diff --git a/backend/services/author_service.py b/backend/services/author_service.py
index f2ce4d1..37fefa4 100644
--- a/backend/services/author_service.py
+++ b/backend/services/author_service.py
@@ -1,5 +1,5 @@
 from datetime import datetime
-from sqlalchemy import select, func, desc as sa_desc, asc as sa_asc, literal
+from sqlalchemy import select, func, desc as sa_desc, asc as sa_asc
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from backend.models.author import Author
@@ -17,51 +17,62 @@ async def list_authors(
     page: int = 1,
     per_page: int = 25,
 ) -> tuple[list[dict], int]:
-    # Always compute counts from actual data
-    post_count = select(func.count(Post.id)).where(Post.author_id == Author.id)
-    comment_count = select(func.count(Comment.id)).where(Comment.author_id == Author.id)
+    # Build count subqueries
+    post_q = select(func.count(Post.id)).where(Post.author_id == Author.id)
+    comment_q = select(func.count(Comment.id)).where(Comment.author_id == Author.id)
 
     if subreddit_id:
-        post_count = post_count.where(Post.subreddit_id == subreddit_id)
-        comment_count = comment_count.join(Post).where(Post.subreddit_id == subreddit_id)
+        post_q = post_q.where(Post.subreddit_id == subreddit_id)
+        comment_q = comment_q.join(Post).where(Post.subreddit_id == subreddit_id)
     if since:
-        post_count = post_count.where(Post.created_utc >= since)
-        comment_count = comment_count.where(Comment.created_utc >= since)
+        post_q = post_q.where(Post.created_utc >= since)
+        comment_q = comment_q.where(Comment.created_utc >= since)
     if until:
-        post_count = post_count.where(Post.created_utc <= until)
-        comment_count = comment_count.where(Comment.created_utc <= until)
+        post_q = post_q.where(Post.created_utc <= until)
+        comment_q = comment_q.where(Comment.created_utc <= until)
 
-    post_sub = post_count.correlate(Author).scalar_subquery().label("total_posts")
-    comment_sub = comment_count.correlate(Author).scalar_subquery().label("total_comments")
+    post_sub = post_q.correlate(Author).scalar_subquery().label("total_posts")
+    comment_sub = comment_q.correlate(Author).scalar_subquery().label("total_comments")
 
-    base = select(Author, post_sub, comment_sub)
+    # Build main query as a subquery so we can filter on computed columns
+    inner = select(
+        Author.id,
+        Author.username,
+        Author.first_seen_at,
+        Author.last_seen_at,
+        post_sub,
+        comment_sub,
+    ).subquery()
 
-    # Only show authors with activity
-    having_activity = base.having(
-        (post_sub > 0) | (comment_sub > 0)
-    ).group_by(Author.id)
-
-    # Count total active authors
-    count_stmt = select(func.count()).select_from(having_activity.subquery())
+    # Count authors with any activity
+    count_stmt = select(func.count()).select_from(inner).where(
+        (inner.c.total_posts > 0) | (inner.c.total_comments > 0)
+    )
     total = (await db.execute(count_stmt)).scalar() or 0
 
-    # Sort by computed counts
-    if sort_by == "total_posts":
-        sort_col = post_sub
-    else:
-        sort_col = comment_sub
-
+    # Sort and paginate
+    sort_col = inner.c.total_posts if sort_by == "total_posts" else inner.c.total_comments
     order_fn = sa_desc if sort_order == "desc" else sa_asc
-    query = base.order_by(order_fn(sort_col)).offset((page - 1) * per_page).limit(per_page)
+
+    query = (
+        select(inner)
+        .where((inner.c.total_posts > 0) | (inner.c.total_comments > 0))
+        .order_by(order_fn(sort_col))
+        .offset((page - 1) * per_page)
+        .limit(per_page)
+    )
 
     result = await db.execute(query)
     authors = []
     for row in result.all():
-        author = row[0]
-        data = {c.name: getattr(author, c.name) for c in author.__table__.columns}
-        data["total_posts"] = row[1] or 0
-        data["total_comments"] = row[2] or 0
-        authors.append(data)
+        authors.append({
+            "id": row.id,
+            "username": row.username,
+            "first_seen_at": row.first_seen_at,
+            "last_seen_at": row.last_seen_at,
+            "total_posts": row.total_posts or 0,
+            "total_comments": row.total_comments or 0,
+        })
 
     return authors, total
 
@@ -78,8 +89,11 @@ async def get_author(db: AsyncSession, author_id: int) -> dict | None:
         .scalar_subquery()
     )
     result = await db.execute(
-        select(Author, post_count.label("total_posts"), comment_count.label("total_comments"))
-        .where(Author.id == author_id)
+        select(
+            Author,
+            post_count.label("total_posts"),
+            comment_count.label("total_comments"),
+        ).where(Author.id == author_id)
     )
     row = result.first()
     if not row: