign,
+        grid: grid,
+        lat: lat,
+        lon: lon,
+        elevation_m: nil,
+        selected: true,
+        position: index
+      }
+    end)
+  end
+
+  defp fetch_owned(%User{id: user_id}, id) do
+    case Repo.get(FixedStation, id) do
+      %FixedStation{user_id: ^user_id} = station -> {:ok, station}
+      _ -> {:error, :not_found}
+    end
+  end
+
+  defp next_position(%User{id: user_id}) do
+    query =
+      from s in FixedStation,
+        where: s.user_id == ^user_id,
+        select: count(s.id)
+
+    Repo.one(query) || 0
+  end
+
+  defp maybe_enqueue_elevation({:ok, %FixedStation{elevation_m: nil, id: id}} = result) do
+    enqueue_station_elevation(id)
+    result
+  end
+
+  defp maybe_enqueue_elevation(other), do: other
+
+  # Wrapped behind a function-exported guard so this module compiles
+  # cleanly while Task 8's worker is still being authored — the worker
+  # is referenced by atom and resolved at runtime once it's loaded.
+  defp enqueue_station_elevation(id) do
+    worker = Microwaveprop.Workers.StationElevationWorker
+
+    if Code.ensure_loaded?(worker) and function_exported?(worker, :new, 1) do
+      %{id: id} |> worker.new() |> Oban.insert()
+    end
+  end
+end
diff --git a/test/microwaveprop/rover_test.exs b/test/microwaveprop/rover_test.exs
new file mode 100644
index 00000000..748bfdd5
--- /dev/null
+++ b/test/microwaveprop/rover_test.exs
@@ -0,0 +1,100 @@
+defmodule Microwaveprop.RoverTest do
+  use Microwaveprop.DataCase, async: true
+
+  import Microwaveprop.AccountsFixtures
+
+  alias Microwaveprop.Rover
+  alias Microwaveprop.Rover.FixedStation
+
+  describe "list_stations/1" do
+    test "returns user's stations ordered by position asc" do
+      user = user_fixture()
+      {:ok, _b} = Rover.create_station(user, %{callsign: "B5BBB", lat: 33.0, lon: -96.0})
+      {:ok, _a} = Rover.create_station(user, %{callsign: "A5AAA", lat: 33.0, lon: -96.0})
+
+      stations = Rover.list_stations(user)
+
+      assert Enum.map(stations, & &1.callsign) == ["B5BBB", "A5AAA"]
+      assert Enum.map(stations, & &1.position) == [0, 1]
+    end
+  end
+
+  describe "create_station/2" do
+    test "derives lat/lon from grid only" do
+      user = user_fixture()
+      {:ok, station} = Rover.create_station(user, %{callsign: "W5LUA", grid: "EM13qc"})
+      assert_in_delta station.lat, 33.10, 0.05
+      assert_in_delta station.lon, -96.625, 0.05
+    end
+
+    test "errors with neither grid nor lat/lon" do
+      user = user_fixture()
+      assert {:error, %Ecto.Changeset{}} = Rover.create_station(user, %{callsign: "W5LUA"})
+    end
+
+    test "unique constraint surfaces as changeset error" do
+      user = user_fixture()
+      {:ok, _} = Rover.create_station(user, %{callsign: "W5LUA", lat: 33.0, lon: -96.0})
+
+      assert {:error, %Ecto.Changeset{}} =
+               Rover.create_station(user, %{callsign: "W5LUA", lat: 34.0, lon: -97.0})
+    end
+  end
+
+  describe "update_station/3" do
+    test "foreign user returns :not_found" do
+      user = user_fixture()
+      other = user_fixture()
+      {:ok, station} = Rover.create_station(user, %{callsign: "W5LUA", lat: 33.0, lon: -96.0})
+
+      assert {:error, :not_found} = Rover.update_station(other, station.id, %{selected: false})
+    end
+  end
+
+  describe "delete_station/2" do
+    test "foreign user returns :not_found" do
+      user = user_fixture()
+      other = user_fixture()
+      {:ok, station} = Rover.create_station(user, %{callsign: "W5LUA", lat: 33.0, lon: -96.0})
+
+      assert {:error, :not_found} = Rover.delete_station(other, station.id)
+    end
+
+    test "owner deletes" do
+      user = user_fixture()
+      {:ok, station} = Rover.create_station(user, %{callsign: "W5LUA", lat: 33.0, lon: -96.0})
+      assert {:ok, %FixedStation{}} = Rover.delete_station(user, station.id)
+      assert Rover.list_stations(user) == []
+    end
+  end
+
+  describe "toggle_selected/2" do
+    test "flips boolean" do
+      user = user_fixture()
+      {:ok, station} = Rover.create_station(user, %{callsign: "W5LUA", lat: 33.0, lon: -96.0})
+      assert station.selected == true
+      assert {:ok, updated} = Rover.toggle_selected(user, station.id)
+      assert updated.selected == false
+      assert {:ok, again} = Rover.toggle_selected(user, station.id)
+      assert again.selected == true
+    end
+  end
+
+  describe "default_stations/0" do
+    test "returns 3 hardcoded NTMS stations" do
+      stations = Rover.default_stations()
+      assert length(stations) == 3
+      callsigns = Enum.map(stations, & &1.callsign)
+      assert "W5LUA" in callsigns
+      assert "W5HN" in callsigns
+      assert "N5XU" in callsigns
+      assert Enum.all?(stations, & &1.selected)
+      assert Enum.map(stations, & &1.position) == [0, 1, 2]
+
+      Enum.each(stations, fn s ->
+        assert is_float(s.lat)
+        assert is_float(s.lon)
+      end)
+    end
+  end
+end