feat(discovery): world discovery metadata and world_visits model with migration 0015

backend/app/models/__init__.py

@@ -15,6 +15,7 @@ from app.models.marketplace import (
     CatalogItem, MarketplaceListing, Purchase, CreatorBalance,
     ItemType, ListingStatus, PurchaseStatus,
 )
+from app.models.world_visit import WorldVisit
 
 __all__ = [
     "User", "Session", "World", "Asset", "AvatarLoadout",
@@ -26,4 +27,5 @@ __all__ = [
     "Wallet", "Transaction", "TransactionType",
     "CatalogItem", "MarketplaceListing", "Purchase", "CreatorBalance",
     "ItemType", "ListingStatus", "PurchaseStatus",
+    "WorldVisit",
 ]

backend/app/models/world.py

@@ -1,5 +1,5 @@
-from sqlalchemy import Column, Integer, String, Text, DateTime, ForeignKey
-from sqlalchemy.dialects.postgresql import ENUM
+from sqlalchemy import Column, Integer, String, Text, DateTime, ForeignKey, Index
+from sqlalchemy.dialects.postgresql import ENUM, ARRAY
 from sqlalchemy.orm import relationship
 from sqlalchemy.sql import func
 import enum
@@ -29,11 +29,19 @@ class World(Base):
         ),
         default=WorldVisibility.PUBLIC,
     )
+    category = Column(String(100), nullable=True, index=True)
+    tags = Column(ARRAY(String), nullable=True, server_default="{}")
+    play_count = Column(Integer, nullable=False, server_default="0", index=True)
+    last_played_at = 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())
 
+    __table_args__ = (
+        Index("ix_worlds_tags", "tags", postgresql_using="gin"),
+    )
+
     owner = relationship("User", back_populates="worlds")
     assets = relationship("Asset", back_populates="world", cascade="all, delete-orphan")
-    # world_content.py / world_persistence_impl.md §4.1. Added here (only)
-    # so PC1/PC2 code depending on this module is otherwise untouched.
     rooms = relationship("WorldRoom", back_populates="world", cascade="all, delete-orphan")
+    visits = relationship("WorldVisit", back_populates="world", cascade="all, delete-orphan")
+

backend/app/models/world_visit.py

@@ -0,0 +1,27 @@
+"""World visit tracking model for discovery analytics.
+
+docs/planning/discovery.md (task b377353b8167).
+"""
+
+from sqlalchemy import Column, Integer, String, DateTime, ForeignKey, Index
+from sqlalchemy.orm import relationship
+from sqlalchemy.sql import func
+
+from app.database import Base
+
+
+class WorldVisit(Base):
+    __tablename__ = "world_visits"
+
+    id = Column(Integer, primary_key=True, index=True)
+    world_id = Column(Integer, ForeignKey("worlds.id", ondelete="CASCADE"), nullable=False, index=True)
+    user_id = Column(Integer, ForeignKey("users.id", ondelete="SET NULL"), nullable=True, index=True)
+    anonymous_token = Column(String(255), nullable=True)
+    visited_at = Column(DateTime(timezone=True), server_default=func.now(), nullable=False, index=True)
+
+    __table_args__ = (
+        Index("ix_world_visits_world_visited_at", "world_id", "visited_at"),
+    )
+
+    world = relationship("World", back_populates="visits")
+    user = relationship("User")