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/0002_add_date_of_birth_to_users.py

@@ -1,30 +0,0 @@
-"""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/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

@@ -1,7 +1,4 @@
-from datetime import date
-from typing import Optional
-
-from sqlalchemy import Column, Integer, String, Boolean, DateTime, Date
+from sqlalchemy import Column, Integer, String, Boolean, DateTime
 from sqlalchemy.orm import relationship
 from sqlalchemy.sql import func
 
@@ -15,7 +12,6 @@ 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())
@@ -23,15 +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")
-
-    @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
+    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",
+    )

backend/app/routers/auth.py

@@ -1,10 +1,10 @@
 """Authentication router - login, register, token refresh."""
 
-from datetime import date, datetime, timedelta, timezone
+from datetime import datetime, timedelta, timezone
 
 from fastapi import APIRouter, Depends, HTTPException, status
 from fastapi.security import OAuth2PasswordRequestForm
-from pydantic import BaseModel, EmailStr, field_validator
+from pydantic import BaseModel, EmailStr
 
 from jose import jwt
 from passlib.context import CryptContext
@@ -32,24 +32,12 @@ 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
 
@@ -77,44 +65,11 @@ 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.
-
-    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})",
-        )
-
+    """Register a new user and return an access token."""
     # Check if username already exists
     result = await db.execute(select(User).where(User.username == req.username))
     if result.scalar_one_or_none():
@@ -135,7 +90,6 @@ 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

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

backend/tests/test_auth_age_gate.py

@@ -1,94 +0,0 @@
-"""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)

docs/planning/discovery.md

@@ -1,150 +0,0 @@
-# Discovery — Browse, Search & Home — Plan
-
-> **Status:** Planned
-> **Owner:** Platform team
-> **Feature ID:** `discovery`
-> **Godot version:** 4.6.2 stable
-> **Backend:** FastAPI + SQLAlchemy (async) + PostgreSQL + Redis
-
-## 1. Overview
-
-This document breaks the **Discovery** feature into user stories and
-right-sized implementation tasks. The feature delivers:
-
-- **Home / discover page** — a default listing of experiences a player lands on.
-- **Search** — find worlds by name and by tag.
-- **Categories** — a single category per world plus free-form tags, with
-  filtering.
-- **Simple sorting** — newest, most-played, and trending. Trending starts as a
-  basic **recent-activity heuristic** (weighted recent visits); no real
-  recommendation model for MVP.
-
-Without this, nothing else built (experiences, creator content) is actually
-reachable by a real user. Discovery is the front door.
-
-## 2. Why this matters
-
-The platform's value is *reachable* content. Worlds and creator assets already
-exist in the data model (`World`, `Asset`), but there is currently:
-
-- **No public listing** of worlds (`/api/worlds` requires auth and returns only
-  PUBLIC worlds or your own worlds, ordered by `created_at` only).
-- **No search** by name or tag.
-- **No category/tag metadata** on worlds at all.
-- **No play-count or recency signal** to power "most-played" or "trending".
-- **No client UI** for browsing.
-
-Discovery closes that gap with a small, dependency-free metadata layer plus a
-read-optimized listing endpoint.
-
-## 3. Existing constraints (do not re-build)
-
-- **Auth:** JWT bearer tokens; `get_current_user` / `CurrentUser` dependency in
-  `app/dependencies.py`. Discovery **listing** must work both for anonymous
-  visitors and authenticated users, so it needs an *optional* auth dependency
-  (not `CurrentUser`, which returns 401).
-- **DB:** async SQLAlchemy + Alembic; migration head is `0002_add_date_of_birth_to_users`.
-- **Models:** `World` (id, name, description, owner_id, visibility, created_at,
-  updated_at). `User`, `Asset` (owner_id, is_public) exist. No tags/categories/
-  play-count fields yet.
-- **Routers:** `worlds.py` already owns CRUD under `/api/worlds`. Discovery adds
-  a new read-focused router rather than overloading it.
-- **Redis:** configured (`REDIS_URL`) but unused; **not required** for discovery
-  MVP (Postgres queries are sufficient at this scale).
-- **Client:** Godot 4.6.2, minimal `main_menu.gd`; no networking client, no
-  discovery UI.
-
-## 4. Key design decisions
-
-| Concern | Decision |
-|---|---|
-| Listing transport | REST (`GET /api/discovery/worlds`) — no WebSocket needed for browse |
-| Anonymous browsing | Listing/read endpoints accept **optional** auth; visibility filtering treats anonymous users as "PUBLIC only" |
-| Categories | Single `category` string column on `worlds` (indexed). Free-form for MVP; a distinct-categories list is derived with a `SELECT DISTINCT` |
-| Tags | PostgreSQL `ARRAY(String)` column on `worlds` with a GIN index for `@>` tag containment search |
-| Play count | `play_count` integer (default 0) on `worlds`, incremented atomically on visit |
-| Recency signal | `last_played_at` timestamp on `worlds` + append-only `world_visits` table for the trending heuristic |
-| Trending (MVP) | Weighted score over recent visits: `sum(decay_weight(age))` over the last N days, no ML |
-| Sorting | `newest` (created_at desc), `most_played` (play_count desc), `trending` (score desc) |
-| Pagination | `skip`/`limit` (limit capped at 100), consistent with existing routers |
-| Visibility | Discovery only surfaces `PUBLIC` worlds; never leaks private/friends_only worlds |
-
-## 5. User stories
-
-### US-1 Home / discover feed
-As a player, I can open a home/discover page and see a default list of
-experiences without searching.
-
-**Acceptance criteria**
-- Returns PUBLIC worlds only, newest-first by default.
-- Paginated with a stable total count.
-- Works anonymously and authenticated.
-- Each result includes id, name, description, category, tags, owner, play_count,
-  and created_at.
-
-### US-2 Search
-As a player, I can search experiences by name and by tag.
-
-**Acceptance criteria**
-- Case-insensitive substring search on `name`.
-- Tag search matches worlds containing *any* of the requested tags.
-- Search combines with category filter and sort.
-
-### US-3 Categories & sorting
-As a player, I can filter by category and sort by newest, most-played, or
-trending.
-
-**Acceptance criteria**
-- `category` filter matches exactly (case-insensitive).
-- Distinct category list is available for UI dropdowns.
-- `newest`, `most_played`, and `trending` sorts are supported.
-- `most_played` uses `play_count`; `trending` uses the recent-visits heuristic.
-
-### US-4 Visit tracking
-As a player, opening a world records a visit so counts and trending stay fresh.
-
-**Acceptance criteria**
-- `POST /api/worlds/{id}/visit` increments `play_count` and updates
-  `last_played_at`.
-- Appends a `world_visits` row (world_id, user_id or anonymous marker,
-  visited_at).
-- Idempotent per request; rate-limitable later.
-
-### US-5 Godot client
-As a player, I can browse, search, filter, and sort experiences from the game UI.
-
-**Acceptance criteria**
-- An HTTP API client handles the discovery endpoints (JWT + anonymous).
-- A discover/home screen lists experiences with search, category filter, and
-  sort controls.
-- Results render name, category, tags, play count, and description.
-
-## 6. Task breakdown
-
-Right-sized to 1–3 files / one coherent piece of functionality each.
-
-| # | Task | Story | Depends on |
-|---|------|-------|-----------|
-| 1 | World discovery metadata + visits model & Alembic migration | US-2, US-3, US-4 | — |
-| 2 | World visit tracking endpoint (play count + last played + visit log) | US-4 | 1 |
-| 3 | Browse + search endpoint (name/tag/category, newest + most-played) | US-1, US-2, US-3 | 1, 2 |
-| 4 | Trending sort (recent-activity heuristic over `world_visits`) | US-3 | 3 |
-| 5 | Godot discovery API client (HTTP + optional JWT) | US-5 | 3 |
-| 6 | Godot discover/home UI (feed, search, category filter, sort) | US-5 | 4, 5 |
-
-## 7. Phasing
-
-- **Phase 1 (data + core read API):** tasks 1–3 (metadata, visit tracking,
-  browse/search).
-- **Phase 2 (trending):** task 4 — the only non-trivial query; isolated so it
-  can be tuned without touching the browse surface.
-- **Phase 3 (client):** tasks 5–6, each landing after its backend dependency.
-
-## 8. Out of scope for this feature
-
-- Real recommendation models / personalization (collaborative filtering, ML).
-- Full-text search (Postgres FTS); MVP uses ILIKE substring match.
-- Faceted search with multiple simultaneous category/tag AND-semantics.
-- Featured/editorial curation and admin-curated carousels.
-- Search result relevance scoring beyond the three explicit sorts.
-- Analytics dashboards; `world_visits` is append-only signal, not a BI surface.