fix: collapse markup whitespace so blockquotes render without blank lines

app/lib/mews/parser.dart

@@ -155,23 +155,7 @@ void _appendBlocks(XmlElement element, String pageUrl, List<MewsBlock> out) {
       out.add(ParagraphBlock(_inline(element, pageUrl, embedded)));
       out.addAll(embedded);
     case 'blockquote':
-      final children = <MewsBlock>[];
-      final embedded = <MewsBlock>[];
-      // Bare inline content (quotes are often written as plain text) becomes
-      // a paragraph, like in list items.
-      final inline = <MewsInline>[];
-      for (final node in element.children) {
-        final isInlineNode = node is XmlText ||
-            (node is XmlElement && _inlineElements.contains(node.name.qualified));
-        if (isInlineNode) {
-          _appendInline(node, pageUrl, inline, embedded);
-        } else if (node is XmlElement) {
-          _appendBlocks(node, pageUrl, children);
-        }
-      }
-      if (inline.isNotEmpty) children.insert(0, ParagraphBlock(inline));
-      children.addAll(embedded);
-      out.add(QuoteBlock(children));
+      out.add(QuoteBlock(_mixedBlocks(element, pageUrl)));
     case 'pre':
       out.add(PreBlock(element.innerText));
     case 'address':
@@ -212,27 +196,42 @@ const _inlineElements = {
   'cite', 'abbr', 'dfn', 'img',
 };
 
+/// Builds blocks from mixed content: consecutive inline runs (text, links,
+/// images) become paragraphs, block-level children append as blocks. Runs
+/// that are nothing but markup whitespace never produce a paragraph, so
+/// pretty-printed quotes and list items start without a blank line.
+List<MewsBlock> _mixedBlocks(XmlElement element, String pageUrl) {
+  final blocks = <MewsBlock>[];
+  final embedded = <MewsBlock>[];
+  final inline = <MewsInline>[];
+
+  void flush() {
+    _dropEdgeWhitespace(inline);
+    if (inline.isNotEmpty) {
+      blocks.add(ParagraphBlock(List.of(inline)));
+      inline.clear();
+    }
+  }
+
+  for (final node in element.children) {
+    final isInlineNode = node is XmlText ||
+        (node is XmlElement && _inlineElements.contains(node.name.qualified));
+    if (isInlineNode) {
+      _appendInline(node, pageUrl, inline, embedded);
+    } else if (node is XmlElement) {
+      flush();
+      _appendBlocks(node, pageUrl, blocks);
+    }
+  }
+  flush();
+  blocks.addAll(embedded);
+  return blocks;
+}
+
 ListBlock _listBlock(XmlElement element, String pageUrl) {
   final items = <MewsListItem>[];
   for (final li in element.findElements('li')) {
-    final blocks = <MewsBlock>[];
-    final embedded = <MewsBlock>[];
-    // List items commonly hold bare inline content (the dated-link entry
-    // pattern in spec 6.1), so direct text and inline elements form a
-    // paragraph while block-level children append as blocks.
-    final inline = <MewsInline>[];
-    for (final node in li.children) {
-      final isInlineNode = node is XmlText ||
-          (node is XmlElement && _inlineElements.contains(node.name.qualified));
-      if (isInlineNode) {
-        _appendInline(node, pageUrl, inline, embedded);
-      } else if (node is XmlElement) {
-        _appendBlocks(node, pageUrl, blocks);
-      }
-    }
-    if (inline.isNotEmpty) blocks.insert(0, ParagraphBlock(inline));
-    blocks.addAll(embedded);
-    items.add(MewsListItem(blocks));
+    items.add(MewsListItem(_mixedBlocks(li, pageUrl)));
   }
   return ListBlock(
     ordered: element.name.qualified == 'ol',
@@ -395,18 +394,54 @@ MewsFormField _inputField(XmlElement element, String? label) {
 
 // Inline ---------------------------------------------------------------------
 
+/// Pretty-printed markup leaves whitespace runs between tags; browsers treat
+/// them as a single space, and whitespace-only runs at the edges of inline
+/// content as nothing at all.
+final _whitespaceRun = RegExp(r'\s+');
+
 List<MewsInline> _inline(XmlElement element, String pageUrl, [List<MewsBlock>? embedded]) {
   final out = <MewsInline>[];
   for (final child in element.children) {
     _appendInline(child, pageUrl, out, embedded);
   }
+  _dropEdgeWhitespace(out);
   return out;
 }
 
+/// Trims markup whitespace from the edges of a run: whitespace-only nodes are
+/// dropped, and the first/last text node loses its leading/trailing spaces,
+/// so indented markup renders no blank first or last lines. Interior
+/// whitespace stays: it separates inline elements the author typed apart.
+void _dropEdgeWhitespace(List<MewsInline> out) {
+  bool blank(MewsInline node) => node is MewsText && node.text.trim().isEmpty;
+  while (out.isNotEmpty && blank(out.first)) {
+    out.removeAt(0);
+  }
+  while (out.isNotEmpty && blank(out.last)) {
+    out.removeLast();
+  }
+  if (out.isNotEmpty && out.first is MewsText) {
+    final text = (out.first as MewsText).text.trimLeft();
+    if (text.isEmpty) {
+      out.removeAt(0);
+    } else {
+      out[0] = MewsText(text);
+    }
+  }
+  if (out.isNotEmpty && out.last is MewsText) {
+    final text = (out.last as MewsText).text.trimRight();
+    if (text.isEmpty) {
+      out.removeLast();
+    } else {
+      out[out.length - 1] = MewsText(text);
+    }
+  }
+}
+
 void _appendInline(XmlNode node, String pageUrl, List<MewsInline> out,
     [List<MewsBlock>? embedded]) {
   if (node is XmlText) {
-    final text = node.value;
+    final text = node.value.replaceAll(_whitespaceRun, ' ');
     if (text.isNotEmpty) out.add(MewsText(text));
     return;
   }