diff --git a/export_todoist.py b/export_todoist.py
index 5938a85..735663e 100644
--- a/export_todoist.py
+++ b/export_todoist.py
@@ -9,6 +9,7 @@ from todoist_api_python.api import TodoistAPI
 from jinja2 import Environment, FileSystemLoader, select_autoescape
 
 ATTACHMENTS_DIR = "attachments"
+TODOIST_API_TOKEN: str | None = None
 
 
 def usage():
@@ -38,19 +39,66 @@ def ensure_attachments_dir():
         os.makedirs(ATTACHMENTS_DIR)
 
 
+def _file_looks_like_html(path):
+    try:
+        with open(path, 'rb') as handle:
+            prefix = handle.read(256)
+    except OSError:
+        return False
+    if not prefix:
+        return True
+    snippet = prefix.lstrip().lower()
+    return snippet.startswith(b"<!doctype") or snippet.startswith(b"<html")
+
+
 def download_attachment(url, filename):
     local_path = os.path.join(ATTACHMENTS_DIR, filename)
     if os.path.exists(local_path):
-        return local_path
+        if _file_looks_like_html(local_path) and not filename.lower().endswith(('.htm', '.html')):
+            try:
+                os.remove(local_path)
+            except OSError:
+                pass
+        else:
+            return local_path
     print(f"Downloading attachment {url}")
-    r = requests.get(url, stream=True)
-    if r.status_code == 200:
-        with open(local_path, 'wb') as f:
-            for chunk in r.iter_content(1024):
-                f.write(chunk)
-        return local_path
-    else:
+    headers = {}
+    if TODOIST_API_TOKEN:
+        headers["Authorization"] = f"Bearer {TODOIST_API_TOKEN}"
+    try:
+        response = requests.get(url, stream=True, headers=headers, timeout=30)
+    except requests.RequestException as exc:  # pylint: disable=broad-except
+        print(f"Failed to download attachment {url}: {exc}")
         return None
+    if response.status_code != 200:
+        print(f"Failed to download attachment {url}: HTTP {response.status_code}")
+        return None
+    content_type = (response.headers.get("Content-Type") or "").lower()
+    first_chunk = b""
+    try:
+        with open(local_path, 'wb') as handle:
+            for chunk in response.iter_content(chunk_size=8192):
+                if not chunk:
+                    continue
+                if not first_chunk:
+                    first_chunk = chunk
+                handle.write(chunk)
+    except OSError as exc:  # pylint: disable=broad-except
+        print(f"Failed to save attachment {filename}: {exc}")
+        return None
+    looks_like_html = (
+        "text/html" in content_type
+        or (first_chunk and _file_looks_like_html(local_path))
+    )
+    if looks_like_html and not filename.lower().endswith(('.htm', '.html')):
+        try:
+            os.remove(local_path)
+        except OSError:
+            pass
+        print(f"Skipped attachment {url}: received HTML response instead of file")
+        return None
+    print(f"Downloaded attachment {url}")
+    return local_path
 
 
 def _get_retry_delay(response, attempt, base_delay=5, max_delay=120):
@@ -134,8 +182,9 @@ def fetch_completed_tasks_by_project(api, since, until):
     return tasks_by_project
 
 
-def fetch_comments_by_task(api, project_ids):
+def fetch_comments_by_task(api, project_ids, task_ids):
     comments_by_task = defaultdict(list)
+    total_comments = 0
     for project_id in project_ids:
         try:
             comments_iter = execute_with_rate_limit(api.get_comments, project_id=project_id)
@@ -144,9 +193,24 @@ def fetch_comments_by_task(api, project_ids):
                     task_id = str(getattr(comment, "task_id", ""))
                     if task_id:
                         comments_by_task[task_id].append(comment)
+                        total_comments += 1
         except Exception as error:  # pylint: disable=broad-except
             print(f"Error fetching comments for project {project_id}: {error}")
-    print(f"Fetched comments for {len(comments_by_task)} tasks")
+    missing_task_ids = [task_id for task_id in task_ids if task_id not in comments_by_task]
+    for task_id in missing_task_ids:
+        try:
+            comments_iter = execute_with_rate_limit(api.get_comments, task_id=task_id)
+            for batch in comments_iter:
+                for comment in batch:
+                    key = str(getattr(comment, "task_id", ""))
+                    if key:
+                        comments_by_task[key].append(comment)
+                        total_comments += 1
+        except Exception as error:  # pylint: disable=broad-except
+            print(f"Error fetching comments for task {task_id}: {error}")
+    print(
+        f"Fetched {total_comments} comments mapped to {len(comments_by_task)} tasks"
+    )
     return comments_by_task
 
 
@@ -171,33 +235,138 @@ def process_task(task, comments_lookup):
     # Comments
     comment_key = str(task_id) if task_id is not None else None
     if comment_key and comment_key in comments_lookup:
-        task_dict['comments'] = [c.__dict__ for c in comments_lookup[comment_key]]
+        serialized_comments = []
+        for comment in comments_lookup[comment_key]:
+            comment_dict = comment.__dict__.copy()
+            attachment = getattr(comment, "attachment", None)
+            if attachment:
+                attachment_dict = attachment.__dict__.copy()
+                file_url = attachment_dict.get("file_url")
+                if file_url:
+                    filename = attachment_dict.get("file_name") or os.path.basename(file_url)
+                    local_path = download_attachment(file_url, filename)
+                    if local_path:
+                        attachment_dict['local_file'] = os.path.relpath(local_path)
+                comment_dict['attachment'] = attachment_dict
+            serialized_comments.append(comment_dict)
+        task_dict['comments'] = serialized_comments
     return task_dict
 
 
+def build_task_hierarchy(task_dicts):
+    task_lookup = {}
+    order_lookup = {}
+    for index, task in enumerate(task_dicts):
+        task_id = task.get('id')
+        if task_id is None:
+            continue
+        task_lookup[str(task_id)] = task
+        order_lookup[str(task_id)] = index
+        task.setdefault('subtasks', [])
+
+    roots = []
+    for task in task_dicts:
+        task_id = task.get('id')
+        if task_id is None:
+            roots.append(task)
+            continue
+        parent_id = task.get('parent_id')
+        if parent_id:
+            parent = task_lookup.get(str(parent_id))
+            if parent:
+                parent.setdefault('subtasks', [])
+                parent['subtasks'].append(task)
+                continue
+        roots.append(task)
+
+    def sort_children(children):
+        children.sort(key=lambda item: order_lookup.get(str(item.get('id')), 0))
+        for child in children:
+            child_children = child.get('subtasks') or []
+            if child_children:
+                sort_children(child_children)
+
+    sort_children(roots)
+
+    # Remove empty subtasks lists for cleanliness
+    def prune(task):
+        subtasks = task.get('subtasks')
+        if subtasks:
+            for sub in subtasks:
+                prune(sub)
+        else:
+            task.pop('subtasks', None)
+
+    for root in roots:
+        prune(root)
+
+    return roots
+
+
 def main():
     if len(sys.argv) != 2 or sys.argv[1] != "export":
         usage()
         return
     ensure_attachments_dir()
-    api = TodoistAPI(get_api_key())
+    token = get_api_key()
+    global TODOIST_API_TOKEN  # pylint: disable=global-statement
+    TODOIST_API_TOKEN = token
+    api = TodoistAPI(token)
     projects = fetch_all_projects(api)
     since = (datetime.now() - timedelta(days=90)).replace(hour=0, minute=0, second=0, microsecond=0)
     until = datetime.now()
     active_tasks_by_project = fetch_active_tasks_by_project(api)
     completed_tasks_by_project = fetch_completed_tasks_by_project(api, since=since, until=until)
     comment_project_ids = sorted(
-        pid for pid in (set(active_tasks_by_project.keys()) | set(completed_tasks_by_project.keys())) if pid
+        pid
+        for pid in (set(active_tasks_by_project.keys()) | set(completed_tasks_by_project.keys()))
+        if pid
+    )
+    task_ids_for_comments: set[str] = set()
+    for task_list in active_tasks_by_project.values():
+        for task in task_list:
+            task_id = getattr(task, "id", None)
+            if task_id:
+                task_ids_for_comments.add(str(task_id))
+    for task_list in completed_tasks_by_project.values():
+        for task in task_list:
+            task_id = getattr(task, "id", None)
+            if task_id:
+                task_ids_for_comments.add(str(task_id))
+    comments_by_task = fetch_comments_by_task(
+        api, comment_project_ids, sorted(task_ids_for_comments)
     )
-    comments_by_task = fetch_comments_by_task(api, comment_project_ids)
     data = []
     for project in projects:
         project_dict = project.__dict__.copy()
         project_id = str(getattr(project, "id", ""))
         active_tasks = active_tasks_by_project.get(project_id, [])
         completed_tasks = completed_tasks_by_project.get(project_id, [])
-        project_dict['tasks'] = [process_task(t, comments_by_task) for t in active_tasks]
-        project_dict['completed_tasks'] = [process_task(t, comments_by_task) for t in completed_tasks]
+
+        processed_active = [process_task(t, comments_by_task) for t in active_tasks]
+        processed_completed = [process_task(t, comments_by_task) for t in completed_tasks]
+
+        # Build hierarchy for active tasks
+        project_dict['tasks'] = build_task_hierarchy(processed_active)
+
+        # Map task IDs to names for parent lookups
+        name_lookup = {}
+        for task in active_tasks + completed_tasks:
+            task_id = getattr(task, "id", None)
+            if task_id:
+                name_lookup[str(task_id)] = getattr(task, "content", "")
+
+        for task in processed_completed:
+            parent_id = task.get('parent_id')
+            if parent_id:
+                parent_name = name_lookup.get(str(parent_id))
+                if parent_name:
+                    task['parent_task'] = {
+                        "id": str(parent_id),
+                        "content": parent_name,
+                    }
+
+        project_dict['completed_tasks'] = processed_completed
         data.append(project_dict)
     # Write JSON
     today = datetime.now().strftime("%Y-%m-%d")
diff --git a/todoist_backup_template.html b/todoist_backup_template.html
index 1df672d..d33ac93 100644
--- a/todoist_backup_template.html
+++ b/todoist_backup_template.html
@@ -5,24 +5,118 @@
     <title>Todoist Backup - {{ date }}</title>
     <style>
         body { font-family: Arial, sans-serif; background: #f8f9fa; color: #222; margin: 0; padding: 0; }
-        .container { max-width: 900px; margin: 2em auto; background: #fff; padding: 2em; border-radius: 8px; box-shadow: 0 2px 8px #0001; }
+        .container { max-width: 960px; margin: 2em auto; background: #fff; padding: 2em; border-radius: 8px; box-shadow: 0 2px 8px #0001; }
         h1, h2, h3 { color: #2d72d9; }
-        .project { margin-bottom: 2em; }
-        .task-list { margin: 0 0 1em 1em; }
-        .task { border-bottom: 1px solid #eee; padding: 0.5em 0; }
-        .completed { color: #888; }
-        .attachments { margin: 0.5em 0 0.5em 1em; }
-        .comments { margin: 0.5em 0 0.5em 1em; font-size: 0.95em; color: #444; }
-        .task-name { font-weight: bold; }
-        .field-label { font-style: italic; }
-        a.attachment-link { color: #2d72d9; text-decoration: underline; }
-        .meta { color: #666; font-size: 0.95em; }
+        nav ul { list-style: none; padding: 0; margin: 0; }
+        nav li { margin: 0.25em 0; }
+        nav a { text-decoration: none; color: #2d72d9; }
+        nav a:hover { text-decoration: underline; }
+        .project { margin-bottom: 3em; }
+        .task-list { margin: 0 0 1em 0; }
+        .task { border-bottom: 1px solid #eee; padding: 0.75em 0; }
+        .task:last-child { border-bottom: none; }
+        .task.level-0 { margin-left: 0; }
+        .task.level-1 { margin-left: 1.5em; }
+        .task.level-2 { margin-left: 3em; }
+        .task.level-3 { margin-left: 4.5em; }
+        .taskname { font-weight: 600; }
+        .taskdesc { margin: 0.35em 0; color: #555; }
+        .meta { color: #777; font-size: 0.9em; display: inline-block; margin-top: 0.25em; }
+        .field-name { font-weight: 600; }
+        .attachments ul,
+        .comments ul { margin: 0.5em 0 0 1.2em; }
+        .attachments li,
+        .comments li { margin-bottom: 0.35em; }
+        .attachment-link { color: #2d72d9; }
+        .attachment-link:hover { text-decoration: underline; }
+        .comments { margin-top: 0.5em; }
+        .comment-attachment { margin-top: 0.25em; }
+        .task.completed { background: #f3f6ff; padding: 0.75em; border-radius: 6px; border: 1px solid #d6e2ff; }
     </style>
 </head>
 <body>
 <div class="container">
     <h1>Todoist Backup ({{ date }})</h1>
-    <!-- Table of Contents -->
+
+    {% macro render_task(task, level=0) %}
+    <div class="task level-{{ level }}">
+        <span class="taskname">{{ task.content | markdown | safe }}</span><br>
+        {% if task.description %}
+        <div class="taskdesc">{{ task.description | markdown | safe }}</div>
+        {% endif %}
+        <span class="meta">
+            {% set meta_fields = [] %}
+            {% if task.id is not none %}
+                {% set _ = meta_fields.append('ID: ' ~ task.id) %}
+            {% endif %}
+            {% if task.due and task.due.date %}
+                {% set due_dt = task.due.date %}
+                {% if due_dt.__class__.__name__ == 'datetime' or due_dt.__class__.__name__ == 'date' %}
+                    {% set due_fmt = due_dt.strftime('%Y-%m-%d') %}
+                {% else %}
+                    {% set due_str = due_dt|string %}
+                    {% if 'T' in due_str %}
+                        {% set due_fmt = due_str[:10] %}
+                    {% else %}
+                        {% set due_fmt = due_str %}
+                    {% endif %}
+                {% endif %}
+                {% set _ = meta_fields.append('Due: ' ~ due_fmt) %}
+            {% endif %}
+            {% if task.due and task.due.is_recurring %}
+                {% if task.due.string %}
+                    {% set _ = meta_fields.append('Recurring: ' ~ task.due.string) %}
+                {% endif %}
+            {% endif %}
+            {% if task.priority is not none %}
+                {% set _ = meta_fields.append('Priority: ' ~ task.priority) %}
+            {% endif %}
+            {{ meta_fields|join(' | ') }}
+        </span><br>
+        {% if task.attachments %}
+        <div class="attachments">
+            <span class="field-name">Attachments:</span>
+            <ul>
+                {% for att in task.attachments %}
+                <li><a class="attachment-link" href="{{ att.local_file }}" download>{{ att.file_name or att.local_file }}</a></li>
+                {% endfor %}
+            </ul>
+        </div>
+        {% endif %}
+        {% if task.comments %}
+        <div class="comments">
+            <span class="field-name">Comments:</span>
+            <ul>
+                {% for comment in task.comments %}
+                <li>
+                    {{ comment.content | markdown | safe }}
+                    <span class="meta">({{ comment.posted_at }})</span>
+                        {% set attachment = comment.attachment %}
+                        {% if attachment and (attachment.local_file or attachment.file_url) %}
+                        <div class="comment-attachment">
+                            Attachment:
+                            {% if attachment.local_file %}
+                            <a class="attachment-link" href="{{ attachment.local_file }}" download>{{ attachment.file_name or attachment.local_file }}</a>
+                            {% elif attachment.file_url %}
+                            <a class="attachment-link" href="{{ attachment.file_url }}" target="_blank">{{ attachment.file_name or attachment.file_url }}</a>
+                            {% endif %}
+                        </div>
+                        {% endif %}
+                </li>
+                {% endfor %}
+            </ul>
+        </div>
+        {% endif %}
+        {% if task.subtasks %}
+        <div class="subtasks">
+            {% for child in task.subtasks %}
+            {{ render_task(child, level + 1) }}
+            {% endfor %}
+        </div>
+        {% endif %}
+    </div>
+    {% endmacro %}
+
     <nav style="margin-bottom:2em;">
         <h2 style="font-size:1.2em;">Projects</h2>
         <ul>
@@ -31,21 +125,32 @@
             {% endfor %}
         </ul>
     </nav>
+
     {% for project in projects %}
     <div class="project" id="project-{{ project.id }}">
         <h2>{{ project.name }} {% if project.is_archived %}<span class="meta">[Archived]</span>{% endif %}</h2>
         <div class="meta">
             <span>ID: {{ project.id }}</span> | <span>Color: {{ project.color }}</span> | <span>Created: {{ project.created_at }}</span>
         </div>
+
         <h3>Active Tasks</h3>
         <div class="task-list">
             {% for task in project.tasks %}
-            <div class="task">
-                <div class="task-name">{{ task.content | markdown | safe }}</div>
+                {{ render_task(task, 0) }}
+            {% else %}
+                <p class="meta">No active tasks.</p>
+            {% endfor %}
+        </div>
+
+        <h3>Completed Tasks</h3>
+        <div class="task-list">
+            {% for task in project.completed_tasks %}
+            <div class="task completed">
+                <span class="task-name">{{ task.content | markdown | safe }}</span><br>
                 {% if task.description %}
-                <div class="task-desc">{{ task.description | markdown | safe }}</div>
+                <div class="taskdesc">{{ task.description | markdown | safe }}</div>
                 {% endif %}
-                <div class="meta">
+                <span class="meta">
                     {% set meta_fields = [] %}
                     {% if task.id is not none %}
                         {% set _ = meta_fields.append('ID: ' ~ task.id) %}
@@ -72,66 +177,6 @@
                     {% if task.priority is not none %}
                         {% set _ = meta_fields.append('Priority: ' ~ task.priority) %}
                     {% endif %}
-                    {{ meta_fields|join(' | ') }}
-                </div>
-                {% if task.attachments %}
-                <div class="attachments">
-                    <span class="field-name">Attachments:</span>
-                    <ul>
-                        {% for att in task.attachments %}
-                        <li><a class="attachment-link" href="{{ att.local_file }}" download>{{ att.file_name or att.local_file }}</a></li>
-                        {% endfor %}
-                    </ul>
-                </div>
-                {% endif %}
-                {% if task.comments %}
-                <div class="comments">
-                    <span class="field-name">Comments:</span>
-                    <ul>
-                        {% for comment in task.comments %}
-                        <li>{{ comment.content }} <span class="meta">({{ comment.posted_at }})</span></li>
-                        {% endfor %}
-                    </ul>
-                </div>
-                {% endif %}
-            </div>
-            {% endfor %}
-        </div>
-        <h3>Completed Tasks</h3>
-        <div class="task-list">
-            {% for task in project.completed_tasks %}
-            <div class="task completed">
-                <div class="task-name">{{ task.content | markdown | safe }}</div>
-                {% if task.description %}
-                <div class="task-desc">{{ task.description | markdown | safe }}</div>
-                {% endif %}
-                <div class="meta">
-                    {% set meta_fields = [] %}
-                    {% if task.id is not none %}
-                        {% set _ = meta_fields.append('ID: ' ~ task.id) %}
-                    {% endif %}
-                    {% if task.due and task.due.date %}
-                        {% set due_dt = task.due.date %}
-                        {% if due_dt.__class__.__name__ == 'datetime' or due_dt.__class__.__name__ == 'date' %}
-                            {% set due_fmt = due_dt.strftime('%Y-%m-%d %H:%M') if due_dt.__class__.__name__ == 'datetime' else due_dt.strftime('%Y-%m-%d 00:00') %}
-                        {% else %}
-                            {% set due_str = due_dt|string %}
-                            {% if 'T' in due_str %}
-                                {% set due_fmt = due_str[:16].replace('T', ' ') %}
-                            {% else %}
-                                {% set due_fmt = due_str %}
-                            {% endif %}
-                        {% endif %}
-                        {% set _ = meta_fields.append('Due: ' ~ due_fmt) %}
-                    {% endif %}
-                    {% if task.due and task.due.is_recurring %}
-                        {% if task.due.string %}
-                            {% set _ = meta_fields.append('Recurring: ' ~ task.due.string) %}
-                        {% endif %}
-                    {% endif %}
-                    {% if task.priority is not none %}
-                        {% set _ = meta_fields.append('Priority: ' ~ task.priority) %}
-                    {% endif %}
                     {% if task.completed_at %}
                         {% if task.completed_at.__class__.__name__ == 'datetime' or task.completed_at.__class__.__name__ == 'date' %}
                             {% set completed_fmt = task.completed_at.strftime('%Y-%m-%d') %}
@@ -146,7 +191,10 @@
                         {% set _ = meta_fields.append('Completed: ' ~ completed_fmt) %}
                     {% endif %}
                     {{ meta_fields|join(' | ') }}
-                </div>
+                </span><br>
+                {% if task.parent_task %}
+                <div class="meta">Parent task: {{ task.parent_task.content | markdown | safe }}</div>
+                {% endif %}
                 {% if task.attachments %}
                 <div class="attachments">
                     <span class="field-name">Attachments:</span>
@@ -159,15 +207,31 @@
                 {% endif %}
                 {% if task.comments %}
                 <div class="comments">
-                    <span class="field">Comments:</span>
+                    <span class="field-name">Comments:</span>
                     <ul>
                         {% for comment in task.comments %}
-                        <li>{{ comment.content }} <span class="meta">({{ comment.posted_at }})</span></li>
+                        <li>
+                            {{ comment.content | markdown | safe }}
+                            <span class="meta">({{ comment.posted_at }})</span>
+                                {% set attachment = comment.attachment %}
+                                {% if attachment and (attachment.local_file or attachment.file_url) %}
+                                <div class="comment-attachment">
+                                    Attachment:
+                                    {% if attachment.local_file %}
+                                    <a class="attachment-link" href="{{ attachment.local_file }}" download>{{ attachment.file_name or attachment.local_file }}</a>
+                                    {% elif attachment.file_url %}
+                                    <a class="attachment-link" href="{{ attachment.file_url }}" target="_blank">{{ attachment.file_name or attachment.file_url }}</a>
+                                    {% endif %}
+                                </div>
+                                {% endif %}
+                        </li>
                         {% endfor %}
                     </ul>
                 </div>
                 {% endif %}
             </div>
+            {% else %}
+                <p class="meta">No completed tasks in this period.</p>
             {% endfor %}
         </div>
     </div>