diff --git a/app/db/memory.py b/app/db/memory.py
index 3e762f6..4916412 100644
--- a/app/db/memory.py
+++ b/app/db/memory.py
@@ -1,31 +1,28 @@
 import json
-import os
 from pathlib import Path
 
-DB_DIR = Path(__file__).resolve().parent.parent.parent / data
+DB_DIR = Path(__file__).resolve().parent.parent.parent / "data"
 DB_DIR.mkdir(exist_ok=True)
 
-USERS_FILE = DB_DIR / users.json
-BOOKINGS_FILE = DB_DIR / bookings.json
+USERS_FILE = DB_DIR / "users.json"
+BOOKINGS_FILE = DB_DIR / "bookings.json"
 
 
 def _load_json(path, default):
     if path.exists():
         try:
-            with open(path, r, encoding=utf-8) as f:
-                return json.load(f)
+            with open(path, "r", encoding="utf-8") as fh:
+                return json.load(fh)
         except (json.JSONDecodeError, OSError):
             return default
     return default
 
 
 def _save_json(path, data):
-    with open(path, w, encoding=utf-8) as f:
-        json.dump(data, f, ensure_ascii=False, indent=2)
+    with open(path, "w", encoding="utf-8") as fh:
+        json.dump(data, fh, ensure_ascii=False, indent=2)
 
 
-# ——— Users ———
-
 def load_users():
     return _load_json(USERS_FILE, {})
 
@@ -45,8 +42,6 @@ def set_user(user_id, data):
     save_users(users)
 
 
-# ——— Bookings ———
-
 def load_bookings():
     return _load_json(BOOKINGS_FILE, [])
 
@@ -58,13 +53,13 @@ def save_bookings(bookings):
 def create_booking(user_id, service, master, date, time):
     bookings = load_bookings()
     booking = {
-        id: len(bookings) + 1,
-        user_id: user_id,
-        service: service,
-        master: master,
-        date: date,
-        time: time,
-        status: active,
+        "id": len(bookings) + 1,
+        "user_id": user_id,
+        "service": service,
+        "master": master,
+        "date": date,
+        "time": time,
+        "status": "active",
     }
     bookings.append(booking)
     save_bookings(bookings)
@@ -74,10 +69,8 @@ def create_booking(user_id, service, master, date, time):
 def get_busy_times(master, date):
     bookings = load_bookings()
     return [
-        b[time] for b in bookings
-        if b[master] == master
-        and b[date] == date
-        and b[status] == active
+        b["time"] for b in bookings
+        if b["master"] == master and b["date"] == date and b["status"] == "active"
     ]
 
 
@@ -85,16 +78,15 @@ def get_user_bookings(user_id):
     bookings = load_bookings()
     return [
         b for b in bookings
-        if b[user_id] == user_id
-        and b[status] == active
+        if b["user_id"] == user_id and b["status"] == "active"
     ]
 
 
 def cancel_booking(booking_id):
     bookings = load_bookings()
     for b in bookings:
-        if b[id] == booking_id:
-            b[status] = cancelled
+        if b["id"] == booking_id:
+            b["status"] = "cancelled"
             save_bookings(bookings)
             return True
     return False
@@ -103,11 +95,11 @@ def cancel_booking(booking_id):
 def update_booking(booking_id, service, master, date, time):
     bookings = load_bookings()
     for b in bookings:
-        if b[id] == booking_id:
-            b[service] = service
-            b[master] = master
-            b[date] = date
-            b[time] = time
+        if b["id"] == booking_id:
+            b["service"] = service
+            b["master"] = master
+            b["date"] = date
+            b["time"] = time
             save_bookings(bookings)
             return b
     return None