fix: issue #14 wrong sorting in category and tag archives

lib/bds/generation/data.ex

@@ -175,6 +175,7 @@ defmodule BDS.Generation.Data do
         end)
       end
     )
+    |> sort_generation_index_posts()
   end
 
   ## --- internals -----------------------------------------------------------
@@ -398,4 +399,17 @@ defmodule BDS.Generation.Data do
   defp append_generation_index(index, field, key, post) do
     update_in(index[field], fn grouped -> Map.update(grouped, key, [post], &[post | &1]) end)
   end
+
+  # Archive listings (categories, tags, dates) must render newest first. The
+  # index is built by prepending, so each grouped list is sorted explicitly by
+  # creation date (descending) to guarantee a stable newest-first order.
+  defp sort_generation_index_posts(index) do
+    Map.new(index, fn {field, grouped} ->
+      {field, Map.new(grouped, fn {key, posts} -> {key, sort_index_posts_desc(posts)} end)}
+    end)
+  end
+
+  defp sort_index_posts_desc(posts) do
+    Enum.sort_by(posts, &{-(&1.created_at || 0), -(&1.published_at || 0), to_string(&1.slug)})
+  end
 end

lib/bds/rendering/list_archive.ex

@@ -273,7 +273,7 @@ defmodule BDS.Rendering.ListArchive do
           |> DateTime.to_date()
           |> Date.to_iso8601())
       )
-      |> Enum.sort_by(fn {label, _posts} -> label end)
+      |> Enum.sort_by(fn {label, _posts} -> label end, :desc)
 
     last_index = length(grouped_blocks) - 1
 
@@ -284,7 +284,7 @@ defmodule BDS.Rendering.ListArchive do
         date_label: date_label,
         show_date_marker: true,
         show_separator: index < last_index,
-        posts: Enum.sort_by(grouped_posts, &Map.get(&1, :created_at))
+        posts: Enum.sort_by(grouped_posts, &Map.get(&1, :created_at), :desc)
       }
     end)
     |> case do