Exclude duplicates from category counts so browse totals match the feed

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

goodnews/queries.py

@@ -112,13 +112,19 @@ def brief(conn: sqlite3.Connection, brief_date: str | None = None, limit: int =
 
 
 def category_counts(conn: sqlite3.Connection, accepted_only: bool = True) -> list[dict]:
-    """Return per topic/flavor article counts for building browse UIs."""
-    where = "WHERE s.accepted = 1" if accepted_only else "WHERE s.topic IS NOT NULL"
+    """Return per topic/flavor article counts for building browse UIs.
+
+    Joins articles and excludes duplicates so the counts match exactly what the
+    feed endpoint will actually return for each topic/flavor.
+    """
+    clauses = ["a.duplicate_of IS NULL"]
+    clauses.append("s.accepted = 1" if accepted_only else "s.topic IS NOT NULL")
     rows = conn.execute(
         f"""
         SELECT s.topic, s.flavor, COUNT(*) AS count
         FROM article_scores s
-        {where}
+        JOIN articles a ON a.id = s.article_id
+        WHERE {" AND ".join(clauses)}
         GROUP BY s.topic, s.flavor
         ORDER BY s.topic, s.flavor
         """