ZCW-Spring26 · Copilot · Apr 17, 2026 · Apr 17, 2026
diff --git a/lib/zip_liner/accounts/member.ex b/lib/zip_liner/accounts/member.ex
@@ -4,6 +4,7 @@ defmodule ZipLiner.Accounts.Member do
 
   @roles ~w(student alumni instructor staff mentor guest)a
   @statuses ~w(active suspended deprovisioned)a
+  @theme_preferences ~w(light dark)a
   @admin_handles ~w(kristofer)
 
   schema "members" do
@@ -21,6 +22,7 @@ defmodule ZipLiner.Accounts.Member do
     field :status, Ecto.Enum, values: @statuses, default: :active
     field :is_admin, :boolean, default: false
     field :open_to_opportunities, :boolean, default: false
+    field :theme_preference, Ecto.Enum, values: @theme_preferences, default: :light
     field :skills, {:array, :string}, default: []
     field :avatar_source, Ecto.Enum, values: [:github, :linkedin], default: :github
 
@@ -57,6 +59,7 @@ defmodule ZipLiner.Accounts.Member do
       :role,
       :status,
       :open_to_opportunities,
+      :theme_preference,
       :skills,
       :avatar_source,
       :cohort_id

diff --git a/lib/zip_liner_web/components/layouts/root.html.heex b/lib/zip_liner_web/components/layouts/root.html.heex
@@ -1,5 +1,5 @@
 <!DOCTYPE html>
-<html lang="en">
+<html lang="en" data-bs-theme={if(assigns[:current_member] && assigns[:current_member].theme_preference == :dark, do: "dark", else: "light")}>
   <head>
     <meta charset="utf-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1" />

diff --git a/lib/zip_liner_web/controllers/settings_html/edit.html.heex b/lib/zip_liner_web/controllers/settings_html/edit.html.heex
@@ -61,6 +61,23 @@
     </div>
   </div>
 
+  <div class="col-12">
+    <h2 class="h5 fw-semibold mb-3">Theme</h2>
+    <input type="hidden" name="member[theme_preference]" value="light" />
+    <div class="form-check form-switch">
+      <input
+        type="checkbox"
+        id="member_theme_preference"
+        name="member[theme_preference]"
+        value="dark"
+        checked={@member.theme_preference == :dark}
+        class="form-check-input"
+        role="switch"
+      />
+      <label for="member_theme_preference" class="form-check-label">Use dark mode</label>
+    </div>
+  </div>
+
   <div class="col-12">
     <button type="submit" class="btn btn-primary">Save Settings</button>
   </div>

diff --git a/priv/repo/migrations/20260417213600_add_theme_preference_to_members.exs b/priv/repo/migrations/20260417213600_add_theme_preference_to_members.exs
@@ -0,0 +1,9 @@
+defmodule ZipLiner.Repo.Migrations.AddThemePreferenceToMembers do
+  use Ecto.Migration
+
+  def change do
+    alter table(:members) do
+      add :theme_preference, :string, default: "light", null: false
+    end
+  end
+end
diff --git a/test/zip_liner/accounts_test.exs b/test/zip_liner/accounts_test.exs
@@ -98,6 +98,12 @@ defmodule ZipLiner.AccountsTest do
       assert updated.bio == "Hello world"
     end
 
+    test "update_member/2 updates theme_preference" do
+      member = member_fixture()
+      {:ok, updated} = Accounts.update_member(member, %{theme_preference: :dark})
+      assert updated.theme_preference == :dark
+    end
+
     test "update_member/2 saves a valid linkedin_url" do
       member = member_fixture()
       {:ok, updated} = Accounts.update_member(member, %{linkedin_url: "https://www.linkedin.com/in/testuser"})

diff --git a/test/zip_liner_web/controllers/settings_controller_test.exs b/test/zip_liner_web/controllers/settings_controller_test.exs
@@ -0,0 +1,29 @@
+defmodule ZipLinerWeb.SettingsControllerTest do
+  use ZipLinerWeb.ConnCase
+
+  alias ZipLiner.Accounts
+
+  describe "settings" do
+    setup :log_in_member
+
+    test "edit renders theme switch with light mode default", %{conn: conn} do
+      conn = get(conn, ~p"/settings")
+      html = html_response(conn, 200)
+
+      assert html =~ "Use dark mode"
+      assert html =~ ~s(name="member[theme_preference]")
+      assert html =~ ~s(data-bs-theme="light")
+    end
+
+    test "update persists dark mode preference", %{conn: conn, member: member} do
+      conn = put(conn, ~p"/settings", member: %{"theme_preference" => "dark"})
+      assert redirected_to(conn) == ~p"/settings"
+
+      updated_member = Accounts.get_member!(member.id)
+      assert updated_member.theme_preference == :dark
+
+      conn = get(recycle(conn), ~p"/settings")
+      assert html_response(conn, 200) =~ ~s(data-bs-theme="dark")
+    end
+  end
+end