WIP checkpoint: US-1..4: Moderation data model + Alembic migration

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_trust_safety.py

@@ -0,0 +1,268 @@
+"""add trust & safety columns and tables
+
+Revision ID: 0003_trust_safety
+Revises: 0002_add_date_of_birth_to_users
+Create Date: 2025-07-10 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_trust_safety"
+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 upgrade() -> None:
+    """Add role/banned_until/suspended_until to users, and create
+    reports, moderation_actions, and appeals tables."""
+
+    # ── ENUM types ──────────────────────────────────────────────
+
+    role_enum = postgresql.ENUM("user", "moderator", "admin", name="role")
+    role_enum.create(op.get_bind(), checkfirst=True)
+
+    target_type_enum = postgresql.ENUM(
+        "user", "world", "asset", "chat_message", name="target_type"
+    )
+    target_type_enum.create(op.get_bind(), checkfirst=True)
+
+    reason_category_enum = postgresql.ENUM(
+        "harassment",
+        "hate_speech",
+        "sexual_content",
+        "violence",
+        "spam",
+        "self_harm",
+        "other",
+        name="reason_category",
+    )
+    reason_category_enum.create(op.get_bind(), checkfirst=True)
+
+    report_status_enum = postgresql.ENUM(
+        "open", "in_review", "resolved", "dismissed", name="report_status"
+    )
+    report_status_enum.create(op.get_bind(), checkfirst=True)
+
+    resolution_enum = postgresql.ENUM(
+        "action_taken",
+        "action_not_needed",
+        "duplicate",
+        "escalated",
+        name="resolution",
+    )
+    resolution_enum.create(op.get_bind(), checkfirst=True)
+
+    moderation_action_enum = postgresql.ENUM(
+        "warn", "suspend", "ban", "restrict", "remove", "restore",
+        name="moderation_action",
+    )
+    moderation_action_enum.create(op.get_bind(), checkfirst=True)
+
+    appeal_status_enum = postgresql.ENUM(
+        "pending", "approved", "rejected", name="appeal_status"
+    )
+    appeal_status_enum.create(op.get_bind(), checkfirst=True)
+
+    # ── users table changes ─────────────────────────────────────
+
+    op.add_column(
+        "users",
+        sa.Column(
+            "role",
+            role_enum,
+            nullable=False,
+            server_default="user",
+        ),
+    )
+    op.add_column(
+        "users",
+        sa.Column("banned_until", sa.DateTime(timezone=True), nullable=True),
+    )
+    op.add_column(
+        "users",
+        sa.Column("suspended_until", sa.DateTime(timezone=True), nullable=True),
+    )
+
+    # ── reports table ───────────────────────────────────────────
+
+    op.create_table(
+        "reports",
+        sa.Column("id", sa.BigInteger(), primary_key=True, autoincrement=True),
+        sa.Column(
+            "reporter_id", sa.Integer(), sa.ForeignKey("users.id", ondelete="CASCADE"), nullable=False
+        ),
+        sa.Column(
+            "target_type",
+            target_type_enum,
+            nullable=False,
+        ),
+        sa.Column("target_id", sa.String(length=64), nullable=False),
+        sa.Column(
+            "reason_category",
+            reason_category_enum,
+            nullable=False,
+        ),
+        sa.Column("details", sa.Text(), nullable=True),
+        sa.Column(
+            "status",
+            report_status_enum,
+            nullable=False,
+            server_default="open",
+        ),
+        sa.Column(
+            "resolved_by",
+            sa.Integer(),
+            sa.ForeignKey("users.id", ondelete="SET NULL"),
+            nullable=True,
+        ),
+        sa.Column(
+            "resolution",
+            resolution_enum,
+            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),
+            onupdate=sa.func.now(),
+            nullable=False,
+        ),
+        sa.Column("resolved_at", sa.DateTime(timezone=True), nullable=True),
+        sa.UniqueConstraint("reporter_id", "target_type", "target_id"),
+    )
+    op.create_index(op.f("ix_reports_id"), "reports", ["id"], unique=False)
+    op.create_index(op.f("ix_reports_reporter_id"), "reports", ["reporter_id"], unique=False)
+
+    # ── moderation_actions table ────────────────────────────────
+
+    op.create_table(
+        "moderation_actions",
+        sa.Column("id", sa.BigInteger(), primary_key=True, autoincrement=True),
+        sa.Column(
+            "moderator_id",
+            sa.Integer(),
+            sa.ForeignKey("users.id", ondelete="CASCADE"),
+            nullable=False,
+        ),
+        sa.Column(
+            "target_user_id",
+            sa.Integer(),
+            sa.ForeignKey("users.id", ondelete="SET NULL"),
+            nullable=True,
+        ),
+        sa.Column(
+            "target_type",
+            target_type_enum,
+            nullable=False,
+        ),
+        sa.Column("target_id", sa.String(length=64), nullable=False),
+        sa.Column(
+            "action",
+            moderation_action_enum,
+            nullable=False,
+        ),
+        sa.Column("reason", sa.Text(), nullable=False),
+        sa.Column(
+            "report_id",
+            sa.Integer(),
+            sa.ForeignKey("reports.id", ondelete="SET NULL"),
+            nullable=True,
+        ),
+        sa.Column("expires_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column("revoked_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column(
+            "created_at",
+            sa.DateTime(timezone=True),
+            server_default=sa.func.now(),
+            nullable=False,
+        ),
+    )
+    op.create_index(op.f("ix_moderation_actions_id"), "moderation_actions", ["id"], unique=False)
+    op.create_index(
+        op.f("ix_moderation_actions_moderator_id"),
+        "moderation_actions",
+        ["moderator_id"],
+        unique=False,
+    )
+
+    # ── appeals table ───────────────────────────────────────────
+
+    op.create_table(
+        "appeals",
+        sa.Column("id", sa.BigInteger(), primary_key=True, autoincrement=True),
+        sa.Column(
+            "moderation_action_id",
+            sa.Integer(),
+            sa.ForeignKey("moderation_actions.id", ondelete="CASCADE"),
+            nullable=False,
+        ),
+        sa.Column(
+            "user_id",
+            sa.Integer(),
+            sa.ForeignKey("users.id", ondelete="CASCADE"),
+            nullable=False,
+        ),
+        sa.Column("reason", sa.Text(), nullable=False),
+        sa.Column(
+            "status",
+            appeal_status_enum,
+            nullable=False,
+            server_default="pending",
+        ),
+        sa.Column(
+            "reviewed_by",
+            sa.Integer(),
+            sa.ForeignKey("users.id", ondelete="SET NULL"),
+            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,
+        ),
+        sa.UniqueConstraint("moderation_action_id", "user_id"),
+    )
+    op.create_index(op.f("ix_appeals_id"), "appeals", ["id"], unique=False)
+    op.create_index(op.f("ix_appeals_user_id"), "appeals", ["user_id"], unique=False)
+
+
+def downgrade() -> None:
+    """Remove trust & safety tables and columns."""
+
+    op.drop_index(op.f("ix_appeals_user_id"), table_name="appeals")
+    op.drop_index(op.f("ix_appeals_id"), table_name="appeals")
+    op.drop_table("appeals")
+
+    op.drop_index(op.f("ix_moderation_actions_moderator_id"), table_name="moderation_actions")
+    op.drop_index(op.f("ix_moderation_actions_id"), table_name="moderation_actions")
+    op.drop_table("moderation_actions")
+
+    op.drop_index(op.f("ix_reports_reporter_id"), table_name="reports")
+    op.drop_index(op.f("ix_reports_id"), table_name="reports")
+    op.drop_table("reports")
+
+    op.drop_column("users", "suspended_until")
+    op.drop_column("users", "banned_until")
+    op.drop_column("users", "role")
+
+    # Drop ENUM types
+    postgresql.ENUM(name="appeal_status").drop(op.get_bind(), checkfirst=True)
+    postgresql.ENUM(name="moderation_action").drop(op.get_bind(), checkfirst=True)
+    postgresql.ENUM(name="resolution").drop(op.get_bind(), checkfirst=True)
+    postgresql.ENUM(name="report_status").drop(op.get_bind(), checkfirst=True)
+    postgresql.ENUM(name="reason_category").drop(op.get_bind(), checkfirst=True)
+    postgresql.ENUM(name="target_type").drop(op.get_bind(), checkfirst=True)
+    postgresql.ENUM(name="role").drop(op.get_bind(), checkfirst=True)

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 +1,225 @@
+"""Trust & Safety models: reports, moderation actions, and appeals."""
+
+from datetime import datetime
+from typing import Optional
+
+from sqlalchemy import (
+    CheckConstraint,
+    Column,
+    DateTime,
+    Enum,
+    ForeignKey,
+    Integer,
+    String,
+    Text,
+    UniqueConstraint,
+    func,
+)
+from sqlalchemy.dialects.postgresql import ENUM as PG_ENUM
+from sqlalchemy.orm import relationship
+
+from app.database import Base
+
+
+# ---------------------------------------------------------------------------
+# ENUM helpers — created explicitly in Alembic, not via SQLAlchemy create_type
+# ---------------------------------------------------------------------------
+
+_role_enum = PG_ENUM(
+    "user", "moderator", "admin",
+    name="user_role",
+    create_type=False,
+)
+
+_target_type_enum = PG_ENUM(
+    "user", "world", "asset", "chat_message",
+    name="target_type",
+    create_type=False,
+)
+
+_reason_category_enum = PG_ENUM(
+    "harassment", "hate_speech", "sexual_content", "violence",
+    "spam", "self_harm", "other",
+    name="reason_category",
+    create_type=False,
+)
+
+_report_status_enum = PG_ENUM(
+    "open", "in_review", "resolved", "dismissed",
+    name="report_status",
+    create_type=False,
+)
+
+_resolution_enum = PG_ENUM(
+    "action_taken", "action_not_needed", "duplicate", "escalated",
+    name="resolution",
+    create_type=False,
+)
+
+_moderation_action_enum = PG_ENUM(
+    "warn", "suspend", "ban", "restrict", "remove", "restore",
+    name="moderation_action",
+    create_type=False,
+)
+
+_appeal_status_enum = PG_ENUM(
+    "pending", "approved", "rejected",
+    name="appeal_status",
+    create_type=False,
+)
+
+
+class Report(Base):
+    """A user-submitted report about another entity."""
+
+    __tablename__ = "reports"
+
+    id = Column(Integer, primary_key=True, autoincrement=True)
+    reporter_id = Column(
+        Integer,
+        ForeignKey("users.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    target_type = Column(_target_type_enum, nullable=False)
+    target_id = Column(String(64), nullable=False)
+    reason_category = Column(_reason_category_enum, nullable=False)
+    details = Column(Text, nullable=True)
+    status = Column(
+        _report_status_enum,
+        nullable=False,
+        server_default="open",
+    )
+    resolved_by = Column(
+        Integer,
+        ForeignKey("users.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+    resolution = Column(_resolution_enum, nullable=True)
+    created_at = Column(
+        DateTime(timezone=True),
+        server_default=func.now(),
+    )
+    updated_at = Column(
+        DateTime(timezone=True),
+        onupdate=func.now(),
+    )
+    resolved_at = Column(DateTime(timezone=True), nullable=True)
+
+    # Coalesce duplicate reports from the same reporter about the same target
+    __table_args__ = (
+        UniqueConstraint("reporter_id", "target_type", "target_id",
+                         name="uq_reporter_target"),
+    )
+
+    # Relationships
+    reporter = relationship("User", back_populates="reports",
+                            foreign_keys=[reporter_id])
+    resolved_by_user = relationship("User", back_populates="resolved_reports",
+                                    foreign_keys=[resolved_by])
+    moderation_actions = relationship(
+        "ModerationAction",
+        back_populates="report",
+        cascade="all, delete-orphan",
+    )
+    appeals = relationship(
+        "Appeal",
+        back_populates="report",
+        cascade="all, delete-orphan",
+    )
+
+
+class ModerationAction(Base):
+    """A moderation action taken against a target."""
+
+    __tablename__ = "moderation_actions"
+
+    id = Column(Integer, primary_key=True, autoincrement=True)
+    moderator_id = Column(
+        Integer,
+        ForeignKey("users.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    target_user_id = Column(
+        Integer,
+        ForeignKey("users.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+    target_type = Column(_target_type_enum, nullable=False)
+    target_id = Column(String(64), nullable=False)
+    action = Column(_moderation_action_enum, nullable=False)
+    reason = Column(Text, nullable=False)
+    report_id = Column(
+        Integer,
+        ForeignKey("reports.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+    expires_at = Column(DateTime(timezone=True), nullable=True)
+    revoked_at = Column(DateTime(timezone=True), nullable=True)
+    created_at = Column(
+        DateTime(timezone=True),
+        server_default=func.now(),
+    )
+
+    # Relationships
+    moderator = relationship("User", back_populates="moderation_actions",
+                             foreign_keys=[moderator_id])
+    target_user = relationship("User", back_populates="moderation_actions_target",
+                               foreign_keys=[target_user_id])
+    report = relationship(
+        "Report",
+        back_populates="moderation_actions",
+    )
+    appeals = relationship(
+        "Appeal",
+        back_populates="moderation_action",
+        cascade="all, delete-orphan",
+    )
+
+
+class Appeal(Base):
+    """An appeal against a moderation action."""
+
+    __tablename__ = "appeals"
+
+    id = Column(Integer, primary_key=True, autoincrement=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(
+        _appeal_status_enum,
+        nullable=False,
+        server_default="pending",
+    )
+    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(),
+    )
+
+    # Prevent duplicate open appeals per sanction
+    __table_args__ = (
+        UniqueConstraint("moderation_action_id", "user_id",
+                         name="uq_action_user_appeal"),
+    )
+
+    # Relationships
+    moderation_action = relationship(
+        "ModerationAction",
+        back_populates="appeals",
+    )
+    user = relationship("User", back_populates="appeals")
+    reviewed_by_user = relationship("User", back_populates="reviewed_appeals",
+                                    foreign_keys=[reviewed_by])

backend/app/models/user.py

@@ -1,4 +1,7 @@
-from sqlalchemy import Column, Integer, String, Boolean, DateTime
+from datetime import date
+from typing import Optional
+
+from sqlalchemy import Column, Integer, String, Boolean, DateTime, Date
 from sqlalchemy.orm import relationship
 from sqlalchemy.sql import func
 
@@ -12,6 +15,7 @@ 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)
     created_at = Column(DateTime(timezone=True), server_default=func.now())
     updated_at = Column(DateTime(timezone=True), onupdate=func.now())
@@ -19,3 +23,15 @@ class User(Base):
     sessions = relationship("Session", back_populates="user", cascade="all, delete-orphan")
     worlds = relationship("World", back_populates="owner")
     assets = relationship("Asset", back_populates="owner")
+
+    @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)