diff --git a/test/aprsme_web/components/core_components_test.exs b/test/aprsme_web/components/core_components_test.exs
index c084aa3..ad1dff5 100644
--- a/test/aprsme_web/components/core_components_test.exs
+++ b/test/aprsme_web/components/core_components_test.exs
@@ -279,10 +279,218 @@ defmodule AprsmeWeb.CoreComponentsTest do
     test "show_modal returns a JS struct" do
       assert %JS{} = CoreComponents.show_modal("my-modal")
     end
+
+    test "hide_modal returns a JS struct" do
+      assert %JS{} = CoreComponents.hide_modal("my-modal")
+    end
+  end
+
+  describe "translate_error/1" do
+    test "passes plain error tuples through gettext" do
+      # No :count opt → uses dgettext.
+      result = CoreComponents.translate_error({"is invalid", []})
+      assert is_binary(result)
+      assert result =~ "invalid"
+    end
+
+    test "uses dngettext for plural errors" do
+      result = CoreComponents.translate_error({"should be %{count} character(s)", [count: 5]})
+      assert is_binary(result)
+      assert result =~ "5"
+    end
+  end
+
+  describe "translate_errors/2" do
+    test "returns translated errors for the given field" do
+      errors = [
+        {:name, {"can't be blank", []}},
+        {:age, {"is not a number", []}},
+        {:name, {"is too short", []}}
+      ]
+
+      name_errors = CoreComponents.translate_errors(errors, :name)
+      assert length(name_errors) == 2
+      assert Enum.all?(name_errors, &is_binary/1)
+    end
+
+    test "returns an empty list when no errors match the field" do
+      assert CoreComponents.translate_errors([{:other, {"x", []}}], :missing) == []
+    end
+  end
+
+  describe "modal/1" do
+    test "renders a modal with the inner block and close button" do
+      html =
+        render_component(&CoreComponents.modal/1, %{
+          id: "test-modal",
+          show: false,
+          inner_block: text_slot("Modal body content"),
+          title: [],
+          subtitle: [],
+          confirm: [],
+          cancel: [],
+          on_confirm: %JS{},
+          on_cancel: %JS{}
+        })
+
+      assert html =~ ~s(id="test-modal")
+      assert html =~ "Modal body content"
+      assert html =~ ~s(aria-modal="true")
+      assert html =~ ~s(aria-label="close")
+    end
+
+    test "renders the title and subtitle slots when supplied" do
+      html =
+        render_component(&CoreComponents.modal/1, %{
+          id: "sample-modal",
+          show: false,
+          inner_block: text_slot(""),
+          title: slot_with_text(:title, "My Modal Title"),
+          subtitle: slot_with_text(:subtitle, "My subtitle"),
+          confirm: [],
+          cancel: [],
+          on_confirm: %JS{},
+          on_cancel: %JS{}
+        })
+
+      assert html =~ "My Modal Title"
+      assert html =~ "My subtitle"
+    end
+  end
+
+  describe "table/1" do
+    test "renders a row for each entry in :rows" do
+      html =
+        render_component(&CoreComponents.table/1, %{
+          id: "users",
+          rows: [%{id: 1, name: "Alice"}, %{id: 2, name: "Bob"}],
+          row_click: nil,
+          col: [
+            %{
+              __slot__: :col,
+              label: "Name",
+              inner_block: fn _changed, user -> user.name end
+            }
+          ],
+          action: []
+        })
+
+      assert html =~ "Alice"
+      assert html =~ "Bob"
+      assert html =~ ~s(id="users")
+      assert html =~ "Name"
+    end
+
+    test "renders action slot when provided" do
+      html =
+        render_component(&CoreComponents.table/1, %{
+          id: "users",
+          rows: [%{id: 1, name: "Alice"}],
+          row_click: nil,
+          col: [
+            %{
+              __slot__: :col,
+              label: "Name",
+              inner_block: fn _changed, user -> user.name end
+            }
+          ],
+          action: [
+            %{
+              __slot__: :action,
+              inner_block: fn _changed, _user -> "Edit" end
+            }
+          ]
+        })
+
+      assert html =~ "Edit"
+    end
+  end
+
+  describe "list/1" do
+    test "renders a description list with each item" do
+      html =
+        render_component(&CoreComponents.list/1, %{
+          item: [
+            %{
+              __slot__: :item,
+              title: "First",
+              inner_block: fn _changed, _ -> "alpha" end
+            },
+            %{
+              __slot__: :item,
+              title: "Second",
+              inner_block: fn _changed, _ -> "beta" end
+            }
+          ]
+        })
+
+      assert html =~ "First"
+      assert html =~ "alpha"
+      assert html =~ "Second"
+      assert html =~ "beta"
+    end
+  end
+
+  describe "back/1" do
+    test "renders a back link with the given navigate target" do
+      html =
+        render_component(&CoreComponents.back/1, %{
+          navigate: "/somewhere",
+          inner_block: text_slot("Go back")
+        })
+
+      assert html =~ "Go back"
+      assert html =~ ~s(href="/somewhere")
+    end
+  end
+
+  describe "simple_form/1" do
+    test "renders a form with action buttons" do
+      html =
+        render_component(&CoreComponents.simple_form/1, %{
+          for: %{},
+          as: :user,
+          rest: %{},
+          inner_block: text_slot("form fields"),
+          actions: [
+            %{
+              __slot__: :actions,
+              inner_block: fn _changed, _ -> "Save" end
+            }
+          ]
+        })
+
+      assert html =~ "<form"
+      assert html =~ "form fields"
+      assert html =~ "Save"
+    end
+  end
+
+  describe "header/1 with dev mode" do
+    test "shows the DEV badge when dev_mode is true" do
+      html = render_component(&CoreComponents.header/1, %{dev_mode: true})
+      assert html =~ "DEV"
+    end
+
+    test "omits the DEV badge by default" do
+      html = render_component(&CoreComponents.header/1, %{})
+      refute html =~ "\">DEV</"
+    end
+  end
+
+  describe "theme_selector/1" do
+    test "renders the theme dropdown" do
+      html = render_component(&CoreComponents.theme_selector/1, %{})
+      assert html =~ "theme-menu" or html =~ "theme"
+    end
   end
 
   # Helper: build a LiveView inner_block slot that just emits text.
   defp text_slot(text) do
     [%{__slot__: :inner_block, inner_block: fn _changed, _ -> text end}]
   end
+
+  defp slot_with_text(name, text) do
+    [%{__slot__: name, inner_block: fn _changed, _ -> text end}]
+  end
 end