Fix comment tree display (Issue #10)

- Add build_comment_tree() to organize comments hierarchically
- Create recursive Jinja macro to render nested comments
- Add visual styling with left border and indentation
- Comments now display as threaded tree structure

Fixes #10

app.py

@@ -575,6 +575,33 @@ def api_content_timestamp():
         return jsonify({'error': 'Failed to get content timestamp'}), 500
 
 
+def build_comment_tree(comments):
+    """Build a hierarchical comment tree from flat comment list"""
+    # Create lookup dict by UUID
+    comment_dict = {c['uuid']: {**c, 'replies': []} for c in comments}
+
+    # Build tree structure
+    root_comments = []
+    for comment in comments:
+        parent_uuid = comment.get('parent_comment_uuid')
+        if parent_uuid and parent_uuid in comment_dict:
+            # Add as reply to parent
+            comment_dict[parent_uuid]['replies'].append(comment_dict[comment['uuid']])
+        else:
+            # Top-level comment
+            root_comments.append(comment_dict[comment['uuid']])
+
+    # Sort at each level by timestamp
+    def sort_tree(comments_list):
+        comments_list.sort(key=lambda x: x.get('timestamp', 0))
+        for comment in comments_list:
+            if comment.get('replies'):
+                sort_tree(comment['replies'])
+
+    sort_tree(root_comments)
+    return root_comments
+
+
 @app.route('/post/<post_id>')
 def post_detail(post_id):
     """Serve individual post detail page with modern theme"""
@@ -598,11 +625,11 @@ def post_detail(post_id):
         )
 
         # Get comments from cache
-        comments = cached_comments.get(post_id, [])
-        logger.info(f"Loading post {post_id}: found {len(comments)} comments")
+        comments_flat = cached_comments.get(post_id, [])
+        logger.info(f"Loading post {post_id}: found {len(comments_flat)} comments")
 
-        # Sort comments by timestamp
-        comments.sort(key=lambda x: x.get('timestamp', 0))
+        # Build comment tree
+        comments = build_comment_tree(comments_flat)
 
         # Load user settings if authenticated
         user_settings = {}

templates/post_detail.html

@@ -136,10 +136,8 @@
     <section class="comments-section">
         <h2>Comments ({{ comments|length }})</h2>
 
-        {% if comments %}
-            <div class="comments-list">
-                {% for comment in comments %}
-                    <div class="comment">
+        {% macro render_comment(comment, depth=0) %}
+            <div class="comment" style="margin-left: {{ depth * 24 }}px;">
                 <div class="comment-header">
                     <span class="comment-author">{{ comment.author }}</span>
                     <span class="comment-separator">•</span>
@@ -153,7 +151,21 @@
                         <span>▲ {{ comment.score or 0 }}</span>
                     </div>
                 </div>
+
+                {% if comment.replies %}
+                    <div class="comment-replies">
+                        {% for reply in comment.replies %}
+                            {{ render_comment(reply, depth + 1) }}
+                        {% endfor %}
                     </div>
+                {% endif %}
+            </div>
+        {% endmacro %}
+
+        {% if comments %}
+            <div class="comments-list">
+                {% for comment in comments %}
+                    {{ render_comment(comment) }}
                 {% endfor %}
             </div>
         {% else %}
@@ -554,12 +566,24 @@
 .comment {
     padding: 20px 0;
     border-bottom: 1px solid #f1f5f9;
+    position: relative;
 }
 
 .comment:last-child {
     border-bottom: none;
 }
 
+/* Threaded comment styling */
+.comment[style*="margin-left"] {
+    padding-left: 16px;
+    border-left: 2px solid #e2e8f0;
+    border-bottom: none;
+}
+
+.comment-replies {
+    margin-top: 8px;
+}
+
 .comment-header {
     display: flex;
     align-items: center;