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

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])