update

backend/database.py

@@ -482,6 +482,12 @@ async def set_baustein_score(topic: str, baustein: str, score: int) -> int:
     return score
 
 
+async def delete_baustein_progress(topic: str, baustein: str) -> None:
+    """Fortschritt EINES Bausteins zurücksetzen: Zeile löschen (Score/Streak/Flags/offene Frage).
+    Fehlt die Zeile, liefert get_baustein_progress Defaults (0) — also voller Reset."""
+    db = await get_db()
+    await db.execute("DELETE FROM baustein_progress WHERE topic = ? AND baustein = ?", (topic, baustein))
+    await db.commit()
 
 
 async def set_baustein_verstanden(topic: str, baustein: str) -> bool: