diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 2378968..dced61f 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -18,6 +18,10 @@ jobs:
         working-directory: backend
         run: uv sync
 
+      - name: Lint (ruff)
+        working-directory: backend
+        run: uv run ruff check && uv run ruff format --check
+
       - name: Run tests
         working-directory: backend
         env:
@@ -41,6 +45,10 @@ jobs:
         working-directory: bot
         run: uv sync
 
+      - name: Lint (ruff)
+        working-directory: bot
+        run: uv run ruff check && uv run ruff format --check
+
       - name: Run tests
         working-directory: bot
         env:
diff --git a/backend/app/auth.py b/backend/app/auth.py
index 1c37898..0b68566 100644
--- a/backend/app/auth.py
+++ b/backend/app/auth.py
@@ -1,4 +1,4 @@
-from datetime import datetime, timedelta, timezone
+from datetime import UTC, datetime, timedelta
 
 import jwt
 from fastapi import Depends, HTTPException, status
@@ -10,16 +10,24 @@
 
 
 def create_token() -> str:
-    expire = datetime.now(timezone.utc) + timedelta(hours=settings.token_expire_hours)
-    return jwt.encode({"sub": "admin", "exp": expire}, settings.secret_key, algorithm="HS256")
+    expire = datetime.now(UTC) + timedelta(hours=settings.token_expire_hours)
+    return jwt.encode(
+        {"sub": "admin", "exp": expire}, settings.secret_key, algorithm="HS256"
+    )
 
 
 def verify_token(credentials: HTTPAuthorizationCredentials = Depends(bearer_scheme)):
     try:
-        payload = jwt.decode(credentials.credentials, settings.secret_key, algorithms=["HS256"])
+        payload = jwt.decode(
+            credentials.credentials, settings.secret_key, algorithms=["HS256"]
+        )
         if payload.get("sub") != "admin":
             raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED)
     except jwt.ExpiredSignatureError:
-        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Token expired")
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED, detail="Token expired"
+        ) from None
     except jwt.InvalidTokenError:
-        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid token")
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid token"
+        ) from None
diff --git a/backend/app/config.py b/backend/app/config.py
index 95ea3bd..c7ebeb2 100644
--- a/backend/app/config.py
+++ b/backend/app/config.py
@@ -13,4 +13,5 @@ class Settings(BaseSettings):
     #     env_file = "../.env"
     #     extra = "ignore"
 
+
 settings = Settings()
diff --git a/backend/app/models.py b/backend/app/models.py
index 8503fb2..e12373e 100644
--- a/backend/app/models.py
+++ b/backend/app/models.py
@@ -1,5 +1,5 @@
 import json
-from datetime import datetime, timezone
+from datetime import UTC, datetime
 
 from sqlalchemy import Column, DateTime, Integer, String, Text
 from sqlalchemy.orm import validates
@@ -18,9 +18,10 @@ class Card(Base):
     # хранит список тегов как JSON строку: ["list", "dict"]
     tags = Column(Text, default="[]")
     difficulty = Column(String(10), nullable=False, default="normal")
-    created_at = Column(DateTime, default=lambda: datetime.now(timezone.utc))
-    updated_at = Column(DateTime, default=lambda: datetime.now(timezone.utc),
-                        onupdate=lambda: datetime.now(timezone.utc))
+    created_at = Column(DateTime, default=lambda: datetime.now(UTC))
+    updated_at = Column(
+        DateTime, default=lambda: datetime.now(UTC), onupdate=lambda: datetime.now(UTC)
+    )
 
     @validates("difficulty")
     def validate_difficulty(self, key, value):
diff --git a/backend/app/routers/admin.py b/backend/app/routers/admin.py
index 881228f..dc9517c 100644
--- a/backend/app/routers/admin.py
+++ b/backend/app/routers/admin.py
@@ -8,7 +8,13 @@
 from app.config import settings
 from app.database import get_db
 from app.models import Card
-from app.schemas import CardCreate, CardResponse, CardUpdate, LoginRequest, TokenResponse
+from app.schemas import (
+    CardCreate,
+    CardResponse,
+    CardUpdate,
+    LoginRequest,
+    TokenResponse,
+)
 
 router = APIRouter(prefix="/api/admin", tags=["admin"])
 
@@ -21,11 +27,15 @@ def login(body: LoginRequest):
         body.password.encode(), settings.admin_password.encode()
     )
     if not password_ok:
-        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Wrong password")
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED, detail="Wrong password"
+        )
     return TokenResponse(access_token=create_token())
 
 
-@router.post("/cards", response_model=CardResponse, dependencies=[Depends(verify_token)])
+@router.post(
+    "/cards", response_model=CardResponse, dependencies=[Depends(verify_token)]
+)
 def create_card(body: CardCreate, db: Session = Depends(get_db)):
     card = Card(
         question=body.question,
@@ -41,7 +51,11 @@ def create_card(body: CardCreate, db: Session = Depends(get_db)):
     return card
 
 
-@router.put("/cards/{card_id}", response_model=CardResponse, dependencies=[Depends(verify_token)])
+@router.put(
+    "/cards/{card_id}",
+    response_model=CardResponse,
+    dependencies=[Depends(verify_token)],
+)
 def update_card(card_id: int, body: CardUpdate, db: Session = Depends(get_db)):
     card = db.query(Card).filter(Card.id == card_id).first()
     if not card:
diff --git a/backend/app/routers/cards.py b/backend/app/routers/cards.py
index 2882c74..dce215a 100644
--- a/backend/app/routers/cards.py
+++ b/backend/app/routers/cards.py
@@ -1,5 +1,5 @@
 import json
-from typing import Literal, Optional
+from typing import Literal
 
 from fastapi import APIRouter, Depends, HTTPException, Query
 from sqlalchemy import or_
@@ -14,10 +14,10 @@
 
 @router.get("", response_model=CardListResponse)
 def get_cards(
-    search: Optional[str] = Query(None),
-    category: Optional[str] = Query(None),
-    difficulty: Optional[Literal["easy", "normal", "hard"]] = Query(None),
-    tags: Optional[str] = Query(None),  # через запятую: "list,dict"
+    search: str | None = Query(None),
+    category: str | None = Query(None),
+    difficulty: Literal["easy", "normal", "hard"] | None = Query(None),
+    tags: str | None = Query(None),  # через запятую: "list,dict"
     page: int = Query(1, ge=1),
     per_page: int = Query(20, ge=1, le=500),
     db: Session = Depends(get_db),
@@ -26,9 +26,7 @@ def get_cards(
 
     if search:
         term = f"%{search}%"
-        query = query.filter(
-            or_(Card.question.ilike(term), Card.answer.ilike(term))
-        )
+        query = query.filter(or_(Card.question.ilike(term), Card.answer.ilike(term)))
 
     if category:
         query = query.filter(Card.category == category)
diff --git a/backend/app/schemas.py b/backend/app/schemas.py
index 922e34d..ba14ae0 100644
--- a/backend/app/schemas.py
+++ b/backend/app/schemas.py
@@ -1,6 +1,6 @@
 import json
 from datetime import datetime
-from typing import Literal, Optional
+from typing import Literal
 
 from pydantic import BaseModel, field_validator
 
@@ -8,7 +8,7 @@
 class CardBase(BaseModel):
     question: str
     answer: str
-    code_example: Optional[str] = None
+    code_example: str | None = None
     category: str
     tags: list[str] = []
     difficulty: Literal["easy", "normal", "hard"] = "normal"
@@ -19,12 +19,12 @@ class CardCreate(CardBase):
 
 
 class CardUpdate(BaseModel):
-    question: Optional[str] = None
-    answer: Optional[str] = None
-    code_example: Optional[str] = None
-    category: Optional[str] = None
-    tags: Optional[list[str]] = None
-    difficulty: Optional[Literal["easy", "normal", "hard"]] = None
+    question: str | None = None
+    answer: str | None = None
+    code_example: str | None = None
+    category: str | None = None
+    tags: list[str] | None = None
+    difficulty: Literal["easy", "normal", "hard"] | None = None
 
     # Optional здесь означает - поле можно не передавать.
     # Для code_example null оставлен допустимым.
diff --git a/backend/app/scripts/migrate_md.py b/backend/app/scripts/migrate_md.py
index 87c7022..086086e 100644
--- a/backend/app/scripts/migrate_md.py
+++ b/backend/app/scripts/migrate_md.py
@@ -11,6 +11,7 @@
 код пример
 ```
 """
+
 import argparse
 import json
 import os
@@ -53,14 +54,16 @@ def flush_card():
         else:
             code = None
 
-        cards.append({
-            "question": current_question.strip(),
-            "answer": answer,
-            "code_example": code,
-            "category": current_category,
-            "tags": [],
-            "difficulty": "normal",
-        })
+        cards.append(
+            {
+                "question": current_question.strip(),
+                "answer": answer,
+                "code_example": code,
+                "category": current_category,
+                "tags": [],
+                "difficulty": "normal",
+            }
+        )
 
     for line in lines:
         # отслеживает блоки кода
@@ -111,7 +114,9 @@ def flush_card():
 def main():
     parser = argparse.ArgumentParser()
     parser.add_argument("--file", required=True, help="Path to questions.md")
-    parser.add_argument("--clear", action="store_true", help="Удалить все карточки перед импортом")
+    parser.add_argument(
+        "--clear", action="store_true", help="Удалить все карточки перед импортом"
+    )
     args = parser.parse_args()
 
     with open(args.file, encoding="utf-8") as f:
diff --git a/backend/pyproject.toml b/backend/pyproject.toml
index 7782816..56ca718 100644
--- a/backend/pyproject.toml
+++ b/backend/pyproject.toml
@@ -17,4 +17,15 @@ dev = [
     "pytest>=8.0.0",
     "httpx>=0.27.0",
     "pytest-env>=1.1.0",
-]
\ No newline at end of file
+    "ruff>=0.16.10",
+]
+
+[tool.ruff]
+# Markdown файлы со скриптов миграции содержат контент карточек, форматировать нельзя
+extend-exclude = ["*.md"]
+
+[tool.ruff.lint]
+select = ["E4", "E7", "E9", "F", "I", "UP", "B"]
+
+[tool.ruff.lint.flake8-bugbear]
+extend-immutable-calls = ["fastapi.Depends"]
diff --git a/backend/tests/conftest.py b/backend/tests/conftest.py
index 69f73d8..682a336 100644
--- a/backend/tests/conftest.py
+++ b/backend/tests/conftest.py
@@ -1,4 +1,5 @@
 import json
+
 import pytest
 from fastapi.testclient import TestClient
 from sqlalchemy import create_engine
diff --git a/backend/tests/test_admin.py b/backend/tests/test_admin.py
index 0cb6d17..9c65f44 100644
--- a/backend/tests/test_admin.py
+++ b/backend/tests/test_admin.py
@@ -94,9 +94,7 @@ def test_unknown_id_returns_404(self, client):
     )
     def test_null_for_required_field_rejected(self, client, db, field):
         card = make_card(db)
-        response = client.put(
-            f"{URL}/{card.id}", json={field: None}, headers=auth()
-        )
+        response = client.put(f"{URL}/{card.id}", json={field: None}, headers=auth())
         assert response.status_code == 422
         # карточка не испортилась и по-прежнему читается
         assert client.get(f"/api/cards/{card.id}").status_code == 200
diff --git a/backend/tests/test_auth.py b/backend/tests/test_auth.py
index 5b8b760..4d17bd0 100644
--- a/backend/tests/test_auth.py
+++ b/backend/tests/test_auth.py
@@ -1,4 +1,4 @@
-from datetime import datetime, timedelta, timezone
+from datetime import UTC, datetime, timedelta
 
 import jwt
 
@@ -13,7 +13,7 @@ def auth_headers(token: str) -> dict:
 
 
 def make_jwt(sub="admin", key=None, expires_in=timedelta(hours=1)) -> str:
-    payload = {"sub": sub, "exp": datetime.now(timezone.utc) + expires_in}
+    payload = {"sub": sub, "exp": datetime.now(UTC) + expires_in}
     return jwt.encode(payload, key or settings.secret_key, algorithm="HS256")
 
 
diff --git a/backend/tests/test_cards.py b/backend/tests/test_cards.py
index ecdd797..d0aa6c8 100644
--- a/backend/tests/test_cards.py
+++ b/backend/tests/test_cards.py
@@ -1,5 +1,5 @@
 import json
-import pytest
+
 from tests.conftest import make_card
 
 
diff --git a/backend/uv.lock b/backend/uv.lock
index 7518859..a83f774 100644
--- a/backend/uv.lock
+++ b/backend/uv.lock
@@ -344,6 +344,7 @@ dev = [
     { name = "httpx" },
     { name = "pytest" },
     { name = "pytest-env" },
+    { name = "ruff" },
 ]
 
 [package.metadata]
@@ -362,6 +363,7 @@ dev = [
     { name = "httpx", specifier = ">=0.27.0" },
     { name = "pytest", specifier = ">=8.0.0" },
     { name = "pytest-env", specifier = ">=1.1.0" },
+    { name = "ruff", specifier = ">=0.16.10" },
 ]
 
 [[package]]
@@ -409,6 +411,31 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/f1/12/de94a39c2ef588c7e6455cfbe7343d3b2dc9d6b6b2f40c4c6565744c873d/pyyaml-6.0.3-cp314-cp314t-win_arm64.whl", hash = "sha256:ebc55a14a21cb14062aa4162f906cd962b28e2e9ea38f9b4391244cd8de4ae0b", size = 149341, upload-time = "2025-09-25T21:32:56.828Z" },
 ]
 
+[[package]]
+name = "ruff"
+version = "0.16.10"
+source = { registry = "https://pypi.org/simple" }
+sdist = { url = "https://files.pythonhosted.org/packages/c4/49/23802c45f093eb14bde54b141d2b2f058edfa63a06db7beed047308cc08f/ruff-0.16.10.tar.gz", hash = "sha256:eff4728c4eaae93f0955cd264d24b2ab348e74bf59986ccf282ba6dc16b3b017", size = 4958724, upload-time = "2026-10-01T18:03:21.697Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/2f/21/ebce22e1d90cdb2cd691026b9c6e9bec6499f0b396089481755b5d49efff/ruff-0.16.10-py3-none-linux_armv6l.whl", hash = "sha256:488b0fe3f3574210e5cf80d9f59b9e3ab17a127a8155de3f307b392589cfb511", size = 10095557, upload-time = "2026-10-01T18:02:36.072Z" },
+    { url = "https://files.pythonhosted.org/packages/cb/98/a54de85876a8b2612bfa0d84c7b9abfb39c6a3354aee7800b09c1649b9e3/ruff-0.16.10-py3-none-macosx_10_12_x86_64.whl", hash = "sha256:e748ff95c934c4e978783b8e687bc174e7bd84e8ad24e3243e1ecfcda5e0282d", size = 10340577, upload-time = "2026-10-01T18:02:39.258Z" },
+    { url = "https://files.pythonhosted.org/packages/9f/16/1a5a4a2657effe4806110f2b907313802f1367fcdbb29e8122766e407fab/ruff-0.16.10-py3-none-macosx_11_0_arm64.whl", hash = "sha256:3031a4a2e8e7b8a46f70be45f198c35a11ece509a94b80334d8d397a33c67550", size = 9774282, upload-time = "2026-10-01T18:02:41.79Z" },
+    { url = "https://files.pythonhosted.org/packages/6e/fb/470085af734da396e68cd80fb0a3e7c109a459716ae59588c0f6fab8a17d/ruff-0.16.10-py3-none-manylinux_2_17_aarch64.manylinux2014_aarch64.whl", hash = "sha256:494401c86df4c4c25f69b9419605d944467ee98c42fb6ad405ef4fa40b8fb67d", size = 9920895, upload-time = "2026-10-01T18:02:44.458Z" },
+    { url = "https://files.pythonhosted.org/packages/57/de/f10cffe4f88a37ea6615ec460f01bf76f0bc1477737a35d9ee61a630a78b/ruff-0.16.10-py3-none-manylinux_2_17_armv7l.manylinux2014_armv7l.whl", hash = "sha256:d203abc0ff2b773ee33d00ab8df0bb67046fbc7c07b119332f08b9b345cf8221", size = 9902707, upload-time = "2026-10-01T18:02:47.041Z" },
+    { url = "https://files.pythonhosted.org/packages/ff/44/3fdcedf83ae60ef837dd239170e480dce606a9142cfa2db911afdf855fd9/ruff-0.16.10-py3-none-manylinux_2_17_i686.manylinux2014_i686.whl", hash = "sha256:bd83d1235a5258d318477bc5b576303974cbdef5df0c01a1bff14efcc23bd12a", size = 10619287, upload-time = "2026-10-01T18:02:49.485Z" },
+    { url = "https://files.pythonhosted.org/packages/c1/62/02e76a5574002153618eafbb70e159468addc72a5d2c488e65cbb4639d2d/ruff-0.16.10-py3-none-manylinux_2_17_ppc64le.manylinux2014_ppc64le.whl", hash = "sha256:bc2610fb269fa56dd8a68669ae470fa6272902668c0fc2ebc3aa112b2633d5b8", size = 11339942, upload-time = "2026-10-01T18:02:52.008Z" },
+    { url = "https://files.pythonhosted.org/packages/6b/c4/cde27d47ad8d4126c587e608c67c46e7feac11763f606d261a1bc8a489e6/ruff-0.16.10-py3-none-manylinux_2_17_s390x.manylinux2014_s390x.whl", hash = "sha256:3e70175e29cc94c26ea296c80e470180b744b7419026898e58f520c6ab32578e", size = 10934316, upload-time = "2026-10-01T18:02:54.811Z" },
+    { url = "https://files.pythonhosted.org/packages/e4/03/17234145f302a645a123e8c3bb2411ecf4669fbc350de3b0d803230a1729/ruff-0.16.10-py3-none-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:f33f43a864a8483eebd160e713336c8bab02c934feaff0a33cf5ccb41546d09a", size = 10387968, upload-time = "2026-10-01T18:02:57.497Z" },
+    { url = "https://files.pythonhosted.org/packages/71/29/2493af60240ee7644b38a4b821f5f9c3b5a4fa3178770fe1d0c685217395/ruff-0.16.10-py3-none-manylinux_2_31_riscv64.whl", hash = "sha256:1dfc6f0088149fb6a362c1c446bcbb3fd2157b3852fe2fa68409276eab9ad9b3", size = 10537906, upload-time = "2026-10-01T18:03:00.006Z" },
+    { url = "https://files.pythonhosted.org/packages/2e/9a/f56b28f3b143bb9e518c34fb89ab191b626bca8b70dbf8af0d2e2d473572/ruff-0.16.10-py3-none-musllinux_1_2_aarch64.whl", hash = "sha256:6553498afc35f580f036030795810b9e6bcea31604b0fd9e8d352795473042e3", size = 10012938, upload-time = "2026-10-01T18:03:03.006Z" },
+    { url = "https://files.pythonhosted.org/packages/c2/c4/fca37362848ea4d4d80712df13632e645e7c7cfb1bdedf140699ac7a090b/ruff-0.16.10-py3-none-musllinux_1_2_armv7l.whl", hash = "sha256:a3b8471dea115d37f123882be852bed13403746d3a76c11de4a19ec5f9ff5a03", size = 9897945, upload-time = "2026-10-01T18:03:05.818Z" },
+    { url = "https://files.pythonhosted.org/packages/7d/c7/e0bc57664d6e0c61fd22f620af260fe9662d7e1ddb320ea7f160e76ef165/ruff-0.16.10-py3-none-musllinux_1_2_i686.whl", hash = "sha256:92e59a70bcbd9d3a5483656da906ec28edfdacfce00afd99edb8b4e9d15644be", size = 10333134, upload-time = "2026-10-01T18:03:08.25Z" },
+    { url = "https://files.pythonhosted.org/packages/21/aa/5c9f3b68737c0e4a33a1db5dfab44f7b786d96ca91a7233112ddab1e6dc2/ruff-0.16.10-py3-none-musllinux_1_2_x86_64.whl", hash = "sha256:7ae7375f803b5520dc9f546bed7e3a0acb70b91812e9bb4b19927de22f25b77d", size = 10741702, upload-time = "2026-10-01T18:03:10.775Z" },
+    { url = "https://files.pythonhosted.org/packages/78/fa/0f9c2020dc316c53d983be011720b8157cc052b97e3f4dfa7db6d0f880a6/ruff-0.16.10-py3-none-win32.whl", hash = "sha256:2a12e01cb9156c10c466f63b46eaae5ecea28dfbd21b5836353ae498e7d1349a", size = 10139176, upload-time = "2026-10-01T18:03:13.267Z" },
+    { url = "https://files.pythonhosted.org/packages/99/29/cfb0df9448d4d4ad48c2de029ada9ebd71baa6da983a6c77ee6c6cd0fe82/ruff-0.16.10-py3-none-win_amd64.whl", hash = "sha256:97f2015c92aa97105b0eab19eb5d224884399281cfc5da86a92db4ab5e7fb2ca", size = 10584734, upload-time = "2026-10-01T18:03:16.006Z" },
+    { url = "https://files.pythonhosted.org/packages/fc/05/c16957eb287c3fc062e032619a25868d93d408a844b725bcf514f7a378ff/ruff-0.16.10-py3-none-win_arm64.whl", hash = "sha256:25a65fe998c4e6861ec079ada5826a2fc605e6cbccbe9dcd7fac1f54e791621b", size = 10366440, upload-time = "2026-10-01T18:03:19.04Z" },
+]
+
 [[package]]
 name = "sqlalchemy"
 version = "2.1.3"
diff --git a/bot/cards.py b/bot/cards.py
index f456380..4b0c772 100644
--- a/bot/cards.py
+++ b/bot/cards.py
@@ -1,7 +1,9 @@
 import json
 import random
 from html import escape
+
 from sqlalchemy.orm import Session
+
 from config import settings
 from models import Card
 
@@ -10,12 +12,16 @@
 _PRE_OPEN = '<pre><code class="language-python">'
 _PRE_CLOSE = "</code></pre>"
 
+
 def _difficulty_emoji(difficulty: str) -> str:
     return {"easy": "🟢", "normal": "🟡", "hard": "🔴"}.get(difficulty, "⚪")
 
+
 def get_next_cards(db: Session, count: int, last_id: int = 0) -> list[Card]:
     """Возвращает следующие карточки по порядку начиная с last_id."""
-    cards = db.query(Card).filter(Card.id > last_id).order_by(Card.id).limit(count).all()
+    cards = (
+        db.query(Card).filter(Card.id > last_id).order_by(Card.id).limit(count).all()
+    )
 
     if len(cards) < count:
         extra = db.query(Card).order_by(Card.id).limit(count - len(cards)).all()
@@ -37,7 +43,8 @@ def format_card(card: Card) -> list[str]:
     text = (
         f"{difficulty_emoji} <b>{escape(card.category)}</b>\n\n"
         f"❓ <b>{escape(card.question)}</b>\n\n"
-        f"{escape(card.answer)}")
+        f"{escape(card.answer)}"
+    )
 
     tags = json.loads(card.tags or "[]")
     if tags:
@@ -76,6 +83,7 @@ def _split_code_telegram(code: str, limit: int = 4096) -> list[str]:
         code = code[cut:].lstrip("\n")
     return parts
 
+
 def _split_telegram(text: str, limit: int = 4096) -> list[str]:
     if len(text) <= limit:
         return [text]
@@ -100,7 +108,8 @@ def format_card_discord(card: Card) -> list[str]:
     text = (
         f"{difficulty_emoji} **{card.category}**\n\n"
         f"**```{card.question} ```**"
-        f"{card.answer}\n")
+        f"{card.answer}\n"
+    )
 
     tags = json.loads(card.tags or "[]")
     if tags:
diff --git a/bot/config.py b/bot/config.py
index 019b5ed..8a31f9e 100644
--- a/bot/config.py
+++ b/bot/config.py
@@ -1,4 +1,5 @@
 import os
+
 from dotenv import load_dotenv
 
 load_dotenv("../.env")
@@ -36,11 +37,14 @@ class Settings:
     database_url: str = os.getenv("DATABASE_URL", "sqlite:///./data/cards.db")
     cards_per_session: int = int(os.getenv("CARDS_PER_SESSION", "4"))
     # schedule_interval_hours: int = int(os.getenv("SCHEDULE_INTERVAL_HOURS", "5"))  # не нужен при настройке почасового крона
-    pause_between_cards_seconds: int = int(os.getenv("PAUSE_BETWEEN_CARDS_SECONDS", "240"))
+    pause_between_cards_seconds: int = int(
+        os.getenv("PAUSE_BETWEEN_CARDS_SECONDS", "240")
+    )
     telegram_enabled: bool = os.getenv("TELEGRAM_ENABLED", "true").lower() == "true"
 
     discord_webhook_url: str = os.getenv("DISCORD_WEBHOOK_URL", "")
     discord_max_length: int = 2000
     discord_timeout: int = 15
 
+
 settings = Settings()
diff --git a/bot/discord_sender.py b/bot/discord_sender.py
index 1792015..d49fbd8 100644
--- a/bot/discord_sender.py
+++ b/bot/discord_sender.py
@@ -1,22 +1,24 @@
 import asyncio
-import aiohttp
 import logging
-from typing import Optional
+
+import aiohttp
+
 from config import settings
 
 log = logging.getLogger(__name__)
 
 _MAX_ATTEMPTS = 8
-_NETWORK_RETRY_DELAY = 5   # пауза после сетевой ошибки, сек
-_DEFAULT_RETRY_AFTER = 5   # пауза при 429, если Discord не сказал сколько, сек
-_MAX_RETRY_AFTER = 60      # потолок паузы при 429, сек
+_NETWORK_RETRY_DELAY = 5  # пауза после сетевой ошибки, сек
+_DEFAULT_RETRY_AFTER = 5  # пауза при 429, если Discord не сказал сколько, сек
+_MAX_RETRY_AFTER = 60  # потолок паузы при 429, сек
+
 
 class DiscordSender:
     def __init__(self, webhook_url: str) -> None:
         if not webhook_url:
             raise ValueError("Discord webhook URL не задан")
         self.webhook_url = webhook_url
-        self.session: Optional[aiohttp.ClientSession] = None
+        self.session: aiohttp.ClientSession | None = None
 
     async def start(self) -> None:
         self.session = aiohttp.ClientSession(
@@ -56,19 +58,24 @@ async def _post(self, content: str) -> bool:
             delay: float = _NETWORK_RETRY_DELAY
             try:
                 async with self.session.post(
-                        self.webhook_url, json={"content": content}) as r:
+                    self.webhook_url, json={"content": content}
+                ) as r:
                     if r.status in (200, 204):
                         return True
                     if r.status != 429:
-                        log.error(f"Discord: webhook вернул {r.status}: {await r.text()}")
+                        log.error(
+                            f"Discord: webhook вернул {r.status}: {await r.text()}"
+                        )
                         return False
                     delay = await _read_retry_after(r)
                     log.warning(
                         f"Discord: rate limit, попытка {attempt}/{_MAX_ATTEMPTS}, "
-                        f"повтор через {delay} сек")
-            except (aiohttp.ClientError, asyncio.TimeoutError) as e:
+                        f"повтор через {delay} сек"
+                    )
+            except (TimeoutError, aiohttp.ClientError) as e:
                 log.warning(
-                    f"Discord: ошибка сети, попытка {attempt}/{_MAX_ATTEMPTS}: {e}")
+                    f"Discord: ошибка сети, попытка {attempt}/{_MAX_ATTEMPTS}: {e}"
+                )
 
             if attempt < _MAX_ATTEMPTS:
                 await asyncio.sleep(delay)
@@ -76,6 +83,7 @@ async def _post(self, content: str) -> bool:
         log.error(f"Discord: не удалось отправить за {_MAX_ATTEMPTS} попыток")
         return False
 
+
 async def _read_retry_after(r) -> float:
     """Достаёт retry_after из тела ответа 429.
     При любой проблеме берёт значение по умолчанию.
@@ -86,6 +94,7 @@ async def _read_retry_after(r) -> float:
         return _DEFAULT_RETRY_AFTER
     return min(max(value, 0.0), _MAX_RETRY_AFTER)
 
+
 def _split_into_chunks(text: str) -> list[str]:
     limit = settings.discord_max_length
     if len(text) <= limit:
diff --git a/bot/main.py b/bot/main.py
index 4a8476e..bf40402 100644
--- a/bot/main.py
+++ b/bot/main.py
@@ -1,7 +1,7 @@
 import asyncio
 import logging
+from datetime import UTC, datetime, timedelta
 
-from datetime import datetime, timedelta, timezone
 from aiogram import Bot, Dispatcher, Router
 from aiogram.exceptions import TelegramBadRequest
 from aiogram.filters import Command
@@ -14,10 +14,11 @@
 from discord_sender import DiscordSender
 from state import load_last_id, save_last_id
 
-logging.basicConfig(level=logging.INFO,
-                    format="%(asctime)s %(levelname)s %(name)s: %(message)s",
-                    datefmt="%d-%m-%Y %H:%M:%S",
-                    )
+logging.basicConfig(
+    level=logging.INFO,
+    format="%(asctime)s %(levelname)s %(name)s: %(message)s",
+    datefmt="%d-%m-%Y %H:%M:%S",
+)
 log = logging.getLogger(__name__)
 
 bot = Bot(token=settings.bot_token)
@@ -40,7 +41,9 @@ async def send_card_to_telegram(chat_id: int, card) -> None:
                 await bot.send_message(chat_id, part, parse_mode="HTML")
                 break
             except TelegramBadRequest as e:
-                log.error(f"Telegram BadRequest карточка id={card.id} чат {chat_id}: {e}")
+                log.error(
+                    f"Telegram BadRequest карточка id={card.id} чат {chat_id}: {e}"
+                )
                 break
             except asyncio.CancelledError:
                 raise
@@ -55,7 +58,9 @@ async def send_card_to_telegram(chat_id: int, card) -> None:
                 await asyncio.sleep(delay)
 
 
-async def send_scheduled_cards(scheduler: AsyncIOScheduler, discord: DiscordSender) -> None:
+async def send_scheduled_cards(
+    scheduler: AsyncIOScheduler, discord: DiscordSender
+) -> None:
     """Отправляет серию карточек по расписанию всем пользователям.
     При провале повторно отправляет через 15 минут.
     # Discord и Telegram запускаются параллельно. Discord приоритетен
@@ -84,18 +89,21 @@ async def send_scheduled_cards(scheduler: AsyncIOScheduler, discord: DiscordSend
                     tg_task = asyncio.create_task(_send_tg_to_all(card))
 
                     discord_result, tg_result = await asyncio.gather(
-                        discord_task, tg_task, return_exceptions=True)
+                        discord_task, tg_task, return_exceptions=True
+                    )
 
                     if isinstance(discord_result, Exception):
                         log.error(
-                            f"Discord: исключение карточка id={card.id}: {discord_result}")
+                            f"Discord: исключение карточка id={card.id}: {discord_result}"
+                        )
                     elif not discord_result:
                         log.error(f"Discord: ошибка отправки карточка id={card.id}")
 
                     if isinstance(tg_result, Exception):
                         log.error(
                             f"Telegram: все попытки исчерпаны карточка id={card.id}: {tg_result}. "
-                            f"Повтор сессии через 15 минут.")
+                            f"Повтор сессии через 15 минут."
+                        )
                         save_last_id(last_sent_id)
                         _schedule_retry(scheduler, discord)
                         return
@@ -113,6 +121,7 @@ async def send_scheduled_cards(scheduler: AsyncIOScheduler, discord: DiscordSend
         finally:
             db.close()
 
+
 async def _send_tg_to_all(card) -> None:
     """Отправляет карточку всем admin_ids в Telegram."""
     for chat_id in settings.admin_ids:
@@ -121,7 +130,7 @@ async def _send_tg_to_all(card) -> None:
 
 def _schedule_retry(scheduler: AsyncIOScheduler, discord: DiscordSender) -> None:
     """Планирует повторную попытку отправки через 15 мин."""
-    run_at = datetime.now(timezone.utc) + timedelta(minutes=15)
+    run_at = datetime.now(UTC) + timedelta(minutes=15)
     scheduler.add_job(
         send_scheduled_cards,
         trigger="date",
@@ -178,7 +187,7 @@ async def main() -> None:
     scheduler = AsyncIOScheduler()
     scheduler.add_job(
         send_scheduled_cards,
-        trigger="cron", # interval
+        trigger="cron",  # interval
         hour="7,12,17,22",
         # hours=settings.schedule_interval_hours,
         args=[scheduler, discord],
@@ -200,7 +209,8 @@ async def main() -> None:
             await _run_polling()
         else:
             log.info(
-                "Telegram отключён (TELEGRAM_ENABLED=false), работает только Discord")
+                "Telegram отключён (TELEGRAM_ENABLED=false), работает только Discord"
+            )
             await asyncio.Event().wait()
     finally:
         await discord.stop()
diff --git a/bot/pyproject.toml b/bot/pyproject.toml
index 3f67070..62a71c5 100644
--- a/bot/pyproject.toml
+++ b/bot/pyproject.toml
@@ -13,5 +13,8 @@ dependencies = [
 [dependency-groups]
 dev = [
     "pytest>=8.0.0",
+    "ruff>=0.16.10",
 ]
 
+[tool.ruff.lint]
+select = ["E4", "E7", "E9", "F", "I", "UP", "B"]
diff --git a/bot/tests/test_cards.py b/bot/tests/test_cards.py
index 4808111..06d42a7 100644
--- a/bot/tests/test_cards.py
+++ b/bot/tests/test_cards.py
@@ -1,4 +1,9 @@
 import json
+import os
+import sys
+from html import unescape
+from unittest.mock import MagicMock
+
 from cards import (
     _PRE_CLOSE,
     _PRE_OPEN,
@@ -8,22 +13,9 @@
     get_next_cards,
     get_random_card,
 )
-from html import unescape
-from unittest.mock import MagicMock
-
-import pytest
-import sys
-import os
 
 sys.path.insert(0, os.path.join(os.path.dirname(__file__), ".."))
 
-from cards import (
-    _split_telegram,
-    format_card,
-    format_card_discord,
-    get_next_cards,
-    get_random_card,
-)
 from config import settings
 from models import Card
 
@@ -116,7 +108,9 @@ def test_code_example_in_separate_message(self):
     def test_no_code_example(self):
         card = make_card(code_example=None)
         result = format_card(card)
-        assert any("list" in part.lower() or "последовательность" in part for part in result)
+        assert any(
+            "list" in part.lower() or "последовательность" in part for part in result
+        )
 
     def test_code_example_none_no_pre_tag(self):
         card = make_card(code_example=None)
@@ -200,6 +194,7 @@ def test_returns_none_for_empty_db(self):
         result = get_random_card(db)
         assert result is None
 
+
 class TestFormatCardDiscord:
     def test_long_code_parts_within_discord_limit(self):
         """Каждое сообщение вместе с обёрткой ```python не длиннее лимита Discord."""
diff --git a/bot/tests/test_discord_sender.py b/bot/tests/test_discord_sender.py
index 2c509af..c0b8b80 100644
--- a/bot/tests/test_discord_sender.py
+++ b/bot/tests/test_discord_sender.py
@@ -11,6 +11,7 @@
 
 class FakeResponse:
     """Подменяет ответ aiohttp: статус, json() и text()."""
+
     def __init__(self, status, body=None, json_error=False):
         self.status = status
         self._body = body if body is not None else {}
@@ -33,6 +34,7 @@ async def __aexit__(self, *exc):
 
 class FakeSession:
     """Отдаёт ответы по очереди; последний повторяется бесконечно."""
+
     closed = False
 
     def __init__(self, responses):
diff --git a/bot/tests/test_state.py b/bot/tests/test_state.py
index b57f735..bff71be 100644
--- a/bot/tests/test_state.py
+++ b/bot/tests/test_state.py
@@ -1,4 +1,3 @@
-import json
 import os
 import sys
 
diff --git a/bot/uv.lock b/bot/uv.lock
index 913079e..e88cab1 100644
--- a/bot/uv.lock
+++ b/bot/uv.lock
@@ -619,6 +619,7 @@ dependencies = [
 [package.dev-dependencies]
 dev = [
     { name = "pytest" },
+    { name = "ruff" },
 ]
 
 [package.metadata]
@@ -631,7 +632,10 @@ requires-dist = [
 ]
 
 [package.metadata.requires-dev]
-dev = [{ name = "pytest", specifier = ">=8.0.0" }]
+dev = [
+    { name = "pytest", specifier = ">=8.0.0" },
+    { name = "ruff", specifier = ">=0.16.10" },
+]
 
 [[package]]
 name = "python-dotenv"
@@ -642,6 +646,31 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/60/d1/38f3a3405989a89ac18390803e70c6ad7c7760da4f9b83cbeca0c44a0c72/python_dotenv-1.2.4-py3-none-any.whl", hash = "sha256:42269a8a5b3fd54ffa6f3d84b18abed50064717576b4ecf03dc4a55d8aa04fdc", size = 23266, upload-time = "2026-10-01T05:36:08.633Z" },
 ]
 
+[[package]]
+name = "ruff"
+version = "0.16.10"
+source = { registry = "https://pypi.org/simple" }
+sdist = { url = "https://files.pythonhosted.org/packages/c4/49/23802c45f093eb14bde54b141d2b2f058edfa63a06db7beed047308cc08f/ruff-0.16.10.tar.gz", hash = "sha256:eff4728c4eaae93f0955cd264d24b2ab348e74bf59986ccf282ba6dc16b3b017", size = 4958724, upload-time = "2026-10-01T18:03:21.697Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/2f/21/ebce22e1d90cdb2cd691026b9c6e9bec6499f0b396089481755b5d49efff/ruff-0.16.10-py3-none-linux_armv6l.whl", hash = "sha256:488b0fe3f3574210e5cf80d9f59b9e3ab17a127a8155de3f307b392589cfb511", size = 10095557, upload-time = "2026-10-01T18:02:36.072Z" },
+    { url = "https://files.pythonhosted.org/packages/cb/98/a54de85876a8b2612bfa0d84c7b9abfb39c6a3354aee7800b09c1649b9e3/ruff-0.16.10-py3-none-macosx_10_12_x86_64.whl", hash = "sha256:e748ff95c934c4e978783b8e687bc174e7bd84e8ad24e3243e1ecfcda5e0282d", size = 10340577, upload-time = "2026-10-01T18:02:39.258Z" },
+    { url = "https://files.pythonhosted.org/packages/9f/16/1a5a4a2657effe4806110f2b907313802f1367fcdbb29e8122766e407fab/ruff-0.16.10-py3-none-macosx_11_0_arm64.whl", hash = "sha256:3031a4a2e8e7b8a46f70be45f198c35a11ece509a94b80334d8d397a33c67550", size = 9774282, upload-time = "2026-10-01T18:02:41.79Z" },
+    { url = "https://files.pythonhosted.org/packages/6e/fb/470085af734da396e68cd80fb0a3e7c109a459716ae59588c0f6fab8a17d/ruff-0.16.10-py3-none-manylinux_2_17_aarch64.manylinux2014_aarch64.whl", hash = "sha256:494401c86df4c4c25f69b9419605d944467ee98c42fb6ad405ef4fa40b8fb67d", size = 9920895, upload-time = "2026-10-01T18:02:44.458Z" },
+    { url = "https://files.pythonhosted.org/packages/57/de/f10cffe4f88a37ea6615ec460f01bf76f0bc1477737a35d9ee61a630a78b/ruff-0.16.10-py3-none-manylinux_2_17_armv7l.manylinux2014_armv7l.whl", hash = "sha256:d203abc0ff2b773ee33d00ab8df0bb67046fbc7c07b119332f08b9b345cf8221", size = 9902707, upload-time = "2026-10-01T18:02:47.041Z" },
+    { url = "https://files.pythonhosted.org/packages/ff/44/3fdcedf83ae60ef837dd239170e480dce606a9142cfa2db911afdf855fd9/ruff-0.16.10-py3-none-manylinux_2_17_i686.manylinux2014_i686.whl", hash = "sha256:bd83d1235a5258d318477bc5b576303974cbdef5df0c01a1bff14efcc23bd12a", size = 10619287, upload-time = "2026-10-01T18:02:49.485Z" },
+    { url = "https://files.pythonhosted.org/packages/c1/62/02e76a5574002153618eafbb70e159468addc72a5d2c488e65cbb4639d2d/ruff-0.16.10-py3-none-manylinux_2_17_ppc64le.manylinux2014_ppc64le.whl", hash = "sha256:bc2610fb269fa56dd8a68669ae470fa6272902668c0fc2ebc3aa112b2633d5b8", size = 11339942, upload-time = "2026-10-01T18:02:52.008Z" },
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