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/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/alembic/versions/0003_trust_safety.py

@@ -1,268 +0,0 @@
-"""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/moderation.py

@@ -1,142 +1,182 @@
-"""Trust & Safety models: reports, moderation actions, and appeals."""
+"""Moderation-related models: Report, ModerationAction, Appeal."""
 
 from datetime import datetime
 from typing import Optional
 
 from sqlalchemy import (
-    CheckConstraint,
     Column,
-    DateTime,
     Enum,
     ForeignKey,
     Integer,
     String,
     Text,
-    UniqueConstraint,
+    DateTime,
-    func,
+    Index,
 )
-from sqlalchemy.dialects.postgresql import ENUM as PG_ENUM
 from sqlalchemy.orm import relationship
+from sqlalchemy.sql import func
 
 from app.database import Base
 
 
-# ---------------------------------------------------------------------------
+# --- Enums ---
-# ENUM helpers — created explicitly in Alembic, not via SQLAlchemy create_type
-# ---------------------------------------------------------------------------
 
-_role_enum = PG_ENUM(
+class TargetType(str):
-    "user", "moderator", "admin",
+    USER = "user"
-    name="user_role",
+    WORLD = "world"
-    create_type=False,
+    ASSET = "asset"
-)
+    CHAT_MESSAGE = "chat_message"
 
-_target_type_enum = PG_ENUM(
-    "user", "world", "asset", "chat_message",
-    name="target_type",
-    create_type=False,
-)
 
-_reason_category_enum = PG_ENUM(
+class ReasonCategory(str):
-    "harassment", "hate_speech", "sexual_content", "violence",
+    HARASSMENT = "harassment"
-    "spam", "self_harm", "other",
+    HATE_SPEECH = "hate_speech"
-    name="reason_category",
+    SEXUAL_CONTENT = "sexual_content"
-    create_type=False,
+    VIOLENCE = "violence"
-)
+    SPAM = "spam"
+    SELF_HARM = "self_harm"
+    OTHER = "other"
 
-_report_status_enum = PG_ENUM(
-    "open", "in_review", "resolved", "dismissed",
-    name="report_status",
-    create_type=False,
-)
 
-_resolution_enum = PG_ENUM(
+class ReportStatus(str):
-    "action_taken", "action_not_needed", "duplicate", "escalated",
+    OPEN = "open"
-    name="resolution",
+    IN_REVIEW = "in_review"
-    create_type=False,
+    RESOLVED = "resolved"
-)
+    DISMISSED = "dismissed"
 
-_moderation_action_enum = PG_ENUM(
-    "warn", "suspend", "ban", "restrict", "remove", "restore",
-    name="moderation_action",
-    create_type=False,
-)
 
-_appeal_status_enum = PG_ENUM(
+class ResolutionAction(str):
-    "pending", "approved", "rejected",
+    WARN = "warn"
-    name="appeal_status",
+    SUSPEND = "suspend"
-    create_type=False,
+    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 user-submitted report about another entity."""
+    """A moderation report filed by a user or system."""
 
     __tablename__ = "reports"
 
-    id = Column(Integer, primary_key=True, autoincrement=True)
+    id = Column(Integer, primary_key=True)
     reporter_id = Column(
         Integer,
-        ForeignKey("users.id", ondelete="CASCADE"),
+        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_type = Column(_target_type_enum, nullable=False)
     target_id = Column(String(64), nullable=False)
-    reason_category = Column(_reason_category_enum, 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(
-        _report_status_enum,
+        Enum(
+            ReportStatus.OPEN,
+            ReportStatus.IN_REVIEW,
+            ReportStatus.RESOLVED,
+            ReportStatus.DISMISSED,
+            name="report_status",
+            create_type=False,
+        ),
+        default=ReportStatus.OPEN,
         nullable=False,
-        server_default="open",
     )
     resolved_by = Column(
         Integer,
         ForeignKey("users.id", ondelete="SET NULL"),
         nullable=True,
     )
-    resolution = Column(_resolution_enum, 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)
 
-    # 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",
+    reporter = relationship("User", foreign_keys=[reporter_id])
-                            foreign_keys=[reporter_id])
+    resolver = relationship("User", foreign_keys=[resolved_by])
-    resolved_by_user = relationship("User", back_populates="resolved_reports",
+    actions = relationship(
-                                    foreign_keys=[resolved_by])
-    moderation_actions = relationship(
         "ModerationAction",
         back_populates="report",
         cascade="all, delete-orphan",
     )
-    appeals = relationship(
+
-        "Appeal",
+    __table_args__ = (
-        back_populates="report",
+        Index("ix_reports_target", "target_type", "target_id"),
-        cascade="all, delete-orphan",
+        Index("ix_reports_status", "status"),
+        Index("ix_reports_created_at", "created_at"),
     )
 
 
 class ModerationAction(Base):
-    """A moderation action taken against a target."""
+    """A moderation action taken by a moderator/admin."""
 
     __tablename__ = "moderation_actions"
 
-    id = Column(Integer, primary_key=True, autoincrement=True)
+    id = Column(Integer, primary_key=True)
     moderator_id = Column(
         Integer,
-        ForeignKey("users.id", ondelete="CASCADE"),
+        ForeignKey("users.id", ondelete="SET NULL"),
         nullable=False,
     )
     target_user_id = Column(
@@ -144,44 +184,62 @@ class ModerationAction(Base):
         ForeignKey("users.id", ondelete="SET NULL"),
         nullable=True,
     )
-    target_type = Column(_target_type_enum, nullable=False)
+    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(_moderation_action_enum, nullable=False)
+    action = Column(
-    reason = Column(Text, nullable=False)
+        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)
-    revoked_at = Column(DateTime(timezone=True), nullable=True)
     created_at = Column(
         DateTime(timezone=True),
         server_default=func.now(),
+        nullable=False,
     )
 
     # Relationships
-    moderator = relationship("User", back_populates="moderation_actions",
+    moderator = relationship("User", foreign_keys=[moderator_id])
-                             foreign_keys=[moderator_id])
+    target_user = relationship("User", foreign_keys=[target_user_id])
-    target_user = relationship("User", back_populates="moderation_actions_target",
+    report = relationship("Report", back_populates="actions")
-                               foreign_keys=[target_user_id])
+    appeals = relationship("Appeal", back_populates="moderation_action")
-    report = relationship(
+
-        "Report",
+    __table_args__ = (
-        back_populates="moderation_actions",
+        Index("ix_moderation_actions_target", "target_type", "target_id"),
-    )
+        Index("ix_moderation_actions_created_at", "created_at"),
-    appeals = relationship(
-        "Appeal",
-        back_populates="moderation_action",
-        cascade="all, delete-orphan",
     )
 
 
 class Appeal(Base):
-    """An appeal against a moderation action."""
+    """An appeal filed by a user against a moderation action."""
 
     __tablename__ = "appeals"
 
-    id = Column(Integer, primary_key=True, autoincrement=True)
+    id = Column(Integer, primary_key=True)
     moderation_action_id = Column(
         Integer,
         ForeignKey("moderation_actions.id", ondelete="CASCADE"),
@@ -194,9 +252,15 @@ class Appeal(Base):
     )
     reason = Column(Text, nullable=False)
     status = Column(
-        _appeal_status_enum,
+        Enum(
+            AppealStatus.PENDING,
+            AppealStatus.APPROVED,
+            AppealStatus.REJECTED,
+            name="appeal_status",
+            create_type=False,
+        ),
+        default=AppealStatus.PENDING,
         nullable=False,
-        server_default="pending",
     )
     reviewed_by = Column(
         Integer,
@@ -207,19 +271,16 @@ class Appeal(Base):
     created_at = Column(
         DateTime(timezone=True),
         server_default=func.now(),
-    )
+        nullable=False,
-
-    # Prevent duplicate open appeals per sanction
-    __table_args__ = (
-        UniqueConstraint("moderation_action_id", "user_id",
-                         name="uq_action_user_appeal"),
     )
 
     # Relationships
     moderation_action = relationship(
-        "ModerationAction",
+        "ModerationAction", back_populates="appeals"
-        back_populates="appeals",
+    )
+    reviewer = relationship("User", foreign_keys=[reviewed_by])
+
+    __table_args__ = (
+        Index("ix_appeals_status", "status"),
+        Index("ix_appeals_created_at", "created_at"),
     )
-    user = relationship("User", back_populates="appeals")
-    reviewed_by_user = relationship("User", back_populates="reviewed_appeals",
-                                    foreign_keys=[reviewed_by])

backend/app/models/user.py

@@ -1,7 +1,7 @@
-from datetime import date
+from datetime import date, datetime
 from typing import Optional
 
-from sqlalchemy import Column, Integer, String, Boolean, DateTime, Date
+from sqlalchemy import Column, Integer, String, Boolean, DateTime, Date, Enum
 from sqlalchemy.orm import relationship
 from sqlalchemy.sql import func
 
@@ -17,12 +17,45 @@ class User(Base):
     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: