NarrClient.in_coverage?/1 + callsite guards (1979 → 2014-10-02)

Post-2014 contacts with hrrr_status=:unavailable were being dispatched to
NARR, which 404s because NCEI's archive ends 2014-10-02. 14K of the 14.3K
candidates in prod are post-2014 — these are HRRR's responsibility.

- NarrClient.in_coverage?/1 returns true only inside 1979-01-01 → 2014-10-02
- narr_jobs_for_contact and maybe_enqueue_narr (contact_live) bail out of
  coverage returning []
- BackfillEnqueueWorker.type_filter scopes :narr to qso_timestamp <
  coverage_end so the cron doesn't keep picking post-2014 candidates

lib/microwaveprop/weather/narr_client.ex

@@ -20,6 +20,12 @@ defmodule Microwaveprop.Weather.NarrClient do
   @base_url "https://www.ncei.noaa.gov/data/north-american-regional-reanalysis/access/3-hourly"
   @valid_hours [0, 3, 6, 9, 12, 15, 18, 21]
 
+  # NCEI's NARR archive publishes 1979-01-01 through 2014-10-01 21 UTC
+  # (the last 3-hourly analysis). Dispatching fetches outside that window
+  # just 404s, so callers filter on `in_coverage?/1` first.
+  @coverage_start ~U[1979-01-01 00:00:00Z]
+  @coverage_end ~U[2014-10-02 00:00:00Z]
+
   # Surface records we need from the inventory. Tuples of {var, level} keyed
   # exactly as `parse_inventory/2` returns them. Pressure-level records are
   # added dynamically below from whatever (TMP|HGT|SPFH):"NN mb" tuples the
@@ -89,6 +95,21 @@ defmodule Microwaveprop.Weather.NarrClient do
     %{datetime | hour: snapped_hour, minute: 0, second: 0, microsecond: {0, 0}}
   end
 
+  @doc """
+  True when `datetime` falls inside NCEI's NARR 3-hourly archive window
+  (1979-01-01 through 2014-10-01 21 UTC). Callers use this to avoid
+  dispatching fetches that would just 404.
+  """
+  @spec in_coverage?(DateTime.t()) :: boolean()
+  def in_coverage?(%DateTime{} = datetime) do
+    DateTime.compare(datetime, @coverage_start) != :lt and
+      DateTime.before?(datetime, @coverage_end)
+  end
+
+  @doc "Exclusive end of the NARR coverage window (first timestamp NOT covered)."
+  @spec coverage_end() :: DateTime.t()
+  def coverage_end, do: @coverage_end
+
   @doc """
   Parses the raw text of a NARR `.inv` file into a map keyed by
   `{var, level}` with values of `{byte_offset, length}`.

lib/microwaveprop/workers/backfill_enqueue_worker.ex

@@ -9,6 +9,7 @@ defmodule Microwaveprop.Workers.BackfillEnqueueWorker do
 
   alias Microwaveprop.Radio.Contact
   alias Microwaveprop.Repo
+  alias Microwaveprop.Weather.NarrClient
   alias Microwaveprop.Workers.ContactWeatherEnqueueWorker
 
   require Logger
@@ -147,8 +148,12 @@ defmodule Microwaveprop.Workers.BackfillEnqueueWorker do
   defp type_filter(types) do
     Enum.reduce(types, dynamic(false), fn
       :narr, acc ->
-        # NARR targets contacts where HRRR is unavailable (pre-2014, missing from archive)
-        dynamic([c], ^acc or c.hrrr_status == :unavailable)
+        # NARR targets pre-2014 contacts where HRRR is unavailable. The NCEI
+        # archive ends 2014-10-02 — post-cutoff fetches would 404, so scope
+        # the candidate set here to keep the cron from scanning contacts we
+        # can't serve.
+        coverage_end = NarrClient.coverage_end()
+        dynamic([c], ^acc or (c.hrrr_status == :unavailable and c.qso_timestamp < ^coverage_end))
 
       type, acc ->
         field = :"#{type}_status"

lib/microwaveprop/workers/contact_weather_enqueue_worker.ex

@@ -186,6 +186,17 @@ defmodule Microwaveprop.Workers.ContactWeatherEnqueueWorker do
     # rejects anything else, so snap here in the caller.
     valid_time = NarrClient.snap_to_analysis_hour(contact.qso_timestamp)
 
+    # NCEI's NARR archive covers 1979-01-01 → 2014-10-02. Post-coverage contacts
+    # (hrrr_status = :unavailable but qso_timestamp >= 2014-10-02) are HRRR's
+    # responsibility — NARR would just 404.
+    if NarrClient.in_coverage?(valid_time) do
+      narr_jobs_for_path(contact, valid_time)
+    else
+      []
+    end
+  end
+
+  defp narr_jobs_for_path(contact, valid_time) do
     contact
     |> Radio.contact_path_points()
     |> Enum.flat_map(fn {lat, lon} ->

lib/microwaveprop_web/live/contact_live/show.ex

@@ -669,10 +669,9 @@ defmodule MicrowavepropWeb.ContactLive.Show do
   defp maybe_enqueue_narr(nil, %{hrrr_status: :unavailable} = contact) do
     lat = contact.pos1 && contact.pos1["lat"]
     lon = contact.pos1 && (contact.pos1["lon"] || contact.pos1["lng"])
+    valid_time = NarrClient.snap_to_analysis_hour(contact.qso_timestamp)
 
-    if lat && lon do
-      valid_time = NarrClient.snap_to_analysis_hour(contact.qso_timestamp)
-
+    if lat && lon && NarrClient.in_coverage?(valid_time) do
       %{
         "lat" => lat,
         "lon" => lon,

test/microwaveprop/weather/narr_client_test.exs

@@ -74,6 +74,27 @@ defmodule Microwaveprop.Weather.NarrClientTest do
     end
   end
 
+  # NCEI's NARR archive stops at 2014-10-02. Post-cutoff fetches hit a 404.
+  # Callers filter on this helper to skip post-coverage dispatches.
+  describe "in_coverage?/1" do
+    test "true for dates inside NARR's 1979-01-01 → 2014-10-02 window" do
+      assert NarrClient.in_coverage?(~U[1979-01-01 00:00:00Z])
+      assert NarrClient.in_coverage?(~U[1995-07-04 12:00:00Z])
+      assert NarrClient.in_coverage?(~U[2014-10-01 21:00:00Z])
+    end
+
+    test "false on or after the 2014-10-02 cutoff" do
+      refute NarrClient.in_coverage?(~U[2014-10-02 00:00:00Z])
+      refute NarrClient.in_coverage?(~U[2020-09-20 21:00:00Z])
+      refute NarrClient.in_coverage?(~U[2026-04-16 12:00:00Z])
+    end
+
+    test "false before the 1979-01-01 start" do
+      refute NarrClient.in_coverage?(~U[1978-12-31 23:00:00Z])
+      refute NarrClient.in_coverage?(~U[1970-01-01 00:00:00Z])
+    end
+  end
+
   describe "parse_inventory/2" do
     @fixture_path "test/fixtures/narr/narr-a_221_20100615_1200_000.inv"
     @fixture_file_size 56_221_430

test/microwaveprop/workers/contact_weather_enqueue_worker_test.exs

@@ -638,6 +638,29 @@ defmodule Microwaveprop.Workers.ContactWeatherEnqueueWorkerTest do
       assert ContactWeatherEnqueueWorker.build_narr_jobs([contact]) == []
     end
 
+    test "skips post-2014 contacts (outside NARR coverage — HRRR's job)" do
+      # NARR's NCEI archive stops at 2014-10-02; post-coverage fetches 404.
+      contact =
+        create_contact(%{
+          qso_timestamp: ~U[2020-09-20 21:00:00Z],
+          pos1: %{"lat" => 43.25, "lon" => -78.25},
+          pos2: nil
+        })
+
+      assert ContactWeatherEnqueueWorker.build_narr_jobs([contact]) == []
+    end
+
+    test "skips pre-1979 contacts (below NARR coverage start)" do
+      contact =
+        create_contact(%{
+          qso_timestamp: ~U[1975-06-15 12:00:00Z],
+          pos1: %{"lat" => 32.9, "lon" => -97.0},
+          pos2: nil
+        })
+
+      assert ContactWeatherEnqueueWorker.build_narr_jobs([contact]) == []
+    end
+
     test "deduplicates jobs with identical args across contacts" do
       q1 =
         create_contact(%{