diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
new file mode 100644
index 0000000..31b3f7c
--- /dev/null
+++ b/.github/workflows/tests.yml
@@ -0,0 +1,153 @@
+name: Tests
+
+on:
+  push:
+    branches: [ main, develop ]
+  pull_request:
+    branches: [ main, develop ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        python-version: ['3.10', '3.11', '3.12', '3.13']
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Cache pip packages
+        uses: actions/cache@v4
+        with:
+          path: ~/.cache/pip
+          key: ${{ runner.os }}-pip-${{ hashFiles('**/pyproject.toml') }}
+          restore-keys: |
+            ${{ runner.os }}-pip-
+
+      - name: Install runtime + test tools
+        run: |
+          python -m pip install --upgrade pip
+          # Устанавливаем package (runtime deps)
+          pip install -e "."
+          # Явно ставим инструменты для тестов/линта, чтобы они были доступны в runner
+          pip install pytest pytest-asyncio pytest-cov pytest-timeout flake8 mypy
+
+      - name: Lint with flake8
+        run: |
+          flake8 src/pymax tests \
+            --count \
+            --select=E9,F63,F7,F82 \
+            --show-source \
+            --statistics
+          flake8 src/pymax tests \
+            --count \
+            --exit-zero \
+            --max-complexity=10 \
+            --max-line-length=79 \
+            --statistics
+        continue-on-error: true
+
+      - name: Type check with mypy
+        run: |
+          mypy src/pymax \
+            --ignore-missing-imports \
+            --no-error-summary
+        continue-on-error: true
+
+      - name: Run unit tests
+        run: |
+          pytest -m "not mockserver" \
+            --cov=src/pymax \
+            --cov-report=xml \
+            --cov-report=term-missing
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v4
+        with:
+          files: coverage.xml
+          flags: unittests
+          name: codecov-umbrella
+          fail_ci_if_error: false
+
+      - name: Archive pytest cache
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: pytest-cache-${{ matrix.python-version }}
+          path: .pytest_cache/
+          retention-days: 5
+
+  integration-tests:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository (with submodules)
+        uses: actions/checkout@v4
+        with:
+          submodules: recursive
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.13'
+
+      - name: Install runtime + test tools (integration)
+        run: |
+          python -m pip install --upgrade pip
+          pip install -e "."
+          pip install pytest pytest-asyncio pytest-cov pytest-timeout flake8 mypy
+
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: '1.22'
+
+      - name: Start MockServer
+        run: |
+          git clone https://github.com/fresh-milkshake/gomax-prerelease.git
+          cd gomax-prerelease/mockserver
+          go mod download
+          go run cmd/server/main.go &
+          sleep 3
+
+      - name: Run integration tests
+        run: |
+          pytest -m mockserver -v --tb=short
+        continue-on-error: true
+        env:
+          MOCKSERVER_WS_URL: ws://localhost:8080/
+          MOCKSERVER_HTTP_URL: http://localhost:8080
+
+  code-quality:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.13'
+
+      - name: Install dependencies + quality tools
+        run: |
+          python -m pip install --upgrade pip
+          pip install -e "."
+          # black/isort/pylint используются только в этом job
+          pip install black isort pylint
+
+      - name: Check code formatting with black
+        run: black --check src/pymax tests
+        continue-on-error: true
+
+      - name: Check import sorting with isort
+        run: isort --check-only src/pymax tests
+        continue-on-error: true
diff --git a/README.md b/README.md
index c67520d..277e713 100644
--- a/README.md
+++ b/README.md
@@ -54,6 +54,41 @@ uv add -U maxapi-python
 
 ## Быстрый старт
 
+### Аутентификация (`device_type`)
+
+> [!IMPORTANT]
+> Параметр `device_type` в `UserAgentPayload` **критически важен** для выбора способа авторизации:
+
+**Вход по номеру телефона (DESKTOP):**
+
+```python
+from pymax import MaxClient
+from pymax.payloads import UserAgentPayload
+
+ua = UserAgentPayload(device_type="DESKTOP", app_version="25.12.13")
+
+client = MaxClient(
+    phone="+79111111111",
+    work_dir="cache",
+    headers=ua,
+)
+```
+
+**Вход через QR-код (WEB)** — токен совместим с веб-версией Max:
+
+```python
+from pymax import MaxClient
+from pymax.payloads import UserAgentPayload
+
+ua = UserAgentPayload(device_type="WEB", app_version="25.12.13")
+
+client = MaxClient(
+    phone="+7911111111",
+    work_dir="cache",
+    headers=ua,
+)
+```
+
 ### Базовый пример использования
 
 ```python
diff --git a/examples/test.py b/examples/test.py
index 38030d6..5929cb3 100644
--- a/examples/test.py
+++ b/examples/test.py
@@ -3,10 +3,10 @@
 from pymax import MaxClient
 from pymax.payloads import UserAgentPayload
 
-ua = UserAgentPayload(device_type="WEB")
+ua = UserAgentPayload(device_type="DESKTOP", app_version="25.12.13")
 
 client = MaxClient(
-    phone="+79911111111",
+    phone="+79116290861",
     work_dir="cache",
     headers=ua,
 )
diff --git a/pyproject.toml b/pyproject.toml
index fcf6b10..c6a4fb3 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "maxapi-python"
-version = "1.2.1"
+version = "1.2.2"
 description = "Python wrapper для API мессенджера Max"
 readme = "README.md"
 requires-python = ">=3.10"
@@ -36,7 +36,25 @@ where = ["src"]
 [tool.setuptools.package-dir]
 "" = "src"
 
+[project.optional-dependencies]
+test = [
+  "pytest>=8.0.0",
+  "pytest-asyncio>=0.24.0",
+  "pytest-cov>=5.0.0",
+  "pytest-timeout>=2.1.0",
+  "flake8",
+  "mypy",
+]
+
 [dependency-groups]
+test = [
+  "pytest>=8.0.0",
+  "pytest-asyncio>=0.24.0",
+  "pytest-cov>=5.0.0",
+  "pytest-timeout>=2.1.0",
+  "flake8",
+  "mypy",
+]
 dev = [
   "furo>=2025.9.25",
   "ghp-import>=2.1.0",
@@ -46,6 +64,10 @@ dev = [
   "pre-commit>=4.3.0",
   "pydocstring>=0.2.1",
   "sphinx>=8.1.3",
+  "pytest>=8.0.0",
+  "pytest-asyncio>=0.24.0",
+  "pytest-cov>=5.0.0",
+  "pytest-timeout>=2.1.0",
 ]
 
 [tool.hatch.build.targets.wheel]
@@ -74,3 +96,33 @@ profile = "black"
 line_length = 79
 multi_line_output = 3
 include_trailing_comma = true
+
+[tool.pytest.ini_options]
+asyncio_mode = "auto"
+testpaths = ["tests"]
+python_files = ["test_*.py"]
+python_classes = ["Test*"]
+python_functions = ["test_*"]
+addopts = "-v --tb=short --strict-markers"
+markers = [
+  "asyncio: marker for asyncio tests",
+  "mockserver: marker for MockServer integration tests",
+  "integration: marker for integration tests",
+  "slow: marker for slow tests",
+]
+
+[tool.coverage.run]
+source = ["src/pymax"]
+branch = true
+
+[tool.coverage.report]
+exclude_lines = [
+  "pragma: no cover",
+  "def __repr__",
+  "raise AssertionError",
+  "raise NotImplementedError",
+  "if __name__ == .__main__.:",
+  "if TYPE_CHECKING:",
+  "class .*\\bProtocol\\):",
+  "@(abc\\.)?abstractmethod",
+]
diff --git a/pytest.ini b/pytest.ini
index 13bc1da..4e31bfb 100644
--- a/pytest.ini
+++ b/pytest.ini
@@ -1,6 +1,26 @@
 [pytest]
+
+asyncio_mode = auto
+
 testpaths = tests
+
 python_files = test_*.py
 python_classes = Test*
 python_functions = test_*
-addopts = -v --tb=short
\ No newline at end of file
+
+addopts =
+    -v
+    --tb=short
+    --strict-markers
+    -ra
+    --color=yes
+
+markers =
+    asyncio: асинхронные тесты
+    mockserver: интеграционные тесты с MockServer
+    integration: интеграционные тесты
+    slow: медленные тесты
+    unit: модульные тесты
+    skip_ci: пропустить в CI
+
+timeout = 30
diff --git a/redocs/source/clients.rst b/redocs/source/clients.rst
index c498df8..dbba07e 100644
--- a/redocs/source/clients.rst
+++ b/redocs/source/clients.rst
@@ -20,6 +20,28 @@ MaxClient
         logger=None,                    # Пользовательский логгер
     )
 
+.. warning::
+
+    Параметр ``device_type`` в ``UserAgentPayload`` **критически важен** для выбора способа авторизации:
+
+    **DESKTOP** — вход по номеру телефона:
+
+    .. code-block:: python
+
+        from pymax.payloads import UserAgentPayload
+
+        ua = UserAgentPayload(device_type="DESKTOP", app_version="25.12.13")
+        client = MaxClient(phone="+79111111111", headers=ua)
+
+    **WEB** — вход через QR-код; токен совместим с веб-версией Max:
+
+    .. code-block:: python
+
+        from pymax.payloads import UserAgentPayload
+
+        ua = UserAgentPayload(device_type="WEB", app_version="25.12.13")
+        client = MaxClient(phone="+79111111111", headers=ua)
+
 Основные методы:
 
 .. code-block:: python
diff --git a/src/pymax/core.py b/src/pymax/core.py
index 3733a1d..77791a1 100644
--- a/src/pymax/core.py
+++ b/src/pymax/core.py
@@ -295,7 +295,7 @@ async def start(self) -> None:
                 if self._token is None:
                     await self._login()
 
-                await self._sync()
+                await self._sync(self.user_agent)
 
                 await self._post_login_tasks(sync=False)
 
diff --git a/src/pymax/mixins/websocket.py b/src/pymax/mixins/websocket.py
index 0f4465e..8fbecb4 100644
--- a/src/pymax/mixins/websocket.py
+++ b/src/pymax/mixins/websocket.py
@@ -50,9 +50,7 @@ def _make_message(
             payload=payload,
         ).model_dump(by_alias=True)
 
-        self.logger.debug(
-            "make_message opcode=%s cmd=%s seq=%s", opcode, cmd, self._seq
-        )
+        self.logger.debug("make_message opcode=%s cmd=%s seq=%s", opcode, cmd, self._seq)
         return msg
 
     async def _send_interactive_ping(self) -> None:
@@ -68,9 +66,7 @@ async def _send_interactive_ping(self) -> None:
                 self.logger.warning("Interactive ping failed", exc_info=True)
             await asyncio.sleep(DEFAULT_PING_INTERVAL)
 
-    async def connect(
-        self, user_agent: UserAgentPayload | None = None
-    ) -> dict[str, Any] | None:
+    async def connect(self, user_agent: UserAgentPayload | None = None) -> dict[str, Any] | None:
         """
         Устанавливает соединение WebSocket с сервером и выполняет handshake.
 
@@ -173,9 +169,7 @@ async def _handle_file_upload(self, data: dict[str, Any]) -> None:
                 fut = self._file_upload_waiters.pop(id_, None)
                 if fut and not fut.done():
                     fut.set_result(data)
-                    self.logger.debug(
-                        "Fulfilled file upload waiter for %s=%s", key, id_
-                    )
+                    self.logger.debug("Fulfilled file upload waiter for %s=%s", key, id_)
 
     async def _handle_message_notifications(self, data: dict) -> None:
         if data.get("opcode") != Opcode.NOTIF_MESSAGE.value:
@@ -359,9 +353,7 @@ async def _send_and_wait(
             )
             return data
         except Exception:
-            self.logger.exception(
-                "Send and wait failed (opcode=%s, seq=%s)", opcode, msg["seq"]
-            )
+            self.logger.exception("Send and wait failed (opcode=%s, seq=%s)", opcode, msg["seq"])
             raise RuntimeError("Send and wait failed")
         finally:
             self._pending.pop(msg["seq"], None)
@@ -442,7 +434,7 @@ def _get_retry_delay(self, error: Exception, retry_count: int) -> float:
         else:
             return float(2**retry_count)
 
-    async def _sync(self) -> None:
+    async def _sync(self, user_agent: UserAgentPayload) -> None:
         self.logger.info("Starting initial sync")
 
         payload = SyncPayload(
@@ -453,6 +445,7 @@ async def _sync(self) -> None:
             presence_sync=0,
             drafts_sync=0,
             chats_count=40,
+            user_agent=user_agent,
         ).model_dump(by_alias=True)
         try:
             data = await self._send_and_wait(opcode=Opcode.LOGIN, payload=payload)
@@ -473,9 +466,7 @@ async def _sync(self) -> None:
                     self.logger.exception("Error parsing chat entry")
 
             if raw_payload.get("profile", {}).get("contact"):
-                self.me = Me.from_dict(
-                    raw_payload.get("profile", {}).get("contact", {})
-                )
+                self.me = Me.from_dict(raw_payload.get("profile", {}).get("contact", {}))
 
             self.logger.info(
                 "Sync completed: dialogs=%d chats=%d channels=%d",
diff --git a/src/pymax/payloads.py b/src/pymax/payloads.py
index faf8bf9..4f31f09 100644
--- a/src/pymax/payloads.py
+++ b/src/pymax/payloads.py
@@ -39,6 +39,20 @@ class BaseWebSocketMessage(BaseModel):
     payload: dict[str, Any]
 
 
+class UserAgentPayload(CamelModel):
+    device_type: str = Field(default=DEFAULT_DEVICE_TYPE)
+    locale: str = Field(default=DEFAULT_LOCALE)
+    device_locale: str = Field(default=DEFAULT_DEVICE_LOCALE)
+    os_version: str = Field(default=DEFAULT_OS_VERSION)
+    device_name: str = Field(default=DEFAULT_DEVICE_NAME)
+    header_user_agent: str = Field(default=DEFAULT_USER_AGENT)
+    app_version: str = Field(default=DEFAULT_APP_VERSION)
+    screen: str = Field(default=DEFAULT_SCREEN)
+    timezone: str = Field(default=DEFAULT_TIMEZONE)
+    client_session_id: int = Field(default=DEFAULT_CLIENT_SESSION_ID)
+    build_number: int = Field(default=DEFAULT_BUILD_NUMBER)
+
+
 class RequestCodePayload(CamelModel):
     phone: str
     type: AuthType = AuthType.START_AUTH
@@ -59,6 +73,21 @@ class SyncPayload(CamelModel):
     presence_sync: int = 0
     drafts_sync: int = 0
     chats_count: int = 40
+    user_agent: UserAgentPayload = Field(
+        default_factory=lambda: UserAgentPayload(
+            device_type=DEFAULT_DEVICE_TYPE,
+            locale=DEFAULT_LOCALE,
+            device_locale=DEFAULT_DEVICE_LOCALE,
+            os_version=DEFAULT_OS_VERSION,
+            device_name=DEFAULT_DEVICE_NAME,
+            header_user_agent=DEFAULT_USER_AGENT,
+            app_version=DEFAULT_APP_VERSION,
+            screen=DEFAULT_SCREEN,
+            timezone=DEFAULT_TIMEZONE,
+            client_session_id=DEFAULT_CLIENT_SESSION_ID,
+            build_number=DEFAULT_BUILD_NUMBER,
+        ),
+    )
 
 
 class ReplyLink(CamelModel):
@@ -276,20 +305,6 @@ class RemoveReactionPayload(CamelModel):
     message_id: str
 
 
-class UserAgentPayload(CamelModel):
-    device_type: str = Field(default=DEFAULT_DEVICE_TYPE)
-    locale: str = Field(default=DEFAULT_LOCALE)
-    device_locale: str = Field(default=DEFAULT_DEVICE_LOCALE)
-    os_version: str = Field(default=DEFAULT_OS_VERSION)
-    device_name: str = Field(default=DEFAULT_DEVICE_NAME)
-    header_user_agent: str = Field(default=DEFAULT_USER_AGENT)
-    app_version: str = Field(default=DEFAULT_APP_VERSION)
-    screen: str = Field(default=DEFAULT_SCREEN)
-    timezone: str = Field(default=DEFAULT_TIMEZONE)
-    client_session_id: int = Field(default=DEFAULT_CLIENT_SESSION_ID)
-    build_number: int = Field(default=DEFAULT_BUILD_NUMBER)
-
-
 class ReworkInviteLinkPayload(CamelModel):
     revoke_private_link: bool = True
     chat_id: int
diff --git a/src/pymax/static/constant.py b/src/pymax/static/constant.py
index aa87c30..3729827 100644
--- a/src/pymax/static/constant.py
+++ b/src/pymax/static/constant.py
@@ -9,7 +9,7 @@
 HOST: Final[str] = "api.oneme.ru"
 PORT: Final[int] = 443
 DEFAULT_TIMEOUT: Final[float] = 20.0
-DEFAULT_DEVICE_TYPE: Final[str] = "WEB"
+DEFAULT_DEVICE_TYPE: Final[str] = "DESKTOP"
 DEFAULT_LOCALE: Final[str] = "ru"
 DEFAULT_DEVICE_LOCALE: Final[str] = "ru"
 DEFAULT_DEVICE_NAME: Final[str] = "Chrome"