perf(rover): tighten Overpass timeout and log per-step compute timing

Calculate occasionally hung in production for ~30s. Adds per-phase
timing logs to Compute.run so the slow step is visible in pod logs,
and trims the Overpass road-proximity request to a 10s server-side
timeout / 12s receive timeout (no Req retries) so a slow road API
fails soft to no road penalty instead of stalling Calculate.

lib/microwaveprop/rover/compute.ex

@@ -17,6 +17,8 @@ defmodule Microwaveprop.Rover.Compute do
   alias Microwaveprop.Rover.Prominence
   alias Microwaveprop.Rover.RoadProximity
 
+  require Logger
+
   @avg_speed_kmh 65.0
   @drive_penalty_db_per_hour 2.0
   @top_n 5
@@ -86,23 +88,25 @@ defmodule Microwaveprop.Rover.Compute do
     radius_km = max_distance_km * 1.0
     bbox = bbox_around(home, radius_km)
 
-    raw_cells = scores_at.(band_mhz, valid_time, bbox)
+    raw_cells = time_step("scores_at", fn -> scores_at.(band_mhz, valid_time, bbox) end)
 
-    # First filter: drive radius
     in_radius =
       Enum.filter(raw_cells, fn cell ->
         DriveTime.haversine_km({home.lat, home.lon}, {cell.lat, cell.lon}) <= radius_km
       end)
 
-    # Bulk SRTM lookup for cell centers, then per-link path-terrain clearance.
+    Logger.info(
+      "rover compute: radius=#{radius_km}km cells=#{length(raw_cells)} in_radius=#{length(in_radius)} stations=#{length(selected_stations)}"
+    )
+
     points = Enum.map(in_radius, &{&1.lat, &1.lon})
-    elev_map = elev_lookup.(points)
+    elev_map = time_step("elev_lookup", fn -> elev_lookup.(points) end)
-    clearance_map = clearance_lookup.(in_radius, selected_stations)
+    clearance_map = time_step("clearance", fn -> clearance_lookup.(in_radius, selected_stations) end)
-    prominence_map = prominence_lookup.(in_radius)
+    prominence_map = time_step("prominence", fn -> prominence_lookup.(in_radius) end)
 
     road_map =
       if Application.get_env(:microwaveprop, :rover_road_proximity_enabled, true),
-        do: fetch_road_map(road_lookup, in_radius, bbox),
+        do: time_step("road_proximity", fn -> fetch_road_map(road_lookup, in_radius, bbox) end),
         else: %{}
 
     home_elev = home.elev_m || 0
@@ -203,6 +207,12 @@ defmodule Microwaveprop.Rover.Compute do
     end
   end
 
+  defp time_step(label, fun) do
+    {us, result} = :timer.tc(fun)
+    Logger.info("rover compute: #{label} took #{div(us, 1000)} ms")
+    result
+  end
+
   defp fetch_road_map(road_lookup, cells, bbox) do
     case road_lookup.(cells, bbox) do
       {:ok, map} -> map

lib/microwaveprop/rover/road_proximity.ex

@@ -16,6 +16,8 @@ defmodule Microwaveprop.Rover.RoadProximity do
 
   @overpass_url "https://overpass-api.de/api/interpreter"
   @road_types ~w(motorway trunk primary secondary tertiary unclassified residential)
+  @overpass_query_timeout_s 10
+  @overpass_receive_timeout_ms 12_000
 
   @type latlon :: {float(), float()}
   @type segment :: {latlon(), latlon()}
@@ -44,12 +46,16 @@ defmodule Microwaveprop.Rover.RoadProximity do
     types = Enum.join(@road_types, "|")
 
     query = """
-    [out:json][timeout:25];
+    [out:json][timeout:#{@overpass_query_timeout_s}];
     way["highway"~"^(#{types})$"](#{s},#{w},#{n},#{e});
     out geom;
     """
 
-    case Req.post(@overpass_url, form: [data: query], receive_timeout: 30_000) do
+    case Req.post(@overpass_url,
+           form: [data: query],
+           receive_timeout: @overpass_receive_timeout_ms,
+           retry: false
+         ) do
       {:ok, %{status: 200, body: %{"elements" => elements}}} ->
         {:ok, segments_from_elements(elements)}