diff --git a/README.md b/README.md
index 5a7c085..6d1afbe 100644
--- a/README.md
+++ b/README.md
@@ -59,6 +59,56 @@ npm run dev
 - Backend API Docs: http://localhost:8000/docs
 - Backend Health: http://localhost:8000/health
 
+## Code Quality & Linting
+
+### Unified Linting (All Languages)
+
+```bash
+# Check all code (Python + TypeScript/Svelte)
+./scripts/lint.sh
+# OR using nix:
+nix run .#lint
+
+# Auto-fix all issues
+nix run .#lint-fix
+```
+
+### Git Hooks (Automatic)
+
+Install git hooks to run linting automatically:
+
+```bash
+./scripts/install-hooks.sh
+```
+
+This installs:
+- **pre-commit**: Runs linting before each commit
+- **pre-push**: Runs tests before push (optional)
+
+To skip hooks when committing:
+```bash
+git commit --no-verify
+```
+
+### Manual Linting
+
+**Backend (Python):**
+```bash
+cd backend
+ruff check app/          # Check for issues
+ruff check --fix app/    # Auto-fix issues  
+ruff format app/         # Format code
+```
+
+**Frontend (TypeScript/Svelte):**
+```bash
+cd frontend
+npm run lint             # ESLint check
+npm run check            # TypeScript check
+npx prettier --check src/  # Prettier check
+npx prettier --write src/  # Auto-format
+```
+
 ## Project Structure
 
 ```
diff --git a/backend/app/__init__.py b/backend/app/__init__.py
index 18d182b..5211a77 100644
--- a/backend/app/__init__.py
+++ b/backend/app/__init__.py
@@ -1,4 +1,3 @@
 """Reference Board Viewer - Backend API."""
 
 __version__ = "1.0.0"
-
diff --git a/backend/app/api/auth.py b/backend/app/api/auth.py
index e14074d..5461ed5 100644
--- a/backend/app/api/auth.py
+++ b/backend/app/api/auth.py
@@ -1,4 +1,5 @@
 """Authentication endpoints."""
+
 from fastapi import APIRouter, Depends, HTTPException, status
 from sqlalchemy.orm import Session
 
@@ -16,37 +17,31 @@ router = APIRouter(prefix="/auth", tags=["auth"])
 def register_user(user_data: UserCreate, db: Session = Depends(get_db)):
     """
     Register a new user.
-    
+
     Args:
         user_data: User registration data
         db: Database session
-        
+
     Returns:
         Created user information
-        
+
     Raises:
         HTTPException: If email already exists or password is weak
     """
     repo = UserRepository(db)
-    
+
     # Check if email already exists
     if repo.email_exists(user_data.email):
-        raise HTTPException(
-            status_code=status.HTTP_409_CONFLICT,
-            detail="Email already registered"
-        )
-    
+        raise HTTPException(status_code=status.HTTP_409_CONFLICT, detail="Email already registered")
+
     # Validate password strength
     is_valid, error_message = validate_password_strength(user_data.password)
     if not is_valid:
-        raise HTTPException(
-            status_code=status.HTTP_400_BAD_REQUEST,
-            detail=error_message
-        )
-    
+        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=error_message)
+
     # Create user
     user = repo.create_user(email=user_data.email, password=user_data.password)
-    
+
     return UserResponse.model_validate(user)
 
 
@@ -54,22 +49,22 @@ def register_user(user_data: UserCreate, db: Session = Depends(get_db)):
 def login_user(login_data: UserLogin, db: Session = Depends(get_db)):
     """
     Login user and return JWT token.
-    
+
     Args:
         login_data: Login credentials
         db: Database session
-        
+
     Returns:
         JWT access token and user information
-        
+
     Raises:
         HTTPException: If credentials are invalid
     """
     repo = UserRepository(db)
-    
+
     # Get user by email
     user = repo.get_user_by_email(login_data.email)
-    
+
     # Verify user exists and password is correct
     if not user or not verify_password(login_data.password, user.password_hash):
         raise HTTPException(
@@ -77,34 +72,26 @@ def login_user(login_data: UserLogin, db: Session = Depends(get_db)):
             detail="Incorrect email or password",
             headers={"WWW-Authenticate": "Bearer"},
         )
-    
+
     # Check if user is active
     if not user.is_active:
-        raise HTTPException(
-            status_code=status.HTTP_403_FORBIDDEN,
-            detail="User account is deactivated"
-        )
-    
+        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="User account is deactivated")
+
     # Create access token
     access_token = create_access_token(user_id=user.id, email=user.email)
-    
-    return TokenResponse(
-        access_token=access_token,
-        token_type="bearer",
-        user=UserResponse.model_validate(user)
-    )
+
+    return TokenResponse(access_token=access_token, token_type="bearer", user=UserResponse.model_validate(user))
 
 
 @router.get("/me", response_model=UserResponse)
 def get_current_user_info(current_user: User = Depends(get_current_user)):
     """
     Get current authenticated user information.
-    
+
     Args:
         current_user: Current authenticated user (from JWT)
-        
+
     Returns:
         Current user information
     """
     return UserResponse.model_validate(current_user)
-
diff --git a/backend/app/auth/__init__.py b/backend/app/auth/__init__.py
index 3c6f19a..7db5be4 100644
--- a/backend/app/auth/__init__.py
+++ b/backend/app/auth/__init__.py
@@ -1,2 +1 @@
 """Authentication module."""
-
diff --git a/backend/app/auth/jwt.py b/backend/app/auth/jwt.py
index c995aed..6bd5411 100644
--- a/backend/app/auth/jwt.py
+++ b/backend/app/auth/jwt.py
@@ -1,6 +1,6 @@
 """JWT token generation and validation."""
+
 from datetime import datetime, timedelta
-from typing import Optional
 from uuid import UUID
 
 from jose import JWTError, jwt
@@ -8,15 +8,15 @@ from jose import JWTError, jwt
 from app.core.config import settings
 
 
-def create_access_token(user_id: UUID, email: str, expires_delta: Optional[timedelta] = None) -> str:
+def create_access_token(user_id: UUID, email: str, expires_delta: timedelta | None = None) -> str:
     """
     Create a new JWT access token.
-    
+
     Args:
         user_id: User's UUID
         email: User's email address
         expires_delta: Optional custom expiration time
-        
+
     Returns:
         Encoded JWT token string
     """
@@ -24,26 +24,20 @@ def create_access_token(user_id: UUID, email: str, expires_delta: Optional[timed
         expire = datetime.utcnow() + expires_delta
     else:
         expire = datetime.utcnow() + timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)
-    
-    to_encode = {
-        "sub": str(user_id),
-        "email": email,
-        "exp": expire,
-        "iat": datetime.utcnow(),
-        "type": "access"
-    }
-    
+
+    to_encode = {"sub": str(user_id), "email": email, "exp": expire, "iat": datetime.utcnow(), "type": "access"}
+
     encoded_jwt = jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)
     return encoded_jwt
 
 
-def decode_access_token(token: str) -> Optional[dict]:
+def decode_access_token(token: str) -> dict | None:
     """
     Decode and validate a JWT access token.
-    
+
     Args:
         token: JWT token string to decode
-        
+
     Returns:
         Decoded token payload if valid, None otherwise
     """
@@ -52,4 +46,3 @@ def decode_access_token(token: str) -> Optional[dict]:
         return payload
     except JWTError:
         return None
-
diff --git a/backend/app/auth/repository.py b/backend/app/auth/repository.py
index 13d2558..f682e0f 100644
--- a/backend/app/auth/repository.py
+++ b/backend/app/auth/repository.py
@@ -1,9 +1,7 @@
 """User repository for database operations."""
-from typing import Optional
+
 from uuid import UUID
 
-from sqlalchemy import select
-from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy.orm import Session
 
 from app.auth.security import hash_password
@@ -16,7 +14,7 @@ class UserRepository:
     def __init__(self, db: Session):
         """
         Initialize repository.
-        
+
         Args:
             db: Database session
         """
@@ -25,48 +23,45 @@ class UserRepository:
     def create_user(self, email: str, password: str) -> User:
         """
         Create a new user.
-        
+
         Args:
             email: User email (will be lowercased)
             password: Plain text password (will be hashed)
-            
+
         Returns:
             Created user instance
         """
         email = email.lower()
         password_hash = hash_password(password)
-        
-        user = User(
-            email=email,
-            password_hash=password_hash
-        )
-        
+
+        user = User(email=email, password_hash=password_hash)
+
         self.db.add(user)
         self.db.commit()
         self.db.refresh(user)
-        
+
         return user
 
-    def get_user_by_email(self, email: str) -> Optional[User]:
+    def get_user_by_email(self, email: str) -> User | None:
         """
         Get user by email address.
-        
+
         Args:
             email: User email to search for
-            
+
         Returns:
             User if found, None otherwise
         """
         email = email.lower()
         return self.db.query(User).filter(User.email == email).first()
 
-    def get_user_by_id(self, user_id: UUID) -> Optional[User]:
+    def get_user_by_id(self, user_id: UUID) -> User | None:
         """
         Get user by ID.
-        
+
         Args:
             user_id: User UUID
-            
+
         Returns:
             User if found, None otherwise
         """
@@ -75,13 +70,12 @@ class UserRepository:
     def email_exists(self, email: str) -> bool:
         """
         Check if email already exists.
-        
+
         Args:
             email: Email to check
-            
+
         Returns:
             True if email exists, False otherwise
         """
         email = email.lower()
         return self.db.query(User).filter(User.email == email).first() is not None
-
diff --git a/backend/app/auth/schemas.py b/backend/app/auth/schemas.py
index dddb971..ef0cab6 100644
--- a/backend/app/auth/schemas.py
+++ b/backend/app/auth/schemas.py
@@ -1,6 +1,6 @@
 """Authentication schemas for request/response validation."""
+
 from datetime import datetime
-from typing import Optional
 from uuid import UUID
 
 from pydantic import BaseModel, EmailStr, Field
@@ -42,4 +42,3 @@ class TokenResponse(BaseModel):
     access_token: str
     token_type: str = "bearer"
     user: UserResponse
-
diff --git a/backend/app/auth/security.py b/backend/app/auth/security.py
index 22c049b..c0eafc1 100644
--- a/backend/app/auth/security.py
+++ b/backend/app/auth/security.py
@@ -1,5 +1,7 @@
 """Password hashing utilities using passlib."""
+
 import re
+
 from passlib.context import CryptContext
 
 # Create password context for hashing and verification
@@ -9,10 +11,10 @@ pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
 def hash_password(password: str) -> str:
     """
     Hash a password using bcrypt.
-    
+
     Args:
         password: Plain text password
-        
+
     Returns:
         Hashed password string
     """
@@ -22,11 +24,11 @@ def hash_password(password: str) -> str:
 def verify_password(plain_password: str, hashed_password: str) -> bool:
     """
     Verify a plain password against a hashed password.
-    
+
     Args:
         plain_password: Plain text password to verify
         hashed_password: Hashed password from database
-        
+
     Returns:
         True if password matches, False otherwise
     """
@@ -36,30 +38,29 @@ def verify_password(plain_password: str, hashed_password: str) -> bool:
 def validate_password_strength(password: str) -> tuple[bool, str]:
     """
     Validate password meets complexity requirements.
-    
+
     Requirements:
     - At least 8 characters
     - At least 1 uppercase letter
     - At least 1 lowercase letter
     - At least 1 number
-    
+
     Args:
         password: Plain text password to validate
-        
+
     Returns:
         Tuple of (is_valid, error_message)
     """
     if len(password) < 8:
         return False, "Password must be at least 8 characters long"
-    
+
     if not re.search(r"[A-Z]", password):
         return False, "Password must contain at least one uppercase letter"
-    
+
     if not re.search(r"[a-z]", password):
         return False, "Password must contain at least one lowercase letter"
-    
+
     if not re.search(r"\d", password):
         return False, "Password must contain at least one number"
-    
-    return True, ""
 
+    return True, ""
diff --git a/backend/app/core/__init__.py b/backend/app/core/__init__.py
index 3dbf255..6ee6af5 100644
--- a/backend/app/core/__init__.py
+++ b/backend/app/core/__init__.py
@@ -1,2 +1 @@
 """Core application modules."""
-
diff --git a/backend/app/core/config.py b/backend/app/core/config.py
index 6741b93..cfbc3bd 100644
--- a/backend/app/core/config.py
+++ b/backend/app/core/config.py
@@ -90,4 +90,3 @@ def get_settings() -> Settings:
 
 # Export settings instance
 settings = get_settings()
-
diff --git a/backend/app/core/deps.py b/backend/app/core/deps.py
index 5f4deea..7e76934 100644
--- a/backend/app/core/deps.py
+++ b/backend/app/core/deps.py
@@ -1,6 +1,6 @@
 """Dependency injection utilities."""
 
-from typing import Annotated, Generator
+from typing import Annotated
 from uuid import UUID
 
 from fastapi import Depends, HTTPException, status
@@ -19,33 +19,32 @@ security = HTTPBearer()
 
 
 def get_current_user(
-    credentials: HTTPAuthorizationCredentials = Depends(security),
-    db: Session = Depends(get_db)
+    credentials: HTTPAuthorizationCredentials = Depends(security), db: Session = Depends(get_db)
 ) -> User:
     """
     Get current authenticated user from JWT token.
-    
+
     Args:
         credentials: HTTP Authorization Bearer token
         db: Database session
-        
+
     Returns:
         Current authenticated user
-        
+
     Raises:
         HTTPException: If token is invalid or user not found
     """
     # Decode token
     token = credentials.credentials
     payload = decode_access_token(token)
-    
+
     if payload is None:
         raise HTTPException(
             status_code=status.HTTP_401_UNAUTHORIZED,
             detail="Invalid authentication credentials",
             headers={"WWW-Authenticate": "Bearer"},
         )
-    
+
     # Extract user ID from token
     user_id_str: str = payload.get("sub")
     if user_id_str is None:
@@ -54,7 +53,7 @@ def get_current_user(
             detail="Invalid token payload",
             headers={"WWW-Authenticate": "Bearer"},
         )
-    
+
     try:
         user_id = UUID(user_id_str)
     except ValueError:
@@ -62,23 +61,19 @@ def get_current_user(
             status_code=status.HTTP_401_UNAUTHORIZED,
             detail="Invalid user ID in token",
             headers={"WWW-Authenticate": "Bearer"},
-        )
-    
+        ) from None
+
     # Get user from database
     user = db.query(User).filter(User.id == user_id).first()
-    
+
     if user is None:
         raise HTTPException(
             status_code=status.HTTP_401_UNAUTHORIZED,
             detail="User not found",
             headers={"WWW-Authenticate": "Bearer"},
         )
-    
-    if not user.is_active:
-        raise HTTPException(
-            status_code=status.HTTP_403_FORBIDDEN,
-            detail="User account is deactivated"
-        )
-    
-    return user
 
+    if not user.is_active:
+        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="User account is deactivated")
+
+    return user
diff --git a/backend/app/core/errors.py b/backend/app/core/errors.py
index beb249e..bd6f6d4 100644
--- a/backend/app/core/errors.py
+++ b/backend/app/core/errors.py
@@ -65,4 +65,3 @@ class UnsupportedFileTypeError(WebRefException):
     def __init__(self, file_type: str, allowed_types: list[str]):
         message = f"File type '{file_type}' not supported. Allowed types: {', '.join(allowed_types)}"
         super().__init__(message, status_code=415)
-
diff --git a/backend/app/core/logging.py b/backend/app/core/logging.py
index e277c68..e661f29 100644
--- a/backend/app/core/logging.py
+++ b/backend/app/core/logging.py
@@ -8,27 +8,24 @@ from app.core.config import settings
 
 def setup_logging() -> None:
     """Configure application logging."""
-    
+
     # Get log level from settings
     log_level = getattr(logging, settings.LOG_LEVEL.upper(), logging.INFO)
-    
+
     # Configure root logger
     logging.basicConfig(
         level=log_level,
         format="%(asctime)s - %(name)s - %(levelname)s - %(message)s",
         datefmt="%Y-%m-%d %H:%M:%S",
-        handlers=[
-            logging.StreamHandler(sys.stdout)
-        ],
+        handlers=[logging.StreamHandler(sys.stdout)],
     )
-    
+
     # Set library log levels
     logging.getLogger("uvicorn").setLevel(logging.INFO)
     logging.getLogger("uvicorn.access").setLevel(logging.INFO)
     logging.getLogger("sqlalchemy.engine").setLevel(logging.WARNING)
     logging.getLogger("boto3").setLevel(logging.WARNING)
     logging.getLogger("botocore").setLevel(logging.WARNING)
-    
+
     logger = logging.getLogger(__name__)
     logger.info(f"Logging configured with level: {settings.LOG_LEVEL}")
-
diff --git a/backend/app/core/middleware.py b/backend/app/core/middleware.py
index 3d7a6a8..917677f 100644
--- a/backend/app/core/middleware.py
+++ b/backend/app/core/middleware.py
@@ -2,7 +2,6 @@
 
 from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
-from fastapi.middleware.trustedhost import TrustedHostMiddleware
 
 from app.core.config import settings
 
@@ -26,4 +25,3 @@ def setup_middleware(app: FastAPI) -> None:
     #     TrustedHostMiddleware,
     #     allowed_hosts=["yourdomain.com", "*.yourdomain.com"]
     # )
-
diff --git a/backend/app/core/schemas.py b/backend/app/core/schemas.py
index af90fa3..79509e8 100644
--- a/backend/app/core/schemas.py
+++ b/backend/app/core/schemas.py
@@ -10,13 +10,7 @@ from pydantic import BaseModel, ConfigDict, Field
 class BaseSchema(BaseModel):
     """Base schema with common configuration."""
 
-    model_config = ConfigDict(
-        from_attributes=True,
-        populate_by_name=True,
-        json_schema_extra={
-            "example": {}
-        }
-    )
+    model_config = ConfigDict(from_attributes=True, populate_by_name=True, json_schema_extra={"example": {}})
 
 
 class TimestampSchema(BaseSchema):
@@ -61,4 +55,3 @@ class PaginatedResponse(BaseSchema):
 
     items: list[Any] = Field(..., description="List of items")
     pagination: PaginationSchema = Field(..., description="Pagination metadata")
-
diff --git a/backend/app/core/storage.py b/backend/app/core/storage.py
index bd6f9e7..c71772c 100644
--- a/backend/app/core/storage.py
+++ b/backend/app/core/storage.py
@@ -116,4 +116,3 @@ class StorageClient:
 
 # Global storage client instance
 storage_client = StorageClient()
-
diff --git a/backend/app/database/__init__.py b/backend/app/database/__init__.py
index 25bbef1..d974e2a 100644
--- a/backend/app/database/__init__.py
+++ b/backend/app/database/__init__.py
@@ -1,2 +1 @@
 """Database models and session management."""
-
diff --git a/backend/app/database/base.py b/backend/app/database/base.py
index 924fb14..2118370 100644
--- a/backend/app/database/base.py
+++ b/backend/app/database/base.py
@@ -14,10 +14,10 @@ class Base(DeclarativeBase):
 
     # Generate __tablename__ automatically from class name
     @declared_attr.directive
-    def __tablename__(cls) -> str:
+    def __tablename__(self) -> str:
         """Generate table name from class name."""
         # Convert CamelCase to snake_case
-        name = cls.__name__
+        name = self.__name__
         return "".join(["_" + c.lower() if c.isupper() else c for c in name]).lstrip("_")
 
     # Common columns for all models
@@ -27,4 +27,3 @@ class Base(DeclarativeBase):
     def dict(self) -> dict[str, Any]:
         """Convert model to dictionary."""
         return {c.name: getattr(self, c.name) for c in self.__table__.columns}
-
diff --git a/backend/app/database/models/__init__.py b/backend/app/database/models/__init__.py
index 9456706..d32b801 100644
--- a/backend/app/database/models/__init__.py
+++ b/backend/app/database/models/__init__.py
@@ -1,11 +1,12 @@
 """Database models."""
-from app.database.models.user import User
+
 from app.database.models.board import Board
-from app.database.models.image import Image
 from app.database.models.board_image import BoardImage
-from app.database.models.group import Group
-from app.database.models.share_link import ShareLink
 from app.database.models.comment import Comment
+from app.database.models.group import Group
+from app.database.models.image import Image
+from app.database.models.share_link import ShareLink
+from app.database.models.user import User
 
 __all__ = [
     "User",
diff --git a/backend/app/database/models/board.py b/backend/app/database/models/board.py
index 532404c..055926b 100644
--- a/backend/app/database/models/board.py
+++ b/backend/app/database/models/board.py
@@ -1,6 +1,8 @@
 """Board model for reference boards."""
+
 import uuid
 from datetime import datetime
+
 from sqlalchemy import Boolean, Column, DateTime, ForeignKey, String, Text
 from sqlalchemy.dialects.postgresql import JSONB, UUID
 from sqlalchemy.orm import relationship
@@ -17,11 +19,7 @@ class Board(Base):
     user_id = Column(UUID(as_uuid=True), ForeignKey("users.id", ondelete="CASCADE"), nullable=False, index=True)
     title = Column(String(255), nullable=False)
     description = Column(Text, nullable=True)
-    viewport_state = Column(
-        JSONB,
-        nullable=False,
-        default={"x": 0, "y": 0, "zoom": 1.0, "rotation": 0}
-    )
+    viewport_state = Column(JSONB, nullable=False, default={"x": 0, "y": 0, "zoom": 1.0, "rotation": 0})
     created_at = Column(DateTime, nullable=False, default=datetime.utcnow)
     updated_at = Column(DateTime, nullable=False, default=datetime.utcnow, onupdate=datetime.utcnow)
     is_deleted = Column(Boolean, nullable=False, default=False)
@@ -35,4 +33,3 @@ class Board(Base):
 
     def __repr__(self) -> str:
         return f"<Board(id={self.id}, title={self.title})>"
-
diff --git a/backend/app/database/models/board_image.py b/backend/app/database/models/board_image.py
index 1ee43f1..57db565 100644
--- a/backend/app/database/models/board_image.py
+++ b/backend/app/database/models/board_image.py
@@ -1,6 +1,8 @@
 """BoardImage junction model."""
+
 import uuid
 from datetime import datetime
+
 from sqlalchemy import Column, DateTime, ForeignKey, Integer, UniqueConstraint
 from sqlalchemy.dialects.postgresql import JSONB, UUID
 from sqlalchemy.orm import relationship
@@ -26,17 +28,15 @@ class BoardImage(Base):
             "opacity": 1.0,
             "flipped_h": False,
             "flipped_v": False,
-            "greyscale": False
-        }
+            "greyscale": False,
+        },
     )
     z_order = Column(Integer, nullable=False, default=0, index=True)
     group_id = Column(UUID(as_uuid=True), ForeignKey("groups.id", ondelete="SET NULL"), nullable=True, index=True)
     created_at = Column(DateTime, nullable=False, default=datetime.utcnow)
     updated_at = Column(DateTime, nullable=False, default=datetime.utcnow, onupdate=datetime.utcnow)
 
-    __table_args__ = (
-        UniqueConstraint("board_id", "image_id", name="uq_board_image"),
-    )
+    __table_args__ = (UniqueConstraint("board_id", "image_id", name="uq_board_image"),)
 
     # Relationships
     board = relationship("Board", back_populates="board_images")
@@ -45,4 +45,3 @@ class BoardImage(Base):
 
     def __repr__(self) -> str:
         return f"<BoardImage(board_id={self.board_id}, image_id={self.image_id})>"
-
diff --git a/backend/app/database/models/comment.py b/backend/app/database/models/comment.py
index 59fb8c4..6246777 100644
--- a/backend/app/database/models/comment.py
+++ b/backend/app/database/models/comment.py
@@ -1,6 +1,8 @@
 """Comment model for board comments."""
+
 import uuid
 from datetime import datetime
+
 from sqlalchemy import Boolean, Column, DateTime, ForeignKey, String, Text
 from sqlalchemy.dialects.postgresql import JSONB, UUID
 from sqlalchemy.orm import relationship
@@ -15,7 +17,9 @@ class Comment(Base):
 
     id = Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
     board_id = Column(UUID(as_uuid=True), ForeignKey("boards.id", ondelete="CASCADE"), nullable=False, index=True)
-    share_link_id = Column(UUID(as_uuid=True), ForeignKey("share_links.id", ondelete="SET NULL"), nullable=True, index=True)
+    share_link_id = Column(
+        UUID(as_uuid=True), ForeignKey("share_links.id", ondelete="SET NULL"), nullable=True, index=True
+    )
     author_name = Column(String(100), nullable=False)
     content = Column(Text, nullable=False)
     position = Column(JSONB, nullable=True)  # Optional canvas position
@@ -28,4 +32,3 @@ class Comment(Base):
 
     def __repr__(self) -> str:
         return f"<Comment(id={self.id}, author={self.author_name})>"
-
diff --git a/backend/app/database/models/group.py b/backend/app/database/models/group.py
index 9c79326..a9a9387 100644
--- a/backend/app/database/models/group.py
+++ b/backend/app/database/models/group.py
@@ -1,6 +1,8 @@
 """Group model for image grouping."""
+
 import uuid
 from datetime import datetime
+
 from sqlalchemy import Column, DateTime, ForeignKey, String, Text
 from sqlalchemy.dialects.postgresql import UUID
 from sqlalchemy.orm import relationship
@@ -27,4 +29,3 @@ class Group(Base):
 
     def __repr__(self) -> str:
         return f"<Group(id={self.id}, name={self.name})>"
-
diff --git a/backend/app/database/models/image.py b/backend/app/database/models/image.py
index c8c0a34..1e37e53 100644
--- a/backend/app/database/models/image.py
+++ b/backend/app/database/models/image.py
@@ -1,6 +1,8 @@
 """Image model for uploaded images."""
+
 import uuid
 from datetime import datetime
+
 from sqlalchemy import BigInteger, Column, DateTime, ForeignKey, Integer, String
 from sqlalchemy.dialects.postgresql import JSONB, UUID
 from sqlalchemy.orm import relationship
@@ -31,4 +33,3 @@ class Image(Base):
 
     def __repr__(self) -> str:
         return f"<Image(id={self.id}, filename={self.filename})>"
-
diff --git a/backend/app/database/models/share_link.py b/backend/app/database/models/share_link.py
index d21da9b..3bf5cbb 100644
--- a/backend/app/database/models/share_link.py
+++ b/backend/app/database/models/share_link.py
@@ -1,6 +1,8 @@
 """ShareLink model for board sharing."""
+
 import uuid
 from datetime import datetime
+
 from sqlalchemy import Boolean, Column, DateTime, ForeignKey, Integer, String
 from sqlalchemy.dialects.postgresql import UUID
 from sqlalchemy.orm import relationship
@@ -29,4 +31,3 @@ class ShareLink(Base):
 
     def __repr__(self) -> str:
         return f"<ShareLink(id={self.id}, token={self.token[:8]}...)>"
-
diff --git a/backend/app/database/models/user.py b/backend/app/database/models/user.py
index 9e16680..ebfec48 100644
--- a/backend/app/database/models/user.py
+++ b/backend/app/database/models/user.py
@@ -1,6 +1,8 @@
 """User model for authentication and ownership."""
+
 import uuid
 from datetime import datetime
+
 from sqlalchemy import Boolean, Column, DateTime, String
 from sqlalchemy.dialects.postgresql import UUID
 from sqlalchemy.orm import relationship
@@ -26,4 +28,3 @@ class User(Base):
 
     def __repr__(self) -> str:
         return f"<User(id={self.id}, email={self.email})>"
-
diff --git a/backend/app/database/session.py b/backend/app/database/session.py
index cf9b02b..cb299d6 100644
--- a/backend/app/database/session.py
+++ b/backend/app/database/session.py
@@ -25,4 +25,3 @@ def get_db():
         yield db
     finally:
         db.close()
-
diff --git a/backend/app/main.py b/backend/app/main.py
index 29102e4..887aad1 100644
--- a/backend/app/main.py
+++ b/backend/app/main.py
@@ -5,6 +5,7 @@ import logging
 from fastapi import FastAPI, Request
 from fastapi.responses import JSONResponse
 
+from app.api import auth
 from app.core.config import settings
 from app.core.errors import WebRefException
 from app.core.logging import setup_logging
@@ -81,7 +82,6 @@ async def root():
 
 
 # API routers
-from app.api import auth
 app.include_router(auth.router, prefix=f"{settings.API_V1_PREFIX}")
 # Additional routers will be added in subsequent phases
 # from app.api import boards, images
@@ -101,4 +101,3 @@ async def startup_event():
 async def shutdown_event():
     """Application shutdown tasks."""
     logger.info(f"Shutting down {settings.APP_NAME}")
-
diff --git a/backend/pyproject.toml b/backend/pyproject.toml
index b703974..5af083a 100644
--- a/backend/pyproject.toml
+++ b/backend/pyproject.toml
@@ -33,10 +33,6 @@ requires = ["setuptools>=61.0"]
 build-backend = "setuptools.build_meta"
 
 [tool.ruff]
-# Enable pycodestyle (`E`), Pyflakes (`F`), isort (`I`)
-select = ["E", "F", "I", "W", "N", "UP", "B", "C4", "SIM"]
-ignore = []
-
 # Exclude common paths
 exclude = [
     ".git",
@@ -46,16 +42,24 @@ exclude = [
     "alembic/versions",
 ]
 
-# Same as Black.
-line-length = 100
-
-# Allow unused variables when underscore-prefixed.
-dummy-variable-rgx = "^(_+|(_+[a-zA-Z0-9_]*[a-zA-Z0-9]+?))$"
+# Line length (slightly longer for SQLAlchemy models)
+line-length = 120
 
 # Target Python 3.12
 target-version = "py312"
 
-[tool.ruff.per-file-ignores]
+[tool.ruff.lint]
+# Enable pycodestyle (`E`), Pyflakes (`F`), isort (`I`)
+select = ["E", "F", "I", "W", "N", "UP", "B", "C4", "SIM"]
+ignore = [
+    "B008",  # Allow Depends() in FastAPI function defaults
+    "N818",  # Allow WebRefException without Error suffix
+]
+
+# Allow unused variables when underscore-prefixed.
+dummy-variable-rgx = "^(_+|(_+[a-zA-Z0-9_]*[a-zA-Z0-9]+?))$"
+
+[tool.ruff.lint.per-file-ignores]
 "__init__.py" = ["F401"]  # Allow unused imports in __init__.py
 "tests/*" = ["S101"]  # Allow assert in tests
 
diff --git a/flake.nix b/flake.nix
index d25dc9b..b8c92bf 100644
--- a/flake.nix
+++ b/flake.nix
@@ -96,6 +96,67 @@
           '';
         };
 
+        # Apps - Scripts that can be run with `nix run`
+        apps = {
+          # Unified linting for all code
+          lint = {
+            type = "app";
+            program = "${pkgs.writeShellScript "lint" ''
+              set -e
+              cd ${self}
+              
+              # Backend Python linting
+              echo "🔍 Linting backend Python code..."
+              cd backend
+              ${pkgs.ruff}/bin/ruff check --no-cache app/
+              ${pkgs.ruff}/bin/ruff format --check app/
+              cd ..
+              
+              # Frontend linting (if node_modules exists)
+              if [ -d "frontend/node_modules" ]; then
+                echo ""
+                echo "🔍 Linting frontend TypeScript/Svelte code..."
+                cd frontend
+                npm run lint
+                npx prettier --check src/
+                npm run check
+                cd ..
+              else
+                echo "⚠  Frontend node_modules not found, run 'npm install' first"
+              fi
+              
+              echo ""
+              echo "✅ All linting checks passed!"
+            ''}";
+          };
+          
+          # Auto-fix linting issues
+          lint-fix = {
+            type = "app";
+            program = "${pkgs.writeShellScript "lint-fix" ''
+              set -e
+              cd ${self}
+              
+              echo "🔧 Auto-fixing backend Python code..."
+              cd backend
+              ${pkgs.ruff}/bin/ruff check --fix --no-cache app/
+              ${pkgs.ruff}/bin/ruff format app/
+              cd ..
+              
+              if [ -d "frontend/node_modules" ]; then
+                echo ""
+                echo "🔧 Auto-fixing frontend code..."
+                cd frontend
+                npx prettier --write src/
+                cd ..
+              fi
+              
+              echo ""
+              echo "✅ Auto-fix complete!"
+            ''}";
+          };
+        };
+
         # Package definitions (for production deployment)
         packages = {
           # Backend package
diff --git a/scripts/install-hooks.sh b/scripts/install-hooks.sh
new file mode 100755
index 0000000..e72113f
--- /dev/null
+++ b/scripts/install-hooks.sh
@@ -0,0 +1,102 @@
+#!/usr/bin/env bash
+# Install git hooks for the project
+
+set -e
+
+HOOKS_DIR=".git/hooks"
+SCRIPTS_DIR="scripts"
+
+echo "Installing git hooks..."
+echo ""
+
+# Create hooks directory if it doesn't exist
+mkdir -p "$HOOKS_DIR"
+
+# Pre-commit hook
+cat > "$HOOKS_DIR/pre-commit" << 'EOF'
+#!/usr/bin/env bash
+# Git pre-commit hook - runs linting before commit
+
+echo "🔍 Running pre-commit linting..."
+echo ""
+
+# Try to use nix run if available, otherwise use script directly
+if command -v nix &> /dev/null && [ -f "flake.nix" ]; then
+    # Use nix run for consistent environment
+    if ! nix run .#lint; then
+        echo ""
+        echo "❌ Linting failed. Fix errors or use --no-verify to skip."
+        echo "   Auto-fix: nix run .#lint-fix"
+        exit 1
+    fi
+else
+    # Fallback to script
+    if ! ./scripts/lint.sh; then
+        echo ""
+        echo "❌ Linting failed. Fix errors or use --no-verify to skip."
+        echo "   Auto-fix: ./scripts/lint.sh --fix"
+        exit 1
+    fi
+fi
+
+echo ""
+echo "✅ Pre-commit checks passed!"
+EOF
+
+chmod +x "$HOOKS_DIR/pre-commit"
+echo "✓ Installed pre-commit hook"
+
+# Pre-push hook (optional - runs tests)
+cat > "$HOOKS_DIR/pre-push" << 'EOF'
+#!/usr/bin/env bash
+# Git pre-push hook - runs tests before push (optional)
+# Comment out or remove if you want to push without running tests
+
+echo "🧪 Running tests before push..."
+echo ""
+
+# Backend tests (if pytest is available)
+if [ -d "backend" ] && command -v pytest &> /dev/null; then
+    cd backend
+    if ! pytest -xvs --tb=short; then
+        echo ""
+        echo "❌ Backend tests failed. Fix tests or use --no-verify to skip."
+        exit 1
+    fi
+    cd ..
+fi
+
+# Frontend tests (if npm test is available)
+if [ -d "frontend/node_modules" ]; then
+    cd frontend
+    if ! npm test -- --run; then
+        echo ""
+        echo "❌ Frontend tests failed. Fix tests or use --no-verify to skip."
+        exit 1
+    fi
+    cd ..
+fi
+
+echo ""
+echo "✅ All tests passed!"
+EOF
+
+chmod +x "$HOOKS_DIR/pre-push"
+echo "✓ Installed pre-push hook (optional - runs tests)"
+
+echo ""
+echo "========================================="
+echo "✅ Git hooks installed successfully!"
+echo "========================================="
+echo ""
+echo "Hooks installed:"
+echo "  • pre-commit  - Runs linting before commit"
+echo "  • pre-push    - Runs tests before push (optional)"
+echo ""
+echo "To skip hooks when committing:"
+echo "  git commit --no-verify"
+echo ""
+echo "To uninstall:"
+echo "  rm .git/hooks/pre-commit .git/hooks/pre-push"
+echo ""
+
diff --git a/scripts/lint.sh b/scripts/lint.sh
new file mode 100755
index 0000000..5210874
--- /dev/null
+++ b/scripts/lint.sh
@@ -0,0 +1,131 @@
+#!/usr/bin/env bash
+# Unified linting script for all project code
+# Can be run manually or via git hooks
+
+set -e
+
+GREEN='\033[0;32m'
+RED='\033[0;31m'
+YELLOW='\033[1;33m'
+BLUE='\033[0;34m'
+NC='\033[0m'
+
+FAILED=0
+
+# Detect if we're in nix shell
+if ! command -v ruff &> /dev/null && command -v nix &> /dev/null; then
+    echo "🔄 Entering nix development environment..."
+    exec nix develop -c bash "$0" "$@"
+fi
+
+echo "========================================="
+echo "🔍 Reference Board Viewer - Code Linting"
+echo "========================================="
+echo ""
+
+# Backend Python linting
+echo -e "${BLUE}📦 Backend (Python)${NC}"
+echo "-----------------------------------"
+
+if [ -d "backend" ]; then
+    cd backend
+    
+    # Ruff check
+    echo -n "  Ruff check... "
+    if ruff check app/ 2>&1 | grep -q "All checks passed!"; then
+        echo -e "${GREEN}✓${NC}"
+    else
+        echo -e "${RED}✗${NC}"
+        echo ""
+        ruff check app/
+        FAILED=1
+    fi
+    
+    # Ruff format check
+    echo -n "  Ruff format... "
+    if ruff format --check app/ > /dev/null 2>&1; then
+        echo -e "${GREEN}✓${NC}"
+    else
+        echo -e "${RED}✗${NC}"
+        echo ""
+        echo "Run: cd backend && ruff format app/"
+        FAILED=1
+    fi
+    
+    cd ..
+else
+    echo -e "${YELLOW}  ⚠ Backend directory not found, skipping${NC}"
+fi
+
+echo ""
+
+# Frontend linting
+echo -e "${BLUE}🎨 Frontend (TypeScript/Svelte)${NC}"
+echo "-----------------------------------"
+
+if [ -d "frontend" ] && [ -f "frontend/package.json" ]; then
+    cd frontend
+    
+    # Check if node_modules exists
+    if [ ! -d "node_modules" ]; then
+        echo -e "${YELLOW}  ⚠ node_modules not found, run 'npm install' first${NC}"
+        cd ..
+    else
+        # ESLint
+        echo -n "  ESLint... "
+        if npm run lint > /dev/null 2>&1; then
+            echo -e "${GREEN}✓${NC}"
+        else
+            echo -e "${RED}✗${NC}"
+            echo ""
+            npm run lint
+            FAILED=1
+        fi
+        
+        # Prettier check
+        if [ -f ".prettierrc" ]; then
+            echo -n "  Prettier... "
+            if npx prettier --check src/ > /dev/null 2>&1; then
+                echo -e "${GREEN}✓${NC}"
+            else
+                echo -e "${RED}✗${NC}"
+                echo ""
+                echo "Run: cd frontend && npx prettier --write src/"
+                FAILED=1
+            fi
+        fi
+        
+        # TypeScript check
+        echo -n "  TypeScript... "
+        if npm run check > /dev/null 2>&1; then
+            echo -e "${GREEN}✓${NC}"
+        else
+            echo -e "${RED}✗${NC}"
+            echo ""
+            npm run check
+            FAILED=1
+        fi
+        
+        cd ..
+    fi
+else
+    echo -e "${YELLOW}  ⚠ Frontend directory not found, skipping${NC}"
+fi
+
+echo ""
+echo "========================================="
+
+if [ $FAILED -eq 0 ]; then
+    echo -e "${GREEN}✅ All linting checks passed!${NC}"
+    echo "========================================="
+    exit 0
+else
+    echo -e "${RED}❌ Some linting checks failed${NC}"
+    echo "========================================="
+    echo ""
+    echo "To auto-fix issues:"
+    echo "  Backend:  cd backend && ruff check --fix app/ && ruff format app/"
+    echo "  Frontend: cd frontend && npx prettier --write src/"
+    exit 1
+fi
+