update

backend/app/db.py

@@ -22,10 +22,12 @@ CREATE INDEX IF NOT EXISTS items_seq ON items(seq);
 """
 
 
+# Große Datei-Uploads halten die Datenbank sekundenlang. WAL lässt Leser derweil durch,
+# Schreiber warten bis zu 60 s statt mit "database is locked" abzubrechen.
 @contextmanager
 def connect():
     DB_PATH.parent.mkdir(parents=True, exist_ok=True)
-    conn = sqlite3.connect(DB_PATH)
+    conn = sqlite3.connect(DB_PATH, timeout=60)
     conn.row_factory = sqlite3.Row
     try:
         yield conn
@@ -37,6 +39,7 @@ def connect():
 def init():
     with connect() as conn:
         conn.executescript(SCHEMA)
+        conn.execute("PRAGMA journal_mode=WAL")
 
 
 def cursor(conn):