"Contacts callsign is in" section on /u/:callsign

Add a new card on the profile page listing every contact where the
callsign appears as either station1 or station2, case-insensitive,
newest first. Backed by a new `Radio.list_contacts_involving_callsign/1`
query with unit coverage for station1/station2 matching, case handling,
ordering, and blank input.

lib/microwaveprop/radio.ex

@@ -128,6 +128,22 @@ defmodule Microwaveprop.Radio do
     |> Repo.all()
   end
 
+  @doc """
+  Returns all contacts where the given callsign appears as either
+  `station1` or `station2`, newest first. Matching is case-insensitive.
+  """
+  @spec list_contacts_involving_callsign(String.t() | nil) :: [Contact.t()]
+  def list_contacts_involving_callsign(callsign) when callsign in [nil, ""], do: []
+
+  def list_contacts_involving_callsign(callsign) when is_binary(callsign) do
+    upcased = String.upcase(callsign)
+
+    Contact
+    |> where([c], fragment("upper(?)", c.station1) == ^upcased or fragment("upper(?)", c.station2) == ^upcased)
+    |> order_by([c], desc: c.qso_timestamp, desc: c.id)
+    |> Repo.all()
+  end
+
   @spec list_contacts(keyword()) :: contact_page()
   def list_contacts(opts \\ []) do
     page = max(Keyword.get(opts, :page, 1), 1)

lib/microwaveprop_web/live/user_profile_live.ex

@@ -19,13 +19,15 @@ defmodule MicrowavepropWeb.UserProfileLive do
       user ->
         contacts = Radio.list_contacts_for_user(user)
         beacons = Beacons.list_beacons_for_user(user)
+        involving = Radio.list_contacts_involving_callsign(user.callsign)
 
         {:ok,
          assign(socket,
            page_title: user.callsign,
            profile: user,
            contacts: contacts,
-           beacons: beacons
+           beacons: beacons,
+           involving: involving
          )}
     end
   end
@@ -106,7 +108,7 @@ defmodule MicrowavepropWeb.UserProfileLive do
         </div>
       </div>
 
-      <div class="card bg-base-200 shadow-sm">
+      <div class="card bg-base-200 shadow-sm mb-6">
         <div class="card-body">
           <h2 class="card-title">Beacons</h2>
           <%= if @beacons == [] do %>
@@ -150,6 +152,44 @@ defmodule MicrowavepropWeb.UserProfileLive do
           <% end %>
         </div>
       </div>
+
+      <div class="card bg-base-200 shadow-sm">
+        <div class="card-body">
+          <h2 class="card-title">Contacts {@profile.callsign} is in</h2>
+          <%= if @involving == [] do %>
+            <p class="text-sm opacity-70">No contacts on file with this callsign yet.</p>
+          <% else %>
+            <div class="overflow-x-auto">
+              <table class="table table-zebra table-sm">
+                <thead>
+                  <tr>
+                    <th>When</th>
+                    <th>Stations</th>
+                    <th>Band</th>
+                    <th>Mode</th>
+                    <th>Distance</th>
+                  </tr>
+                </thead>
+                <tbody>
+                  <tr :for={contact <- @involving} class="hover">
+                    <td class="whitespace-nowrap">
+                      {Calendar.strftime(contact.qso_timestamp, "%Y-%m-%d %H:%M UTC")}
+                    </td>
+                    <td>
+                      <.link navigate={~p"/contacts/#{contact.id}"} class="link link-hover font-mono">
+                        {contact.station1} &harr; {contact.station2}
+                      </.link>
+                    </td>
+                    <td>{contact.band && "#{contact.band} MHz"}</td>
+                    <td>{contact.mode}</td>
+                    <td>{contact.distance_km && "#{contact.distance_km} km"}</td>
+                  </tr>
+                </tbody>
+              </table>
+            </div>
+          <% end %>
+        </div>
+      </div>
     </Layouts.app>
     """
   end

test/microwaveprop/radio_test.exs

@@ -498,4 +498,59 @@ defmodule Microwaveprop.RadioTest do
       assert Radio.list_contacts_for_user(user) == []
     end
   end
+
+  describe "list_contacts_involving_callsign/1" do
+    test "returns contacts where the callsign is station1" do
+      match = create_contact(%{station1: "W5ISP", station2: "K5OTR"})
+      _other = create_contact(%{station1: "W5OTH", station2: "K5OTR"})
+
+      assert [found] = Radio.list_contacts_involving_callsign("W5ISP")
+      assert found.id == match.id
+    end
+
+    test "returns contacts where the callsign is station2" do
+      match = create_contact(%{station1: "W5OTH", station2: "W5ISP"})
+      _other = create_contact(%{station1: "W5OTH", station2: "K5OTR"})
+
+      assert [found] = Radio.list_contacts_involving_callsign("W5ISP")
+      assert found.id == match.id
+    end
+
+    test "matching is case-insensitive" do
+      match = create_contact(%{station1: "W5ISP", station2: "K5OTR"})
+
+      assert [found] = Radio.list_contacts_involving_callsign("w5isp")
+      assert found.id == match.id
+    end
+
+    test "orders newest first" do
+      _old =
+        create_contact(%{
+          station1: "W5ISP",
+          station2: "K5A",
+          qso_timestamp: ~U[2020-01-01 00:00:00Z]
+        })
+
+      new =
+        create_contact(%{
+          station1: "K5B",
+          station2: "W5ISP",
+          qso_timestamp: ~U[2026-06-15 12:00:00Z]
+        })
+
+      assert [first, _] = Radio.list_contacts_involving_callsign("W5ISP")
+      assert first.id == new.id
+    end
+
+    test "returns empty list when no contacts match" do
+      create_contact(%{station1: "W5OTH", station2: "K5OTR"})
+
+      assert Radio.list_contacts_involving_callsign("W5ISP") == []
+    end
+
+    test "returns empty list for blank or nil callsign" do
+      assert Radio.list_contacts_involving_callsign("") == []
+      assert Radio.list_contacts_involving_callsign(nil) == []
+    end
+  end
 end