diff --git a/src/time_tracker/__main__.py b/src/time_tracker/__main__.py
index dfac8b3..6f4f4ae 100644
--- a/src/time_tracker/__main__.py
+++ b/src/time_tracker/__main__.py
@@ -5,7 +5,9 @@ from .app import Application
 def main():
     try:
         app = Application()
-        app.run()
+        from .ui.overlay import OverlayWindow
+        overlay = OverlayWindow(app)
+        overlay.run()
     except RuntimeError as e:
         print(f"Ошибка: {e}", file=sys.stderr)
         input("Нажмите Enter для выхода...")
diff --git a/src/time_tracker/app.py b/src/time_tracker/app.py
index 7d9b6cb..7864bf9 100644
--- a/src/time_tracker/app.py
+++ b/src/time_tracker/app.py
@@ -1,26 +1,218 @@
 import json
+import time
+import threading
 from pathlib import Path
-from typing import Optional
-from .models import TrackerConfig, TrackedTask
+from datetime import datetime
+from typing import Optional, List
+from pynput import mouse, keyboard
+
+from .models import TrackerConfig, TrackedTask, WorkDetail, WorkSession
 from .utils import get_platform, ensure_dir
-from .ui.overlay import OverlayWindow
 
 
 class Application:
     def __init__(self):
+        self._lock = threading.Lock()
         self.config_path = Path("config.json")
         self.tasks_dir = Path("tasks")
         self.config: TrackerConfig = self._load_or_create_config()
         self.current_task: Optional[TrackedTask] = None
         self.platform = get_platform()
 
-        # Загружаем текущую задачу, если указан ID
+        # Состояние трекинга
+        self.tracking_enabled = self.config.tracking_enabled
+        self.last_activity: float = time.time()  # timestamp
+        self.last_window_group: Optional[str] = None
+        self.is_idle: bool = False
+        self._tracking_thread: Optional[threading.Thread] = None
+        self._running = True
+
+        # Загружаем задачу
         if self.config.current_task_id:
             self.current_task = self._load_task(self.config.current_task_id)
 
-        # Создаём директорию для задач, если нужно
         ensure_dir(self.tasks_dir)
 
+        # Запускаем слушатели активности (только если tracking_enabled)
+        self._start_activity_listeners()
+        # Запускаем фоновый трекер
+        self._start_tracking_loop()
+
+    def _start_activity_listeners(self):
+        def on_activity(*_):
+            with self._lock:
+                self.last_activity = time.time()
+                self.is_idle = False
+
+        self.mouse_listener = mouse.Listener(on_move=on_activity, on_click=on_activity)
+        self.keyboard_listener = keyboard.Listener(on_press=on_activity)
+        self.mouse_listener.start()
+        self.keyboard_listener.start()
+
+    def _start_tracking_loop(self):
+        def loop():
+            while self._running:
+                time.sleep(5)
+                self._check_and_update_tracking()
+
+        self._tracking_thread = threading.Thread(target=loop, daemon=True)
+        self._tracking_thread.start()
+
+    def _check_and_update_tracking(self):
+        with self._lock:
+            if not self.tracking_enabled or not self.current_task:
+                return
+
+            # Проверка: спит ли система? (упрощённо — если активность > 60 сек назад)
+            current_time = time.time()
+            if current_time - self.last_activity > 60:
+                self.is_idle = True
+                self.last_window_group = None
+                return
+
+            # Получаем текущее окно
+            window_info = self.platform.get_active_window()
+            if not window_info.title and not window_info.process_name:
+                self.is_idle = True
+                return
+
+            # Определяем группу по политике
+            group_name = self._match_window_to_policy(window_info)
+            is_blocked = self._is_group_blocked(group_name)
+
+            if is_blocked:
+                self.is_idle = True
+                self.last_window_group = None
+                return
+
+            # Если рабочая группа — накапливаем время
+            self.is_idle = False
+            if self.last_window_group != group_name:
+                # Новая группа — завершаем предыдущую сессию (если была)
+                self.last_window_group = group_name
+
+            # Добавляем 5 секунд к текущей группе
+            self._add_work_detail(group_name, 5.0)
+
+    def _match_window_to_policy(self, window_info) -> str:
+        title = window_info.title.lower()
+        proc = window_info.process_name.lower()
+
+        for policy in self.config.window_policies:
+            for pattern in policy.window_patterns:
+                if pattern.lower() in title:
+                    return policy.group_name
+            for pname in policy.process_names:
+                if pname.lower() == proc:
+                    return policy.group_name
+        return "Неизвестное приложение"
+
+    def _is_group_blocked(self, group_name: str) -> bool:
+        for policy in self.config.window_policies:
+            if policy.group_name == group_name:
+                return policy.policy_type == "blocked"
+        return False  # по умолчанию — не блокируем
+
+    def _add_work_detail(self, group_name: str, seconds: float):
+        if not self.current_task:
+            return
+
+        # Создаём новую сессию или используем последнюю
+        if not self.current_task.sessions:
+            session = WorkSession(
+                start_time=datetime.now(),
+                end_time=datetime.now(),
+                details=[],
+                synchronized=False
+            )
+            self.current_task.sessions.append(session)
+        else:
+            session = self.current_task.sessions[-1]
+
+        # Ищем detail с такой же группой
+        for detail in session.details:
+            if detail.group_name == group_name:
+                detail.duration_seconds += seconds
+                break
+        else:
+            session.details.append(WorkDetail(group_name=group_name, duration_seconds=seconds))
+
+        # Обновляем время сессии
+        session.end_time = datetime.now()
+
+    # === Публичные методы с локом ===
+
+    def toggle_tracking(self):
+        with self._lock:
+            if not self.current_task:
+                self.tracking_enabled = False
+                return
+
+            self.tracking_enabled = not self.tracking_enabled
+            self.config.tracking_enabled = self.tracking_enabled
+            self._save_config(self.config)
+
+    def create_task(self, task_id: str, project_id: Optional[str], estimated_minutes: Optional[float]):
+        with self._lock:
+            ensure_dir(self.tasks_dir)
+            new_task = TrackedTask(
+                task_id=task_id,
+                project_id=project_id,
+                estimated_seconds=estimated_minutes * 60 if estimated_minutes else None,
+                start_time=datetime.now()
+            )
+            self.save_task(new_task)
+            self.current_task = new_task
+            self.config.current_task_id = task_id
+            self.config.tracking_enabled = True
+            self.tracking_enabled = True
+            self._save_config(self.config)
+
+    def select_task(self, task_id: str):
+        with self._lock:
+            task = self._load_task(task_id)
+            if task:
+                self.current_task = task
+                self.config.current_task_id = task_id
+                self.config.tracking_enabled = True
+                self.tracking_enabled = True
+                self._save_config(self.config)
+
+    def add_manual_time(self, minutes: float):
+        with self._lock:
+            if not self.current_task:
+                return
+            seconds = abs(minutes) * 60
+            sign = 1 if minutes >= 0 else -1
+            self._add_work_detail("Manual", sign * seconds)
+
+    def get_display_status(self) -> str:
+        with self._lock:
+            if not self.tracking_enabled:
+                return "Пауза"
+            if not self.current_task:
+                return "Пауза"
+            if self.is_idle:
+                return "Бездействие"
+            return "Активная работа"
+
+    def get_current_window_info(self) -> dict:
+        with self._lock:
+            if not self.tracking_enabled or not self.current_task:
+                return {"group": "Пауза", "detail": "Трекинг остановлен. Нажмите «Пауза» для запуска."}
+
+            if self.is_idle:
+                return {"group": "Бездействие", "detail": "Нет активности более 60 сек или отвлекающее окно"}
+
+            window_info = self.platform.get_active_window()
+            group = self._match_window_to_policy(window_info)
+            return {
+                "group": group,
+                "detail": f"{window_info.title} | {window_info.process_name}"
+            }
+
+    # === Остальные методы (без изменений, но с локом где нужно) ===
+
     def _load_or_create_config(self) -> TrackerConfig:
         if self.config_path.exists():
             with open(self.config_path, "r", encoding="utf-8") as f:
@@ -51,8 +243,9 @@ class Application:
         with open(task_file, "w", encoding="utf-8") as f:
             f.write(task.model_dump_json(indent=2))
 
-    def run(self):
-        # Пока просто запускаем UI
-        # Позже сюда добавим трекинг в фоне
-        overlay = OverlayWindow()
-        overlay.run()
\ No newline at end of file
+    def shutdown(self):
+        self._running = False
+        if hasattr(self, 'mouse_listener'):
+            self.mouse_listener.stop()
+        if hasattr(self, 'keyboard_listener'):
+            self.keyboard_listener.stop()
\ No newline at end of file
diff --git a/src/time_tracker/ui/adjust_time_window.py b/src/time_tracker/ui/adjust_time_window.py
index 6eb7658..4dbc11d 100644
--- a/src/time_tracker/ui/adjust_time_window.py
+++ b/src/time_tracker/ui/adjust_time_window.py
@@ -1,9 +1,18 @@
 import tkinter as tk
+from datetime import datetime
 from tkinter import Toplevel, Label, Entry, Button
+from typing import Callable, TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from ..app import Application
 
 
 class AdjustTimeWindow:
-    def __init__(self, parent):
+    def __init__(self, parent, app: "Application", on_close_callback: Callable):
+        self.parent = parent
+        self.app = app
+        self.on_close_callback = on_close_callback
+
         self.window = Toplevel(parent)
         self.window.title("Изменить время")
         self.window.geometry("250x120")
@@ -20,5 +29,39 @@ class AdjustTimeWindow:
         Button(self.window, text="Применить", command=self.on_apply).pack(pady=5)
 
     def on_apply(self):
-        # Позже: применить изменение
+        if not self.app.current_task:
+            self.window.destroy()
+            return
+
+        try:
+            minutes = float(self.minutes_entry.get())
+        except ValueError:
+            return
+
+        if minutes == 0:
+            self.window.destroy()
+            return
+
+        seconds = abs(minutes * 60)
+        # Создаём новую сессию или добавляем в последнюю?
+        # Для простоты — добавим новую сессию с одним WorkDetail
+
+        from ..models import WorkDetail, WorkSession
+
+        detail = WorkDetail(
+            group_name="Manual",
+            duration_seconds=seconds if minutes > 0 else -seconds  # можно хранить отрицательное
+        )
+
+        session = WorkSession(
+            start_time=datetime.now(),
+            end_time=datetime.now(),
+            details=[detail],
+            synchronized=False
+        )
+
+        self.app.current_task.sessions.append(session)
+        self.app.save_task(self.app.current_task)
+
+        self.on_close_callback()
         self.window.destroy()
\ No newline at end of file
diff --git a/src/time_tracker/ui/new_task_window.py b/src/time_tracker/ui/new_task_window.py
index c9a83ab..ae5798e 100644
--- a/src/time_tracker/ui/new_task_window.py
+++ b/src/time_tracker/ui/new_task_window.py
@@ -1,14 +1,23 @@
 import tkinter as tk
-from tkinter import Toplevel, Label, Entry, Button, Frame
+from datetime import datetime
+from tkinter import Toplevel, Label, Entry, Button
+from typing import Callable, TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from ..app import Application
 
 
 class NewTaskWindow:
-    def __init__(self, parent):
+    def __init__(self, parent, app: "Application", on_close_callback: Callable):
+        self.parent = parent
+        self.app = app
+        self.on_close_callback = on_close_callback
+
         self.window = Toplevel(parent)
         self.window.title("Новая задача")
         self.window.geometry("300x200")
         self.window.transient(parent)
-        self.window.grab_set()  # модальное
+        self.window.grab_set()
 
         Label(self.window, text="ID задачи:").pack(pady=(10, 0))
         self.task_id_entry = Entry(self.window)
@@ -25,5 +34,36 @@ class NewTaskWindow:
         Button(self.window, text="Создать", command=self.on_create).pack(pady=10)
 
     def on_create(self):
-        # Позже: сохранить задачу
+        task_id = self.task_id_entry.get().strip()
+        if not task_id:
+            return
+
+        try:
+            estimate_str = self.estimate_entry.get().strip()
+            estimate_seconds = float(estimate_str) * 60 if estimate_str else None
+        except ValueError:
+            return
+
+        project_id = self.project_id_entry.get().strip() or None
+
+        # Создаём новую задачу
+        from ..models import TrackedTask
+        new_task = TrackedTask(
+            task_id=task_id,
+            project_id=project_id,
+            estimated_seconds=estimate_seconds,
+            start_time=datetime.now()
+        )
+
+        # Сохраняем
+        self.app.save_task(new_task)
+
+        # Обновляем конфиг
+        self.app.config.current_task_id = task_id
+        self.app._save_config(self.app.config)
+
+        # Обновляем текущую задачу в памяти
+        self.app.current_task = new_task
+
+        self.on_close_callback()
         self.window.destroy()
\ No newline at end of file
diff --git a/src/time_tracker/ui/overlay.py b/src/time_tracker/ui/overlay.py
index ea8b780..7729058 100644
--- a/src/time_tracker/ui/overlay.py
+++ b/src/time_tracker/ui/overlay.py
@@ -1,10 +1,14 @@
 import tkinter as tk
 from tkinter import Menu, Label, Button, Frame
-from typing import Optional
+from typing import TYPE_CHECKING
+if TYPE_CHECKING:
+    from ..app import Application
+
 
 
 class OverlayWindow:
-    def __init__(self):
+    def __init__(self, app: "Application"):
+        self.app = app
         self.root = tk.Tk()
         self.root.title("Citrus Time Tracker")
         self.root.geometry("320x180")
@@ -30,6 +34,8 @@ class OverlayWindow:
         # Содержимое
         self._build_ui()
 
+        self._auto_update()
+
     def center_window(self):
         self.root.update_idletasks()
         screen_width = self.root.winfo_screenwidth()
@@ -66,27 +72,72 @@ class OverlayWindow:
         btn_frame = Frame(main_frame)
         btn_frame.pack(side="bottom", fill="x", pady=(10, 0))
 
-        Button(btn_frame, text="⏸ Пауза", command=self.on_pause).pack(side="left", fill="x", expand=True, padx=(0, 2))
-        Button(btn_frame, text="➕ Новая", command=self.on_new_task).pack(side="left", fill="x", expand=True, padx=2)
-        Button(btn_frame, text="🔍 Выбрать", command=self.on_select_task).pack(side="left", fill="x", expand=True, padx=2)
-        Button(btn_frame, text="✏️ Время", command=self.on_adjust_time).pack(side="left", fill="x", expand=True, padx=(2, 0))
+        self.pause_button = Button(btn_frame, text="⏸ Пауза", command=self.on_pause)
+        self.pause_button.pack(side="left", fill="x", expand=True, padx=(0, 2))
+        self.new_task_btn = Button(btn_frame, text="➕ Новая", command=self.on_new_task)
+        self.new_task_btn.pack(side="left", fill="x", expand=True, padx=2)
+        self.select_task_btn = Button(btn_frame, text="🔍 Выбрать", command=self.on_select_task)
+        self.select_task_btn.pack(side="left", fill="x", expand=True, padx=2)
+        self.adjust_time_btn = Button(btn_frame, text="✏️ Время", command=self.on_adjust_time)
+        self.adjust_time_btn.pack(side="left", fill="x", expand=True, padx=(2, 0))
+
+        self._update_display()
+
+    def _update_display(self):
+        status = self.app.get_display_status()
+        self.status_label.config(text=f"Citrus Time Tracker: {status}")
+
+        task_id = self.app.config.current_task_id or "<Не выбрано>"
+        self.task_label.config(text=f"Задача: {task_id}")
+
+        # Время
+        if self.app.current_task:
+            worked = self.app.current_task.total_worked_seconds / 60
+            est = self.app.current_task.estimated_seconds
+            if est is not None:
+                est_min = est / 60
+                rem = self.app.current_task.remaining_seconds / 60
+                time_info = f"Затрачено: {worked:.1f} мин | Оценка: {est_min:.1f} мин"
+            else:
+                time_info = f"Затрачено: {worked:.1f} мин | Оценка: —"
+        else:
+            time_info = "Задача не выбрана"
+        self.time_info_label.config(text=time_info)
+
+        # Окно
+        win_info = self.app.get_current_window_info()
+        self.window_group_label.config(text=win_info["group"])
+        self.window_detail_label.config(text=win_info["detail"])
+
+        # Активность кнопок
+        has_task = self.app.current_task is not None
+        self.pause_button.config(state="normal" if has_task else "disabled")
+        for btn in [self.new_task_btn, self.select_task_btn, self.adjust_time_btn]:
+            btn.config(state="normal")
+
+        # Но "Добавить время" — только если есть задача
+        self.adjust_time_btn.config(state="normal" if has_task else "disabled")
+
+    def _auto_update(self):
+        self._update_display()
+        self.root.after(2000, self._auto_update)  # обновляем каждые 2 сек
 
     # === Обработчики событий (пока без логики, только открытие окон) ===
 
     def on_pause(self):
-        pass  # будет реализовано позже
+        self.app.toggle_tracking()
 
     def on_new_task(self):
         from .new_task_window import NewTaskWindow
-        NewTaskWindow(self.root)
+        NewTaskWindow(self.root, self.app, self._update_display)
 
     def on_select_task(self):
         from .select_task_window import SelectTaskWindow
-        SelectTaskWindow(self.root)
+        SelectTaskWindow(self.root, self.app, self._update_display)
 
     def on_adjust_time(self):
         from .adjust_time_window import AdjustTimeWindow
-        AdjustTimeWindow(self.root)
+        AdjustTimeWindow(self.root, self.app, self._update_display)
 
     # === UI-управление ===
 
diff --git a/src/time_tracker/ui/select_task_window.py b/src/time_tracker/ui/select_task_window.py
index 22ebc5c..af6a366 100644
--- a/src/time_tracker/ui/select_task_window.py
+++ b/src/time_tracker/ui/select_task_window.py
@@ -1,32 +1,55 @@
 import tkinter as tk
-from tkinter import Toplevel, Listbox, Scrollbar, Button, Frame
+from pathlib import Path
+from tkinter import Toplevel, Listbox, Scrollbar, Button
+from typing import Callable, TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from ..app import Application
 
 
 class SelectTaskWindow:
-    def __init__(self, parent):
+    def __init__(self, parent, app: "Application", on_close_callback: Callable):
+        self.parent = parent
+        self.app = app
+        self.on_close_callback = on_close_callback
+
         self.window = Toplevel(parent)
         self.window.title("Выбрать задачу")
         self.window.geometry("300x250")
         self.window.transient(parent)
         self.window.grab_set()
 
-        list_frame = Frame(self.window)
+        # Сканируем папку tasks/
+        task_files = list(Path("tasks").glob("*.json")) if Path("tasks").exists() else []
+        self.task_ids = [f.stem for f in task_files]
+
+        list_frame = tk.Frame(self.window)
         list_frame.pack(fill="both", expand=True, padx=10, pady=10)
 
         scrollbar = Scrollbar(list_frame)
         scrollbar.pack(side="right", fill="y")
 
         self.listbox = Listbox(list_frame, yscrollcommand=scrollbar.set)
+        for tid in self.task_ids:
+            self.listbox.insert("end", tid)
         self.listbox.pack(side="left", fill="both", expand=True)
 
-        # Заглушка: список задач
-        for i in range(5):
-            self.listbox.insert("end", f"TASK-{i+1} (1 ч 20 мин)")
-
         scrollbar.config(command=self.listbox.yview)
 
         Button(self.window, text="Выбрать", command=self.on_select).pack(pady=5)
 
     def on_select(self):
-        # Позже: выбрать задачу
+        selection = self.listbox.curselection()
+        if not selection:
+            return
+        task_id = self.task_ids[selection[0]]
+
+        # Загружаем задачу
+        task = self.app._load_task(task_id)
+        if task:
+            self.app.current_task = task
+            self.app.config.current_task_id = task_id
+            self.app._save_config(self.app.config)
+            self.on_close_callback()
+
         self.window.destroy()
\ No newline at end of file