WIP checkpoint: Trust & Safety: Moderation data model + Alembic migration

backend/alembic/env.py

@@ -8,7 +8,7 @@ from sqlalchemy.ext.asyncio import create_async_engine
 
 from app.config import settings
 from app.database import Base
-from app.models import user, session, world, asset  # noqa: F401
+from app.models import user, session, world, asset, moderation  # noqa: F401
 
 # this is the Alembic Config object, which provides
 # access to the values within the .ini file in use.

backend/alembic/versions/0001_initial.py

@@ -69,7 +69,7 @@ def upgrade() -> None:
         sa.Column(
             "visibility",
             postgresql.ENUM(
-                "public", "private", "friends_only", name="world_visibility"
+                "public", "private", "friends_only", name="world_visibility", create_type=False
             ),
             nullable=True,
         ),
@@ -89,7 +89,7 @@ def upgrade() -> None:
             "asset_type",
             postgresql.ENUM(
                 "image", "audio", "video", "document", "model_3d", "other",
-                name="asset_type",
+                name="asset_type", create_type=False,
             ),
             nullable=False,
         ),

backend/alembic/versions/0002_add_date_of_birth_to_users.py

@@ -0,0 +1,30 @@
+"""add date_of_birth column to users table
+
+Revision ID: 0002_add_date_of_birth_to_users
+Revises: 0001_initial
+Create Date: 2025-01-01 00:00:00.000000
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+# revision identifiers, used by Alembic.
+revision: str = "0002_add_date_of_birth_to_users"
+down_revision: Union[str, None] = "0001_initial"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Add date_of_birth column to users table."""
+    op.add_column(
+        "users",
+        sa.Column("date_of_birth", sa.Date(), nullable=True),
+    )
+
+
+def downgrade() -> None:
+    """Remove date_of_birth column from users table."""
+    op.drop_column("users", "date_of_birth")

backend/alembic/versions/0003_moderation.py

@@ -0,0 +1,211 @@
+"""add moderation tables and extend users table
+
+Revision ID: 0003_moderation
+Revises: 0002_add_date_of_birth_to_users
+Create Date: 2025-01-01 00:00:00.000000
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects import postgresql
+
+# revision identifiers, used by Alembic.
+revision: str = "0003_moderation"
+down_revision: Union[str, None] = "0002_add_date_of_birth_to_users"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def _create_enum_if_not_exists(enum_name: str, values: list[str]) -> None:
+    """Create a PostgreSQL ENUM type if it does not already exist."""
+    bind = op.get_bind()
+    # Check if the type already exists in pg_type
+    result = bind.execute(
+        sa.text(
+            "SELECT 1 FROM pg_type WHERE typname = :name"
+        ).bindparams(name=enum_name)
+    ).fetchone()
+    if result is None:
+        values_str = ", ".join(f"'{v}'" for v in values)
+        op.execute(f"CREATE TYPE {enum_name} AS ENUM ({values_str})")
+
+
+def upgrade() -> None:
+    """Add role, banned_until, suspended_until to users table
+    and create reports, moderation_actions, appeals tables."""
+
+    # --- Create ENUM types if they don't exist ---
+    _create_enum_if_not_exists("user_role", ["user", "moderator", "admin"])
+    _create_enum_if_not_exists("report_target_type", ["user", "world", "asset", "chat_message"])
+    _create_enum_if_not_exists("report_reason_category", [
+        "harassment", "hate_speech", "sexual_content",
+        "violence", "spam", "self_harm", "other"
+    ])
+    _create_enum_if_not_exists("report_status", ["open", "in_review", "resolved", "dismissed"])
+    _create_enum_if_not_exists("report_resolution", ["warn", "suspend", "ban", "restrict", "remove"])
+    _create_enum_if_not_exists("moderation_target_type", ["user", "world", "asset", "chat_message"])
+    _create_enum_if_not_exists("moderation_action_type", ["warn", "suspend", "ban", "restrict", "remove", "restore"])
+    _create_enum_if_not_exists("appeal_status", ["pending", "approved", "rejected"])
+
+    # --- Extend users table ---
+
+    # Add role column
+    op.add_column(
+        "users",
+        sa.Column(
+            "role",
+            postgresql.ENUM("user", "moderator", "admin", name="user_role", create_type=False),
+            nullable=False,
+            server_default="user",
+        ),
+    )
+
+    # Add banned_until column
+    op.add_column(
+        "users",
+        sa.Column("banned_until", sa.DateTime(timezone=True), nullable=True),
+    )
+
+    # Add suspended_until column
+    op.add_column(
+        "users",
+        sa.Column("suspended_until", sa.DateTime(timezone=True), nullable=True),
+    )
+
+    # --- Create reports table ---
+
+    op.create_table(
+        "reports",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column("reporter_id", sa.Integer(), sa.ForeignKey("users.id"), nullable=False),
+        sa.Column(
+            "target_type",
+            postgresql.ENUM("user", "world", "asset", "chat_message", name="report_target_type", create_type=False),
+            nullable=False,
+        ),
+        sa.Column("target_id", sa.String(64), nullable=False),
+        sa.Column(
+            "reason_category",
+            postgresql.ENUM(
+                "harassment", "hate_speech", "sexual_content",
+                "violence", "spam", "self_harm", "other",
+                name="report_reason_category", create_type=False,
+            ),
+            nullable=False,
+        ),
+        sa.Column("details", sa.Text(), nullable=True),
+        sa.Column(
+            "status",
+            postgresql.ENUM("open", "in_review", "resolved", "dismissed", name="report_status", create_type=False),
+            nullable=False,
+            server_default="open",
+        ),
+        sa.Column("resolved_by", sa.Integer(), sa.ForeignKey("users.id"), nullable=True),
+        sa.Column(
+            "resolution",
+            postgresql.ENUM("warn", "suspend", "ban", "restrict", "remove", name="report_resolution", create_type=False),
+            nullable=True,
+        ),
+        sa.Column("created_at", sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False),
+        sa.Column("updated_at", sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False),
+        sa.Column("resolved_at", sa.DateTime(timezone=True), nullable=True),
+    )
+
+    # Indexes for reports
+    op.create_index("ix_reports_reporter_id", "reports", ["reporter_id"])
+    op.create_index("ix_reports_target", "reports", ["target_type", "target_id"])
+    op.create_index("ix_reports_status", "reports", ["status"])
+
+    # --- Create moderation_actions table ---
+
+    op.create_table(
+        "moderation_actions",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column("moderator_id", sa.Integer(), sa.ForeignKey("users.id"), nullable=False),
+        sa.Column("target_user_id", sa.Integer(), sa.ForeignKey("users.id"), nullable=True),
+        sa.Column(
+            "target_type",
+            postgresql.ENUM("user", "world", "asset", "chat_message", name="moderation_target_type", create_type=False),
+            nullable=False,
+        ),
+        sa.Column("target_id", sa.String(64), nullable=False),
+        sa.Column(
+            "action",
+            postgresql.ENUM("warn", "suspend", "ban", "restrict", "remove", "restore", name="moderation_action_type", create_type=False),
+            nullable=False,
+        ),
+        sa.Column("reason", sa.Text(), nullable=True),
+        sa.Column("report_id", sa.Integer(), sa.ForeignKey("reports.id"), nullable=True),
+        sa.Column("expires_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column("created_at", sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False),
+    )
+
+    # Indexes for moderation_actions
+    op.create_index("ix_moderation_actions_moderator_id", "moderation_actions", ["moderator_id"])
+    op.create_index("ix_moderation_actions_target_user", "moderation_actions", ["target_user_id"])
+    op.create_index("ix_moderation_actions_target", "moderation_actions", ["target_type", "target_id"])
+    op.create_index("ix_moderation_actions_report_id", "moderation_actions", ["report_id"])
+
+    # --- Create appeals table ---
+
+    op.create_table(
+        "appeals",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column("moderation_action_id", sa.Integer(), sa.ForeignKey("moderation_actions.id"), nullable=False),
+        sa.Column("user_id", sa.Integer(), sa.ForeignKey("users.id"), nullable=False),
+        sa.Column("reason", sa.Text(), nullable=False),
+        sa.Column(
+            "status",
+            postgresql.ENUM("pending", "approved", "rejected", name="appeal_status", create_type=False),
+            nullable=False,
+            server_default="pending",
+        ),
+        sa.Column("reviewed_by", sa.Integer(), sa.ForeignKey("users.id"), nullable=True),
+        sa.Column("reviewed_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column("created_at", sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False),
+    )
+
+    # Indexes for appeals
+    op.create_index("ix_appeals_moderation_action_id", "appeals", ["moderation_action_id"])
+    op.create_index("ix_appeals_user_id", "appeals", ["user_id"])
+    op.create_index("ix_appeals_status", "appeals", ["status"])
+
+
+def downgrade() -> None:
+    """Remove moderation tables and revert users table changes."""
+
+    # Drop appeals table
+    op.drop_index("ix_appeals_status", table_name="appeals")
+    op.drop_index("ix_appeals_user_id", table_name="appeals")
+    op.drop_index("ix_appeals_moderation_action_id", table_name="appeals")
+    op.drop_table("appeals")
+
+    # Drop moderation_actions table
+    op.drop_index("ix_moderation_actions_report_id", table_name="moderation_actions")
+    op.drop_index("ix_moderation_actions_target", table_name="moderation_actions")
+    op.drop_index("ix_moderation_actions_target_user", table_name="moderation_actions")
+    op.drop_index("ix_moderation_actions_moderator_id", table_name="moderation_actions")
+    op.drop_table("moderation_actions")
+
+    # Drop reports table
+    op.drop_index("ix_reports_status", table_name="reports")
+    op.drop_index("ix_reports_target", table_name="reports")
+    op.drop_index("ix_reports_reporter_id", table_name="reports")
+    op.drop_table("reports")
+
+    # Remove columns from users table
+    op.drop_column("users", "suspended_until")
+    op.drop_column("users", "banned_until")
+    op.drop_column("users", "role")
+
+    # Drop the enum types
+    op.execute("DROP TYPE IF EXISTS user_role")
+    op.execute("DROP TYPE IF EXISTS report_target_type")
+    op.execute("DROP TYPE IF EXISTS report_reason_category")
+    op.execute("DROP TYPE IF EXISTS report_status")
+    op.execute("DROP TYPE IF EXISTS report_resolution")
+    op.execute("DROP TYPE IF EXISTS moderation_target_type")
+    op.execute("DROP TYPE IF EXISTS moderation_action_type")
+    op.execute("DROP TYPE IF EXISTS appeal_status")

backend/app/models/__init__.py

@@ -2,5 +2,6 @@ from app.models.user import User
 from app.models.session import Session
 from app.models.world import World
 from app.models.asset import Asset
+from app.models.moderation import Report, ModerationAction, Appeal
 
-__all__ = ["User", "Session", "World", "Asset"]
+__all__ = ["User", "Session", "World", "Asset", "Report", "ModerationAction", "Appeal"]

backend/app/models/moderation.py

@@ -0,0 +1,286 @@
+"""Moderation-related models: Report, ModerationAction, Appeal."""
+
+from datetime import datetime
+from typing import Optional
+
+from sqlalchemy import (
+    Column,
+    Enum,
+    ForeignKey,
+    Integer,
+    String,
+    Text,
+    DateTime,
+    Index,
+)
+from sqlalchemy.orm import relationship
+from sqlalchemy.sql import func
+
+from app.database import Base
+
+
+# --- Enums ---
+
+class TargetType(str):
+    USER = "user"
+    WORLD = "world"
+    ASSET = "asset"
+    CHAT_MESSAGE = "chat_message"
+
+
+class ReasonCategory(str):
+    HARASSMENT = "harassment"
+    HATE_SPEECH = "hate_speech"
+    SEXUAL_CONTENT = "sexual_content"
+    VIOLENCE = "violence"
+    SPAM = "spam"
+    SELF_HARM = "self_harm"
+    OTHER = "other"
+
+
+class ReportStatus(str):
+    OPEN = "open"
+    IN_REVIEW = "in_review"
+    RESOLVED = "resolved"
+    DISMISSED = "dismissed"
+
+
+class ResolutionAction(str):
+    WARN = "warn"
+    SUSPEND = "suspend"
+    BAN = "ban"
+    RESTRICT = "restrict"
+    REMOVE = "remove"
+    RESTORE = "restore"
+
+
+class ModerationActionType(str):
+    WARN = "warn"
+    SUSPEND = "suspend"
+    BAN = "ban"
+    RESTRICT = "restrict"
+    REMOVE = "remove"
+    RESTORE = "restore"
+
+
+class AppealStatus(str):
+    PENDING = "pending"
+    APPROVED = "approved"
+    REJECTED = "rejected"
+
+
+# --- Models ---
+
+class Report(Base):
+    """A moderation report filed by a user or system."""
+
+    __tablename__ = "reports"
+
+    id = Column(Integer, primary_key=True)
+    reporter_id = Column(
+        Integer,
+        ForeignKey("users.id", ondelete="SET NULL"),
+        nullable=False,
+    )
+    target_type = Column(
+        Enum(
+            TargetType.USER,
+            TargetType.WORLD,
+            TargetType.ASSET,
+            TargetType.CHAT_MESSAGE,
+            name="target_type",
+            create_type=False,
+        ),
+        nullable=False,
+    )
+    target_id = Column(String(64), nullable=False)
+    reason_category = Column(
+        Enum(
+            ReasonCategory.HARASSMENT,
+            ReasonCategory.HATE_SPEECH,
+            ReasonCategory.SEXUAL_CONTENT,
+            ReasonCategory.VIOLENCE,
+            ReasonCategory.SPAM,
+            ReasonCategory.SELF_HARM,
+            ReasonCategory.OTHER,
+            name="reason_category",
+            create_type=False,
+        ),
+        nullable=False,
+    )
+    details = Column(Text, nullable=True)
+    status = Column(
+        Enum(
+            ReportStatus.OPEN,
+            ReportStatus.IN_REVIEW,
+            ReportStatus.RESOLVED,
+            ReportStatus.DISMISSED,
+            name="report_status",
+            create_type=False,
+        ),
+        default=ReportStatus.OPEN,
+        nullable=False,
+    )
+    resolved_by = Column(
+        Integer,
+        ForeignKey("users.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+    resolution = Column(
+        Enum(
+            ResolutionAction.WARN,
+            ResolutionAction.SUSPEND,
+            ResolutionAction.BAN,
+            ResolutionAction.RESTRICT,
+            ResolutionAction.REMOVE,
+            ResolutionAction.RESTORE,
+            name="resolution_action",
+            create_type=False,
+        ),
+        nullable=True,
+    )
+    created_at = Column(
+        DateTime(timezone=True),
+        server_default=func.now(),
+        nullable=False,
+    )
+    updated_at = Column(
+        DateTime(timezone=True),
+        server_default=func.now(),
+        onupdate=func.now(),
+        nullable=False,
+    )
+    resolved_at = Column(DateTime(timezone=True), nullable=True)
+
+    # Relationships
+    reporter = relationship("User", foreign_keys=[reporter_id])
+    resolver = relationship("User", foreign_keys=[resolved_by])
+    actions = relationship(
+        "ModerationAction",
+        back_populates="report",
+        cascade="all, delete-orphan",
+    )
+
+    __table_args__ = (
+        Index("ix_reports_target", "target_type", "target_id"),
+        Index("ix_reports_status", "status"),
+        Index("ix_reports_created_at", "created_at"),
+    )
+
+
+class ModerationAction(Base):
+    """A moderation action taken by a moderator/admin."""
+
+    __tablename__ = "moderation_actions"
+
+    id = Column(Integer, primary_key=True)
+    moderator_id = Column(
+        Integer,
+        ForeignKey("users.id", ondelete="SET NULL"),
+        nullable=False,
+    )
+    target_user_id = Column(
+        Integer,
+        ForeignKey("users.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+    target_type = Column(
+        Enum(
+            TargetType.USER,
+            TargetType.WORLD,
+            TargetType.ASSET,
+            TargetType.CHAT_MESSAGE,
+            name="mod_target_type",
+            create_type=False,
+        ),
+        nullable=False,
+    )
+    target_id = Column(String(64), nullable=False)
+    action = Column(
+        Enum(
+            ModerationActionType.WARN,
+            ModerationActionType.SUSPEND,
+            ModerationActionType.BAN,
+            ModerationActionType.RESTRICT,
+            ModerationActionType.REMOVE,
+            ModerationActionType.RESTORE,
+            name="moderation_action_type",
+            create_type=False,
+        ),
+        nullable=False,
+    )
+    reason = Column(Text, nullable=True)
+    report_id = Column(
+        Integer,
+        ForeignKey("reports.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+    expires_at = Column(DateTime(timezone=True), nullable=True)
+    created_at = Column(
+        DateTime(timezone=True),
+        server_default=func.now(),
+        nullable=False,
+    )
+
+    # Relationships
+    moderator = relationship("User", foreign_keys=[moderator_id])
+    target_user = relationship("User", foreign_keys=[target_user_id])
+    report = relationship("Report", back_populates="actions")
+    appeals = relationship("Appeal", back_populates="moderation_action")
+
+    __table_args__ = (
+        Index("ix_moderation_actions_target", "target_type", "target_id"),
+        Index("ix_moderation_actions_created_at", "created_at"),
+    )
+
+
+class Appeal(Base):
+    """An appeal filed by a user against a moderation action."""
+
+    __tablename__ = "appeals"
+
+    id = Column(Integer, primary_key=True)
+    moderation_action_id = Column(
+        Integer,
+        ForeignKey("moderation_actions.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    user_id = Column(
+        Integer,
+        ForeignKey("users.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    reason = Column(Text, nullable=False)
+    status = Column(
+        Enum(
+            AppealStatus.PENDING,
+            AppealStatus.APPROVED,
+            AppealStatus.REJECTED,
+            name="appeal_status",
+            create_type=False,
+        ),
+        default=AppealStatus.PENDING,
+        nullable=False,
+    )
+    reviewed_by = Column(
+        Integer,
+        ForeignKey("users.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+    reviewed_at = Column(DateTime(timezone=True), nullable=True)
+    created_at = Column(
+        DateTime(timezone=True),
+        server_default=func.now(),
+        nullable=False,
+    )
+
+    # Relationships
+    moderation_action = relationship(
+        "ModerationAction", back_populates="appeals"
+    )
+    reviewer = relationship("User", foreign_keys=[reviewed_by])
+
+    __table_args__ = (
+        Index("ix_appeals_status", "status"),
+        Index("ix_appeals_created_at", "created_at"),
+    )

backend/app/models/user.py

@@ -1,4 +1,7 @@
-from sqlalchemy import Column, Integer, String, Boolean, DateTime
+from datetime import date, datetime
+from typing import Optional
+
+from sqlalchemy import Column, Integer, String, Boolean, DateTime, Date, Enum
 from sqlalchemy.orm import relationship
 from sqlalchemy.sql import func
 
@@ -12,10 +15,56 @@ class User(Base):
     username = Column(String(50), unique=True, index=True, nullable=False)
     email = Column(String(120), unique=True, index=True, nullable=False)
     hashed_password = Column(String(255), nullable=False)
+    date_of_birth = Column(Date, nullable=True)
     is_active = Column(Boolean, default=True)
+    role = Column(
+        Enum("user", "moderator", "admin", name="user_role", create_type=False),
+        default="user",
+        nullable=False,
+    )
+    banned_until = Column(DateTime(timezone=True), nullable=True)
+    suspended_until = Column(DateTime(timezone=True), nullable=True)
     created_at = Column(DateTime(timezone=True), server_default=func.now())
     updated_at = Column(DateTime(timezone=True), onupdate=func.now())
 
     sessions = relationship("Session", back_populates="user", cascade="all, delete-orphan")
     worlds = relationship("World", back_populates="owner")
     assets = relationship("Asset", back_populates="owner")
+    reported_by = relationship(
+        "Report",
+        foreign_keys="Report.reporter_id",
+        back_populates="reporter",
+    )
+    resolved_reports = relationship(
+        "Report",
+        foreign_keys="Report.resolved_by",
+        back_populates="resolver",
+    )
+    moderation_actions = relationship(
+        "ModerationAction",
+        foreign_keys="ModerationAction.moderator_id",
+        back_populates="moderator",
+    )
+    target_moderation_actions = relationship(
+        "ModerationAction",
+        foreign_keys="ModerationAction.target_user_id",
+        back_populates="target_user",
+    )
+    appeals = relationship("Appeal", back_populates="user")
+    reviewed_appeals = relationship(
+        "Appeal",
+        foreign_keys="Appeal.reviewed_by",
+        back_populates="reviewer",
+    )
+
+    @property
+    def is_adult(self) -> bool:
+        """Return True if the user is 18 or older based on date_of_birth."""
+        if self.date_of_birth is None:
+            return False
+        today = date.today()
+        age = today.year - self.date_of_birth.year
+        # Adjust if birthday hasn't occurred yet this year
+        if (today.month, today.day) < (self.date_of_birth.month, self.date_of_birth.day):
+            age -= 1
+        return age >= 18

backend/app/routers/auth.py

@@ -1,10 +1,10 @@
 """Authentication router - login, register, token refresh."""
 
-from datetime import datetime, timedelta, timezone
+from datetime import date, datetime, timedelta, timezone
 
 from fastapi import APIRouter, Depends, HTTPException, status
 from fastapi.security import OAuth2PasswordRequestForm
-from pydantic import BaseModel, EmailStr
+from pydantic import BaseModel, EmailStr, field_validator
 
 from jose import jwt
 from passlib.context import CryptContext
@@ -32,12 +32,24 @@ class RegisterRequest(BaseModel):
     username: str
     email: EmailStr
     password: str
+    date_of_birth: str  # ISO format date string (YYYY-MM-DD)
+
+    @field_validator("date_of_birth")
+    @classmethod
+    def validate_date_of_birth(cls, v: str) -> str:
+        """Validate that the date string is a valid date in YYYY-MM-DD format."""
+        try:
+            datetime.strptime(v, "%Y-%m-%d")
+        except ValueError:
+            raise ValueError("date_of_birth must be in YYYY-MM-DD format")
+        return v
 
 
 class UserResponse(BaseModel):
     id: int
     username: str
     email: str
+    date_of_birth: str | None = None
     is_active: bool
     created_at: datetime | None = None
 
@@ -65,11 +77,44 @@ def hash_password(password: str) -> str:
     return pwd_context.hash(password)
 
 
+def calculate_age(birth_date: date, today: date | None = None) -> int:
+    """Calculate age in years from a birth date.
+
+    Args:
+        birth_date: The person's date of birth.
+        today: The reference date. Defaults to today's date (UTC).
+
+    Returns:
+        Age in whole years as of the reference date.
+    """
+    if today is None:
+        today = datetime.now(timezone.utc).date()
+
+    age = today.year - birth_date.year
+    # Adjust if birthday hasn't occurred yet this year
+    if (today.month, today.day) < (birth_date.month, birth_date.day):
+        age -= 1
+    return age
+
+
 # --- Endpoints ---
 
 @router.post("/register", response_model=TokenResponse, status_code=status.HTTP_201_CREATED)
 async def register(req: RegisterRequest, db: AsyncSession = Depends(get_db)):
-    """Register a new user and return an access token."""
+    """Register a new user and return an access token.
+
+    Requires date_of_birth and rejects users under 18.
+    """
+    # Parse and validate date_of_birth
+    dob = datetime.strptime(req.date_of_birth, "%Y-%m-%d").date()
+    age = calculate_age(dob)
+
+    if age < 18:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail=f"Must be 18 or older to register (provided date of birth: {req.date_of_birth})",
+        )
+
     # Check if username already exists
     result = await db.execute(select(User).where(User.username == req.username))
     if result.scalar_one_or_none():
@@ -90,6 +135,7 @@ async def register(req: RegisterRequest, db: AsyncSession = Depends(get_db)):
         username=req.username,
         email=req.email,
         hashed_password=hash_password(req.password),
+        date_of_birth=dob,
     )
     db.add(user)
     await db.commit()

backend/pytest.ini

@@ -0,0 +1,3 @@
+[pytest]
+asyncio_mode = auto
+testpaths = tests

backend/tests/test_auth_age_gate.py

@@ -0,0 +1,94 @@
+"""Tests for the 18+ age gate on user registration."""
+
+from datetime import date, timedelta
+
+import pytest
+
+from app.routers.auth import calculate_age
+
+
+class TestCalculateAge:
+    """Unit tests for the calculate_age helper."""
+
+    def test_exactly_18(self):
+        """A person born exactly 18 years ago today is 18."""
+        today = date(2025, 6, 15)
+        dob = today.replace(year=today.year - 18)
+        assert calculate_age(dob, today=today) == 18
+
+    def test_just_turned_18(self):
+        """A person who turned 18 yesterday is 18."""
+        today = date(2025, 6, 15)
+        dob = today.replace(year=today.year - 18) - timedelta(days=1)
+        assert calculate_age(dob, today=today) == 18
+
+    def test_one_day_short_of_18(self):
+        """A person born one day after their 18th birthday is 17."""
+        today = date(2025, 6, 15)
+        dob = today.replace(year=today.year - 18) + timedelta(days=1)
+        assert calculate_age(dob, today=today) == 17
+
+    def test_17_years_old(self):
+        """A person who is 17 years old today is 17."""
+        today = date(2025, 6, 15)
+        dob = date(2008, 6, 15)
+        assert calculate_age(dob, today=today) == 17
+
+    def test_65_years_old(self):
+        """A person who is 65 is correctly calculated."""
+        today = date(2025, 6, 15)
+        dob = today.replace(year=today.year - 65)
+        assert calculate_age(dob, today=today) == 65
+
+    def test_newborn(self):
+        """A newborn is 0."""
+        today = date(2025, 6, 15)
+        dob = today
+        assert calculate_age(dob, today=today) == 0
+
+    def test_birthday_not_yet_this_year(self):
+        """Person born Dec 31, 2000 — on Jan 1, 2025 they are still 24."""
+        dob = date(2000, 12, 31)
+        assert calculate_age(dob, today=date(2025, 1, 1)) == 24
+
+    def test_birthday_today(self):
+        """Person born Dec 31, 2000 — on Dec 31, 2024 they turn 24."""
+        dob = date(2000, 12, 31)
+        assert calculate_age(dob, today=date(2024, 12, 31)) == 24
+
+
+class TestRegisterRequestDateValidation:
+    """Tests for the RegisterRequest date_of_birth field validator."""
+
+    @pytest.mark.parametrize(
+        "dob",
+        [
+            "2000-01-01",
+            "1990-12-31",
+            "2004-02-29",  # leap day
+        ],
+    )
+    def test_valid_dates(self, dob):
+        """Valid YYYY-MM-DD dates pass validation."""
+        from app.routers.auth import RegisterRequest
+
+        req = RegisterRequest(username="u", email="u@example.com", password="p", date_of_birth=dob)
+        assert req.date_of_birth == dob
+
+    @pytest.mark.parametrize(
+        "dob",
+        [
+            "01-01-2000",
+            "2000/01/01",
+            "2000-13-01",
+            "2000-00-10",
+            "not-a-date",
+            "",
+        ],
+    )
+    def test_invalid_dates_rejected(self, dob):
+        """Invalid dates are rejected by the validator."""
+        from app.routers.auth import RegisterRequest
+
+        with pytest.raises(ValueError):
+            RegisterRequest(username="u", email="u@example.com", password="p", date_of_birth=dob)