feat: issue #32 markdown editor for TUI

lib/bds/tui.ex

@@ -25,8 +25,8 @@ defmodule BDS.TUI do
   `yyyy-mm-dd`; enter keeps the filter, esc clears it),
   `:` vi-style command prompt over the Blog-menu shell commands, `?`
   command help (commands whose report/apply UI is GUI-only are marked).
-  Posts open in the rendered markdown preview (new empty posts open in
-  the editor). Editor focus: `ctrl+e` toggles preview/editor, text keys
+  Posts open in the syntax-highlighted, word-wrapping editor. Editor
+  focus: `ctrl+e` toggles editor/rendered-markdown preview, text keys
   edit, `ctrl+s` save, `ctrl+p` publish, `ctrl+t` edit title, `ctrl+l`
   cycle language, `ctrl+g` AI suggestions, `esc` back to sidebar. `ctrl+q`
   quits, `esc` also closes a media preview. The UI locale is the
@@ -42,6 +42,7 @@ defmodule BDS.TUI do
   alias BDS.Git
   alias BDS.Posts
   alias BDS.Projects
+  alias BDS.UI.CodeEditor
   alias BDS.UI.PostEditor.{Draft, Metadata, Persistence}
   alias BDS.UI.SettingsForm
   alias BDS.UI.Sidebar
@@ -49,7 +50,7 @@ defmodule BDS.TUI do
   alias ExRatatui.Layout
   alias ExRatatui.Layout.Rect
   alias ExRatatui.Style
-  alias ExRatatui.Widgets.{Block, Clear, List, Markdown, Paragraph, Tabs, Textarea}
+  alias ExRatatui.Widgets.{Block, Clear, List, Markdown, Paragraph, Tabs}
 
   @views ~w(posts media templates scripts tags settings git)
   @git_diff_scroll_step 10
@@ -230,8 +231,7 @@ defmodule BDS.TUI do
        when is_binary(project_id) do
     case Posts.create_post(%{project_id: project_id, title: "", content: ""}) do
       {:ok, post} ->
-        # A fresh, empty post starts in the editor — there is nothing to
-        # preview yet; existing posts open in the preview instead.
+        # A fresh, empty post starts in the editor — like every post.
         {:noreply, state |> load_sidebar() |> open_post(post.id, false)}
 
       {:error, reason} ->
@@ -1448,10 +1448,9 @@ defmodule BDS.TUI do
     [title_widget, body_widget(state, editor, body_rect)]
   end
 
-  # The editing textarea cannot soft-wrap (upstream ratatui-textarea
-  # limitation), so ctrl+e flips to a word-wrapped read-only Markdown
-  # preview of the current draft. Wrap moves into the editor itself with
-  # the planned MarkdownEditor custom widget.
+  # ctrl+e flips to a word-wrapped read-only Markdown preview of the
+  # current draft; the editor itself is a syntax-highlighted, wrapping
+  # BDS.UI.CodeEditor over the same Rust-owned textarea.
   defp body_widget(_state, %{preview?: true} = editor, body_rect) do
     preview_title =
       "#{dgettext("ui", "Preview (ctrl+e to edit)")} [#{editor.language}]"
@@ -1468,14 +1467,14 @@ defmodule BDS.TUI do
       "#{dgettext("ui", "Content")} [#{editor.language}]" <>
         if(editor.dirty, do: " •", else: "")
 
-    {%Textarea{
-       state: editor.textarea,
+    focused? = state.focus == :editor and not editor.editing_title?
+
+    {%CodeEditor{
+       textarea: editor.textarea,
+       language: :markdown_macros,
        block: %Block{title: body_title, borders: [:all]},
-       cursor_style:
-         if(state.focus == :editor and not editor.editing_title?,
-           do: %Style{bg: :cyan},
-           else: %Style{}
-         )
+       cursor_style: if(focused?, do: %Style{bg: :cyan}, else: %Style{}),
+       line_highlight_style: if(focused?, do: %Style{bg: :dark_gray}, else: %Style{})
      }, body_rect}
   end
 
@@ -1945,9 +1944,9 @@ defmodule BDS.TUI do
 
   # ── Post editor ──────────────────────────────────────────────────────────
 
-  # Posts open in the rendered markdown preview by default — the editor is
-  # one ctrl+e away. New (empty) posts pass preview?: false.
-  defp open_post(state, post_id, preview? \\ true) do
+  # Posts open in the syntax-highlighted editor by default — the rendered
+  # markdown preview is one ctrl+e away.
+  defp open_post(state, post_id, preview? \\ false) do
     case Posts.get_post(post_id) do
       nil ->
         toast(state, dgettext("ui", "Posts"), dgettext("ui", "Post not found."))