WIP checkpoint: Chat data models + migration (conversations, messages, reports)

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, conversation, message  # noqa: F401
 
 # this is the Alembic Config object, which provides
 # access to the values within the .ini file in use.

backend/alembic/versions/1a1983be633a_chat_data_models.py

@@ -0,0 +1,228 @@
+"""chat data models
+
+Revision ID: 1a1983be633a
+Revises: 0001_initial
+Create Date: 2026-08-18 15:06:05.948446
+"""
+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 = "1a1983be633a"
+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:
+    """Create chat tables: conversations, conversation_participants,
+    messages, message_reports."""
+
+    # ── ENUM types ──────────────────────────────────────────────────
+
+    msg_report_reason = postgresql.ENUM(
+        "spam", "inappropriate", "off_topic", "other",
+        name="message_report_reason",
+    )
+    msg_report_reason.create(op.get_bind(), checkfirst=True)
+
+    msg_report_status = postgresql.ENUM(
+        "pending", "resolved", "dismissed",
+        name="message_report_status",
+    )
+    msg_report_status.create(op.get_bind(), checkfirst=True)
+
+    # ── conversations ───────────────────────────────────────────────
+
+    op.create_table(
+        "conversations",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column(
+            "latest_message_id",
+            sa.Integer(),
+            sa.ForeignKey("messages.id", ondelete="SET NULL"),
+            nullable=True,
+        ),
+        sa.Column(
+            "created_at",
+            sa.DateTime(timezone=True),
+            server_default=sa.func.now(),
+        ),
+        sa.Column(
+            "updated_at",
+            sa.DateTime(timezone=True),
+            server_default=sa.func.now(),
+            onupdate=sa.func.now(),
+        ),
+    )
+    op.create_index(op.f("ix_conversations_id"), "conversations", ["id"], unique=False)
+
+    # Unique pair constraint — populated later via participants
+    op.create_unique_constraint(
+        "uq_conversation_participants",
+        "conversations",
+        ["participant_1_id", "participant_2_id"],
+    )
+
+    # ── conversation_participants ───────────────────────────────────
+
+    op.create_table(
+        "conversation_participants",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column(
+            "conversation_id",
+            sa.Integer(),
+            sa.ForeignKey("conversations.id", ondelete="CASCADE"),
+            nullable=False,
+        ),
+        sa.Column(
+            "user_id",
+            sa.Integer(),
+            sa.ForeignKey("users.id", ondelete="CASCADE"),
+            nullable=False,
+        ),
+        sa.Column("left_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column("last_read_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column(
+            "created_at",
+            sa.DateTime(timezone=True),
+            server_default=sa.func.now(),
+        ),
+    )
+    op.create_index(
+        op.f("ix_conversation_participants_id"),
+        "conversation_participants",
+        ["id"],
+        unique=False,
+    )
+    op.create_index(
+        op.f("ix_conversation_participants_user_id"),
+        "conversation_participants",
+        ["user_id"],
+        unique=False,
+    )
+    op.create_unique_constraint(
+        "uq_conversation_user",
+        "conversation_participants",
+        ["conversation_id", "user_id"],
+    )
+
+    # ── messages ────────────────────────────────────────────────────
+
+    op.create_table(
+        "messages",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column(
+            "sender_id",
+            sa.Integer(),
+            sa.ForeignKey("users.id", ondelete="CASCADE"),
+            nullable=False,
+        ),
+        sa.Column(
+            "conversation_id",
+            sa.Integer(),
+            sa.ForeignKey("conversations.id", ondelete="CASCADE"),
+            nullable=True,
+        ),
+        sa.Column(
+            "world_id",
+            sa.Integer(),
+            sa.ForeignKey("worlds.id", ondelete="CASCADE"),
+            nullable=True,
+        ),
+        sa.Column("room_id", sa.String(length=36), nullable=True),
+        sa.Column("body", sa.Text(), nullable=False),
+        sa.Column("is_filtered", sa.Boolean(), nullable=False, server_default="false"),
+        sa.Column(
+            "created_at",
+            sa.DateTime(timezone=True),
+            server_default=sa.func.now(),
+        ),
+    )
+    op.create_index(op.f("ix_messages_id"), "messages", ["id"], unique=False)
+    op.create_index(
+        "ix_messages_conversation_created",
+        "messages",
+        ["conversation_id", "created_at"],
+    )
+    op.create_index(
+        "ix_messages_world_created",
+        "messages",
+        ["world_id", "created_at"],
+    )
+
+    # ── message_reports ─────────────────────────────────────────────
+
+    op.create_table(
+        "message_reports",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column(
+            "message_id",
+            sa.Integer(),
+            sa.ForeignKey("messages.id", ondelete="CASCADE"),
+            nullable=False,
+        ),
+        sa.Column(
+            "reporter_id",
+            sa.Integer(),
+            sa.ForeignKey("users.id", ondelete="SET NULL"),
+            nullable=False,
+        ),
+        sa.Column(
+            "reason",
+            postgresql.ENUM(
+                "spam", "inappropriate", "off_topic", "other",
+                name="message_report_reason",
+                create_type=False,
+            ),
+            nullable=False,
+        ),
+        sa.Column(
+            "status",
+            postgresql.ENUM(
+                "pending", "resolved", "dismissed",
+                name="message_report_status",
+                create_type=False,
+            ),
+            nullable=False,
+            server_default="pending",
+        ),
+        sa.Column(
+            "moderator_id",
+            sa.Integer(),
+            sa.ForeignKey("users.id", ondelete="SET NULL"),
+            nullable=True,
+        ),
+        sa.Column("resolved_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column(
+            "created_at",
+            sa.DateTime(timezone=True),
+            server_default=sa.func.now(),
+        ),
+    )
+    op.create_index(op.f("ix_message_reports_id"), "message_reports", ["id"], unique=False)
+
+
+def downgrade() -> None:
+    """Drop chat tables in reverse dependency order."""
+    op.drop_index(op.f("ix_message_reports_id"), table_name="message_reports")
+    op.drop_table("message_reports")
+
+    op.drop_index(op.f("ix_messages_world_created"), table_name="messages")
+    op.drop_index(op.f("ix_messages_conversation_created"), table_name="messages")
+    op.drop_index(op.f("ix_messages_id"), table_name="messages")
+    op.drop_table("messages")
+
+    op.drop_index(op.f("ix_conversation_participants_user_id"), table_name="conversation_participants")
+    op.drop_index(op.f("ix_conversation_participants_id"), table_name="conversation_participants")
+    op.drop_table("conversation_participants")
+
+    op.drop_index(op.f("ix_conversations_id"), table_name="conversations")
+    op.drop_table("conversations")
+
+    # Drop ENUM types
+    postgresql.ENUM(name="message_report_status").drop(op.get_bind(), checkfirst=True)
+    postgresql.ENUM(name="message_report_reason").drop(op.get_bind(), checkfirst=True)

backend/app/models/__init__.py

@@ -2,5 +2,16 @@ 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.conversation import Conversation, ConversationParticipant
+from app.models.message import Message, MessageReport
 
-__all__ = ["User", "Session", "World", "Asset"]
+__all__ = [
+    "User",
+    "Session",
+    "World",
+    "Asset",
+    "Conversation",
+    "ConversationParticipant",
+    "Message",
+    "MessageReport",
+]

backend/app/models/conversation.py

@@ -0,0 +1,94 @@
+"""Conversation and participant models for DM chat."""
+
+from sqlalchemy import (
+    Column,
+    Integer,
+    String,
+    DateTime,
+    ForeignKey,
+    UniqueConstraint,
+    Index,
+)
+from sqlalchemy.orm import relationship
+from sqlalchemy.sql import func
+
+from app.database import Base
+
+
+class Conversation(Base):
+    """A DM conversation between two users.
+
+    Each conversation is uniquely identified by the pair of participant
+    user IDs (regardless of order).  A conversation is soft-deletable
+    via ``left_at`` on the participant row.
+    """
+
+    __tablename__ = "conversations"
+
+    id = Column(Integer, primary_key=True, index=True)
+    # The most recent message's ID in this conversation (denormalised
+    # for fast listing; updated by triggers or app logic).
+    latest_message_id = Column(
+        Integer, ForeignKey("messages.id", ondelete="SET NULL"), nullable=True
+    )
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now())
+
+    # Relationships
+    latest_message = relationship(
+        "Message",
+        foreign_keys=[latest_message_id],
+        lazy="select",
+    )
+    participants = relationship(
+        "ConversationParticipant",
+        back_populates="conversation",
+        cascade="all, delete-orphan",
+        order_by="ConversationParticipant.id",
+    )
+
+    __table_args__ = (
+        # Ensure exactly one conversation per unique pair of users
+        UniqueConstraint("participant_1_id", "participant_2_id", name="uq_conversation_participants"),
+    )
+
+    def __repr__(self) -> str:
+        return f"<Conversation id={self.id}>"
+
+
+class ConversationParticipant(Base):
+    """Link table between conversations and users.
+
+    Stores per-participant metadata such as when they left the
+    conversation (for soft-delete / archival).
+    """
+
+    __tablename__ = "conversation_participants"
+
+    id = Column(Integer, primary_key=True, index=True)
+    conversation_id = Column(
+        Integer,
+        ForeignKey("conversations.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    user_id = Column(
+        Integer,
+        ForeignKey("users.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    # When the participant left (NULL = still active).
+    left_at = Column(DateTime(timezone=True), nullable=True)
+    # Timestamp of the last message read by this participant.
+    last_read_at = Column(DateTime(timezone=True), nullable=True)
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+
+    conversation = relationship("Conversation", back_populates="participants")
+    user = relationship("User")
+
+    __table_args__ = (
+        UniqueConstraint("conversation_id", "user_id", name="uq_conversation_user"),
+        Index("ix_conversation_participants_user_id", "user_id"),
+    )
+
+    def __repr__(self) -> str:
+        return f"<ConversationParticipant conversation_id={self.conversation_id} user_id={self.user_id}>"

backend/app/models/message.py

@@ -0,0 +1,96 @@
+"""Message models — messages, message reports."""
+
+from sqlalchemy import (
+    Column,
+    Integer,
+    String,
+    Text,
+    DateTime,
+    ForeignKey,
+    Boolean,
+    Index,
+)
+from sqlalchemy.dialects.postgresql import ENUM
+from sqlalchemy.orm import relationship
+from sqlalchemy.sql import func
+import enum
+
+from app.database import Base
+
+
+class MessageReportStatus(str, enum.Enum):
+    PENDING = "pending"
+    RESOLVED = "resolved"
+    DISMISSED = "dismissed"
+
+
+class MessageReportReason(str, enum.Enum):
+    SPAM = "spam"
+    INAPPROPRIATE = "inappropriate"
+    OFF_TOPIC = "off_topic"
+    OTHER = "other"
+
+
+class Message(Base):
+    __tablename__ = "messages"
+
+    id = Column(Integer, primary_key=True, index=True)
+    sender_id = Column(
+        Integer, ForeignKey("users.id", ondelete="CASCADE"), nullable=False
+    )
+    conversation_id = Column(
+        Integer, ForeignKey("conversations.id", ondelete="CASCADE"), nullable=True
+    )
+    world_id = Column(
+        Integer, ForeignKey("worlds.id", ondelete="CASCADE"), nullable=True
+    )
+    room_id = Column(String(36), nullable=True)
+    body = Column(Text, nullable=False)
+    is_filtered = Column(Boolean, default=False, nullable=False)
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+
+    # Relationships
+    sender = relationship("User", back_populates="sent_messages")
+    conversation = relationship("Conversation", back_populates="messages")
+    world = relationship("World")
+    reports = relationship(
+        "MessageReport", back_populates="message", cascade="all, delete-orphan"
+    )
+
+    # Indexes for history queries
+    __table_args__ = (
+        Index("ix_messages_conversation_created", "conversation_id", "created_at"),
+        Index("ix_messages_world_created", "world_id", "created_at"),
+    )
+
+
+class MessageReport(Base):
+    __tablename__ = "message_reports"
+
+    id = Column(Integer, primary_key=True, index=True)
+    message_id = Column(
+        Integer, ForeignKey("messages.id", ondelete="CASCADE"), nullable=False
+    )
+    reporter_id = Column(
+        Integer, ForeignKey("users.id", ondelete="SET NULL"), nullable=False
+    )
+    reason = Column(
+        ENUM(MessageReportReason, name="message_report_reason", create_type=False),
+        nullable=False,
+    )
+    details = Column(Text, nullable=True)
+    status = Column(
+        ENUM(MessageReportStatus, name="message_report_status", create_type=False),
+        default=MessageReportStatus.PENDING,
+        nullable=False,
+    )
+    moderator_id = Column(
+        Integer, ForeignKey("users.id", ondelete="SET NULL"), nullable=True
+    )
+    resolved_at = Column(DateTime(timezone=True), nullable=True)
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+
+    # Relationships
+    message = relationship("Message", back_populates="reports")
+    reporter = relationship("User", foreign_keys=[reporter_id])
+    moderator = relationship("User", foreign_keys=[moderator_id])

backend/app/models/user.py

@@ -19,3 +19,14 @@ 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")
+    sent_messages = relationship("Message", back_populates="sender")
+    reported_messages = relationship(
+        "MessageReport",
+        foreign_keys="MessageReport.reporter_id",
+        back_populates="reporter",
+    )
+    moderated_reports = relationship(
+        "MessageReport",
+        foreign_keys="MessageReport.moderator_id",
+        back_populates="moderator",
+    )