Remove 500-limit on BackfillEnqueueWorker cron

10K+ HRRR-pending contacts were starving the 200-ish NARR candidates
out of the 500 per-run slot each 30 min because NARR candidates sort
last by the :hrrr_status priority. Drop the cap so every eligible
contact gets enqueued on each cron run; queue concurrency still paces
the actual fetches. Worker keeps supporting an explicit "limit" arg
for ad-hoc runs and tests.

config/runtime.exs

@@ -222,7 +222,7 @@ if config_env() == :prod do
          # :unavailable (pre-2014, missing from the HRRR archive) and dispatches
          # NarrFetchWorker against NCEI. See narr_jobs_for_contact/1.
          {"*/30 * * * *", Microwaveprop.Workers.BackfillEnqueueWorker,
-          args: %{"limit" => 500, "types" => ["hrrr", "weather", "terrain", "iemre", "narr"]}},
+          args: %{"types" => ["hrrr", "weather", "terrain", "iemre", "narr"]}},
          # Hourly safety net for pos1/pos2/distance_km. Normally every contact
          # gets positions at insert time via Radio.resolve_grids_and_insert/1,
          # but direct DB writes (manual fixes, bulk imports) can bypass that.

lib/microwaveprop/workers/backfill_enqueue_worker.ex

@@ -32,8 +32,9 @@ defmodule Microwaveprop.Workers.BackfillEnqueueWorker do
   @stale_queued_cutoff_seconds 3 * 86_400
 
   @impl Oban.Worker
-  def perform(%Oban.Job{args: %{"limit" => limit} = args}) do
+  def perform(%Oban.Job{args: args}) do
     types = parse_types(args)
+    limit = Map.get(args, "limit")
 
     reconciled = reconcile_stale_queued(types)
 
@@ -52,7 +53,7 @@ defmodule Microwaveprop.Workers.BackfillEnqueueWorker do
       |> where([c], not is_nil(c.pos1) or not is_nil(c.grid1))
       |> where(^type_filter(types))
       |> order_by(^status_priority_order(types))
-      |> limit(^limit)
+      |> maybe_limit(limit)
       |> Repo.all()
 
     count = length(contacts)
@@ -69,6 +70,9 @@ defmodule Microwaveprop.Workers.BackfillEnqueueWorker do
     :ok
   end
 
+  defp maybe_limit(query, nil), do: query
+  defp maybe_limit(query, n) when is_integer(n), do: limit(query, ^n)
+
   defp parse_types(%{"types" => types}) when is_list(types) do
     types |> Enum.filter(&(&1 in @valid_types)) |> Enum.map(&String.to_existing_atom/1)
   end

test/microwaveprop/workers/backfill_enqueue_worker_test.exs

@@ -109,6 +109,22 @@ defmodule Microwaveprop.Workers.BackfillEnqueueWorkerTest do
                })
     end
 
+    test "enqueues all pending contacts when limit is omitted" do
+      Phoenix.PubSub.subscribe(Microwaveprop.PubSub, "backfill:enqueue_complete")
+
+      for i <- 1..7 do
+        ts = DateTime.add(~U[2026-01-01 00:00:00Z], i * 3600, :second)
+        create_contact(%{qso_timestamp: ts})
+      end
+
+      assert :ok =
+               BackfillEnqueueWorker.perform(%Oban.Job{
+                 args: %{"types" => @non_era5_types}
+               })
+
+      assert_receive {:enqueue_complete, 7}
+    end
+
     test "broadcasts enqueue_complete with count" do
       Phoenix.PubSub.subscribe(Microwaveprop.PubSub, "backfill:enqueue_complete")