Normalize ADIF MODE/SUBMODE and document the mapping

- AdifImport.normalize_mode/2 maps ADIF MODE (and SUBMODE when present)
  onto the fixed set of modes the site accepts: CW/SSB/FM/FT8/FT4/Q65.
  SUBMODE takes precedence so `MODE=MFSK, SUBMODE=FT8` correctly imports
  as FT8. USB/LSB/DSB all become SSB; NBFM/WFM become FM.
- Unknown modes (RTTY, PSK31, etc.) map to nil so the row still imports
  — mode is optional on the submission path now.
- AdifImport.mode_mapping_reference/0 returns the user-facing list of
  recognized inputs and their mappings.
- Submit page's ADIF tab renders that list in a table so users can see
  upfront what will happen to their file before uploading.

lib/microwaveprop/radio/adif_import.ex

@@ -32,6 +32,73 @@ defmodule Microwaveprop.Radio.AdifImport do
   # Our allowed band centers in MHz, sorted ascending for nearest-match
   @allowed_bands [1296, 2304, 3456, 5760, 10_000, 24_000, 47_000, 68_000, 75_000, 122_000, 134_000, 241_000]
 
+  # Map ADIF MODE (and MODE+SUBMODE combinations) onto the fixed set of modes
+  # the site accepts: CW / SSB / FM / FT8 / FT4 / Q65. Unknown values map to
+  # nil — mode is optional on submission so unrecognized contacts still
+  # import, just without a mode label.
+  @allowed_modes ~w(CW SSB FM FT8 FT4 Q65)
+  @mode_map %{
+    "CW" => "CW",
+    "PCW" => "CW",
+    "SSB" => "SSB",
+    "USB" => "SSB",
+    "LSB" => "SSB",
+    "DSB" => "SSB",
+    "FM" => "FM",
+    "NBFM" => "FM",
+    "WFM" => "FM",
+    "FT8" => "FT8",
+    "FT4" => "FT4",
+    "Q65" => "Q65"
+  }
+
+  @doc """
+  Every ADIF MODE / SUBMODE combination we recognize, in display order.
+  Used by the upload page to show users what will happen to their data
+  before they commit the import.
+  """
+  @spec mode_mapping_reference() :: [{String.t(), String.t()}]
+  def mode_mapping_reference do
+    [
+      {"CW / PCW", "CW"},
+      {"SSB / USB / LSB / DSB", "SSB"},
+      {"FM / NBFM / WFM", "FM"},
+      {"FT8 (or MFSK+SUBMODE=FT8)", "FT8"},
+      {"FT4 (or MFSK+SUBMODE=FT4)", "FT4"},
+      {"Q65 (or MFSK+SUBMODE=Q65)", "Q65"},
+      {"anything else", "(blank — row still imports)"}
+    ]
+  end
+
+  @doc """
+  Normalize an ADIF MODE / SUBMODE pair to one of our allowed modes or nil.
+
+  ADIF convention: digital modes are often reported as `MODE=MFSK` with a
+  specific `SUBMODE` (FT8, FT4, Q65, JT65, …), so we prefer SUBMODE when it
+  matches one of our allowed values. For everything else we look up the raw
+  MODE in `@mode_map`; unknown values return nil.
+  """
+  @spec normalize_mode(String.t() | nil, String.t() | nil) :: String.t() | nil
+  def normalize_mode(mode, submode) do
+    cond do
+      allowed = lookup_allowed(submode) -> allowed
+      allowed = lookup_allowed(mode) -> allowed
+      true -> nil
+    end
+  end
+
+  defp lookup_allowed(nil), do: nil
+
+  defp lookup_allowed(raw) do
+    normalized = raw |> to_string() |> String.trim() |> String.upcase()
+
+    cond do
+      normalized == "" -> nil
+      normalized in @allowed_modes -> normalized
+      true -> Map.get(@mode_map, normalized)
+    end
+  end
+
   @doc """
   Parse ADIF string, validate, and deduplicate. Returns the same preview
   shape as `CsvImport.preview/2`.
@@ -144,7 +211,7 @@ defmodule Microwaveprop.Radio.AdifImport do
     station2 = fields["CALL"]
     grid1 = normalize_grid(fields["MY_GRIDSQUARE"])
     grid2 = normalize_grid(fields["GRIDSQUARE"])
-    mode = fields["MODE"]
+    mode = normalize_mode(fields["MODE"], fields["SUBMODE"])
     band = resolve_band(fields)
     timestamp = parse_adif_datetime(fields["QSO_DATE"], fields["TIME_ON"])
 

lib/microwaveprop_web/live/submit_live.ex

@@ -494,6 +494,8 @@ defmodule MicrowavepropWeb.SubmitLive do
   end
 
   defp adif_upload_form(assigns) do
+    assigns = assign(assigns, :mode_mapping, AdifImport.mode_mapping_reference())
+
     ~H"""
     <div class="space-y-6">
       <div class="alert text-sm">
@@ -515,6 +517,31 @@ defmodule MicrowavepropWeb.SubmitLive do
         </div>
       </div>
 
+      <div class="alert text-sm">
+        <div class="w-full">
+          <p class="font-semibold mb-2">Mode handling</p>
+          <p class="mb-2 text-base-content/70">
+            ADIF modes are normalized to the six modes we track. SUBMODE takes
+            precedence when present (e.g. <code>MODE=MFSK, SUBMODE=FT8</code>
+            imports as FT8).
+          </p>
+          <table class="table table-xs mt-2">
+            <thead>
+              <tr>
+                <th>ADIF value</th>
+                <th>Stored as</th>
+              </tr>
+            </thead>
+            <tbody>
+              <tr :for={{adif, mapped} <- @mode_mapping}>
+                <td><code>{adif}</code></td>
+                <td><code>{mapped}</code></td>
+              </tr>
+            </tbody>
+          </table>
+        </div>
+      </div>
+
       <form
         id="adif-upload-form"
         phx-submit="upload_adif"

test/microwaveprop/radio/adif_import_test.exs

@@ -230,6 +230,63 @@ defmodule Microwaveprop.Radio.AdifImportTest do
       assert row.attrs["station1"] == "W5XD"
     end
 
+    test "normalizes USB / LSB / DSB to SSB" do
+      for sideband <- ~w(USB LSB DSB) do
+        adif =
+          "<STATION_CALLSIGN:4>W5XD<CALL:4>K5TR<GRIDSQUARE:4>EM00<MY_GRIDSQUARE:4>EM12<FREQ:9>10368.000<MODE:#{byte_size(sideband)}>#{sideband}<QSO_DATE:8>20260328<TIME_ON:6>180000<EOR>"
+
+        assert {:ok, %{valid: [row]}} = AdifImport.preview(adif, @submitter)
+        assert row.attrs["mode"] == "SSB", "expected #{sideband} to map to SSB"
+      end
+    end
+
+    test "normalizes NBFM / WFM to FM" do
+      for variant <- ~w(NBFM WFM) do
+        adif =
+          "<STATION_CALLSIGN:4>W5XD<CALL:4>K5TR<GRIDSQUARE:4>EM00<MY_GRIDSQUARE:4>EM12<FREQ:9>10368.000<MODE:#{byte_size(variant)}>#{variant}<QSO_DATE:8>20260328<TIME_ON:6>180000<EOR>"
+
+        assert {:ok, %{valid: [row]}} = AdifImport.preview(adif, @submitter)
+        assert row.attrs["mode"] == "FM"
+      end
+    end
+
+    test "uses SUBMODE when MODE is a generic digital mode" do
+      # ADIF convention: digital modes are reported as MODE=MFSK, SUBMODE=FT8
+      adif = """
+      <STATION_CALLSIGN:4>W5XD<CALL:4>K5TR<GRIDSQUARE:4>EM00<MY_GRIDSQUARE:4>EM12<FREQ:9>10368.000<MODE:4>MFSK<SUBMODE:3>FT8<QSO_DATE:8>20260328<TIME_ON:6>180000<EOR>
+      """
+
+      assert {:ok, %{valid: [row]}} = AdifImport.preview(adif, @submitter)
+      assert row.attrs["mode"] == "FT8"
+    end
+
+    test "SUBMODE takes precedence when both are allowed values" do
+      adif = """
+      <STATION_CALLSIGN:4>W5XD<CALL:4>K5TR<GRIDSQUARE:4>EM00<MY_GRIDSQUARE:4>EM12<FREQ:9>10368.000<MODE:3>MFSK<SUBMODE:3>FT4<QSO_DATE:8>20260328<TIME_ON:6>180000<EOR>
+      """
+
+      assert {:ok, %{valid: [row]}} = AdifImport.preview(adif, @submitter)
+      assert row.attrs["mode"] == "FT4"
+    end
+
+    test "unknown modes are stored as nil so the row still imports" do
+      adif = """
+      <STATION_CALLSIGN:4>W5XD<CALL:4>K5TR<GRIDSQUARE:4>EM00<MY_GRIDSQUARE:4>EM12<FREQ:9>10368.000<MODE:4>RTTY<QSO_DATE:8>20260328<TIME_ON:6>180000<EOR>
+      """
+
+      assert {:ok, %{valid: [row]}} = AdifImport.preview(adif, @submitter)
+      assert row.attrs["mode"] == nil
+    end
+
+    test "missing MODE imports as nil" do
+      adif = """
+      <STATION_CALLSIGN:4>W5XD<CALL:4>K5TR<GRIDSQUARE:4>EM00<MY_GRIDSQUARE:4>EM12<FREQ:9>10368.000<QSO_DATE:8>20260328<TIME_ON:6>180000<EOR>
+      """
+
+      assert {:ok, %{valid: [row]}} = AdifImport.preview(adif, @submitter)
+      assert row.attrs["mode"] == nil
+    end
+
     test "parses file with no header at all" do
       adif = """
       <STATION_CALLSIGN:4>W5XD<CALL:4>K5TR<GRIDSQUARE:4>EM00<MY_GRIDSQUARE:4>EM12<FREQ:9>10368.000<MODE:2>CW<QSO_DATE:8>20260328<TIME_ON:6>180000<EOR>