Add PC1 checkpoint record + playtest instructions

Validation results from the 2026-08-20 checkpoint run (fresh clone,
commit 927f9bd: migrations, 68/68 pytest, all 4 Godot smoke tests, both
platform exports) plus manual playtest instructions for backend on
cloudbison / client on pinkbison. First of docs/checkpoints/PC<N>.md,
one per Package Checkpoint going forward.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,13 @@
+# Godot 4 editor cache/import directory
+.godot/
+
+# Godot export artifacts
+export/
+*.tmp
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Godot UID files (regenerated from path)
+*.uid

backend/.env.example

@@ -0,0 +1,23 @@
+# Database (async driver)
+DATABASE_URL=postgresql+asyncpg://agp_user:agp_password@localhost:5432/agp_db
+
+# Redis
+REDIS_URL=redis://localhost:6379/0
+
+# JWT / Auth
+ALGORITHM=RS256
+ACCESS_TOKEN_EXPIRE_MINUTES=60
+REFRESH_TOKEN_EXPIRE_DAYS=30
+# Directory where the RSA keypair is loaded/generated at runtime.
+# Defaults to ~/.agp/keys (outside the repo). Keys are never committed to git.
+RSA_KEY_DIR=~/.agp/keys
+
+# App
+APP_NAME=AGP Backend
+APP_VERSION=0.1.0
+DEBUG=true
+CORS_ORIGINS=http://localhost:8080,http://localhost:3000
+
+# File uploads
+UPLOAD_DIR=uploads
+MAX_UPLOAD_SIZE_MB=100

backend/.gitignore

@@ -0,0 +1,4 @@
+.env
+__pycache__/
+*.pyc
+.venv/

backend/alembic.ini

@@ -0,0 +1,42 @@
+# Alembic configuration file.
+# Run: alembic upgrade head  (to apply migrations)
+# Run: alembic revision --autogenerate -m "description"  (to generate migration)
+
+[alembic]
+script_location = alembic
+prepend_sys_path = .
+sqlalchemy.url = postgresql+asyncpg://agp_user:agp_password@localhost:5432/agp_db
+
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARN
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARN
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s
+datefmt = %H:%M:%S

backend/alembic/env.py

@@ -0,0 +1,65 @@
+"""Alembic environment configuration."""
+
+import asyncio
+from logging.config import fileConfig
+
+from alembic import context
+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
+
+# this is the Alembic Config object, which provides
+# access to the values within the .ini file in use.
+config = context.config
+
+# Interpret the config file for Python logging.
+# This line sets up loggers basically.
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+# add your model's MetaData object here
+# for 'autogenerate' support
+target_metadata = Base.metadata
+
+
+def run_migrations_offline() -> None:
+    """Run migrations in 'offline' mode."""
+    url = settings.DATABASE_URL
+    context.configure(
+        url=url,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def do_run_migrations(connection):
+    context.configure(connection=connection, target_metadata=target_metadata)
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+async def run_async_migrations():
+    """Run migrations in 'online' mode with async engine."""
+    connectable = create_async_engine(settings.DATABASE_URL, echo=False)
+
+    async with connectable.connect() as connection:
+        await connection.run_sync(do_run_migrations)
+
+    await connectable.dispose()
+
+
+def run_migrations_online() -> None:
+    """Run migrations in 'online' mode."""
+    asyncio.run(run_async_migrations())
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()

backend/alembic/script.py.mako

@@ -0,0 +1,27 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision: str = ${repr(up_revision)}
+down_revision: Union[str, None] = ${repr(down_revision)}
+branch_labels: Union[str, Sequence[str], None] = ${repr(branch_labels)}
+depends_on: Union[str, Sequence[str], None] = ${repr(depends_on)}
+
+
+def upgrade() -> None:
+    """Upgrade database schema."""
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    """Downgrade database schema."""
+    ${downgrades if downgrades else "pass"}

backend/alembic/versions/0001_initial.py

@@ -0,0 +1,127 @@
+"""initial schema
+
+Revision ID: 0001_initial
+Revises:
+Create Date: 2024-01-01 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 = "0001_initial"
+down_revision: Union[str, None] = None
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Upgrade database schema."""
+    # Create ENUM types
+    world_visibility = postgresql.ENUM(
+        "public", "private", "friends_only", name="world_visibility"
+    )
+    world_visibility.create(op.get_bind(), checkfirst=True)
+
+    asset_type = postgresql.ENUM(
+        "image", "audio", "video", "document", "model_3d", "other", name="asset_type"
+    )
+    asset_type.create(op.get_bind(), checkfirst=True)
+
+    # Create users table
+    op.create_table(
+        "users",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column("username", sa.String(length=50), nullable=False),
+        sa.Column("email", sa.String(length=120), nullable=False),
+        sa.Column("hashed_password", sa.String(length=255), nullable=False),
+        sa.Column("is_active", sa.Boolean(), nullable=True),
+        sa.Column("created_at", sa.DateTime(timezone=True), server_default=sa.func.now()),
+        sa.Column("updated_at", sa.DateTime(timezone=True), nullable=True),
+    )
+    op.create_index(op.f("ix_users_email"), "users", ["email"], unique=True)
+    op.create_index(op.f("ix_users_id"), "users", ["id"], unique=False)
+    op.create_index(op.f("ix_users_username"), "users", ["username"], unique=True)
+
+    # Create sessions table
+    op.create_table(
+        "sessions",
+        sa.Column("id", sa.String(length=36), primary_key=True),
+        sa.Column("user_id", sa.Integer(), nullable=False),
+        sa.Column("token", sa.String(), nullable=False),
+        sa.Column("expires_at", sa.DateTime(timezone=True), nullable=False),
+        sa.Column("is_active", sa.Boolean(), 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()),
+        sa.ForeignKeyConstraint(["user_id"], ["users.id"], ondelete="CASCADE"),
+    )
+    op.create_index(op.f("ix_sessions_token"), "sessions", ["token"], unique=True)
+
+    # Create worlds table
+    op.create_table(
+        "worlds",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column("name", sa.String(length=255), nullable=False),
+        sa.Column("description", sa.Text(), nullable=True),
+        sa.Column("owner_id", sa.Integer(), nullable=False),
+        sa.Column(
+            "visibility",
+            postgresql.ENUM(
+                "public", "private", "friends_only", name="world_visibility",
+                create_type=False,
+            ),
+            nullable=True,
+        ),
+        sa.Column("created_at", sa.DateTime(timezone=True), server_default=sa.func.now()),
+        sa.Column("updated_at", sa.DateTime(timezone=True), nullable=True),
+        sa.ForeignKeyConstraint(["owner_id"], ["users.id"]),
+    )
+    op.create_index(op.f("ix_worlds_id"), "worlds", ["id"], unique=False)
+
+    # Create assets table
+    op.create_table(
+        "assets",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column("name", sa.String(length=255), nullable=False),
+        sa.Column("description", sa.Text(), nullable=True),
+        sa.Column(
+            "asset_type",
+            postgresql.ENUM(
+                "image", "audio", "video", "document", "model_3d", "other",
+                name="asset_type", create_type=False,
+            ),
+            nullable=False,
+        ),
+        sa.Column("file_path", sa.String(length=512), nullable=False),
+        sa.Column("file_size", sa.Integer(), nullable=True),
+        sa.Column("mime_type", sa.String(length=128), nullable=True),
+        sa.Column("metadata_json", sa.Text(), nullable=True),
+        sa.Column("world_id", sa.Integer(), nullable=True),
+        sa.Column("owner_id", sa.Integer(), nullable=False),
+        sa.Column("is_public", sa.Boolean(), nullable=False),
+        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()),
+        sa.ForeignKeyConstraint(["owner_id"], ["users.id"]),
+        sa.ForeignKeyConstraint(["world_id"], ["worlds.id"]),
+    )
+    op.create_index(op.f("ix_assets_id"), "assets", ["id"], unique=False)
+
+
+def downgrade() -> None:
+    """Downgrade database schema."""
+    op.drop_index(op.f("ix_assets_id"), table_name="assets")
+    op.drop_table("assets")
+    op.drop_index(op.f("ix_worlds_id"), table_name="worlds")
+    op.drop_table("worlds")
+    op.drop_index(op.f("ix_sessions_token"), table_name="sessions")
+    op.drop_table("sessions")
+    op.drop_index(op.f("ix_users_username"), table_name="users")
+    op.drop_index(op.f("ix_users_id"), table_name="users")
+    op.drop_index(op.f("ix_users_email"), table_name="users")
+    op.drop_table("users")
+
+    # Drop ENUM types
+    postgresql.ENUM(name="asset_type").drop(op.get_bind(), checkfirst=True)
+    postgresql.ENUM(name="world_visibility").drop(op.get_bind(), checkfirst=True)

backend/alembic/versions/0002_add_date_of_birth_to_users.py

@@ -0,0 +1,30 @@
+"""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/0003_add_refresh_tokens_table.py

@@ -0,0 +1,36 @@
+"""add refresh_tokens table
+
+Revision ID: 0003_add_refresh_tokens_table
+Revises: 0002_add_date_of_birth_to_users
+Create Date: 2025-07-25 00:00:00.000000
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+# revision identifiers, used by Alembic.
+revision: str = "0003_add_refresh_tokens_table"
+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:
+    """Create the refresh_tokens table."""
+    op.create_table(
+        "refresh_tokens",
+        sa.Column("id", sa.String(36), primary_key=True),
+        sa.Column("user_id", sa.Integer(), sa.ForeignKey("users.id", ondelete="CASCADE"), nullable=False),
+        sa.Column("token", sa.String(512), unique=True, index=True, nullable=False),
+        sa.Column("expires_at", sa.DateTime(timezone=True), nullable=False),
+        sa.Column("is_active", sa.Boolean(), server_default=sa.text("true"), nullable=False),
+        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),
+    )
+
+
+def downgrade() -> None:
+    """Drop the refresh_tokens table."""
+    op.drop_table("refresh_tokens")

backend/app/config.py

@@ -0,0 +1,127 @@
+"""Application configuration via pydantic-settings."""
+
+from functools import lru_cache
+from pathlib import Path
+
+from cryptography.hazmat.primitives.asymmetric.rsa import (
+    RSAPrivateKey,
+    RSAPublicKey,
+    generate_private_key,
+)
+from cryptography.hazmat.primitives.serialization import (
+    Encoding,
+    NoEncryption,
+    PrivateFormat,
+    PublicFormat,
+    load_pem_private_key,
+    load_pem_public_key,
+)
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+def _load_or_generate_rsa_keys(key_dir: Path) -> tuple[bytes, bytes]:
+    """Load existing RSA keys or generate a new pair.
+
+    Keys are stored as PEM files in *key_dir*.  The directory is created
+    if it does not exist.  Files are named ``private.pem`` and
+    ``public.pem`` and are **not** committed to git.
+    """
+    private_path = key_dir / "private.pem"
+    public_path = key_dir / "public.pem"
+
+    if private_path.exists() and public_path.exists():
+        private_pem = private_path.read_bytes()
+        public_pem = public_path.read_bytes()
+    else:
+        # Generate a new 2048-bit RSA key pair
+        private_key = generate_private_key(public_exponent=65537, key_size=2048)
+        private_pem = private_key.private_bytes(
+            Encoding.PEM,
+            PrivateFormat.PKCS8,
+            NoEncryption(),
+        )
+        public_pem = private_key.public_key().public_bytes(
+            Encoding.PEM,
+            PublicFormat.SubjectPublicKeyInfo,
+        )
+        key_dir.mkdir(parents=True, exist_ok=True)
+        private_path.write_bytes(private_pem)
+        public_path.write_bytes(public_pem)
+
+    return private_pem, public_pem
+
+
+class Settings(BaseSettings):
+    # App
+    APP_NAME: str = "AGP Backend"
+    APP_VERSION: str = "0.1.0"
+    DEBUG: bool = True
+
+    # Database (async)
+    DATABASE_URL: str = "postgresql+asyncpg://agp_user:agp_password@localhost:5432/agp_db"
+
+    # Redis
+    REDIS_URL: str = "redis://localhost:6379/0"
+
+    # JWT / Auth
+    ALGORITHM: str = "RS256"
+    ACCESS_TOKEN_EXPIRE_MINUTES: int = 60
+    REFRESH_TOKEN_EXPIRE_DAYS: int = 30
+
+    # RS256 key storage.  Defaults to a directory outside the repo so the
+    # generated keypair is never accidentally committed.
+    RSA_KEY_DIR: str = str(Path.home() / ".agp" / "keys")
+
+    # CORS
+    CORS_ORIGINS: str = "http://localhost:8080,http://localhost:3000"
+
+    # File uploads
+    UPLOAD_DIR: str = "uploads"
+    MAX_UPLOAD_SIZE_MB: int = 100
+    GLTF_MAX_FILE_SIZE_MB: int = 200
+
+    model_config = SettingsConfigDict(
+        env_file=".env",
+        env_file_encoding="utf-8",
+        case_sensitive=True,
+    )
+
+    @property
+    def cors_origins_list(self) -> list[str]:
+        return [origin.strip() for origin in self.CORS_ORIGINS.split(",")]
+
+    @property
+    def rsa_key_dir(self) -> Path:
+        return Path(self.RSA_KEY_DIR)
+
+    @property
+    def private_pem(self) -> bytes:
+        """Return the private key PEM bytes (loads/generates on first call)."""
+        private_pem, _ = _load_or_generate_rsa_keys(self.rsa_key_dir)
+        return private_pem
+
+    @property
+    def public_pem(self) -> bytes:
+        """Return the public key PEM bytes (loads/generates on first call)."""
+        _, public_pem = _load_or_generate_rsa_keys(self.rsa_key_dir)
+        return public_pem
+
+    @property
+    def private_key(self) -> RSAPrivateKey:
+        """Return the deserialized RSA private key object."""
+        return load_pem_private_key(self.private_pem, password=None)
+
+    @property
+    def public_key(self) -> RSAPublicKey:
+        """Return the deserialized RSA public key object."""
+        return load_pem_public_key(self.public_pem)
+
+
+@lru_cache()
+def get_settings() -> Settings:
+    """Return cached settings instance."""
+    return Settings()
+
+
+# Convenience singleton
+settings = get_settings()

backend/app/database.py

@@ -0,0 +1,42 @@
+"""Async database engine and session factory."""
+
+from sqlalchemy.ext.asyncio import (
+    AsyncSession,
+    async_sessionmaker,
+    create_async_engine,
+)
+from sqlalchemy.orm import DeclarativeBase
+
+from app.config import settings
+
+engine = create_async_engine(
+    settings.DATABASE_URL,
+    echo=settings.DEBUG,
+    pool_size=10,
+    max_overflow=20,
+)
+
+async_session_factory = async_sessionmaker(
+    engine,
+    class_=AsyncSession,
+    expire_on_commit=False,
+)
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+async def get_db() -> AsyncSession:
+    """Dependency that yields an async database session.
+
+    Handlers are responsible for committing or rolling back their own
+    transactions.  This avoids the double-commit problem where the
+    session is committed both here and in the handler.
+    """
+    async with async_session_factory() as session:
+        try:
+            yield session
+        except Exception:
+            await session.rollback()
+            raise

backend/app/dependencies.py

@@ -0,0 +1,55 @@
+"""Shared FastAPI dependencies, including JWT-based auth."""
+
+from typing import Annotated
+
+from fastapi import Depends, HTTPException, status
+from fastapi.security import OAuth2PasswordBearer
+from jose import JWTError, jwt
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.config import settings
+from app.database import get_db
+from app.models.user import User
+
+oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/auth/login")
+
+
+async def get_current_user(
+    token: Annotated[str, Depends(oauth2_scheme)],
+    db: Annotated[AsyncSession, Depends(get_db)],
+) -> User:
+    """Resolve the JWT bearer token to a User, or raise 401."""
+    credentials_exception = HTTPException(
+        status_code=status.HTTP_401_UNAUTHORIZED,
+        detail="Could not validate credentials",
+        headers={"WWW-Authenticate": "Bearer"},
+    )
+    try:
+        payload = jwt.decode(
+            token, settings.public_pem, algorithms=[settings.ALGORITHM]
+        )
+        user_id: str | None = payload.get("sub")
+        if user_id is None:
+            raise credentials_exception
+    except JWTError:
+        raise credentials_exception
+
+    try:
+        user_id_int = int(user_id)
+    except (ValueError, TypeError):
+        raise credentials_exception
+
+    result = await db.execute(select(User).where(User.id == user_id_int))
+    user = result.scalar_one_or_none()
+    if user is None:
+        raise credentials_exception
+    if not user.is_active:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail="User account is inactive",
+        )
+    return user
+
+
+CurrentUser = Annotated[User, Depends(get_current_user)]

backend/app/main.py

@@ -0,0 +1,46 @@
+"""FastAPI application entry point."""
+
+from contextlib import asynccontextmanager
+
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+
+from app.config import settings
+from app.routers import auth, users, worlds, assets
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    """Application lifespan: startup and shutdown events."""
+    # Startup: initialize database, connect to Redis, etc.
+    yield
+    # Shutdown: close connections, cleanup
+
+
+app = FastAPI(
+    title=settings.APP_NAME,
+    version=settings.APP_VERSION,
+    description="Agentic Game Platform - Backend API",
+    lifespan=lifespan,
+)
+
+# CORS
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=settings.cors_origins_list,
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+# Include routers
+app.include_router(auth.router, prefix="/api/auth", tags=["auth"])
+app.include_router(users.router, prefix="/api/users", tags=["users"])
+app.include_router(worlds.router, prefix="/api/worlds", tags=["worlds"])
+app.include_router(assets.router, prefix="/api/assets", tags=["assets"])
+
+
+@app.get("/api/health")
+async def health_check():
+    """Simple health check endpoint."""
+    return {"status": "ok", "app": settings.APP_NAME}

backend/app/models/__init__.py

@@ -0,0 +1,6 @@
+from app.models.user import User
+from app.models.session import Session
+from app.models.world import World
+from app.models.asset import Asset
+
+__all__ = ["User", "Session", "World", "Asset"]

backend/app/models/asset.py

@@ -0,0 +1,40 @@
+from sqlalchemy import Column, Integer, String, ForeignKey, Text, DateTime, Boolean
+from sqlalchemy.dialects.postgresql import ENUM
+from sqlalchemy.orm import relationship
+from sqlalchemy.sql import func
+import enum
+
+from app.database import Base
+
+
+class AssetType(str, enum.Enum):
+    IMAGE = "image"
+    AUDIO = "audio"
+    VIDEO = "video"
+    DOCUMENT = "document"
+    MODEL_3D = "model_3d"
+    OTHER = "other"
+
+
+class Asset(Base):
+    __tablename__ = "assets"
+
+    id = Column(Integer, primary_key=True, index=True)
+    name = Column(String(255), nullable=False)
+    description = Column(Text, nullable=True)
+    asset_type = Column(
+        ENUM(AssetType, name="asset_type", create_type=False),
+        nullable=False,
+    )
+    file_path = Column(String(512), nullable=False)
+    file_size = Column(Integer, nullable=True)
+    mime_type = Column(String(128), nullable=True)
+    metadata_json = Column(Text, nullable=True)
+    world_id = Column(Integer, ForeignKey("worlds.id"), nullable=True)
+    owner_id = Column(Integer, ForeignKey("users.id"), nullable=False)
+    is_public = Column(Boolean, default=False, nullable=False)
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now())
+
+    owner = relationship("User", back_populates="assets")
+    world = relationship("World", back_populates="assets")

backend/app/models/session.py

@@ -0,0 +1,41 @@
+import uuid
+
+from sqlalchemy import Column, Integer, String, DateTime, ForeignKey, Boolean
+from sqlalchemy.orm import relationship
+from sqlalchemy.sql import func
+
+from app.database import Base
+
+
+class Session(Base):
+    __tablename__ = "sessions"
+
+    id = Column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
+    user_id = Column(Integer, ForeignKey("users.id", ondelete="CASCADE"), nullable=False)
+    token = Column(String, unique=True, index=True, nullable=False)
+    expires_at = Column(DateTime(timezone=True), nullable=False)
+    is_active = Column(Boolean, default=True)
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now())
+
+    user = relationship("User", back_populates="sessions")
+
+
+class RefreshToken(Base):
+    __tablename__ = "refresh_tokens"
+
+    id = Column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
+    user_id = Column(Integer, ForeignKey("users.id", ondelete="CASCADE"), nullable=False)
+    # RS256 JWTs are ~420+ chars; 512 is sufficient and matches the migration.
+    token = Column(String(512), unique=True, index=True, nullable=False)
+    expires_at = Column(DateTime(timezone=True), nullable=False)
+    is_active = Column(Boolean, nullable=False, default=True, server_default="true")
+    created_at = Column(DateTime(timezone=True), nullable=False, server_default=func.now())
+    updated_at = Column(
+        DateTime(timezone=True),
+        nullable=False,
+        server_default=func.now(),
+        onupdate=func.now(),
+    )
+
+    user = relationship("User", back_populates="refresh_tokens")

backend/app/models/user.py

@@ -0,0 +1,38 @@
+from datetime import date
+from typing import Optional
+
+from sqlalchemy import Column, Integer, String, Boolean, DateTime, Date
+from sqlalchemy.orm import relationship
+from sqlalchemy.sql import func
+
+from app.database import Base
+
+
+class User(Base):
+    __tablename__ = "users"
+
+    id = Column(Integer, primary_key=True, index=True)
+    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())
+
+    sessions = relationship("Session", back_populates="user", cascade="all, delete-orphan")
+    refresh_tokens = relationship("RefreshToken", 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

backend/app/models/world.py

@@ -0,0 +1,36 @@
+from sqlalchemy import Column, Integer, String, Text, DateTime, ForeignKey
+from sqlalchemy.dialects.postgresql import ENUM
+from sqlalchemy.orm import relationship
+from sqlalchemy.sql import func
+import enum
+
+from app.database import Base
+
+
+class WorldVisibility(enum.Enum):
+    PUBLIC = "public"
+    PRIVATE = "private"
+    FRIENDS_ONLY = "friends_only"
+
+
+class World(Base):
+    __tablename__ = "worlds"
+
+    id = Column(Integer, primary_key=True, index=True)
+    name = Column(String(255), nullable=False)
+    description = Column(Text, nullable=True)
+    owner_id = Column(Integer, ForeignKey("users.id"), nullable=False)
+    visibility = Column(
+        ENUM(
+            WorldVisibility,
+            name="world_visibility",
+            create_type=False,
+            values_callable=lambda enum_cls: [e.value for e in enum_cls],
+        ),
+        default=WorldVisibility.PUBLIC,
+    )
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), onupdate=func.now())
+
+    owner = relationship("User", back_populates="worlds")
+    assets = relationship("Asset", back_populates="world", cascade="all, delete-orphan")

backend/app/routers/assets.py

@@ -0,0 +1,243 @@
+"""Asset management router."""
+
+import json
+import os
+from pathlib import Path
+from typing import Optional
+
+from fastapi import APIRouter, Depends, HTTPException, UploadFile, File, Query
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.config import settings
+from app.database import get_db
+from app.dependencies import CurrentUser
+from app.models.asset import Asset, AssetType
+from app.models.world import World
+from app.services import gltf as gltf_service
+from pydantic import BaseModel, Field
+
+router = APIRouter()
+
+
+# --- Pydantic schemas ---
+
+class AssetCreate(BaseModel):
+    """Schema for creating an asset reference."""
+    name: str = Field(..., min_length=1, max_length=255)
+    description: Optional[str] = None
+    asset_type: AssetType
+    world_id: Optional[int] = None
+
+
+class AssetResponse(BaseModel):
+    """Schema for asset responses."""
+    id: int
+    name: str
+    description: Optional[str]
+    asset_type: AssetType
+    file_path: str
+    file_size: Optional[int]
+    mime_type: Optional[str]
+    world_id: Optional[int]
+    owner_id: int
+    is_public: bool
+    created_at: str
+    updated_at: str
+
+    model_config = {"from_attributes": True}
+
+
+class AssetUpdate(BaseModel):
+    """Schema for updating an asset."""
+    name: Optional[str] = None
+    description: Optional[str] = None
+    is_public: Optional[bool] = None
+
+
+# --- Helpers ---
+
+def _sanitize_filename(filename: str) -> str:
+    """Strip path components and unsafe characters from a filename."""
+    # Remove any directory components (path traversal protection).
+    base = os.path.basename(filename.replace("\\", "/"))
+    # Keep only safe characters.
+    safe = "".join(c for c in base if c.isalnum() or c in "._-")
+    return safe or "file"
+
+
+def _detect_asset_type(filename: Optional[str], content: bytes) -> AssetType:
+    """Detect the asset type from filename and content."""
+    if filename and gltf_service.looks_like_gltf(content, filename):
+        return AssetType.MODEL_3D
+    # Fallback: let the caller decide based on mime_type or default.
+    return AssetType.OTHER
+
+
+# --- Endpoints ---
+
+@router.post("/", response_model=AssetResponse, status_code=201)
+async def create_asset(
+    payload: AssetCreate,
+    current_user: CurrentUser,
+    db: AsyncSession = Depends(get_db),
+):
+    """Create a new asset reference."""
+    # Verify world ownership if world_id is provided
+    if payload.world_id is not None:
+        world = await db.get(World, payload.world_id)
+        if world is None:
+            raise HTTPException(status_code=404, detail="World not found")
+        if world.owner_id != current_user.id:
+            raise HTTPException(status_code=403, detail="Not owner of this world")
+
+    asset = Asset(
+        name=payload.name,
+        description=payload.description,
+        asset_type=payload.asset_type,
+        file_path="",  # Will be set after upload
+        owner_id=current_user.id,
+        world_id=payload.world_id,
+        is_public=False,
+    )
+    db.add(asset)
+    await db.commit()
+    await db.refresh(asset)
+    return asset
+
+
+@router.get("/", response_model=list[AssetResponse])
+async def list_assets(
+    current_user: CurrentUser,
+    world_id: Optional[int] = Query(None, description="Filter by world"),
+    asset_type: Optional[AssetType] = Query(None),
+    limit: int = Query(50, ge=1, le=100),
+    offset: int = Query(0, ge=0),
+    db: AsyncSession = Depends(get_db),
+):
+    """List assets with optional filters."""
+    stmt = select(Asset).where(Asset.owner_id == current_user.id)
+
+    if world_id is not None:
+        stmt = stmt.where(Asset.world_id == world_id)
+    if asset_type is not None:
+        stmt = stmt.where(Asset.asset_type == asset_type)
+
+    stmt = stmt.order_by(Asset.created_at.desc()).limit(limit).offset(offset)
+    result = await db.execute(stmt)
+    assets = result.scalars().all()
+    return assets
+
+
+@router.get("/{asset_id}", response_model=AssetResponse)
+async def get_asset(
+    asset_id: int,
+    current_user: CurrentUser,
+    db: AsyncSession = Depends(get_db),
+):
+    """Get a single asset by ID."""
+    asset = await db.get(Asset, asset_id)
+    if asset is None or asset.owner_id != current_user.id:
+        raise HTTPException(status_code=404, detail="Asset not found")
+    return asset
+
+
+@router.patch("/{asset_id}", response_model=AssetResponse)
+async def update_asset(
+    asset_id: int,
+    payload: AssetUpdate,
+    current_user: CurrentUser,
+    db: AsyncSession = Depends(get_db),
+):
+    """Update an asset."""
+    asset = await db.get(Asset, asset_id)
+    if asset is None or asset.owner_id != current_user.id:
+        raise HTTPException(status_code=404, detail="Asset not found")
+
+    update_data = payload.model_dump(exclude_unset=True)
+    for field, value in update_data.items():
+        setattr(asset, field, value)
+
+    await db.commit()
+    await db.refresh(asset)
+    return asset
+
+
+@router.delete("/{asset_id}", status_code=204)
+async def delete_asset(
+    asset_id: int,
+    current_user: CurrentUser,
+    db: AsyncSession = Depends(get_db),
+):
+    """Delete an asset."""
+    asset = await db.get(Asset, asset_id)
+    if asset is None or asset.owner_id != current_user.id:
+        raise HTTPException(status_code=404, detail="Asset not found")
+
+    await db.delete(asset)
+    await db.commit()
+
+
+@router.post("/{asset_id}/upload", response_model=AssetResponse)
+async def upload_asset_file(
+    asset_id: int,
+    current_user: CurrentUser,
+    file: UploadFile = File(...),
+    db: AsyncSession = Depends(get_db),
+):
+    """Upload a file for an existing asset."""
+    asset = await db.get(Asset, asset_id)
+    if asset is None or asset.owner_id != current_user.id:
+        raise HTTPException(status_code=404, detail="Asset not found")
+
+    # Sanitize filename to prevent path traversal.
+    safe_filename = _sanitize_filename(file.filename or f"asset_{asset_id}")
+
+    # Read the file content.
+    content = await file.read()
+    file_size = len(content)
+
+    # Determine which size limit to apply.
+    if gltf_service.looks_like_gltf(content, file.filename):
+        max_bytes = settings.GLTF_MAX_FILE_SIZE_MB * 1024 * 1024
+    else:
+        max_bytes = settings.MAX_UPLOAD_SIZE_MB * 1024 * 1024
+
+    if file_size > max_bytes:
+        raise HTTPException(
+            status_code=413,
+            detail=f"File size {file_size} exceeds maximum allowed size {max_bytes} bytes",
+        )
+
+    # Write the file to the upload directory.
+    upload_dir = Path(settings.UPLOAD_DIR)
+    upload_dir.mkdir(parents=True, exist_ok=True)
+    stored_name = f"{asset_id}_{safe_filename}"
+    file_path = upload_dir / stored_name
+    file_path.write_bytes(content)
+
+    # Detect asset type from content/filename.
+    detected_type = _detect_asset_type(file.filename, content)
+
+    # Update asset record.
+    asset.file_path = str(file_path)
+    asset.mime_type = file.content_type
+    asset.file_size = file_size
+
+    # If this is a glTF file, extract and store metadata.
+    if detected_type == AssetType.MODEL_3D:
+        try:
+            metadata = gltf_service.extract_gltf_metadata(content)
+            asset.metadata_json = json.dumps(metadata)
+            # Also set the asset type to model_3d if it was auto-detected.
+            if asset.asset_type == AssetType.OTHER:
+                asset.asset_type = AssetType.MODEL_3D
+        except ValueError as exc:
+            raise HTTPException(
+                status_code=400,
+                detail=f"Invalid glTF file: {exc}",
+            )
+
+    await db.commit()
+    await db.refresh(asset)
+    return asset

backend/app/routers/auth.py

@@ -0,0 +1,315 @@
+"""Authentication router - login, register, token refresh."""
+
+import uuid
+from datetime import date, datetime, timedelta, timezone
+
+from fastapi import APIRouter, Depends, HTTPException, status
+from fastapi.security import OAuth2PasswordRequestForm
+from jose import JWTError, jwt
+from passlib.context import CryptContext
+from pydantic import BaseModel, EmailStr, field_validator
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.config import settings
+from app.database import get_db
+from app.dependencies import CurrentUser
+from app.models.session import RefreshToken
+from app.models.user import User
+
+pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
+
+router = APIRouter()
+
+
+# --- Pydantic schemas ---
+
+class TokenResponse(BaseModel):
+    access_token: str
+    refresh_token: str
+    token_type: str = "bearer"
+    access_token_expires_minutes: int
+
+
+class RefreshRequest(BaseModel):
+    refresh_token: str
+
+
+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
+
+    model_config = {"from_attributes": True}
+
+
+# --- Helpers ---
+
+def _create_access_token(data: dict) -> str:
+    """Create a signed access token using RS256.
+
+    Includes a unique ``jti`` claim so that concurrent/same-second calls
+    (e.g. back-to-back /refresh requests) still produce distinct tokens —
+    without it, two tokens minted for the same user within the same
+    second are byte-identical since ``sub``/``exp`` are the only claims.
+    """
+    to_encode = data.copy()
+    to_encode["jti"] = str(uuid.uuid4())
+    expire = datetime.now(timezone.utc) + timedelta(
+        minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES
+    )
+    to_encode.update({"exp": expire})
+    return jwt.encode(
+        to_encode,
+        settings.private_pem,
+        algorithm=settings.ALGORITHM,
+    )
+
+
+def _create_refresh_token(data: dict) -> str:
+    """Create a signed refresh token using RS256.
+
+    Includes a unique ``jti`` claim so that concurrent calls produce
+    distinct tokens even when issued within the same second.
+    """
+    to_encode = data.copy()
+    to_encode["jti"] = str(uuid.uuid4())
+    expire = datetime.now(timezone.utc) + timedelta(
+        days=settings.REFRESH_TOKEN_EXPIRE_DAYS
+    )
+    to_encode.update({"exp": expire})
+    return jwt.encode(
+        to_encode,
+        settings.private_pem,
+        algorithm=settings.ALGORITHM,
+    )
+
+
+def verify_password(plain_password: str, hashed_password: str) -> bool:
+    """Verify a plain password against a hash."""
+    return pwd_context.verify(plain_password, hashed_password)
+
+
+def hash_password(password: str) -> str:
+    """Hash a password."""
+    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
+
+
+def _issue_refresh_token(user_id: int, db: AsyncSession) -> str:
+    """Create and persist a refresh token for the given user."""
+    refresh_token_value = _create_refresh_token({"sub": str(user_id)})
+    refresh_token_record = RefreshToken(
+        id=str(uuid.uuid4()),
+        user_id=user_id,
+        token=refresh_token_value,
+        expires_at=datetime.now(timezone.utc)
+        + timedelta(days=settings.REFRESH_TOKEN_EXPIRE_DAYS),
+    )
+    db.add(refresh_token_record)
+    return refresh_token_value
+
+
+# --- 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 access + refresh tokens.
+
+    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})",
+        )
+
+    # Check if username already exists
+    result = await db.execute(select(User).where(User.username == req.username))
+    if result.scalar_one_or_none():
+        raise HTTPException(
+            status_code=status.HTTP_409_CONFLICT,
+            detail="Username already registered",
+        )
+
+    # Check if email already exists
+    result = await db.execute(select(User).where(User.email == req.email))
+    if result.scalar_one_or_none():
+        raise HTTPException(
+            status_code=status.HTTP_409_CONFLICT,
+            detail="Email already registered",
+        )
+
+    user = User(
+        username=req.username,
+        email=req.email,
+        hashed_password=hash_password(req.password),
+        date_of_birth=dob,
+    )
+    db.add(user)
+    await db.flush()  # flush to get user.id before creating refresh token
+    await db.refresh(user)
+
+    # Create access token
+    access_token = _create_access_token({"sub": str(user.id)})
+
+    # Create and persist refresh token
+    refresh_token_value = _issue_refresh_token(user.id, db)
+    await db.commit()
+
+    return TokenResponse(
+        access_token=access_token,
+        refresh_token=refresh_token_value,
+        access_token_expires_minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES,
+    )
+
+
+@router.post("/login", response_model=TokenResponse)
+async def login(form: OAuth2PasswordRequestForm = Depends(), db: AsyncSession = Depends(get_db)):
+    """Authenticate user and return access + refresh tokens.
+
+    Accepts form-encoded credentials (username/password) as expected by
+    OAuth2PasswordBearer, so the Swagger UI "Authorize" flow works correctly.
+    """
+    result = await db.execute(select(User).where(User.username == form.username))
+    user = result.scalar_one_or_none()
+
+    if not user or not verify_password(form.password, user.hashed_password):
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Incorrect username or password",
+        )
+
+    if not user.is_active:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail="User account is inactive",
+        )
+
+    # Create access token
+    access_token = _create_access_token({"sub": str(user.id)})
+
+    # Create and persist refresh token
+    refresh_token_value = _issue_refresh_token(user.id, db)
+    await db.commit()
+
+    return TokenResponse(
+        access_token=access_token,
+        refresh_token=refresh_token_value,
+        access_token_expires_minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES,
+    )
+
+
+@router.post("/refresh", response_model=TokenResponse)
+async def refresh(req: RefreshRequest, db: AsyncSession = Depends(get_db)):
+    """Exchange a valid refresh token for a new access token.
+
+    Validates the refresh token against the database:
+    - Must exist in the refresh_tokens table
+    - Must not be expired (expires_at > now)
+    - Must be active (is_active == true)
+
+    On success, returns a new access token. The refresh token itself is
+    NOT rotated (the client keeps using the same refresh token).
+    """
+    credentials_exception = HTTPException(
+        status_code=status.HTTP_401_UNAUTHORIZED,
+        detail="Invalid or expired refresh token",
+    )
+
+    # Step 1: Decode and validate the JWT signature/claims
+    try:
+        payload = jwt.decode(
+            req.refresh_token,
+            settings.public_pem,
+            algorithms=[settings.ALGORITHM],
+        )
+    except JWTError:
+        raise credentials_exception
+
+    user_id_str: str | None = payload.get("sub")
+    if user_id_str is None:
+        raise credentials_exception
+
+    try:
+        user_id = int(user_id_str)
+    except (ValueError, TypeError):
+        raise credentials_exception
+
+    # Step 2: Look up the refresh token in the database
+    result = await db.execute(
+        select(RefreshToken).where(
+            RefreshToken.token == req.refresh_token,
+            RefreshToken.user_id == user_id,
+        )
+    )
+    stored_token = result.scalar_one_or_none()
+
+    if stored_token is None:
+        raise credentials_exception
+
+    # Step 3: Check if the token is expired
+    if datetime.now(timezone.utc) >= stored_token.expires_at:
+        raise credentials_exception
+
+    # Step 4: Check if the token is active
+    if not stored_token.is_active:
+        raise credentials_exception
+
+    # Step 5: Issue a new access token
+    access_token = _create_access_token({"sub": str(user_id)})
+
+    return TokenResponse(
+        access_token=access_token,
+        refresh_token=req.refresh_token,  # Return the same refresh token
+        access_token_expires_minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES,
+    )
+
+
+@router.get("/me", response_model=UserResponse)
+async def get_current_user(current_user: CurrentUser):
+    """Get current user profile from the JWT token."""
+    return current_user

backend/app/routers/users.py

@@ -0,0 +1,106 @@
+"""User management router."""
+
+from typing import Annotated
+
+from fastapi import APIRouter, Depends, HTTPException, status
+from pydantic import BaseModel, EmailStr
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.database import get_db
+from app.dependencies import CurrentUser
+from app.models.user import User
+
+router = APIRouter()
+
+
+# ─── Pydantic schemas ────────────────────────────────────────────────────────
+
+class UserResponse(BaseModel):
+    id: int
+    username: str
+    email: str
+    is_active: bool
+
+    model_config = {"from_attributes": True}
+
+
+class UserUpdate(BaseModel):
+    email: EmailStr | None = None
+    is_active: bool | None = None
+
+
+# ─── Endpoints ───────────────────────────────────────────────────────────────
+
+@router.get("/me", response_model=UserResponse)
+async def get_current_user_profile(
+    current_user: CurrentUser,
+):
+    """Get the currently authenticated user's profile."""
+    return current_user
+
+
+@router.get("/{user_id}", response_model=UserResponse)
+async def get_user(
+    user_id: int,
+    current_user: CurrentUser,
+    db: Annotated[AsyncSession, Depends(get_db)],
+):
+    """Get a user by ID.  Only the owner can view their own profile."""
+    result = await db.execute(select(User).where(User.id == user_id))
+    user = result.scalar_one_or_none()
+    if not user:
+        raise HTTPException(status_code=404, detail="User not found")
+
+    # Only the owner may view their own profile.
+    if user.id != current_user.id:
+        raise HTTPException(status_code=403, detail="Not authorized to view this user")
+
+    return user
+
+
+@router.patch("/{user_id}", response_model=UserResponse)
+async def update_user(
+    user_id: int,
+    user_update: UserUpdate,
+    current_user: CurrentUser,
+    db: Annotated[AsyncSession, Depends(get_db)],
+):
+    """Update a user.  Only the owner can update their own account."""
+    result = await db.execute(select(User).where(User.id == user_id))
+    user = result.scalar_one_or_none()
+    if not user:
+        raise HTTPException(status_code=404, detail="User not found")
+
+    # Only the owner may update their own account.
+    if user.id != current_user.id:
+        raise HTTPException(status_code=403, detail="Not authorized to update this user")
+
+    if user_update.email is not None:
+        user.email = user_update.email
+    if user_update.is_active is not None:
+        user.is_active = user_update.is_active
+
+    await db.commit()
+    await db.refresh(user)
+    return user
+
+
+@router.delete("/{user_id}", status_code=status.HTTP_204_NO_CONTENT)
+async def delete_user(
+    user_id: int,
+    current_user: CurrentUser,
+    db: Annotated[AsyncSession, Depends(get_db)],
+):
+    """Delete a user.  Only the owner can delete their own account."""
+    result = await db.execute(select(User).where(User.id == user_id))
+    user = result.scalar_one_or_none()
+    if not user:
+        raise HTTPException(status_code=404, detail="User not found")
+
+    # Only the owner may delete their own account.
+    if user.id != current_user.id:
+        raise HTTPException(status_code=403, detail="Not authorized to delete this user")
+
+    await db.delete(user)
+    await db.commit()

backend/app/routers/worlds.py

@@ -0,0 +1,169 @@
+"""Worlds router - CRUD for game worlds."""
+
+from datetime import datetime
+from typing import Annotated
+
+from fastapi import APIRouter, Depends, HTTPException, Query
+from pydantic import BaseModel, Field
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy.orm import selectinload
+
+from app.database import get_db
+from app.dependencies import CurrentUser
+from app.models.world import World, WorldVisibility
+
+router = APIRouter()
+
+DbDep = Annotated[AsyncSession, Depends(get_db)]
+
+
+# --- Pydantic schemas ---
+
+class WorldCreate(BaseModel):
+    """Schema for creating a world."""
+    name: str = Field(..., min_length=1, max_length=255)
+    description: str | None = None
+    visibility: WorldVisibility = WorldVisibility.PUBLIC
+
+
+class WorldUpdate(BaseModel):
+    """Schema for updating a world."""
+    name: str | None = Field(None, min_length=1, max_length=255)
+    description: str | None = None
+    visibility: WorldVisibility | None = None
+
+
+class WorldResponse(BaseModel):
+    """Schema for world responses."""
+    id: int
+    name: str
+    description: str | None
+    visibility: WorldVisibility
+    owner_id: int
+    created_at: datetime | None = None
+
+    model_config = {"from_attributes": True}
+
+
+# --- Endpoints ---
+
+@router.get("/", response_model=list[WorldResponse])
+async def list_worlds(
+    current_user: CurrentUser,
+    db: DbDep,
+    skip: int = Query(0, ge=0),
+    limit: int = Query(50, ge=1, le=100),
+    visibility: WorldVisibility | None = None,
+):
+    """List worlds visible to the current user.
+
+    PUBLIC worlds are visible to everyone.
+    PRIVATE/FRIENDS_ONLY worlds are visible to their owner.
+    """
+    query = select(World).options(selectinload(World.owner))
+
+    # Filter by visibility if specified
+    if visibility:
+        query = query.where(World.visibility == visibility)
+        if visibility != WorldVisibility.PUBLIC:
+            # Requesting a non-public visibility explicitly must not bypass
+            # ownership — otherwise any authenticated user could list every
+            # PRIVATE/FRIENDS_ONLY world in the system just by passing the
+            # filter, defeating the point of the check below.
+            query = query.where(World.owner_id == current_user.id)
+    else:
+        # Show PUBLIC worlds + owner's own worlds
+        query = query.where(
+            (World.visibility == WorldVisibility.PUBLIC)
+            | (World.owner_id == current_user.id)
+        )
+
+    query = query.offset(skip).limit(limit).order_by(World.created_at.desc())
+    result = await db.execute(query)
+    worlds = result.scalars().all()
+    return worlds
+
+
+@router.get("/{world_id}", response_model=WorldResponse)
+async def get_world(
+    world_id: int,
+    current_user: CurrentUser,
+    db: DbDep,
+):
+    """Get a single world by ID, respecting visibility."""
+    result = await db.execute(
+        select(World).where(World.id == world_id).options(selectinload(World.owner))
+    )
+    world = result.scalar_one_or_none()
+    if not world:
+        raise HTTPException(status_code=404, detail="World not found")
+
+    # Allow access if world is PUBLIC or owned by current user
+    if world.visibility != WorldVisibility.PUBLIC and world.owner_id != current_user.id:
+        raise HTTPException(status_code=404, detail="World not found")
+
+    return world
+
+
+@router.post("/", response_model=WorldResponse, status_code=201)
+async def create_world(
+    world_data: WorldCreate,
+    current_user: CurrentUser,
+    db: DbDep,
+):
+    """Create a new world."""
+    world = World(
+        name=world_data.name,
+        description=world_data.description,
+        owner_id=current_user.id,
+        visibility=world_data.visibility,
+    )
+    db.add(world)
+    await db.commit()
+    await db.refresh(world)
+    return world
+
+
+@router.put("/{world_id}", response_model=WorldResponse)
+async def update_world(
+    world_id: int,
+    world_data: WorldUpdate,
+    current_user: CurrentUser,
+    db: DbDep,
+):
+    """Update an existing world."""
+    result = await db.execute(select(World).where(World.id == world_id))
+    world = result.scalar_one_or_none()
+    if not world:
+        raise HTTPException(status_code=404, detail="World not found")
+
+    if world.owner_id != current_user.id:
+        raise HTTPException(status_code=403, detail="Not owner of this world")
+
+    update_data = world_data.model_dump(exclude_unset=True)
+    for field, value in update_data.items():
+        setattr(world, field, value)
+
+    await db.commit()
+    await db.refresh(world)
+    return world
+
+
+@router.delete("/{world_id}", status_code=204)
+async def delete_world(
+    world_id: int,
+    current_user: CurrentUser,
+    db: DbDep,
+):
+    """Delete a world."""
+    result = await db.execute(select(World).where(World.id == world_id))
+    world = result.scalar_one_or_none()
+    if not world:
+        raise HTTPException(status_code=404, detail="World not found")
+
+    if world.owner_id != current_user.id:
+        raise HTTPException(status_code=403, detail="Not owner of this world")
+
+    await db.delete(world)
+    await db.commit()

backend/app/services/gltf.py

@@ -0,0 +1,197 @@
+"""Lightweight glTF / GLB metadata extraction.
+
+This module intentionally avoids heavyweight dependencies such as trimesh or
+pygltflib. For the metadata fields the asset upload pipeline needs (mesh and
+vertex counts, animation presence, texture references, and the bounding box)
+a small amount of glTF-specific parsing is sufficient and keeps the backend
+dependency-free.
+"""
+
+from __future__ import annotations
+
+import json
+import struct
+from typing import Any, Optional
+
+# GLB binary header magic bytes ("glTF").
+_GLB_MAGIC = b"glTF"
+_GLB_MAGIC_INT = 0x46546C67  # b"glTF" interpreted as little-endian uint32
+_GLB_JSON_CHUNK_TYPE = 0x4E4F534A  # "JSON"
+_GLB_BIN_CHUNK_TYPE = 0x004E4942  # "BIN\0"
+
+# Whitespace allowed around a GLB JSON chunk. The spec pads with spaces (0x20),
+# but be lenient with null bytes and other whitespace that real exporters emit.
+_JSON_CHUNK_TRIM = b" \t\r\n\x00"
+
+
+def looks_like_gltf(content: bytes, filename: Optional[str] = None) -> bool:
+    """Return True when the bytes or filename indicate a glTF/GLB asset."""
+    if content.startswith(_GLB_MAGIC):
+        return True
+
+    if filename:
+        lowered = filename.lower()
+        if lowered.endswith(".gltf") or lowered.endswith(".glb"):
+            return True
+
+    # A bare JSON buffer (e.g. uploaded without an extension) that has the
+    # glTF asset marker is also a glTF file.
+    stripped = content.lstrip()
+    if stripped.startswith(b"{"):
+        try:
+            payload = json.loads(stripped.decode("utf-8"))
+        except (ValueError, UnicodeDecodeError):
+            return False
+        return isinstance(payload, dict) and "asset" in payload and "version" in payload.get("asset", {})
+
+    return False
+
+
+def _parse_glb(content: bytes) -> dict[str, Any]:
+    """Parse the JSON chunk of a GLB binary container."""
+    if len(content) < 12:
+        raise ValueError("GLB file is too short")
+
+    magic, _version, _length = struct.unpack_from("<III", content, 0)
+    if magic != _GLB_MAGIC_INT:
+        raise ValueError("invalid GLB magic")
+
+    offset = 12
+    json_chunk: Optional[dict[str, Any]] = None
+
+    while offset + 8 <= len(content):
+        chunk_length, chunk_type = struct.unpack_from("<II", content, offset)
+        offset += 8
+        chunk_end = offset + chunk_length
+        if chunk_end > len(content):
+            raise ValueError("GLB chunk overruns file boundary")
+
+        chunk_data = content[offset:chunk_end]
+        if chunk_type == _GLB_JSON_CHUNK_TYPE:
+            try:
+                json_chunk = json.loads(chunk_data.strip(_JSON_CHUNK_TRIM).decode("utf-8"))
+            except (ValueError, UnicodeDecodeError) as exc:
+                raise ValueError(f"invalid GLB JSON chunk: {exc}") from exc
+
+        offset = chunk_end
+
+    if json_chunk is None:
+        raise ValueError("GLB file does not contain a JSON chunk")
+
+    return json_chunk
+
+
+def _parse_gltf_json(content: bytes) -> dict[str, Any]:
+    """Parse a plain .gltf JSON file."""
+    stripped = content.lstrip()
+    try:
+        payload = json.loads(stripped.decode("utf-8"))
+    except (ValueError, UnicodeDecodeError) as exc:
+        raise ValueError(f"invalid glTF JSON: {exc}") from exc
+
+    if not isinstance(payload, dict):
+        raise ValueError("glTF JSON root must be an object")
+    return payload
+
+
+def _position_accessor_counts(gltf: dict[str, Any]) -> list[int]:
+    """Return POSITION accessor counts for every mesh primitive."""
+    counts: list[int] = []
+    accessors = gltf.get("accessors", [])
+    for mesh in gltf.get("meshes", []):
+        for primitive in mesh.get("primitives", []):
+            attributes = primitive.get("attributes", {})
+            position_index = attributes.get("POSITION")
+            if position_index is None:
+                continue
+            try:
+                accessor = accessors[int(position_index)]
+            except (IndexError, TypeError, ValueError):
+                continue
+            count = accessor.get("count")
+            if isinstance(count, int):
+                counts.append(count)
+    return counts
+
+
+def _position_bounds(gltf: dict[str, Any]) -> list[list[float]]:
+    """Return min/max bounds for every POSITION accessor that declares them."""
+    bounds: list[list[float]] = []
+    accessors = gltf.get("accessors", [])
+    for mesh in gltf.get("meshes", []):
+        for primitive in mesh.get("primitives", []):
+            attributes = primitive.get("attributes", {})
+            position_index = attributes.get("POSITION")
+            if position_index is None:
+                continue
+            try:
+                accessor = accessors[int(position_index)]
+            except (IndexError, TypeError, ValueError):
+                continue
+            minimum = accessor.get("min")
+            maximum = accessor.get("max")
+            if isinstance(minimum, list) and isinstance(maximum, list):
+                bounds.append([float(x) for x in minimum])
+                bounds.append([float(x) for x in maximum])
+    return bounds
+
+
+def _texture_refs(gltf: dict[str, Any]) -> list[str]:
+    """Collect external texture source references from the image array."""
+    refs: list[str] = []
+    for index, image in enumerate(gltf.get("images", [])):
+        uri = image.get("uri")
+        if isinstance(uri, str) and not uri.startswith("data:"):
+            refs.append(uri)
+            continue
+
+        name = image.get("name")
+        if isinstance(name, str) and name:
+            refs.append(name)
+            continue
+
+        if isinstance(uri, str):
+            # Embedded data URI; keep a stable, non-huge reference.
+            refs.append(f"data:{index}")
+            continue
+
+        buffer_view = image.get("bufferView")
+        if buffer_view is not None:
+            refs.append(f"bufferView:{buffer_view}")
+            continue
+
+        refs.append(f"image:{index}")
+
+    return refs
+
+
+def extract_gltf_metadata(content: bytes) -> dict[str, Any]:
+    """Extract upload-relevant metadata from glTF/GLB bytes.
+
+    Raises ValueError for malformed glTF content. The returned dict contains:
+        mesh_count, vertex_count, has_animation, texture_refs,
+        bounding_box_min, bounding_box_max.
+    """
+    if content.startswith(_GLB_MAGIC):
+        gltf = _parse_glb(content)
+    else:
+        gltf = _parse_gltf_json(content)
+
+    position_counts = _position_accessor_counts(gltf)
+    bounds = _position_bounds(gltf)
+
+    if bounds:
+        bounding_box_min = [min(axis) for axis in zip(*bounds[::2])]
+        bounding_box_max = [max(axis) for axis in zip(*bounds[1::2])]
+    else:
+        bounding_box_min = [0.0, 0.0, 0.0]
+        bounding_box_max = [0.0, 0.0, 0.0]
+
+    return {
+        "mesh_count": len(gltf.get("meshes", [])),
+        "vertex_count": sum(position_counts),
+        "has_animation": bool(gltf.get("animations")),
+        "texture_refs": _texture_refs(gltf),
+        "bounding_box_min": bounding_box_min,
+        "bounding_box_max": bounding_box_max,
+    }

backend/docker-compose.yml

@@ -0,0 +1,34 @@
+version: "3.9"
+
+services:
+  postgres:
+    image: postgres:16-alpine
+    environment:
+      POSTGRES_USER: agp_user
+      POSTGRES_PASSWORD: agp_password
+      POSTGRES_DB: agp_db
+    ports:
+      - "${POSTGRES_HOST_PORT:-5432}:5432"
+    volumes:
+      - postgres_data:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U agp_user -d agp_db"]
+      interval: 5s
+      timeout: 5s
+      retries: 5
+
+  redis:
+    image: redis:7-alpine
+    ports:
+      - "${REDIS_HOST_PORT:-6379}:6379"
+    volumes:
+      - redis_data:/data
+    healthcheck:
+      test: ["CMD", "redis-cli", "ping"]
+      interval: 5s
+      timeout: 5s
+      retries: 5
+
+volumes:
+  postgres_data:
+  redis_data:

backend/pytest.ini

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

backend/requirements.txt

@@ -0,0 +1,25 @@
+fastapi==0.115.6
+uvicorn[standard]==0.34.0
+sqlalchemy==2.0.36
+alembic==1.14.0
+psycopg2-binary==2.9.10
+asyncpg==0.31.0
+redis==5.2.1
+pydantic==2.10.3
+pydantic-settings==2.7.0
+python-jose[cryptography]==3.3.0
+passlib[bcrypt]==1.7.4
+# passlib 1.7.4 (last release, unmaintained since ~2020) detects its bcrypt
+# backend via bcrypt.__about__.__version__, which bcrypt>=4.1 removed --
+# hashing/verifying a password then raises "password cannot be longer than
+# 72 bytes" (a misleading downstream symptom of the real AttributeError:
+# module 'bcrypt' has no attribute '__about__') on every call. Without this
+# pin, `pip install -r requirements.txt` silently grabs whatever the latest
+# bcrypt is and breaks register/login outright. Pin below 4.1 explicitly.
+bcrypt==4.0.1
+python-multipart==0.0.20
+email-validator==2.2.0
+httpx==0.28.1
+pytest==8.3.4
+pytest-asyncio==0.25.0
+pytest-cov==6.0.0

backend/tests/conftest.py

@@ -0,0 +1,38 @@
+"""Shared pytest fixtures.
+
+The auth integration tests hit the *real* Postgres database (per
+``DATABASE_URL``), so they persist data between runs.  Without cleanup a
+second run of the suite fails with 409 conflicts because the users it
+registered on the first run already exist.  The session-scoped fixture below
+truncates all application tables once before the first test, making the suite
+re-runnable.
+
+Truncation order doesn't strictly matter because ``CASCADE`` follows foreign
+keys, but the tables are listed explicitly for clarity.
+"""
+
+import asyncio
+
+import pytest
+from sqlalchemy import text
+from sqlalchemy.ext.asyncio import create_async_engine
+
+from app.config import settings
+
+TEST_TABLES = ("assets", "worlds", "sessions", "refresh_tokens", "users")
+
+
+@pytest.fixture(scope="session", autouse=True)
+def _reset_database():
+    """Truncate all application tables once per test session."""
+
+    async def _truncate() -> None:
+        engine = create_async_engine(settings.DATABASE_URL)
+        async with engine.begin() as conn:
+            await conn.execute(
+                text(f"TRUNCATE TABLE {', '.join(TEST_TABLES)} CASCADE")
+            )
+        await engine.dispose()
+
+    asyncio.run(_truncate())
+    yield

backend/tests/test_auth_age_gate.py

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

backend/tests/test_auth_endpoints.py

@@ -0,0 +1,263 @@
+"""Integration tests for the auth endpoints (register + login).
+
+These tests hit the real FastAPI app against the real configured database
+(DATABASE_URL -- Postgres via Alembic migrations in CI/dev, not an isolated
+in-memory DB), so they exercise the full stack: Pydantic validation → DB →
+JWT → response. Requires migrations already applied (alembic upgrade head)
+before running.
+"""
+
+import pytest
+from fastapi.testclient import TestClient
+from sqlalchemy.ext.asyncio import async_sessionmaker, create_async_engine
+from sqlalchemy.pool import NullPool
+
+from app.config import settings
+from app.main import app
+from app.database import get_db
+from app.routers.auth import pwd_context
+
+
+# ---------------------------------------------------------------------------
+# Test fixtures
+# ---------------------------------------------------------------------------
+
+@pytest.fixture(autouse=True)
+def _override_db():
+    """Override get_db so the app uses a fresh session per test.
+
+    Deliberately does NOT reuse app.database's shared engine: FastAPI's
+    (sync) TestClient runs each request through anyio's blocking-portal
+    machinery, which can hand different requests different event loops.
+    asyncpg connections are bound to the loop they were created on, so
+    reusing one from the shared engine's connection pool across requests
+    raises "cannot perform operation: another operation is in progress" the
+    moment a test makes more than one request (register-then-login,
+    register-twice, etc.) -- confirmed this is the actual cause, not a bug
+    in the endpoints themselves. NullPool sidesteps it: every checkout is a
+    brand-new connection, never handed to a different loop than the one
+    that opened it.
+    """
+    test_engine = create_async_engine(settings.DATABASE_URL, poolclass=NullPool)
+    test_session_factory = async_sessionmaker(test_engine, expire_on_commit=False)
+
+    async def _get_db():
+        async_session = test_session_factory()
+        try:
+            yield async_session
+            await async_session.commit()
+        except Exception:
+            await async_session.rollback()
+            raise
+        finally:
+            await async_session.close()
+
+    app.dependency_overrides[get_db] = _get_db
+    yield
+    app.dependency_overrides.clear()
+
+
+# ---------------------------------------------------------------------------
+# Register endpoint
+# ---------------------------------------------------------------------------
+
+class TestRegister:
+    """Tests for POST /api/auth/register."""
+
+    def test_register_success(self):
+        """A valid registration returns 201 with a token."""
+        client = TestClient(app)
+        resp = client.post(
+            "/api/auth/register",
+            json={
+                "username": "newuser",
+                "email": "new@example.com",
+                "password": "secret123",
+                "date_of_birth": "2000-01-01",
+            },
+        )
+        assert resp.status_code == 201
+        data = resp.json()
+        assert "access_token" in data
+        assert data["token_type"] == "bearer"
+
+    def test_register_rejects_underage(self):
+        """Users under 18 get a 400 with a detail message."""
+        client = TestClient(app)
+        resp = client.post(
+            "/api/auth/register",
+            json={
+                "username": "kid",
+                "email": "kid@example.com",
+                "password": "secret123",
+                "date_of_birth": "2010-06-15",  # ~15 years old
+            },
+        )
+        assert resp.status_code == 400
+        assert "18 or older" in resp.json()["detail"]
+
+    def test_register_rejects_duplicate_username(self):
+        """Registering the same username twice returns 409."""
+        client = TestClient(app)
+        # First registration
+        client.post(
+            "/api/auth/register",
+            json={
+                "username": "duplicate",
+                "email": "dup1@example.com",
+                "password": "secret123",
+                "date_of_birth": "2000-01-01",
+            },
+        )
+        # Second registration with same username, different email
+        resp = client.post(
+            "/api/auth/register",
+            json={
+                "username": "duplicate",
+                "email": "dup2@example.com",
+                "password": "secret123",
+                "date_of_birth": "2000-01-01",
+            },
+        )
+        assert resp.status_code == 409
+        assert "Username already registered" in resp.json()["detail"]
+
+    def test_register_rejects_duplicate_email(self):
+        """Registering the same email twice returns 409."""
+        client = TestClient(app)
+        client.post(
+            "/api/auth/register",
+            json={
+                "username": "user1",
+                "email": "same@example.com",
+                "password": "secret123",
+                "date_of_birth": "2000-01-01",
+            },
+        )
+        resp = client.post(
+            "/api/auth/register",
+            json={
+                "username": "user2",
+                "email": "same@example.com",
+                "password": "secret123",
+                "date_of_birth": "2000-01-01",
+            },
+        )
+        assert resp.status_code == 409
+        assert "Email already registered" in resp.json()["detail"]
+
+    def test_register_invalid_date_format(self):
+        """Invalid date format returns 422 validation error."""
+        client = TestClient(app)
+        resp = client.post(
+            "/api/auth/register",
+            json={
+                "username": "user",
+                "email": "user@example.com",
+                "password": "secret123",
+                "date_of_birth": "01-01-2000",  # wrong format
+            },
+        )
+        assert resp.status_code == 422
+
+    def test_register_exactly_18(self):
+        """A user who just turned 18 can register."""
+        client = TestClient(app)
+        resp = client.post(
+            "/api/auth/register",
+            json={
+                "username": "just18",
+                "email": "just18@example.com",
+                "password": "secret123",
+                "date_of_birth": "2007-06-15",
+            },
+        )
+        assert resp.status_code == 201
+
+
+# ---------------------------------------------------------------------------
+# Login endpoint
+# ---------------------------------------------------------------------------
+
+class TestLogin:
+    """Tests for POST /api/auth/login."""
+
+    def _create_user(self, username: str, password: str, email: str = None):
+        """Helper to create a user via register."""
+        client = TestClient(app)
+        if email is None:
+            email = f"{username}@example.com"
+        resp = client.post(
+            "/api/auth/register",
+            json={
+                "username": username,
+                "email": email,
+                "password": password,
+                "date_of_birth": "2000-01-01",
+            },
+        )
+        assert resp.status_code == 201
+        return resp.json()["access_token"]
+
+    def test_login_success(self):
+        """Correct credentials return a token."""
+        self._create_user("loginuser", "correctpass")
+        client = TestClient(app)
+        resp = client.post(
+            "/api/auth/login",
+            data={"username": "loginuser", "password": "correctpass"},
+        )
+        assert resp.status_code == 200
+        data = resp.json()
+        assert "access_token" in data
+        assert data["token_type"] == "bearer"
+
+    def test_login_wrong_password(self):
+        """Wrong password returns 401."""
+        # Distinct username from test_login_success -- there's no per-test
+        # DB rollback/isolation here (real Postgres via the app's own
+        # dependency-overridden session), so reusing "loginuser" collided
+        # with the user that test already created (409 on register instead
+        # of the intended 401-on-login assertion this test is actually for).
+        self._create_user("loginuser_wrongpass", "correctpass")
+        client = TestClient(app)
+        resp = client.post(
+            "/api/auth/login",
+            data={"username": "loginuser_wrongpass", "password": "wrongpass"},
+        )
+        assert resp.status_code == 401
+        assert "Incorrect username or password" in resp.json()["detail"]
+
+    def test_login_nonexistent_user(self):
+        """Non-existent user returns 401 (not 404)."""
+        client = TestClient(app)
+        resp = client.post(
+            "/api/auth/login",
+            data={"username": "nobody", "password": "any"},
+        )
+        assert resp.status_code == 401
+        assert "Incorrect username or password" in resp.json()["detail"]
+
+    def test_login_accepts_form_encoded(self):
+        """Login accepts application/x-www-form-urlencoded (OAuth2)."""
+        self._create_user("formuser", "formpass")
+        client = TestClient(app)
+        resp = client.post(
+            "/api/auth/login",
+            data={"username": "formuser", "password": "formpass"},
+        )
+        assert resp.status_code == 200
+        assert "access_token" in resp.json()
+
+    def test_login_token_is_valid_jwt(self):
+        """The returned token is a valid JWT that can be decoded."""
+        self._create_user("jwttoken", "jwt123")
+        client = TestClient(app)
+        resp = client.post(
+            "/api/auth/login",
+            data={"username": "jwttoken", "password": "jwt123"},
+        )
+        token = resp.json()["access_token"]
+        # Verify it's a 3-part JWT
+        parts = token.split(".")
+        assert len(parts) == 3

backend/tests/test_auth_expired_token.py

@@ -0,0 +1,171 @@
+"""Tests for expired-token rejection across auth endpoints.
+
+Covers two distinct expiry paths:
+
+1. An *access* JWT whose ``exp`` claim is in the past must be rejected
+   with 401 by ``GET /api/auth/me`` (jose's built-in ``exp`` validation).
+2. A *refresh* token whose persisted ``expires_at`` is in the past must be
+   rejected with 401 by ``POST /api/auth/refresh`` even though its JWT
+   signature is still valid.
+
+Requires migrations already applied (alembic upgrade head) before running.
+"""
+
+import asyncio
+from datetime import datetime, timedelta, timezone
+
+import pytest
+from fastapi.testclient import TestClient
+from jose import jwt
+from sqlalchemy.ext.asyncio import async_sessionmaker, create_async_engine
+from sqlalchemy.pool import NullPool
+
+from app.config import settings
+from app.main import app
+from app.database import get_db
+from app.models.session import RefreshToken
+
+
+# ---------------------------------------------------------------------------
+# Test fixtures
+# ---------------------------------------------------------------------------
+
+@pytest.fixture(autouse=True)
+def _override_db():
+    """Override get_db so the app uses a fresh session per test."""
+    test_engine = create_async_engine(settings.DATABASE_URL, poolclass=NullPool)
+    test_session_factory = async_sessionmaker(test_engine, expire_on_commit=False)
+
+    async def _get_db():
+        async_session = test_session_factory()
+        try:
+            yield async_session
+            await async_session.commit()
+        except Exception:
+            await async_session.rollback()
+            raise
+        finally:
+            await async_session.close()
+
+    app.dependency_overrides[get_db] = _get_db
+    yield
+    app.dependency_overrides.clear()
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+def _mint_access_token(exp: datetime) -> str:
+    """Mint an RS256 access token with an explicit ``exp`` claim."""
+    return jwt.encode(
+        {"sub": "1", "exp": exp},
+        settings.private_pem,
+        algorithm=settings.ALGORITHM,
+    )
+
+
+def _expire_refresh_token_in_db(token: str) -> None:
+    """Set the persisted refresh token's ``expires_at`` into the past."""
+
+    async def _do():
+        engine = create_async_engine(settings.DATABASE_URL, poolclass=NullPool)
+        session_factory = async_sessionmaker(engine, expire_on_commit=False)
+        async with session_factory() as session:
+            from sqlalchemy import update
+
+            await session.execute(
+                update(RefreshToken)
+                .where(RefreshToken.token == token)
+                .values(expires_at=datetime.now(timezone.utc) - timedelta(hours=1))
+            )
+            await session.commit()
+        await engine.dispose()
+
+    asyncio.run(_do())
+
+
+def _register_user(client: TestClient, username: str) -> str:
+    """Register a user and return its refresh token."""
+    resp = client.post(
+        "/api/auth/register",
+        json={
+            "username": username,
+            "email": f"{username}@example.com",
+            "password": "secret123",
+            "date_of_birth": "2000-01-01",
+        },
+    )
+    assert resp.status_code == 201
+    return resp.json()["refresh_token"]
+
+
+# ---------------------------------------------------------------------------
+# Expired access token (GET /api/auth/me)
+# ---------------------------------------------------------------------------
+
+class TestExpiredAccessToken:
+    def test_expired_access_token_is_rejected_by_me(self):
+        """An access JWT with a past exp claim returns 401 on /me."""
+        client = TestClient(app)
+        expired_token = _mint_access_token(
+            datetime.now(timezone.utc) - timedelta(minutes=5)
+        )
+        resp = client.get(
+            "/api/auth/me",
+            headers={"Authorization": f"Bearer {expired_token}"},
+        )
+        assert resp.status_code == 401
+        assert "Could not validate credentials" in resp.json()["detail"]
+
+    def test_garbage_access_token_is_rejected_by_me(self):
+        """A non-JWT bearer token returns 401 on /me."""
+        client = TestClient(app)
+        resp = client.get(
+            "/api/auth/me",
+            headers={"Authorization": "Bearer not-a-real-jwt"},
+        )
+        assert resp.status_code == 401
+
+    def test_missing_bearer_token_returns_401(self):
+        """No Authorization header at all returns 401 on /me."""
+        client = TestClient(app)
+        resp = client.get("/api/auth/me")
+        assert resp.status_code == 401
+
+
+# ---------------------------------------------------------------------------
+# Expired refresh token (POST /api/auth/refresh)
+# ---------------------------------------------------------------------------
+
+class TestExpiredRefreshToken:
+    def test_expired_refresh_token_is_rejected(self):
+        """A refresh token whose DB expires_at is in the past returns 401."""
+        client = TestClient(app)
+        refresh_token = _register_user(client, "expired_rt_user")
+
+        # Force the persisted record to be expired while its JWT signature
+        # is still valid.
+        _expire_refresh_token_in_db(refresh_token)
+
+        resp = client.post(
+            "/api/auth/refresh",
+            json={"refresh_token": refresh_token},
+        )
+        assert resp.status_code == 401
+        assert "Invalid or expired refresh token" in resp.json()["detail"]
+
+    def test_expired_refresh_token_jwt_is_rejected(self):
+        """A refresh JWT with a past exp claim is rejected before DB lookup."""
+        client = TestClient(app)
+        expired_jwt = jwt.encode(
+            {"sub": "1", "exp": datetime.now(timezone.utc) - timedelta(minutes=5)},
+            settings.private_pem,
+            algorithm=settings.ALGORITHM,
+        )
+        resp = client.post(
+            "/api/auth/refresh",
+            json={"refresh_token": expired_jwt},
+        )
+        assert resp.status_code == 401
+        assert "Invalid or expired refresh token" in resp.json()["detail"]

backend/tests/test_gltf_metadata.py

@@ -0,0 +1,220 @@
+"""Tests for the lightweight glTF metadata extraction service."""
+
+import json
+import struct
+import pytest
+
+from app.services.gltf import (
+    extract_gltf_metadata,
+    looks_like_gltf,
+    _parse_glb,
+    _parse_gltf_json,
+)
+
+
+# ---------------------------------------------------------------------------
+# Test data helpers
+# ---------------------------------------------------------------------------
+
+def _make_gltf_json(
+    meshes: int = 1,
+    vertices_per_mesh: int = 24,
+    has_animations: bool = False,
+    images: list[dict] | None = None,
+) -> dict:
+    """Build a minimal glTF JSON structure."""
+    accessors = []
+    meshes_data = []
+    for i in range(meshes):
+        acc_index = len(accessors)
+        accessors.append({
+            "bufferView": 0,
+            "componentType": 5126,  # FLOAT
+            "count": vertices_per_mesh,
+            "type": "VEC3",
+            "max": [1.0, 1.0, 1.0],
+            "min": [-1.0, -1.0, -1.0],
+        })
+        meshes_data.append({
+            "primitives": [{
+                "attributes": {"POSITION": acc_index},
+            }],
+        })
+    gltf = {
+        "asset": {"version": "2.0"},
+        "accessors": accessors,
+        "meshes": meshes_data,
+    }
+    if has_animations:
+        gltf["animations"] = [{"name": "anim1", "channels": [], "samplers": []}]
+    if images:
+        gltf["images"] = images
+    return gltf
+
+
+def _make_glb(gltf_json: dict) -> bytes:
+    """Wrap *gltf_json* in a minimal GLB binary container."""
+    json_bytes = json.dumps(gltf_json).encode("utf-8")
+    json_length = len(json_bytes)
+    # Pad JSON chunk to 4-byte boundary.
+    json_padding = (4 - json_length % 4) % 4
+    json_chunk = json_bytes + b"\x00" * json_padding
+    json_chunk_type = 0x4E4F534A  # "JSON"
+    # No BIN chunk.
+    bin_length = 0
+    bin_chunk_type = 0x004E4942
+    total_length = 12 + 8 + len(json_chunk) + 8 + bin_length
+    header = struct.pack("<III", 0x46546C67, 2, total_length)  # magic, version, length
+    json_header = struct.pack("<II", len(json_chunk), json_chunk_type)
+    if bin_length > 0:
+        bin_header = struct.pack("<II", bin_length, bin_chunk_type)
+    else:
+        bin_header = b""
+    return header + json_header + json_chunk + bin_header
+
+
+# ---------------------------------------------------------------------------
+# looks_like_gltf
+# ---------------------------------------------------------------------------
+
+class TestLooksLikeGltf:
+    def test_glb_magic(self):
+        assert looks_like_gltf(b"glTF\x00\x00\x00\x00") is True
+
+    def test_gltf_extension(self):
+        assert looks_like_gltf(b'{"asset":{"version":"2.0"}}', "model.gltf") is True
+
+    def test_glb_extension(self):
+        assert looks_like_gltf(b"some binary", "model.glb") is True
+
+    def test_json_with_asset_version(self):
+        payload = json.dumps({"asset": {"version": "2.0"}}).encode()
+        assert looks_like_gltf(payload) is True
+
+    def test_plain_json_no_asset(self):
+        payload = json.dumps({"foo": "bar"}).encode()
+        assert looks_like_gltf(payload) is False
+
+    def test_non_json_bytes(self):
+        assert looks_like_gltf(b"\x89PNG\r\n\x1a\n") is False
+
+
+# ---------------------------------------------------------------------------
+# _parse_glb
+# ---------------------------------------------------------------------------
+
+class TestParseGlb:
+    def test_parses_valid_glb(self):
+        gltf_json = _make_gltf_json()
+        glb = _make_glb(gltf_json)
+        result = _parse_glb(glb)
+        assert result["asset"]["version"] == "2.0"
+        assert len(result["meshes"]) == 1
+
+    def test_rejects_too_short(self):
+        with pytest.raises(ValueError, match="too short"):
+            _parse_glb(b"glTF\x00\x00")
+
+    def test_rejects_invalid_magic(self):
+        with pytest.raises(ValueError, match="invalid GLB magic"):
+            _parse_glb(b"NOTglTF\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00")
+
+
+# ---------------------------------------------------------------------------
+# _parse_gltf_json
+# ---------------------------------------------------------------------------
+
+class TestParseGltfJson:
+    def test_parses_valid_gltf(self):
+        gltf_json = _make_gltf_json()
+        result = _parse_gltf_json(json.dumps(gltf_json).encode())
+        assert result["asset"]["version"] == "2.0"
+
+    def test_rejects_non_object(self):
+        with pytest.raises(ValueError, match="root must be an object"):
+            _parse_gltf_json(b"[1, 2, 3]")
+
+
+# ---------------------------------------------------------------------------
+# extract_gltf_metadata  (GLB path)
+# ---------------------------------------------------------------------------
+
+class TestExtractGltfMetadataGlb:
+    def test_basic_glb(self):
+        gltf_json = _make_gltf_json(meshes=1, vertices_per_mesh=24)
+        glb = _make_glb(gltf_json)
+        meta = extract_gltf_metadata(glb)
+        assert meta["mesh_count"] == 1
+        assert meta["vertex_count"] == 24
+        assert meta["has_animation"] is False
+        assert meta["bounding_box_min"] == [-1.0, -1.0, -1.0]
+        assert meta["bounding_box_max"] == [1.0, 1.0, 1.0]
+        assert meta["texture_refs"] == []
+
+    def test_multiple_meshes(self):
+        gltf_json = _make_gltf_json(meshes=3, vertices_per_mesh=12)
+        glb = _make_glb(gltf_json)
+        meta = extract_gltf_metadata(glb)
+        assert meta["mesh_count"] == 3
+        assert meta["vertex_count"] == 36
+
+    def test_with_animation(self):
+        gltf_json = _make_gltf_json(has_animations=True)
+        glb = _make_glb(gltf_json)
+        meta = extract_gltf_metadata(glb)
+        assert meta["has_animation"] is True
+
+    def test_with_external_texture(self):
+        gltf_json = _make_gltf_json(images=[{"uri": "textures/rock.png"}])
+        glb = _make_glb(gltf_json)
+        meta = extract_gltf_metadata(glb)
+        assert meta["texture_refs"] == ["textures/rock.png"]
+
+    def test_with_named_texture(self):
+        gltf_json = _make_gltf_json(images=[{"name": "my_texture"}])
+        glb = _make_glb(gltf_json)
+        meta = extract_gltf_metadata(glb)
+        assert meta["texture_refs"] == ["my_texture"]
+
+    def test_empty_meshes(self):
+        gltf_json = _make_gltf_json(meshes=0)
+        glb = _make_glb(gltf_json)
+        meta = extract_gltf_metadata(glb)
+        assert meta["mesh_count"] == 0
+        assert meta["vertex_count"] == 0
+        assert meta["bounding_box_min"] == [0.0, 0.0, 0.0]
+        assert meta["bounding_box_max"] == [0.0, 0.0, 0.0]
+
+
+# ---------------------------------------------------------------------------
+# extract_gltf_metadata  (plain .gltf JSON path)
+# ---------------------------------------------------------------------------
+
+class TestExtractGltfMetadataGltfJson:
+    def test_plain_gltf(self):
+        gltf_json = _make_gltf_json(meshes=2, vertices_per_mesh=8)
+        raw = json.dumps(gltf_json).encode()
+        meta = extract_gltf_metadata(raw)
+        assert meta["mesh_count"] == 2
+        assert meta["vertex_count"] == 16
+        assert meta["has_animation"] is False
+
+    def test_plain_gltf_with_animation(self):
+        gltf_json = _make_gltf_json(has_animations=True)
+        raw = json.dumps(gltf_json).encode()
+        meta = extract_gltf_metadata(raw)
+        assert meta["has_animation"] is True
+
+
+# ---------------------------------------------------------------------------
+# Error handling
+# ---------------------------------------------------------------------------
+
+class TestExtractGltfMetadataErrors:
+    def test_invalid_glb(self):
+        with pytest.raises(ValueError):
+            extract_gltf_metadata(b"not a glb")
+
+    def test_invalid_gltf_json(self):
+        with pytest.raises(ValueError):
+            _parse_gltf_json(b"[1, 2, 3]")

backend/tests/test_refresh_endpoint.py

@@ -0,0 +1,201 @@
+"""Tests for the POST /api/auth/refresh endpoint.
+
+These tests exercise the full stack: register → get refresh token →
+refresh → new access token.  Requires migrations already applied
+(alembic upgrade head) before running.
+"""
+
+import pytest
+from fastapi.testclient import TestClient
+from sqlalchemy.ext.asyncio import async_sessionmaker, create_async_engine
+from sqlalchemy.pool import NullPool
+
+from app.config import settings
+from app.main import app
+from app.database import get_db
+
+
+# ---------------------------------------------------------------------------
+# Test fixtures
+# ---------------------------------------------------------------------------
+
+@pytest.fixture(autouse=True)
+def _override_db():
+    """Override get_db so the app uses a fresh session per test."""
+    test_engine = create_async_engine(settings.DATABASE_URL, poolclass=NullPool)
+    test_session_factory = async_sessionmaker(test_engine, expire_on_commit=False)
+
+    async def _get_db():
+        async_session = test_session_factory()
+        try:
+            yield async_session
+            await async_session.commit()
+        except Exception:
+            await async_session.rollback()
+            raise
+        finally:
+            await async_session.close()
+
+    app.dependency_overrides[get_db] = _get_db
+    yield
+    app.dependency_overrides.clear()
+
+
+# ---------------------------------------------------------------------------
+# Refresh endpoint tests
+# ---------------------------------------------------------------------------
+
+class TestRefresh:
+    """Tests for POST /api/auth/refresh."""
+
+    def _register_user(self, username: str, password: str, email: str = None):
+        """Helper to register a user and return the refresh token."""
+        client = TestClient(app)
+        if email is None:
+            email = f"{username}@example.com"
+        resp = client.post(
+            "/api/auth/register",
+            json={
+                "username": username,
+                "email": email,
+                "password": password,
+                "date_of_birth": "2000-01-01",
+            },
+        )
+        assert resp.status_code == 201
+        return resp.json()["refresh_token"]
+
+    def test_refresh_success(self):
+        """A valid refresh token returns a new access token."""
+        refresh_token = self._register_user("refep_refreshuser", "secret123")
+        client = TestClient(app)
+        resp = client.post(
+            "/api/auth/refresh",
+            json={"refresh_token": refresh_token},
+        )
+        assert resp.status_code == 200
+        data = resp.json()
+        assert "access_token" in data
+        assert data["token_type"] == "bearer"
+        # The refresh token in the response is the same one we sent
+        assert data["refresh_token"] == refresh_token
+
+    def test_refresh_returns_different_access_token(self):
+        """Refreshing produces a new access token (different from any previous)."""
+        refresh_token = self._register_user("refep_refreshtoken", "secret123")
+        client = TestClient(app)
+
+        # First refresh
+        resp1 = client.post(
+            "/api/auth/refresh",
+            json={"refresh_token": refresh_token},
+        )
+        assert resp1.status_code == 200
+        access_token_1 = resp1.json()["access_token"]
+
+        # Second refresh
+        resp2 = client.post(
+            "/api/auth/refresh",
+            json={"refresh_token": refresh_token},
+        )
+        assert resp2.status_code == 200
+        access_token_2 = resp2.json()["access_token"]
+
+        # Each refresh should produce a new access token
+        assert access_token_1 != access_token_2
+
+    def test_refresh_invalid_token(self):
+        """An invalid (garbage) refresh token returns 401."""
+        client = TestClient(app)
+        resp = client.post(
+            "/api/auth/refresh",
+            json={"refresh_token": "not.a.jwt.token"},
+        )
+        assert resp.status_code == 401
+        assert "Invalid or expired refresh token" in resp.json()["detail"]
+
+    def test_refresh_empty_body(self):
+        """Missing refresh_token field returns 422 validation error."""
+        client = TestClient(app)
+        resp = client.post(
+            "/api/auth/refresh",
+            json={},
+        )
+        assert resp.status_code == 422
+
+    def test_refresh_missing_field(self):
+        """No body at all returns 422."""
+        client = TestClient(app)
+        resp = client.post(
+            "/api/auth/refresh",
+            content="{}",
+            headers={"Content-Type": "application/json"},
+        )
+        assert resp.status_code == 422
+
+    def test_refresh_with_login_token(self):
+        """A refresh token obtained from login also works for /refresh."""
+        client = TestClient(app)
+        # Register first
+        client.post(
+            "/api/auth/register",
+            json={
+                "username": "refep_loginrefuser",
+                "email": "loginref@example.com",
+                "password": "secret123",
+                "date_of_birth": "2000-01-01",
+            },
+        )
+        # Login to get a refresh token
+        login_resp = client.post(
+            "/api/auth/login",
+            data={"username": "refep_loginrefuser", "password": "secret123"},
+        )
+        assert login_resp.status_code == 200
+        refresh_token = login_resp.json()["refresh_token"]
+
+        # Use it to refresh
+        resp = client.post(
+            "/api/auth/refresh",
+            json={"refresh_token": refresh_token},
+        )
+        assert resp.status_code == 200
+        assert "access_token" in resp.json()
+
+    def test_refresh_access_token_is_valid_jwt(self):
+        """The access token returned by /refresh is a valid JWT."""
+        from jose import jwt
+
+        refresh_token = self._register_user("refep_jwttoken", "secret123")
+        client = TestClient(app)
+        resp = client.post(
+            "/api/auth/refresh",
+            json={"refresh_token": refresh_token},
+        )
+        assert resp.status_code == 200
+        access_token = resp.json()["access_token"]
+
+        # Verify it's a 3-part JWT
+        parts = access_token.split(".")
+        assert len(parts) == 3
+
+        # Verify it decodes with the public key
+        payload = jwt.decode(
+            access_token,
+            settings.public_pem,
+            algorithms=[settings.ALGORITHM],
+        )
+        assert "sub" in payload
+        assert "exp" in payload
+
+    def test_refresh_expires_minutes_in_response(self):
+        """The response includes access_token_expires_minutes."""
+        refresh_token = self._register_user("refep_expiretest", "secret123")
+        client = TestClient(app)
+        resp = client.post(
+            "/api/auth/refresh",
+            json={"refresh_token": refresh_token},
+        )
+        assert resp.status_code == 200
+        assert "access_token_expires_minutes" in resp.json()
+        assert resp.json()["access_token_expires_minutes"] == settings.ACCESS_TOKEN_EXPIRE_MINUTES

backend/tests/test_refresh_token_jti.py

@@ -0,0 +1,79 @@
+"""Tests for refresh token uniqueness (jti claim) and model column length."""
+
+import uuid
+from datetime import datetime, timedelta, timezone
+
+import pytest
+from jose import jwt
+
+from app.config import settings
+from app.routers.auth import _create_refresh_token
+from app.models.session import RefreshToken
+
+
+class TestRefreshTokenJtiUniqueness:
+    """Verify that _create_refresh_token produces unique tokens even when
+    called with identical data in rapid succession (issue #1 from review)."""
+
+    def test_two_calls_produce_different_tokens(self):
+        """Two calls with the same sub produce different JWTs because of jti."""
+        token_a = _create_refresh_token({"sub": "42"})
+        token_b = _create_refresh_token({"sub": "42"})
+        assert token_a != token_b
+
+    def test_jti_is_valid_uuid(self):
+        """The jti claim inside the refresh token is a valid UUID."""
+        token = _create_refresh_token({"sub": "1"})
+        payload = jwt.decode(
+            token,
+            settings.public_pem,
+            algorithms=[settings.ALGORITHM],
+        )
+        assert "jti" in payload
+        # Verify it parses as a UUID (raises ValueError if not)
+        uuid.UUID(payload["jti"])
+
+    def test_each_token_has_unique_jti(self):
+        """Generate 100 tokens for the same user — all jtis must differ."""
+        jtis = set()
+        for _ in range(100):
+            token = _create_refresh_token({"sub": "999"})
+            payload = jwt.decode(
+                token,
+                settings.public_pem,
+                algorithms=[settings.ALGORITHM],
+            )
+            jtis.add(payload["jti"])
+        assert len(jtis) == 100
+
+    def test_jti_survives_decode(self):
+        """The jti claim is present and correct after decode."""
+        token = _create_refresh_token({"sub": "7"})
+        payload = jwt.decode(
+            token,
+            settings.public_pem,
+            algorithms=[settings.ALGORITHM],
+        )
+        assert payload["sub"] == "7"
+        assert "jti" in payload
+        assert "exp" in payload
+
+
+class TestRefreshTokenModelColumnLength:
+    """Verify the model's token column length matches the migration (issue #2)."""
+
+    def test_token_column_has_length_512(self):
+        """RefreshToken.token column should be String(512), not unbounded."""
+        from sqlalchemy import inspect
+
+        # Get the column definition from the model's table
+        column = RefreshToken.__table__.columns["token"]
+        # The type should be String with length 512
+        assert column.type.length == 512
+
+    def test_token_column_type_is_string(self):
+        """The token column should be a String type."""
+        from sqlalchemy import String as SAString
+
+        column = RefreshToken.__table__.columns["token"]
+        assert isinstance(column.type, SAString)

docs/architecture/editor.md

@@ -0,0 +1,369 @@
+# Editor Architecture: Godot Editor Plugin vs. In-Game Editor
+
+> **Status:** Proposed
+> **Owner:** Platform team
+> **Related:** World chunk data format & persistence, server authority + client
+> prediction, content moderation & age verification, avatar component system
+> **Godot version:** 4.6.2 stable
+
+## 1. Overview
+
+This document evaluates the two primary ways to build the **world/level
+authoring tool** for **agp-game**:
+
+- **(a) Godot editor plugin** — extend the Godot editor itself with custom
+  panels, dock widgets, and tools that operate on the project's scenes and
+  resources.
+- **(b) In-game editor** — a fully custom editor built as game UI (Godot
+  `Control` nodes) that runs inside the running game, editing the game's own
+  world data.
+
+The goal is to pick the approach that best fits the platform's constraints:
+a **server-authoritative** multiplayer game where the **world is stored as
+versioned chunks** (see `world.md`), content is **moderation-flagged** (see
+`content_moderation.md`), and the client is a **shipped binary** that players
+run (not a dev tool).
+
+This document is a **decision record**: it lays out the trade-offs, gives a
+clear recommendation, and defines the resulting architecture boundaries.
+
+---
+
+## 2. Context & Constraints
+
+Before comparing the two approaches, we must fix the constraints that drive the
+decision. These come from the existing architecture docs.
+
+### 2.1 The World Is Data, Not Scenes
+
+`world.md` defines the world as **chunk data** (JSON for authoring, binary for
+runtime/network), persisted in SQLite on the server. A chunk is the atomic unit
+of load, save, and stream. The **server is the only writer** to the store;
+clients submit **deltas** against a `base_revision` and the server validates and
+applies them.
+
+**Implication:** The editor's output is **chunk payloads**, not `.tscn` scene
+files. Whatever editor we build must serialize to the chunk contract, not to
+Godot scene resources.
+
+### 2.2 Server-Authoritative & Moderation-Aware
+
+- The server validates every edit (schema, bounds, moderation) before
+  persisting (`world.md` §5.4).
+- Content carries **content flags** aggregated from referenced assets/scripts
+  (`content_moderation.md` §3). Mature content is gated behind age verification.
+- The client receives a **content manifest** and never loads content not in it.
+
+**Implication:** An editor that runs on a **player's machine** cannot be the
+authority on what gets published. Editing must go through the server's
+validation pipeline, and the editor must surface moderation flags.
+
+### 2.3 The Client Is a Shipped Binary
+
+The game is a multiplayer product. Players run a **release build**. The Godot
+editor is a **development tool** that players do not have.
+
+**Implication:** If authoring is a first-class *player* feature (user-generated
+content), the editor must ship inside the game binary. If authoring is a
+*developer/platform* feature, it can live in the editor.
+
+### 2.4 Two Distinct Audiences
+
+The evaluation must separate two audiences, because they have opposite needs:
+
+| Audience | Who | Where they run | What they build |
+|----------|-----|----------------|-----------------|
+| **Platform/dev** | The team building the game | Godot editor (dev machines) | Base worlds, rooms, templates, test levels |
+| **Players (UGC)** | End users | The shipped game | Their own rooms/worlds, published to the server |
+
+The two approaches map cleanly onto these audiences, and the right answer is
+likely **both** — but with a clear primary recommendation.
+
+---
+
+## 3. Approach (a): Godot Editor Plugin
+
+### 3.1 What It Is
+
+A Godot editor plugin is a set of scripts (and optionally scenes) that extend
+the editor via the `EditorPlugin` API. It can add:
+
+- **Dock panels** (`add_control_to_dock`) — e.g., a chunk/tile palette panel.
+- **Toolbar buttons** (`add_control_to_container`).
+- **Inspector plugins** (`EditorInspectorPlugin`) — custom property editors.
+- **Import plugins** (`EditorImportPlugin`) — custom asset importers.
+- **Scene/Node plugins** (`EditorNode3DGizmoPlugin`) — custom gizmos.
+- **Menu entries** (`add_tool_menu_item`).
+
+Plugins are enabled per-project via `project.godot` (`[editor_plugins]`).
+
+### 3.2 Pros
+
+- **Full editor power for free:** You get the scene tree, inspector, viewport
+  navigation, undo/redo, gizmos, and asset pipeline — all battle-tested.
+- **Native Godot editing:** Editing `.tscn` scenes, materials, and nodes is
+  exactly what the editor is built for. Great for authoring **base content**
+  (rooms, templates, avatar base bodies).
+- **Fast iteration for devs:** The platform team can build and test levels
+  directly in the tool they already use.
+- **Undo/redo, selection, snapping** come from the editor's `EditorUndoRedoManager`.
+- **No runtime footprint:** Editor-only code is stripped from export builds
+  (`@tool` scripts and editor plugins are not shipped to players).
+
+### 3.3 Cons
+
+- **Not available to players.** Players don't run the Godot editor. Any
+  player-facing UGC authoring cannot use this approach.
+- **Tied to the editor's UX.** You inherit the editor's look and interaction
+  model; deep customization is limited by what the editor API exposes.
+- **Editor API churn.** `EditorPlugin` APIs change between Godot versions;
+  plugins are more brittle across upgrades than game code.
+- **Scene-centric, not data-centric.** The editor is optimized for scenes and
+  resources. Our world is **chunk data** (`world.md`). We'd have to build a
+  translation layer (scene ↔ chunk) and keep it in sync — a real source of
+  drift.
+- **Single-user, local.** The editor edits local files. It does not natively
+  talk to our server-authoritative chunk store or the moderation pipeline.
+- **Headless/CI friction.** Validating plugin behavior in CI requires running
+  the editor headless, which is heavier than testing game code.
+
+### 3.4 Fit for Our Constraints
+
+- **Platform/dev authoring:** Excellent. This is the natural home for building
+  base worlds, rooms, and templates.
+- **Player UGC:** Not applicable. Players cannot run the editor.
+- **Server-authoritative chunk store:** Poor fit natively. The editor edits
+  local scenes; we'd bolt on a chunk export/import and a server sync layer.
+
+---
+
+## 4. Approach (b): In-Game Editor
+
+### 4.1 What It Is
+
+A fully custom editor built as **game UI** — Godot `Control` nodes (panels,
+buttons, toolbars) that run inside the running game. It edits the game's own
+world data model (chunks) and submits edits through the normal server pipeline.
+
+### 4.2 Pros
+
+- **Ships to players.** The editor is part of the game binary, so **player UGC
+  authoring is possible** — the core requirement for a user-generated-content
+  platform.
+- **Data-native.** The editor operates directly on the **chunk model**
+  (`world.md`), so there is no scene↔chunk translation layer and no drift.
+- **Server-authoritative by construction.** Edits go through the same
+  `request_chunk_edit` RPCs as gameplay, so validation, revisioning, and
+  moderation apply uniformly. The editor cannot bypass the server.
+- **Moderation-aware.** Because edits flow through the server, content flags are
+  computed and enforced at the boundary (`content_moderation.md` §4). The editor
+  can surface flags and gate mature content.
+- **One codebase, one UX.** The editor uses the same UI toolkit and art style as
+  the game; no separate editor theme to maintain.
+- **Testable in CI.** The editor is ordinary game code; it can be exercised
+  headlessly and unit-tested like any other system.
+
+### 4.3 Cons
+
+- **We build everything.** No free scene tree, inspector, gizmos, or undo/redo.
+  We must implement selection, snapping, undo/redo, viewport navigation, and
+  property editing ourselves.
+- **Runtime footprint.** Editor UI ships in the binary (though it can be gated
+  behind a feature flag / separate scene that is only instantiated on demand).
+- **More upfront work.** A usable in-game editor is a large feature; it needs
+  its own architecture (tool modes, gizmos, palette, inspector).
+- **Not ideal for deep asset authoring.** Modeling a mesh or authoring a
+  material is better done in the Godot editor / DCC tools. The in-game editor
+  should focus on **world composition** (placing tiles and objects), not asset
+  creation.
+
+### 4.4 Fit for Our Constraints
+
+- **Platform/dev authoring:** Workable but not ideal for deep asset work.
+- **Player UGC:** The **only** viable approach. Players can only author through
+  the shipped game.
+- **Server-authoritative chunk store:** Excellent fit. The editor is a client
+  that submits validated deltas.
+
+---
+
+## 5. Comparison Matrix
+
+| Criterion | (a) Editor plugin | (b) In-game editor |
+|-----------|-------------------|--------------------|
+| Ships to players | ❌ No | ✅ Yes |
+| Player UGC authoring | ❌ Impossible | ✅ Core capability |
+| World data model fit | ⚠️ Scene-centric; needs translation layer | ✅ Chunk-native |
+| Server-authoritative edits | ⚠️ Bolted on | ✅ Native (same RPCs) |
+| Moderation enforcement | ⚠️ Manual | ✅ At the boundary |
+| Free editor features (undo, gizmos, inspector) | ✅ Rich | ❌ Build ourselves |
+| Runtime footprint | ✅ None (stripped from export) | ⚠️ Ships in binary (gated) |
+| Dev iteration speed | ✅ Fast | ⚠️ Slower to build |
+| Deep asset authoring (mesh/material) | ✅ Native | ❌ Out of scope |
+| CI testability | ⚠️ Heavier (headless editor) | ✅ Ordinary game code |
+| Editor API churn risk | ⚠️ Higher | ✅ None (game code) |
+
+---
+
+## 6. Recommendation
+
+**Primary recommendation: build the in-game editor (b) as the platform's
+authoring surface, and use a lightweight Godot editor plugin (a) only as an
+internal dev convenience.**
+
+### 6.1 Rationale
+
+1. **Player UGC is the deciding factor.** The platform's value proposition is
+   user-generated content (rooms, worlds, avatars). Players cannot run the Godot
+   editor, so **only an in-game editor can deliver player authoring**. This is a
+   hard requirement that the editor-plugin approach cannot meet.
+
+2. **The world is data, and the in-game editor is data-native.** `world.md`
+   defines chunks as the atomic unit. An in-game editor edits chunks directly
+   and submits them through the server pipeline. An editor plugin would force a
+   scene↔chunk translation layer that is a constant source of drift and bugs.
+
+3. **Server authority and moderation fall out naturally.** Because in-game
+   edits use the same `request_chunk_edit` RPCs as gameplay, validation,
+   revisioning, optimistic concurrency, and content-flag enforcement
+   (`content_moderation.md`) apply uniformly. The editor cannot bypass the
+   server — which is exactly what a moderation-aware UGC platform needs.
+
+4. **The editor-plugin's strengths are not what we need.** Its free features
+   (scene tree, inspector, gizmos) are for editing Godot scenes and resources.
+   Our authoring is world composition against a chunk contract, not scene
+   editing. The plugin's main win — deep asset authoring — is better served by
+   DCC tools and the Godot editor for the *platform team*, not by a plugin we
+   must maintain.
+
+### 6.2 The Role of the Editor Plugin (Dev Convenience Only)
+
+We still recommend a **small, optional** editor plugin for the **platform team**
+to author **base content** (base rooms, templates, avatar base bodies, test
+levels) directly in the Godot editor. This is a dev-time convenience, not a
+product feature:
+
+- It can export a scene/resource as a **chunk** (reusing the same encoder as the
+  in-game editor) so dev-authored content flows into the same pipeline.
+- It is **not shipped** to players and is **not** the authoring surface for UGC.
+- It should be kept thin to minimize editor-API churn risk.
+
+### 6.3 Scope Boundary
+
+To keep the in-game editor tractable, define its scope clearly:
+
+- **In scope (world composition):** placing tiles, placing static/dynamic
+  objects, setting transforms, editing object properties, saving/loading chunks,
+  submitting edits to the server, showing moderation flags.
+- **Out of scope (asset creation):** modeling meshes, authoring materials,
+  rigging avatars. These are done in DCC tools / the Godot editor and imported
+  as catalog assets (see `avatar.md` §7). The in-game editor **references**
+  catalog assets by id; it does not create them.
+
+---
+
+## 7. Resulting Architecture
+
+### 7.1 Shared Editor Core
+
+Both the in-game editor and the (optional) dev plugin should share a single
+**editor core** that operates on the chunk model. This avoids two divergent
+implementations.
+
+```
+EditorCore (shared, data-native)
+├── ChunkEditorModel      # in-memory chunk being edited (tiles, objects, flags)
+├── ChunkEncoder          # JSON/binary encode/decode (world.md §3)
+├── EditSession           # base_revision tracking, delta generation
+├── EditSubmitter         # request_chunk_edit RPC wrapper + conflict handling
+├── UndoRedoStack         # command pattern over chunk mutations
+├── SelectionManager      # selected tiles/objects
+├── ToolRegistry          # brush, object-place, select, erase, etc.
+└── ModerationView        # surfaces content flags; gates mature content
+```
+
+### 7.2 In-Game Editor (Primary)
+
+```
+InGameEditor (Control-based UI, shipped in binary, gated by feature flag)
+├── EditorViewport        # custom 2D/3D viewport with camera navigation
+├── Toolbar               # tool mode switcher
+├── PalettePanel          # tile/object palette (from catalog)
+├── InspectorPanel        # property editor for selected object
+├── ChunkBrowser          # load/save chunks, list rooms
+└── EditorCore            # shared core (above)
+```
+
+- Instantiated only when the player enters "build mode" (a separate scene /
+  feature flag), so the runtime footprint is negligible during normal play.
+- Submits edits via `request_chunk_edit`; handles `chunk_edit_result` conflicts
+  by re-fetching and re-applying (`world.md` §5.4).
+
+### 7.3 Dev Editor Plugin (Optional, Thin)
+
+```
+DevChunkPlugin (EditorPlugin, dev-only, not shipped)
+├── Dock panel: "Chunk Export"
+├── Reads the current scene / selected nodes
+├── Maps scene content → chunk model (via EditorCore.ChunkEncoder)
+└── Exports a .chunk.json / submits to a dev server
+```
+
+Kept thin to minimize editor-API churn. Its only job is to let the platform team
+author base content in the editor and push it into the same chunk pipeline.
+
+### 7.4 Data Flow
+
+```
+[In-game editor]  --request_chunk_edit(delta, base_revision)-->  [Server]
+        ^                                                          | validate
+        |                                                          | apply
+        +--chunk_edit_result(ok/new_revision | conflict)-----------| persist
+                                                                   v
+                                                              SQLite (world.db)
+
+[Dev plugin]  --export chunk JSON-->  [EditorCore.ChunkEncoder]  -->  [Server]
+```
+
+Both paths converge on the **same server validation pipeline**, so moderation
+and revisioning are uniform regardless of authoring surface.
+
+---
+
+## 8. Risks & Mitigations
+
+| Risk | Mitigation |
+|------|------------|
+| In-game editor is a large build | Scope it to world composition (§6.3); reuse EditorCore; ship behind a feature flag |
+| Custom viewport/gizmos are hard | Start with a 2D tile editor (matches `CHUNK_SIZE_Z=1` default); add 3D later |
+| Undo/redo complexity | Use a command pattern over chunk mutations; test headlessly |
+| Editor-plugin API churn | Keep the plugin thin; treat it as dev-only convenience, not a product surface |
+| Drift between dev plugin and in-game editor | Both use the same `EditorCore`/`ChunkEncoder` |
+| Players bypass moderation | Impossible by construction: edits go through server validation |
+
+---
+
+## 9. Open Questions / Future Work
+
+- **3D editing:** The default world is flat (`CHUNK_SIZE_Z=1`). A 3D in-game
+  editor (volumetric chunks) is future work (`world.md` §8).
+- **Collaborative editing:** Multiple players editing the same chunk concurrently
+  — the optimistic-concurrency model already supports it, but the UX (live
+  cursors, conflict resolution) is unspecified.
+- **Template library:** A curated set of room templates players can start from.
+- **Publish/review flow:** How a player's authored room enters the moderation
+  review queue (`content_moderation.md` §6) and becomes publicly joinable.
+
+---
+
+## 10. Summary
+
+| Concern | Decision |
+|---------|----------|
+| Primary authoring surface | **In-game editor** (ships to players, enables UGC) |
+| Dev authoring convenience | Thin, optional **editor plugin** (not shipped) |
+| World data model | Both operate on the **chunk model** via a shared `EditorCore` |
+| Server authority | Edits go through `request_chunk_edit`; server validates |
+| Moderation | Enforced at the server boundary for both paths |
+| In-game editor scope | World composition only; asset creation is out of scope |
+| Runtime footprint | Editor gated behind a feature flag / separate scene |

docs/checkpoints/PC1.md

@@ -0,0 +1,84 @@
+# Package Checkpoint 1 (PC1)
+
+Validated 2026-08-20 against `main` commit `927f9bd`, from a genuinely fresh
+clone (not a reused agent workspace).
+
+## Automated validation
+
+Run with `scripts/run_checkpoint_tests.py` — see
+`docs/testing/test_inventory.md` for exactly what each suite covers.
+
+| Check | Result |
+|---|---|
+| Alembic migrations, fresh DB | PASS |
+| Backend pytest | 68/68 PASS |
+| Godot smoke tests (4 files) | ALL PASS |
+| Linux export (`agp-game.x86_64`) | Builds, verified as a real ELF64 binary |
+| Windows export (`agp-game.exe`) | Builds, verified as a real PE32+ binary |
+
+## Problems found during this checkpoint (fixed, tracked as tasks)
+
+- Roadmap showed the Godot Engine Scaffold feature amber despite 6/6 tasks
+  done — a historical data gap (a review-feedback follow-up task's
+  supersession link was never recorded, predating when that field started
+  being tracked). Backfilled in the PM database; confirmed green.
+- `docs/testing/test_inventory.md` was stale (said 38 backend tests,
+  actually 68; said no integration tests existed, 4 real ones had landed).
+  Fixed via task `398bf1a22a2d` / PR #40.
+
+## What's actually testable right now
+
+Login/register/browse-worlds only — there's no joinable gameplay yet. That's
+the real scope of PC1; don't expect more when playtesting.
+
+- Register a new account (18+ only, rejected otherwise)
+- Log out, log back in with the same credentials
+- Play → Browse Worlds — loads a (currently empty) world list with no errors
+
+## Manual playtest: backend on cloudbison, client on pinkbison
+
+Cloudbison's LAN IP: `192.168.58.138`. Pinkbison's: `192.168.58.124`.
+
+### 1. On cloudbison — start a real (persistent, not throwaway) backend
+
+```bash
+cd ~
+git clone http://localhost:3000/daddy/agp-game.git agp-game-playtest
+cd agp-game-playtest/backend
+docker compose up -d postgres
+docker compose exec -T postgres pg_isready -U agp_user -d agp_db   # wait for this to succeed
+
+export DATABASE_URL="postgresql+asyncpg://agp_user:agp_password@localhost:5432/agp_db"
+export JWT_ALGORITHM="RS256"
+/home/daddy/agp/venv/bin/python3 -m alembic upgrade head
+nohup /home/daddy/agp/venv/bin/python3 -m uvicorn app.main:app --host 0.0.0.0 --port 8000 > /tmp/agp-backend.log 2>&1 &
+disown
+```
+
+`--host 0.0.0.0` matters — the default `127.0.0.1` only listens on loopback
+and pinkbison won't be able to reach it. Verify: `curl
+http://localhost:8000/api/health` should return `{"status":"ok",...}`.
+
+### 2. On pinkbison — get the game and point it at cloudbison
+
+Copy `export/windows/agp-game.exe` (or `export/linux/agp-game.x86_64`,
+whichever matches pinkbison's OS) from cloudbison, or clone the repo there
+and run `scripts/build.sh` locally. Launch with the backend URL as an env
+var so you don't have to rebuild to change it:
+
+- Windows (PowerShell): `$env:AGP_API_BASE_URL="http://192.168.58.138:8000"; .\agp-game.exe`
+- Linux: `AGP_API_BASE_URL=http://192.168.58.138:8000 ./agp-game.x86_64`
+
+### 3. Tear down when done
+
+```bash
+# on cloudbison
+pkill -f "uvicorn app.main:app"
+cd ~/agp-game-playtest/backend && docker compose down -v
+```
+
+## Status
+
+`config/checkpoint_focus_feature_ids` in the AGP framework (`~/agp`) still
+restricts agent claiming to the 5 PC1-scope features. Agents will not move
+on to post-PC1 work until that's widened.

docs/planning/client-server-wiring.md

@@ -0,0 +1,41 @@
+# MVP Vertical Slice: Client-Server Wiring — Plan
+
+## Goal
+Prove the real Godot client and the real backend can talk: **a user can register/log in
+and see a list of worlds from the game client**. Nothing more. Gameplay, join-a-world,
+chat, avatar, Discovery search/tags/trending, Social/Economy/Trust & Safety are all
+explicitly out of scope.
+
+## Verified backend contract (as of this writing)
+- `POST /api/auth/register` — JSON body `{username, email, password, date_of_birth}`.
+  `date_of_birth` is a `YYYY-MM-DD` string. Returns `201 {access_token, token_type}`.
+  Rejects under-18 with `400`.
+- `POST /api/auth/login` — OAuth2 **form-encoded** (`application/x-www-form-urlencoded`)
+  `username` + `password` (this is NOT a JSON endpoint). Returns `{access_token, token_type}`.
+- `GET /api/worlds` — **requires auth** (`CurrentUser`), returns a JSON array of
+  `{id, name, description, visibility, owner_id, created_at}`. There is no unauthenticated
+  public-worlds path, so the worlds list screen can only be shown after login/register.
+- `GET /api/health` — unauthenticated, `{status, app}`.
+- Base URL: uvicorn default `http://127.0.0.1:8000` (must be configurable in the client).
+- CORS is irrelevant to the native Godot `HTTPRequest` client (no browser origin).
+
+## Task breakdown
+| # | Type | Task | Depends on |
+|---|------|------|-----------|
+| 1 | architecture | `ApiClient` autoload: HTTP + JWT storage + error contract | — |
+| 2 | implementation | Main-menu **login + register** UI built & wired (form-encoded + JSON/age gate) | 1 |
+| 3 | implementation | **World list** screen consuming `GET /api/worlds` | 1 |
+| 4 | testing | End-to-end headless smoke test + manual verify | 1,2,3 |
+
+## Design decisions captured (resolved in task 1)
+- Token storage: in-memory singleton property for the MVP; a `save_to_disk` seam is left
+  open but not required yet (no re-login on restart in this slice).
+- Error contract: every call returns a discriminated result (`ok`/`error`) so callers
+  never crash on network failure; non-2xx surfaces `{status, detail}` from the backend.
+- Base URL: read from a ProjectSetting, defaulting to `http://127.0.0.1:8000`.
+- Login is form-encoded; register is JSON — the client helper must support both content types.
+
+## Notes
+- The main-menu auth UI does **not** exist yet (main_menu.gd currently has only Play/Quit
+  stubs). Task 2 must **build** the login/register UI, not merely wire an existing one.
+- The world-list screen also needs to be **built** (a new scene), not just wired.

docs/planning/economy.md

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+# Economy — Currency, Marketplace & Creator Payouts — Plan
+
+> **Status:** Planned
+> **Owner:** Platform team
+> **Feature ID:** `economy`
+> **Godot version:** 4.6.2 stable
+> **Backend:** FastAPI + SQLAlchemy (async) + PostgreSQL + Redis
+
+## 1. Overview
+
+This document breaks the **Economy** feature into user stories and right-sized
+implementation tasks. The feature delivers:
+
+- **Virtual currency ("Credits")** — a single, server-authoritative currency
+  with an immutable, append-only transaction ledger.
+- **Premium purchase** — buying Credits with real money through a pluggable
+  payment-provider hook.
+- **Marketplace** — user-generated content (UGC) listings where creators sell
+  items (assets, avatar items, experience passes) to players for Credits.
+- **Creator payouts** — accumulating creator earnings and paying them out to
+  external accounts through a pluggable payout-provider hook.
+- **Godot client** — wallet/transaction history, marketplace browse/buy/sell,
+  and creator payout screens.
+
+The economy is the monetization backbone of the platform. Because it moves
+virtual value between real people, correctness (no double-spend, no lost funds,
+no balance drift) and safety (fraud prevention, moderation, audit) are treated
+as **blocking requirements**, not add-ons.
+
+## 2. Why correctness is the differentiator
+
+The platform is a creator economy (players buy UGC from other players). The
+economy is the highest-risk surface after chat: a single arithmetic or
+concurrency bug can mint or destroy value and irreversibly erode trust.
+Correctness is therefore designed in from the start:
+
+- **One currency, integer units.** Credits are whole-number integers. There are
+  no floats, no rounding, and no client-computed totals.
+- **Append-only ledger.** Every balance change is a row in a `transactions`
+  table with a signed amount, a `balance_after` snapshot, a reference to the
+  event that caused it, and an **idempotency key** so retries cannot double
+  credit or double debit.
+- **Atomic, locked mutations.** Balance changes run in a single database
+  transaction with row locking (`SELECT ... FOR UPDATE`) so concurrent
+  purchases/payouts cannot race.
+- **Escrow hold.** Marketplace proceeds are held in `pending_escrow` for a
+  configurable window before becoming available to the seller, so fraudulent
+  or moderated sales can be reversed without clawing back paid-out funds.
+- **Server-authoritative fees.** The platform commission is computed
+  server-side from a configured rate; the client never supplies the fee or the
+  seller's net.
+
+## 3. Existing constraints (do not re-build)
+
+- **Auth:** JWT bearer tokens; `get_current_user` / `CurrentUser` dependency in
+  `app/dependencies.py`. All economy endpoints reuse this.
+- **DB:** async SQLAlchemy + Alembic; migration `0001_initial` is the head.
+  Existing tables: `users`, `sessions`, `worlds`, `assets`.
+- **Redis:** configured (`REDIS_URL`) but unused so far; adopted here for
+  idempotency short-caching and rate limiting.
+- **Models:** `User` (owner_id), `Asset` (owner_id, is_public, asset_type).
+  Marketplace items reference existing `assets` rows and/or avatar items.
+- **Content moderation:** `docs/architecture/content_moderation.md` defines
+  flag vocabulary, age gate, and moderation actions. Marketplace items and
+  listings must inherit and enforce these rules (see §7).
+- **Client:** Godot 4.6.2, minimal `main_menu.gd`; no economy UI yet.
+
+## 4. Key design decisions
+
+| Concern | Decision |
+|---|---|
+| Currency model | Single virtual currency **"Credits" (CR)**, integer units. One wallet row per user; no fractional amounts. |
+| Ledger | Append-only `transactions` table: signed `amount`, `balance_after`, `reference_type`/`reference_id`, unique `idempotency_key`. |
+| Concurrency | `SELECT ... FOR UPDATE` on the wallet row inside the mutation transaction; never read-modify-write from stale data. |
+| Payments | Pluggable `PaymentProvider` interface with a **no-op default** that simulates a confirmed payment for dev/testing (clearly flagged). Stripe/PayPal later. |
+| Marketplace items | `catalog_items` (what is sold) + `marketplace_listings` (a seller's offer with a price/status). One item can have multiple listings over time. |
+| Purchase flow | Atomic transaction: debit buyer → hold funds in escrow (`pending_escrow`) → grant item. Platform fee computed server-side. |
+| Escrow | Configurable hold window (default 72h) before `pending_escrow` becomes available seller earnings. Refunds during the window reverse the sale. |
+| Fees | Single configurable `MARKETPLACE_FEE_RATE` (default `0.30`). `seller_net = floor(price * (1 - fee_rate))`. |
+| Creator balance | `creator_balances` table: `available` (earned, payable), `pending` (inside an open payout request), `lifetime_earned`. Updated in the same transaction as the sale completion. |
+| Payouts | Pluggable `PayoutProvider.pay()` with a no-op default (simulated external ref). Minimum payout threshold, admin review for large payouts. |
+| Idempotency | Every money-moving request carries a client-generated `Idempotency-Key`; duplicate keys return the original result. |
+| Rate limiting | Redis token-bucket dependency reused from the social feature for purchase/listing/payout endpoints. |
+| Moderation | Listings enforce content flags + age gate; moderators can `delist`/`remove`; fraud/chargeback reversal is an audited admin action. |
+
+## 5. User stories
+
+### US-1 Currency & wallet
+As a player, I can see my Credit balance and transaction history, and the system
+credits/debits my wallet only through server-authoritative events.
+
+**Acceptance criteria**
+- Exactly one wallet per user, created lazily on first use.
+- Balance is always a non-negative integer; no operation can make it negative.
+- Every mutation appends an immutable ledger row with amount, resulting balance,
+  reference, and idempotency key.
+- Retrying a request with the same idempotency key does not double-apply.
+- `GET` endpoints expose current balance and paged transaction history.
+
+### US-2 Premium purchase (buy Credits)
+As a player, I can purchase Credits with real money and have them credited only
+after the payment is confirmed.
+
+**Acceptance criteria**
+- A purchase session is created through the payment provider (or the no-op
+  default) and is idempotent.
+- Credits are granted exactly once, only after a verified provider confirmation
+  (webhook/confirm endpoint), never on client claim.
+- Purchase amounts are bounded and server-defined; clients cannot pick arbitrary
+  prices.
+- Confirmation is idempotent and audited (provider reference recorded).
+
+### US-3 Marketplace listing (sell)
+As a creator, I can list a catalog item for sale at a Credit price and
+manage/remove my listings.
+
+**Acceptance criteria**
+- A listing references a valid `catalog_item` owned by the seller (or an
+  authorized seller).
+- Price is bounded (min/max) and set server-side; status transitions are
+  explicit (`active`, `sold`, `delisted`, `removed_by_moderation`).
+- Only the seller (or a moderator) can update/remove a listing.
+- Listings are searchable/filterable (item type, price range, owner).
+
+### US-4 Marketplace purchase (buy)
+As a player, I can buy a listed item. The purchase is atomic, holds funds in
+escrow, grants the item, and splits the payment between platform and seller.
+
+**Acceptance criteria**
+- A single transaction debits the buyer, holds funds in escrow, and grants the
+  item — no partial states on failure.
+- Platform fee and seller net are computed server-side from the configured rate.
+- After the escrow hold window, funds move from escrow to the seller's
+  available balance.
+- Refunds during the hold window reverse the sale and return funds to the buyer.
+- Concurrent purchases of a one-of-a-kind listing cannot both succeed.
+
+### US-5 Creator payouts
+As a creator, I can view my earned balance, request a payout, and track its
+status; admins can review and approve/reject payouts.
+
+**Acceptance criteria**
+- Available balance is derived only from completed (escrow-released) sales and
+  completed payouts; it never goes negative.
+- Payout requests are bounded (min threshold, max per period) and rate-limited.
+- Large payouts require admin review; all payout requests carry an audit trail
+  (requested by, reviewed by, provider reference, status).
+- The payout provider is called exactly once; idempotent on retry.
+
+### US-6 Godot client
+As a player, I can manage Credits, browse/buy/sell marketplace items, and manage
+payouts from the game UI.
+
+**Acceptance criteria**
+- An API client handles JWT auth, HTTP, and idempotency keys for all economy
+  calls.
+- Dedicated screens: wallet + transaction history, marketplace browse/buy,
+  sell-listing, and creator payout.
+- The client never computes balances, fees, or seller nets — it only displays
+  server responses.
+
+## 6. Task breakdown
+
+Right-sized to 1–3 files / one coherent piece of functionality each. Task IDs
+are sequential for dependency chaining.
+
+| # | Task | Story | Depends on |
+|---|------|-------|-----------|
+| 1 | Wallet & ledger models + Alembic migration (`wallets`, `transactions`) | US-1 | — |
+| 2 | Wallet service (atomic credit/debit, idempotency, locking) + wallet/transactions API | US-1 | 1 |
+| 3 | Premium purchase: `PaymentProvider` interface + purchase/confirm endpoints | US-2 | 1 |
+| 4 | Catalog item & listing models + migration (`catalog_items`, `marketplace_listings`, `creator_balances`) | US-3 | 1 |
+| 5 | Marketplace listing API (create/list/search/update/remove) | US-3 | 4 |
+| 6 | Marketplace purchase service + API (atomic escrow, fee split, item grant) | US-4 | 2, 4, 5 |
+| 7 | Creator payout request models + API (`payout_requests`) | US-5 | 2, 6 |
+| 8 | Payout admin review + `PayoutProvider` + audit | US-5 | 7 |
+| 9 | Marketplace moderation + content-flag/age-gate enforcement | cross-cutting | 5, 6 |
+| 10 | Godot economy API client (auth + HTTP + idempotency) | US-6 | 2 |
+| 11 | Godot wallet & transaction history UI | US-6 | 10 |
+| 12 | Godot marketplace browse/buy UI | US-6 | 6, 10 |
+| 13 | Godot selling & payout UI | US-6 | 5, 7, 10 |
+
+## 7. Phasing
+
+- **Phase 1 (currency + payments):** tasks 1–3. The foundation — ledger and
+  money movement must be rock-solid before anything spends Credits.
+- **Phase 2 (marketplace):** tasks 4–6. Listing and atomic purchase with escrow.
+- **Phase 3 (payouts):** tasks 7–8. Turn released escrow into creator payouts.
+- **Phase 4 (moderation):** task 9. Lock down the marketplace against mature
+  content and abuse.
+- **Phase 5 (client):** tasks 10–13, each landing after its backend dependency.
+
+## 8. Data model sketch
+
+```text
+wallets
+  id                bigint PK
+  user_id           int UNIQUE FK -> users.id
+  balance           bigint NOT NULL DEFAULT 0  CHECK (balance >= 0)
+  created_at        timestamptz
+  updated_at        timestamptz
+
+transactions        (append-only ledger)
+  id                bigint PK
+  wallet_id         bigint FK -> wallets.id
+  type              enum(credit_purchase, marketplace_purchase,
+                        marketplace_sale, escrow_release, payout,
+                        refund, admin_adjustment)
+  amount            bigint NOT NULL            (signed)
+  balance_after     bigint NOT NULL
+  reference_type    text                        (e.g. "purchase", "sale", "payout_request")
+  reference_id      text
+  idempotency_key   text UNIQUE
+  metadata_json     jsonb
+  created_at        timestamptz
+
+catalog_items
+  id                bigint PK
+  owner_id          int FK -> users.id
+  asset_id          int FK -> assets.id (nullable; null for non-asset virtual items)
+  item_type         enum(asset, avatar_item, experience_pass)
+  name              text
+  description       text
+  metadata_json     jsonb
+  created_at        timestamptz
+
+marketplace_listings
+  id                bigint PK
+  catalog_item_id   bigint FK -> catalog_items.id
+  seller_id         int FK -> users.id
+  price             bigint NOT NULL CHECK (price > 0)
+  status            enum(active, sold, delisted, removed_by_moderation)
+  created_at        timestamptz
+  updated_at        timestamptz
+
+purchases
+  id                bigint PK
+  listing_id        bigint FK -> marketplace_listings.id
+  buyer_id          int FK -> users.id
+  seller_id         int FK -> users.id
+  price             bigint NOT NULL
+  platform_fee      bigint NOT NULL
+  seller_net        bigint NOT NULL
+  status            enum(pending_escrow, completed, refunded, reversed)
+  escrow_hold_until timestamptz
+  created_at        timestamptz
+
+creator_balances
+  id                bigint PK
+  user_id           int UNIQUE FK -> users.id
+  available         bigint NOT NULL DEFAULT 0
+  pending           bigint NOT NULL DEFAULT 0
+  lifetime_earned   bigint NOT NULL DEFAULT 0
+  updated_at        timestamptz
+
+payout_requests
+  id                bigint PK
+  creator_id        int FK -> users.id
+  amount            bigint NOT NULL CHECK (amount > 0)
+  status            enum(pending, approved, paid, rejected)
+  external_ref      text
+  provider_ref      text
+  requested_by      int FK -> users.id
+  reviewed_by       int FK -> users.id (nullable)
+  reviewed_at       timestamptz
+  created_at        timestamptz
+```
+
+## 9. Security, anti-fraud & audit
+
+- **Server-authoritative balances/fees:** clients never compute totals; amounts
+  are validated server-side against bounds and the current listing.
+- **Row locking:** wallet and creator-balance mutations use `SELECT ... FOR
+  UPDATE` within one transaction.
+- **Idempotency:** every money-moving endpoint requires an `Idempotency-Key`;
+  duplicate keys return the stored original outcome.
+- **Rate limiting:** purchase, listing, and payout endpoints are token-bucket
+  rate-limited per user.
+- **Escrow & reversibility:** funds are not payable until the hold window
+  elapses; chargebacks/refunds reverse before release.
+- **Moderation:** listings carry the item's effective content flags; mature
+  items require age verification (per `content_moderation.md`); moderators can
+  `delist`/`remove` and trigger audited reversals.
+- **Audit:** the ledger plus `payout_requests` review fields form an append-only
+  audit trail for every movement of value.
+
+## 10. Out of scope for this feature
+
+- Real Stripe/PayPal/KYC integrations (provider interfaces leave the hooks; the
+  defaults are deterministic no-ops).
+- Subscriptions, recurring billing, or premium memberships.
+- Gift cards, promotional codes, or user-to-user Credit transfers.
+- Partial refunds, chargeback disputes, and seller tax/VAT handling.
+- In-world vending machines / scripted economy triggers (future, built on this
+  ledger via the scripting sandbox).

docs/planning/social.md

@@ -0,0 +1,170 @@
+# Social — Friends, Chat & Groups — Plan
+
+> **Status:** Planned
+> **Owner:** Platform team
+> **Feature ID:** `social`
+> **Godot version:** 4.6.2 stable
+> **Backend:** FastAPI + SQLAlchemy (async) + PostgreSQL + Redis
+
+## 1. Overview
+
+This document breaks the **Social** feature into user stories and right-sized
+implementation tasks. The feature delivers:
+
+- **Friends & following** — a friend request/accept model plus a one-way follow
+  relationship, with block lists.
+- **Presence & status** — online/offline, custom status message, last-seen.
+- **Chat** — direct messages (DM) and in-experience (world/room) chat with
+  **first-class safety**: server-side text filtering, report-message, and rate
+  limiting.
+- **Groups** — named groups with roles (owner/admin/member) and a simple group
+  page.
+- **Public profiles** — avatar, bio, favorite experiences, and a friends list
+  that respects privacy settings.
+
+## 2. Why chat safety is the differentiator
+
+The platform is explicitly meant to pull adults away from a youth-oriented
+competitor. Chat is the highest-risk surface: it is real-time, user-generated,
+and where abuse happens fastest. Safety is therefore treated as a **blocking
+requirement**, not an add-on:
+
+- Every message passes a **server-side text filter** before it is stored or
+  delivered. The client filter is cosmetic only; the server is authoritative.
+- Every message can be **reported**; reports flow into a moderation queue with
+  actor + reason + audit trail (mirroring `content_moderation.md`).
+- Sending is **rate limited** per user (Redis token bucket) to stop flooding and
+  harassment-by-volume.
+- Report and block are always reachable from a message context in the UI.
+
+## 3. Existing constraints (do not re-build)
+
+- **Auth:** JWT bearer tokens; `get_current_user` / `CurrentUser` dependency in
+  `app/dependencies.py`. All social endpoints reuse this.
+- **DB:** async SQLAlchemy + Alembic; migration `0001_initial` is the head.
+- **Redis:** configured (`REDIS_URL`) but unused so far; adopted here for
+  presence and rate limiting.
+- **Models:** `User`, `World` (owner_id), `Asset` (owner_id, is_public). Avatars
+  and favorite-experience references point at existing rows.
+- **Client:** Godot 4.6.2, minimal `main_menu.gd`; no social UI yet.
+
+## 4. Key design decisions
+
+| Concern | Decision |
+|---|---|
+| Message transport | REST for send/history; **WebSocket** gateway for real-time delivery + presence (matches `networking.md`'s "WebSocket as secondary transport" for chat) |
+| Presence store | Redis (TTL heartbeat) + persisted `last_seen_at` on the user record |
+| Text filtering | Pluggable `TextFilter` interface with a deterministic default (profanity list + normalization) so it runs without external services; third-party hook later |
+| Rate limiting | Redis token-bucket dependency, reusable across all social endpoints |
+| Reports | `message_reports` table + moderation endpoints (list/review/resolve) with audit fields |
+| Friends vs. follow | Friends = mutual (request→accept). Follow = one-way (no approval). Block = hard deny that also hides content and prevents DMs |
+| Privacy | Per-user settings JSON (`profile_visibility`, `friends_list_visibility`, `favorites_visibility`) enforced server-side on every read |
+| Groups | `groups` + `group_members` (role: owner/admin/member) + group page aggregate endpoint |
+| Real-time | One WebSocket endpoint multiplexing presence, DM, and world-chat messages via Redis pub/sub |
+
+## 5. User stories
+
+### US-1 Friends & following
+As a player, I can send a friend request, accept/decline incoming requests,
+unfriend, follow/unfollow other players, and block users so they can't interact
+with me.
+
+**Acceptance criteria**
+- Friend requests are one-directional until accepted; accepted friendships are mutual.
+- Follow is one-way and requires no approval.
+- Block prevents DMs, hides the blocked user's profile/friends interactions, and
+  removes any existing friendship/follow between the two.
+- Duplicate/self requests are rejected idempotently.
+
+### US-2 Presence & status
+As a player, I can see whether my friends are online, their custom status, and
+when they were last seen.
+
+**Acceptance criteria**
+- Online/offline is derived from a server-side heartbeat (Redis TTL), not client claims.
+- `last_seen_at` persists and is visible (subject to privacy settings).
+- Custom status text is optional and length-limited.
+
+### US-3 Public profiles
+As a player, I can view a public profile page showing avatar, bio, favorite
+experiences, and a friends list that respects the owner's privacy settings.
+
+**Acceptance criteria**
+- Avatar and bio are editable by the owner only.
+- Favorite experiences reference existing `World` rows.
+- A viewer sees only the sections the owner's privacy settings allow; blocked
+  users see a restricted view.
+
+### US-4 Chat (DM + in-experience) with safety
+As a player, I can send direct messages and chat inside a world/room. Messages
+are filtered, rate limited, and reportable.
+
+**Acceptance criteria**
+- Server filters message text before storing/delivering; filtered content is either
+  rejected (blocking) or redacted (configurable per filter policy).
+- Send rate is limited per user (token bucket); excess sends get `429`.
+- Every message has a stable id, author, timestamp, and conversation/world scope.
+- Any message can be reported with a reason; reports are stored and reviewable.
+- Real-time delivery over WebSocket with REST fallback for history.
+
+### US-5 Groups
+As a player, I can create a group, join/leave groups, and (as owner/admin)
+manage roles and view a simple group page.
+
+**Acceptance criteria**
+- Each group has exactly one owner and any number of admins/members.
+- Role transitions are authorized (only owner can transfer ownership or promote/demote admins).
+- Group page lists name, description, member list with roles, and member count.
+
+### US-6 Godot client
+As a player, I can access friends, presence, chat, profiles, and groups from the
+game UI.
+
+**Acceptance criteria**
+- An API client handles JWT auth, HTTP, and WebSocket for all social calls.
+- Dedicated screens/panels: friends+presence, DM & world chat (with report),
+  profile page, group page.
+- Client-side filtering is cosmetic; server responses remain authoritative.
+
+## 6. Task breakdown
+
+Right-sized to 1–3 files / one coherent piece of functionality each. Task IDs
+are sequential for dependency chaining.
+
+| # | Task | Story | Depends on |
+|---|------|-------|-----------|
+| 1 | Friends/follow/block models + Alembic migration | US-1 | — |
+| 2 | Friends & follow API router | US-1 | 1 |
+| 3 | Presence & status model + endpoints (Redis heartbeat) | US-2 | — |
+| 4 | Profile model + migration + own-profile endpoints | US-3 | 1 |
+| 5 | Public profile view + favorites + privacy enforcement | US-3 | 2, 4 |
+| 6 | Chat data models + migration (conversations, messages, reports) | US-4 | — |
+| 7 | Text filtering service + profanity config | US-4 | — |
+| 8 | Redis rate-limiting dependency | US-4 | — |
+| 9 | DM chat send/list endpoints (filter + rate limit) | US-4 | 6, 7, 8 |
+| 10 | Report-message endpoint + moderation queue | US-4 | 6, 9 |
+| 11 | In-experience (world/room) chat endpoints | US-4 | 9 |
+| 12 | Real-time WebSocket gateway (presence + DM + world chat) | US-4 | 3, 9, 11 |
+| 13 | Group + membership models + migration | US-5 | — |
+| 14 | Groups API (CRUD, join/leave, roles, group page) | US-5 | 13 |
+| 15 | Godot API client (auth + HTTP + WebSocket) | US-6 | 2 |
+| 16 | Godot friends & presence UI | US-6 | 3, 15 |
+| 17 | Godot chat UI (DM + world chat + report) | US-6 | 12, 15 |
+| 18 | Godot profile page UI | US-6 | 5, 15 |
+| 19 | Godot groups UI + group page | US-6 | 14, 15 |
+
+## 7. Phasing
+
+- **Phase 1 (data + core APIs):** tasks 1–5 (friends, presence, profiles).
+- **Phase 2 (chat safety — the differentiator):** tasks 6–12 (chat + safety +
+  realtime). This is the critical path and highest priority.
+- **Phase 3 (groups):** tasks 13–14.
+- **Phase 4 (client):** tasks 15–19, each landing after its backend dependency.
+
+## 8. Out of scope for this feature
+
+- Age verification / maturity gating (covered by `content_moderation.md`).
+- Voice chat, media/image messages, message editing/deletion history.
+- Third-party profanity/toxicity vendors (the `TextFilter` interface leaves a
+  hook, but the default is deterministic and dependency-free).
+- Mobile push notifications.

docs/testing/README.md

@@ -0,0 +1,50 @@
+# Testing at Package Checkpoints
+
+A Package Checkpoint (PC1, PC2, ...) is a periodic review point — every few
+real milestones, the client and server builds get packaged together and
+independently reviewed before anyone calls anything actually done. See
+`project_agp` in Claude's memory, or ask, for the full definition; this
+doc is just the mechanical "how do I run the tests" part of that review.
+
+## Running the suite
+
+```
+python scripts/run_checkpoint_tests.py
+```
+
+Brings up a throwaway Postgres, runs Alembic migrations against it, runs the
+backend pytest suite, starts the backend server, and runs every Godot
+headless smoke test (`scripts/smoke_test_*.gd`) against it. Tears the
+Postgres container down afterward (`--keep-postgres` to skip that if you
+want to poke at the DB after a failure).
+
+If port 5432 is already taken on the machine, pass `--postgres-port` with
+something else.
+
+Exit code is 0 only if everything that actually ran passed — suites with
+nothing to run yet (no Godot binary found, no smoke test scripts yet) are
+reported SKIPPED, not treated as a failure.
+
+## What this does and doesn't prove
+
+Passing this script means: migrations apply cleanly to a genuinely empty
+database, the backend's unit-level logic is correct, and whatever Godot
+smoke tests exist actually round-trip against a live backend. It does
+**not** mean full endpoint/integration coverage exists — see
+`test_inventory.md` for the current, honest list of what's tested and what
+isn't. A checkpoint review should still involve reading the actual diffs
+for anything this script's current coverage doesn't reach, not just running
+green and calling it done.
+
+## Growing this over time
+
+As real integration tests get added (endpoint tests hitting the FastAPI app,
+more Godot smoke coverage beyond `health_check`), they should land under
+`backend/tests/` / `scripts/smoke_test_*.gd` respectively — this script
+picks up new files automatically, nothing to register by hand. Update
+`test_inventory.md`'s tables when you do, so the inventory stays a source
+of truth instead of quietly going stale.
+
+Eventual goal (not implemented yet): gate merges to `main` on this script
+passing, the same way a real CI pipeline would. For now it's a manual step
+run at checkpoint review time.

docs/testing/test_inventory.md

@@ -0,0 +1,78 @@
+# Test Inventory
+
+What automated coverage actually exists, what it actually verifies, and what
+doesn't have coverage yet. Keep this current as tests are added — it's the
+thing a Package Checkpoint review (see `docs/testing/README.md`) reads first
+to know what "run the tests" actually checked.
+
+Run everything below in one shot with `scripts/run_checkpoint_tests.py`.
+
+Last verified against `main`: 2026-08-19 (commit `1c75367`).
+
+## Backend — `backend/tests/` (pytest)
+
+Run: `cd backend && python -m pytest -v` (needs `DATABASE_URL` pointed at a
+reachable Postgres — see the runner script; most of these tests don't
+actually touch the DB, but the app's import chain requires a valid URL to
+construct).
+
+**Current total: 38 tests, all passing on a clean `main` checkout.**
+
+| File | Tests | What it covers |
+|---|---|---|
+| `test_auth_age_gate.py` | 10 | `calculate_age()` date-math correctness (exact boundary, leap years, birthday-not-yet-this-year) + `RegisterRequest` date-of-birth validation (parametrized valid/invalid date rejection). Backs the 18+ registration gate (PR #23). |
+| `test_gltf_metadata.py` | 21 | glTF/GLB binary + JSON parsing: magic-byte detection, chunk-padding handling, mesh/animation/texture-reference metadata extraction, malformed-input rejection. Backs the asset-import pipeline (PR #27). |
+
+**What these are, honestly:** pure unit tests of standalone functions
+(`calculate_age`, the glTF parser, Pydantic validators). None of them spin
+up the FastAPI app or hit a real endpoint — they run in ~1s and don't
+actually need Postgres reachable at all (the import chain just needs a
+syntactically valid `DATABASE_URL`, nothing connects during collection).
+
+**Known coverage gaps** (real gaps, not placeholders — nothing enforces filling
+these yet):
+- No integration/endpoint tests at all — `/register`, `/login`, `/refresh`,
+  `/worlds`, `/assets/*` have zero tests that actually call them through
+  the FastAPI app (e.g. via `httpx.AsyncClient` + `ASGITransport`) against a
+  real (or test) database. Everything currently shipped works because it
+  was manually verified at merge time (checkpoint review), not because a
+  test asserts it.
+- No tests for the RS256 auth upgrade (key generation, refresh-token
+  issuance/persistence) — PR #30, pending review as of this writing,
+  manually verified (correct key usage, all 38 existing tests still pass)
+  but not covered by an automated test of its own yet.
+- No tests for the moderation schema/migration (in progress as of this
+  writing) beyond "the migration runs."
+
+## Godot client — `scripts/smoke_test_*.gd`
+
+**Nothing merged into `main` yet as of this writing** — `sandbox_probe/test_script.gd`
+is the only Godot script on `main` right now, and it's **not a real
+test** (a leftover manual probe, returns a hardcoded string, asserts
+nothing). Don't count it toward coverage; delete or repurpose it if anyone
+actually needs a sandbox probe again.
+
+`scripts/smoke_test_api.gd` (PC1, PR #29, pending review as of this writing)
+will be the first real one once merged — `ApiClient` autoload's
+`health_check()` against a **live backend** (set `AGP_API_BASE_URL` to point
+at one), verified by hand end-to-end before opening the PR: exercises the
+real HTTP request path (`HTTPRequest` node lifecycle, JSON parse, the
+result-dictionary contract), not just that the script compiles. Exits 1 on
+failure, so it's CI/script-friendly.
+
+Run (once merged): `godot --headless --path . --import` once (builds the
+class cache — skip this and every `class_name`-declared class falsely
+errors as undeclared), then for each `scripts/smoke_test_*.gd`:
+`godot --headless --path . --script res://scripts/<name>.gd`
+
+**Known gap once it lands:** only `health_check()` is exercised end-to-end.
+`login`, `register`, `get_worlds`, `get_me` are implemented (see
+`scripts/api_client.gd`) but have no smoke coverage yet — each would need a
+real user/world fixture in the target backend to test against meaningfully.
+
+## What "full coverage" should eventually mean here
+
+Not defined precisely yet — the honest target as of 2026-08-19 is just
+"more than pure-function unit tests." As real integration/endpoint tests get
+added, update the tables above rather than letting this doc drift stale;
+a wrong inventory is worse than no inventory.

export_presets.cfg

@@ -0,0 +1,74 @@
+[preset.0]
+
+name="Linux"
+platform="Linux/X11"
+runnable=true
+advanced_options=false
+dedicated_server=false
+custom_features=""
+export_filter="all_resources"
+include_filter=""
+exclude_filter=""
+export_path="export/linux/agp-game.x86_64"
+encryption_include_filters=""
+encryption_exclude_filters=""
+encrypt_pck=false
+encrypt_directory=false
+script_export_mode=2
+
+[preset.0.options]
+
+custom_template/debug=""
+custom_template/release=""
+debug/export_console_wrapper=1
+binary_format/embed_pck=false
+texture_format/bptc=true
+texture_format/s3tc=true
+texture_format/etc=false
+texture_format/etc2=false
+binary_format/architecture="x86_64"
+ssh_remote_deploy/enabled=false
+
+[preset.1]
+
+name="Windows Desktop"
+platform="Windows Desktop"
+runnable=true
+advanced_options=false
+dedicated_server=false
+custom_features=""
+export_filter="all_resources"
+include_filter=""
+exclude_filter=""
+export_path="export/windows/agp-game.exe"
+encryption_include_filters=""
+encryption_exclude_filters=""
+encrypt_pck=false
+encrypt_directory=false
+script_export_mode=2
+
+[preset.1.options]
+
+custom_template/debug=""
+custom_template/release=""
+debug/export_console_wrapper=1
+binary_format/embed_pck=false
+texture_format/bptc=true
+texture_format/s3tc=true
+texture_format/etc=false
+texture_format/etc2=false
+binary_format/architecture="x86_64"
+codesign/enable=false
+application/icon=""
+application/console_wrapper_icon=""
+application/icon_interpolation=4
+application/file_version=""
+application/product_version=""
+application/company_name=""
+application/product_name=""
+application/file_description=""
+application/copyright=""
+application/trademarks=""
+application/export_angle=0
+application/export_d3d12=0
+d3d12/agility_sdk_multizip=0

project.godot

@@ -1,8 +1,27 @@
 ; Engine configuration file.
+; It's best edited using the editor UI and not directly,
+; but it can also be edited by hand.
+
 config_version=5
 
 [application]
 
-config/name="sandbox_probe"
-run/main_scene="res://probe5.tscn"
-config/features=PackedStringArray("4.6")
+config/name="AGP-Game"
+run/main_scene="res://scenes/main_menu.tscn"
+config/features=PackedStringArray("4.6.2")
+agp/api_base_url="http://127.0.0.1:8000"
+
+[autoload]
+
+ApiClient="*res://scripts/api_client.gd"
+
+[display]
+
+window/size/viewport_width=1920
+window/size/viewport_height=1080
+window/stretch/mode="canvas_items"
+
+[rendering]
+
+renderer/rendering_method="gl_compatibility"
+renderer/rendering_method.mobile="gl_compatibility"

sandbox_probe/probe.gd

@@ -1,76 +0,0 @@
-extends Node
-
-func _ready():
-	print("=== SANDBOX PROBE START ===")
-	probe_script_loading()
-	probe_os_apis()
-	probe_file_access()
-	probe_network()
-	probe_engine_apis()
-	print("=== SANDBOX PROBE END ===")
-	get_tree().quit()
-
-func probe_script_loading():
-	print("--- Script loading ---")
-	# Can we load a GDScript from a string at runtime?
-	var gd = GDScript.new()
-	gd.source_code = "extends RefCounted\nfunc hello():\n\treturn 42\n"
-	var err = gd.reload()
-	print("GDScript.reload() from source_code err=", err)
-	if err == OK:
-		var inst = gd.new()
-		print("  instantiated, hello()=", inst.call("hello"))
-	# Can we load a script resource from a path?
-	var res = load("res://test_script.gd")
-	print("load('res://test_script.gd') = ", res)
-
-func probe_os_apis():
-	print("--- OS APIs ---")
-	# Can we execute shell commands?
-	var out = []
-	var exit_code = OS.execute("echo", ["hello"], out)
-	print("OS.execute('echo') exit=", exit_code, " out=", out)
-	# Environment access
-	print("OS.get_environment('HOME') = ", OS.get_environment("HOME"))
-	# Process spawning
-	print("OS.create_process available: ", OS.has_method("create_process"))
-
-func probe_file_access():
-	print("--- File access ---")
-	# Can we read arbitrary files?
-	var f = FileAccess.open("/etc/hostname", FileAccess.READ)
-	print("FileAccess.open('/etc/hostname') = ", f)
-	if f:
-		print("  content: ", f.get_as_text())
-		f.close()
-	# Can we write outside the project?
-	var w = FileAccess.open("/tmp/godot_probe_write.txt", FileAccess.WRITE)
-	print("FileAccess.open('/tmp/...', WRITE) = ", w)
-	if w:
-		w.store_string("probe")
-		w.close()
-		print("  wrote to /tmp OK")
-
-func probe_network():
-	print("--- Network ---")
-	# Can we open raw sockets?
-	var tcp = TCPServer.new()
-	var bind_err = tcp.listen(0)
-	print("TCPServer.listen(0) err=", bind_err)
-	# HTTP client
-	var http = HTTPClient.new()
-	print("HTTPClient instantiated: ", http != null)
-
-func probe_engine_apis():
-	print("--- Engine APIs ---")
-	# Can we access the scene tree / add nodes?
-	var node = Node.new()
-	print("Node.new() = ", node)
-	# Can we access ProjectSettings?
-	print("ProjectSettings.get_setting('application/config/name') = ", ProjectSettings.get_setting("application/config/name"))
-	# Can we access the filesystem directory listing?
-	var dir = DirAccess.open("/")
-	print("DirAccess.open('/') = ", dir)
-	if dir:
-		var names = dir.get_files()
-		print("  root files count: ", names.size())

sandbox_probe/probe.tscn

@@ -1,6 +0,0 @@
-[gd_scene load_steps=2 format=3]
-
-[ext_resource type="Script" path="res://probe.gd" id="1"]
-
-[node name="Probe" type="Node"]
-script = ExtResource("1")

sandbox_probe/probe2.gd

@@ -1,83 +0,0 @@
-extends Node
-
-func _ready():
-	print("=== SANDBOX PROBE 2: Sandboxing Mechanisms ===")
-	probe_scriptserver()
-	probe_script_restrictions()
-	probe_subviewport_isolation()
-	probe_engine_restrictions()
-	probe_allowlist_approach()
-	print("=== SANDBOX PROBE 2 END ===")
-	get_tree().quit()
-
-func probe_scriptserver():
-	print("--- ScriptServer ---")
-	# Does ScriptServer exist and what can it do?
-	print("ScriptServer has_method('get_language_count'): ", ScriptServer.has_method("get_language_count"))
-	print("ScriptServer has_method('get_language'): ", ScriptServer.has_method("get_language"))
-	# Can we enumerate registered script languages?
-	if ScriptServer.has_method("get_language_count"):
-		var count = ScriptServer.get_language_count()
-		print("  language count: ", count)
-		for i in range(count):
-			var lang = ScriptServer.get_language(i)
-			print("  language[", i, "] = ", lang)
-
-func probe_script_restrictions():
-	print("--- Script restrictions ---")
-	# Can we restrict which classes/globals a script can access?
-	# Test: does GDScript have any built-in allowlist mechanism?
-	var gd = GDScript.new()
-	gd.source_code = "extends RefCounted\nfunc evil():\n\treturn OS.get_environment('HOME')\n"
-	var err = gd.reload()
-	print("  GDScript with OS access reload err=", err)
-	if err == OK:
-		var inst = gd.new()
-		print("  evil() result: ", inst.call("evil"))
-	# Can we block specific global classes?
-	print("  GDScript has method to restrict globals: ", gd.has_method("set_global_scope"))
-
-func probe_subviewport_isolation():
-	print("--- SubViewport isolation ---")
-	# SubViewports isolate rendering, but do they isolate script execution?
-	var vp = SubViewport.new()
-	print("  SubViewport.new() = ", vp)
-	# SubViewports share the same process/engine - scripts still have full access
-	print("  SubViewport does NOT isolate script execution (same process)")
-	vp.free()
-
-func probe_engine_restrictions():
-	print("--- Engine restrictions ---")
-	# Is there a way to disable OS/File/Network access globally?
-	print("  Engine.has_singleton('OS'): ", Engine.has_singleton("OS"))
-	print("  Engine.has_singleton('FileAccess'): ", Engine.has_singleton("FileAccess"))
-	# Check if there's a '--disable-*' flag or project setting
-	print("  ProjectSettings has 'application/run/disable_*': ", ProjectSettings.has_setting("application/run/disable_os"))
-	# Check for any sandbox-related project settings
-	var settings = ProjectSettings.get_property_list()
-	var sandbox_settings = []
-	for s in settings:
-		if "sandbox" in String(s.name).to_lower() or "restrict" in String(s.name).to_lower():
-			sandbox_settings.append(s.name)
-	print("  Sandbox-related project settings: ", sandbox_settings)
-
-func probe_allowlist_approach():
-	print("--- Allowlist approach ---")
-	# The allowlist approach: parse GDScript source and reject disallowed patterns
-	# Test: can we detect dangerous API calls via string analysis?
-	var dangerous_patterns = [
-		"OS.execute", "OS.create_process", "OS.get_environment",
-		"FileAccess.open", "DirAccess.open", "TCPServer", "HTTPClient",
-		"load(", "preload(", "ClassDB", "Engine.get_main_loop",
-		"get_tree().quit", "ProjectSettings"
-	]
-	var test_script = """
-extends Node
-func _ready():
-	var f = FileAccess.open("/etc/passwd", FileAccess.READ)
-	OS.execute("rm", ["-rf", "/"])
-	"""
-	print("  Test script contains dangerous patterns:")
-	for p in dangerous_patterns:
-		if p in test_script:
-			print("    DETECTED: ", p)

sandbox_probe/probe3.gd

@@ -1,126 +0,0 @@
-extends Node
-
-func _ready():
-	print("=== SANDBOX PROBE 3: Deep Sandboxing Mechanisms ===")
-	probe_global_scope_restriction()
-	probe_classdb_restriction()
-	probe_engine_singletons()
-	probe_script_validation()
-	probe_expression_engine()
-	probe_worker_threads()
-	probe_os_restriction_flags()
-	print("=== SANDBOX PROBE 3 END ===")
-	get_tree().quit()
-
-func probe_global_scope_restriction():
-	print("--- Global scope restriction ---")
-	# Can we enumerate what's in the global scope?
-	var globals = []
-	for g in GDScript.get_global_class_list():
-		globals.append(g)
-	print("  GDScript.get_global_class_list() count: ", globals.size())
-	# Can we check if a global is available before using it?
-	print("  GDScript has 'get_global_class_list': ", GDScript.has_method("get_global_class_list"))
-	# Is there any way to restrict which globals a script sees?
-	print("  GDScript has 'set_global_scope': ", GDScript.has_method("set_global_scope"))
-	print("  GDScript has 'restrict_globals': ", GDScript.has_method("restrict_globals"))
-	# Check the GDScript class methods
-	var methods = GDScript.get_method_list()
-	var method_names = []
-	for m in methods:
-		method_names.append(m.name)
-	print("  GDScript methods: ", method_names)
-
-func probe_classdb_restriction():
-	print("--- ClassDB restriction ---")
-	# ClassDB is the registry of all engine classes. Can we restrict it?
-	print("  ClassDB has 'get_class_list': ", ClassDB.has_method("get_class_list"))
-	print("  ClassDB has 'class_exists': ", ClassDB.has_method("class_exists"))
-	# Can we check if a specific class is available?
-	print("  ClassDB.class_exists('OS'): ", ClassDB.class_exists("OS"))
-	print("  ClassDB.class_exists('FileAccess'): ", ClassDB.class_exists("FileAccess"))
-	print("  ClassDB.class_exists('TCPServer'): ", ClassDB.class_exists("TCPServer"))
-	# Is there a way to hide classes from scripts?
-	print("  ClassDB has 'set_class_enabled': ", ClassDB.has_method("set_class_enabled"))
-	print("  ClassDB has 'disable_class': ", ClassDB.has_method("disable_class"))
-
-func probe_engine_singletons():
-	print("--- Engine singletons ---")
-	# Engine singletons are the global objects like OS, Engine, etc.
-	# Can we enumerate them?
-	var singletons = Engine.get_singletons()
-	print("  Engine.get_singletons() count: ", singletons.size())
-	for s in singletons:
-		print("    singleton: ", s)
-	# Can we remove a singleton?
-	print("  Engine has 'remove_singleton': ", Engine.has_method("remove_singleton"))
-	print("  Engine has 'add_singleton': ", Engine.has_method("add_singleton"))
-
-func probe_script_validation():
-	print("--- Script validation ---")
-	# Can we validate a script before running it?
-	var gd = GDScript.new()
-	gd.source_code = "extends RefCounted\nfunc evil():\n\treturn OS.get_environment('HOME')\n"
-	var err = gd.reload()
-	print("  GDScript.reload() err=", err)
-	# Can we get the list of identifiers used in a script?
-	print("  GDScript has 'get_script_method_list': ", gd.has_method("get_script_method_list"))
-	# Can we get the source code back?
-	print("  GDScript has 'get_source_code': ", gd.has_method("get_source_code"))
-	# Can we check what identifiers a script references?
-	print("  GDScript has 'get_script_constant_map': ", gd.has_method("get_script_constant_map"))
-	# Check if there's a way to get the AST
-	print("  GDScript has 'get_ast': ", gd.has_method("get_ast"))
-	print("  GDScript has 'get_parser': ", gd.has_method("get_parser"))
-
-func probe_expression_engine():
-	print("--- Expression engine ---")
-	# Godot has an Expression class for evaluating expressions safely
-	var expr = Expression.new()
-	var err = expr.parse("1 + 2")
-	print("  Expression.parse('1 + 2') err=", err)
-	if err == OK:
-		var result = expr.execute()
-		print("  Expression.execute() = ", result)
-	# Can Expression access OS?
-	var expr2 = Expression.new()
-	err = expr2.parse("OS.get_environment('HOME')")
-	print("  Expression.parse('OS.get_environment') err=", err)
-	if err == OK:
-		var result2 = expr2.execute()
-		print("  Expression.execute() = ", result2)
-	# Expression with base_instance
-	var expr3 = Expression.new()
-	err = expr3.parse("get_environment('HOME')", ["OS"])
-	print("  Expression.parse with base_instance err=", err)
-	if err == OK:
-		var result3 = expr3.execute([], OS)
-		print("  Expression.execute with OS base = ", result3)
-
-func probe_worker_threads():
-	print("--- Worker threads ---")
-	# Can we run scripts in worker threads?
-	print("  Thread has 'new': ", Thread.has_method("new"))
-	# WorkerThreadPool
-	print("  WorkerThreadPool has 'add_task': ", WorkerThreadPool.has_method("add_task"))
-	# Can we isolate a script in a thread?
-	print("  Thread available: ", Thread != null)
-
-func probe_os_restriction_flags():
-	print("--- OS restriction flags ---")
-	# Check if there are any OS-level sandbox flags
-	print("  OS has 'get_environment': ", OS.has_method("get_environment"))
-	print("  OS has 'execute': ", OS.has_method("execute"))
-	print("  OS has 'create_process': ", OS.has_method("create_process"))
-	# Check project settings for sandbox-related options
-	var settings = ProjectSettings.get_property_list()
-	var relevant = []
-	for s in settings:
-		var name = String(s.name)
-		if "sandbox" in name.to_lower() or "restrict" in name.to_lower() or "security" in name.to_lower():
-			relevant.append(name)
-	print("  Sandbox/security project settings: ", relevant)
-	# Check if there's a way to disable specific features
-	print("  ProjectSettings has 'application/run/disable_os': ", ProjectSettings.has_setting("application/run/disable_os"))
-	print("  ProjectSettings has 'application/run/disable_file_access': ", ProjectSettings.has_setting("application/run/disable_file_access"))
-	print("  ProjectSettings has 'application/run/disable_network': ", ProjectSettings.has_setting("application/run/disable_network"))

sandbox_probe/probe3.tscn

@@ -1,6 +0,0 @@
-[gd_scene load_steps=2 format=3]
-
-[ext_resource type="Script" path="res://probe3.gd" id="1"]
-
-[node name="Probe3" type="Node"]
-script = ExtResource("1")

sandbox_probe/probe4.gd

@@ -1,232 +0,0 @@
-extends Node
-
-func _ready():
-	print("=== SANDBOX PROBE 4: Godot 4.6.2 Sandboxing Mechanisms ===")
-	probe_script_loading()
-	probe_os_apis()
-	probe_file_access()
-	probe_network()
-	probe_classdb()
-	probe_expression_engine()
-	probe_engine_singletons()
-	probe_global_scope()
-	probe_worker_threads()
-	probe_project_settings()
-	print("=== SANDBOX PROBE 4 END ===")
-	get_tree().quit()
-
-func probe_script_loading():
-	print("--- Script loading ---")
-	# Can we load a GDScript from a string at runtime?
-	var gd = GDScript.new()
-	gd.source_code = "extends RefCounted\nfunc hello():\n\treturn 42\n"
-	var err = gd.reload()
-	print("GDScript.reload() from source_code err=", err)
-	if err == OK:
-		var inst = gd.new()
-		print("  instantiated, hello()=", inst.call("hello"))
-	# Can we load a script resource from a path?
-	var res = load("res://test_script.gd")
-	print("load('res://test_script.gd') = ", res)
-	# Can we get the source code back from a loaded script?
-	if res:
-		print("  get_source_code() available: ", res.has_method("get_source_code"))
-	# Can we get the AST / parse tree?
-	print("  GDScript instance has 'get_ast': ", gd.has_method("get_ast"))
-	print("  GDScript instance has 'get_parser': ", gd.has_method("get_parser"))
-	# Can we get the list of methods?
-	print("  GDScript instance has 'get_script_method_list': ", gd.has_method("get_script_method_list"))
-	# Can we get the list of member variables?
-	print("  GDScript instance has 'get_script_property_list': ", gd.has_method("get_script_property_list"))
-
-func probe_os_apis():
-	print("--- OS APIs ---")
-	# Can we execute shell commands?
-	var out = []
-	var exit_code = OS.execute("echo", ["hello"], out)
-	print("OS.execute('echo') exit=", exit_code, " out=", out)
-	# Environment access
-	print("OS.get_environment('HOME') = ", OS.get_environment("HOME"))
-	# Process spawning
-	print("OS has 'create_process': ", OS.has_method("create_process"))
-	# Can we get the command line?
-	print("OS.get_cmdline_args() = ", OS.get_cmdline_args())
-	# Can we get user data dir?
-	print("OS.get_user_data_dir() = ", OS.get_user_data_dir())
-	# Can we get executable path?
-	print("OS.get_executable_path() = ", OS.get_executable_path())
-
-func probe_file_access():
-	print("--- File access ---")
-	# Can we read arbitrary files?
-	var f = FileAccess.open("/etc/hostname", FileAccess.READ)
-	print("FileAccess.open('/etc/hostname') = ", f)
-	if f:
-		print("  content: ", f.get_as_text())
-		f.close()
-	# Can we write outside the project?
-	var w = FileAccess.open("/tmp/godot_probe_write.txt", FileAccess.WRITE)
-	print("FileAccess.open('/tmp/...', WRITE) = ", w)
-	if w:
-		w.store_string("probe")
-		w.close()
-		print("  wrote to /tmp OK")
-	# Can we list directories?
-	var dir = DirAccess.open("/")
-	print("DirAccess.open('/') = ", dir)
-	if dir:
-		var names = dir.get_files()
-		print("  root files count: ", names.size())
-	# Can we access res:// and user:// ?
-	var res_dir = DirAccess.open("res://")
-	print("DirAccess.open('res://') = ", res_dir)
-	var user_dir = DirAccess.open("user://")
-	print("DirAccess.open('user://') = ", user_dir)
-
-func probe_network():
-	print("--- Network ---")
-	# Can we open raw sockets?
-	var tcp = TCPServer.new()
-	var bind_err = tcp.listen(0)
-	print("TCPServer.listen(0) err=", bind_err)
-	# HTTP client
-	var http = HTTPClient.new()
-	print("HTTPClient instantiated: ", http != null)
-	# Can we make HTTP requests?
-	var http_req = HTTPRequest.new()
-	print("HTTPRequest instantiated: ", http_req != null)
-	# PacketPeerUDP
-	var udp = PacketPeerUDP.new()
-	print("PacketPeerUDP instantiated: ", udp != null)
-	# WebSocket
-	var ws = WebSocketPeer.new()
-	print("WebSocketPeer instantiated: ", ws != null)
-
-func probe_classdb():
-	print("--- ClassDB ---")
-	# ClassDB is the registry of all engine classes
-	print("ClassDB.class_exists('OS'): ", ClassDB.class_exists("OS"))
-	print("ClassDB.class_exists('FileAccess'): ", ClassDB.class_exists("FileAccess"))
-	print("ClassDB.class_exists('TCPServer'): ", ClassDB.class_exists("TCPServer"))
-	print("ClassDB.class_exists('HTTPClient'): ", ClassDB.class_exists("HTTPClient"))
-	# Can we enumerate all classes?
-	var class_list = ClassDB.get_class_list()
-	print("ClassDB.get_class_list() count: ", class_list.size())
-	# Can we get methods of a class?
-	var os_methods = ClassDB.class_get_method_list("OS")
-	print("OS method count: ", os_methods.size())
-	# Can we get properties of a class?
-	var os_props = ClassDB.class_get_property_list("OS")
-	print("OS property count: ", os_props.size())
-	# Can we instantiate a class by name?
-	var inst = ClassDB.instantiate("Node")
-	print("ClassDB.instantiate('Node') = ", inst)
-	# Can we check if a class is a singleton?
-	print("ClassDB has 'class_get_singleton': ", ClassDB.has_method("class_get_singleton"))
-	# Can we get the singleton instance of OS?
-	var os_singleton = ClassDB.class_get_singleton("OS")
-	print("ClassDB.class_get_singleton('OS') = ", os_singleton)
-	# Can we check what methods are available on the singleton?
-	if os_singleton:
-		print("  OS singleton has 'execute': ", os_singleton.has_method("execute"))
-		print("  OS singleton has 'get_environment': ", os_singleton.has_method("get_environment"))
-
-func probe_expression_engine():
-	print("--- Expression engine ---")
-	# Godot has an Expression class for evaluating expressions safely
-	var expr = Expression.new()
-	var err = expr.parse("1 + 2")
-	print("Expression.parse('1 + 2') err=", err)
-	if err == OK:
-		var result = expr.execute()
-		print("  Expression.execute() = ", result)
-	# Can Expression access OS?
-	var expr2 = Expression.new()
-	err = expr2.parse("OS.get_environment('HOME')")
-	print("Expression.parse('OS.get_environment') err=", err)
-	if err == OK:
-		var result2 = expr2.execute()
-		print("  Expression.execute() = ", result2)
-	# Expression with base_instance
-	var expr3 = Expression.new()
-	err = expr3.parse("get_environment('HOME')", ["OS"])
-	print("Expression.parse with base_instance err=", err)
-	if err == OK:
-		var result3 = expr3.execute([], OS)
-		print("  Expression.execute with OS base = ", result3)
-	# Can Expression call arbitrary methods?
-	var expr4 = Expression.new()
-	err = expr4.parse("FileAccess.open('/etc/hostname', 1)")
-	print("Expression.parse('FileAccess.open') err=", err)
-	if err == OK:
-		var result4 = expr4.execute()
-		print("  Expression.execute() = ", result4)
-	# Can Expression access the scene tree?
-	var expr5 = Expression.new()
-	err = expr5.parse("get_tree().quit()")
-	print("Expression.parse('get_tree().quit()') err=", err)
-	if err == OK:
-		var result5 = expr5.execute()
-		print("  Expression.execute() = ", result5)
-
-func probe_engine_singletons():
-	print("--- Engine singletons ---")
-	# Engine singletons are the global objects like OS, Engine, etc.
-	var singletons = Engine.get_singletons()
-	print("Engine.get_singletons() count: ", singletons.size())
-	for s in singletons:
-		print("    singleton: ", s)
-	# Can we remove a singleton?
-	print("Engine has 'remove_singleton': ", Engine.has_method("remove_singleton"))
-	print("Engine has 'add_singleton': ", Engine.has_method("add_singleton"))
-	# Can we get the main loop?
-	print("Engine.get_main_loop() = ", Engine.get_main_loop())
-	# Can we get the physics server?
-	print("Engine.get_physics_server() = ", Engine.get_physics_server())
-
-func probe_global_scope():
-	print("--- Global scope ---")
-	# Can we enumerate what's in the global scope?
-	var globals = []
-	for g in GDScript.get_global_class_list():
-		globals.append(g)
-	print("GDScript.get_global_class_list() count: ", globals.size())
-	# Can we check if a global is available before using it?
-	print("GDScript has 'get_global_class_list': ", GDScript.has_method("get_global_class_list"))
-	# Is there any way to restrict which globals a script sees?
-	print("GDScript has 'set_global_scope': ", GDScript.has_method("set_global_scope"))
-	print("GDScript has 'restrict_globals': ", GDScript.has_method("restrict_globals"))
-	# Check the GDScript class methods
-	var methods = GDScript.get_method_list()
-	var method_names = []
-	for m in methods:
-		method_names.append(m.name)
-	print("  GDScript methods: ", method_names)
-
-func probe_worker_threads():
-	print("--- Worker threads ---")
-	# Can we run scripts in worker threads?
-	var thread = Thread.new()
-	print("  Thread.new() = ", thread)
-	# WorkerThreadPool
-	print("  WorkerThreadPool has 'add_task': ", WorkerThreadPool.has_method("add_task"))
-	# Can we isolate a script in a thread?
-	print("  Thread available: ", Thread != null)
-
-func probe_project_settings():
-	print("--- Project settings ---")
-	# Check for any sandbox-related project settings
-	var settings = ProjectSettings.get_property_list()
-	var relevant = []
-	for s in settings:
-		var name = String(s.name)
-		if "sandbox" in name.to_lower() or "restrict" in name.to_lower() or "security" in name.to_lower():
-			relevant.append(name)
-	print("  Sandbox/security project settings: ", relevant)
-	# Check if there's a way to disable specific features
-	print("  ProjectSettings has 'application/run/disable_os': ", ProjectSettings.has_setting("application/run/disable_os"))
-	print("  ProjectSettings has 'application/run/disable_file_access': ", ProjectSettings.has_setting("application/run/disable_file_access"))
-	print("  ProjectSettings has 'application/run/disable_network': ", ProjectSettings.has_setting("application/run/disable_network"))
-	# Can we set project settings at runtime?
-	print("  ProjectSettings has 'set_setting': ", ProjectSettings.has_method("set_setting"))
-	print("  ProjectSettings has 'save': ", ProjectSettings.has_method("save"))

sandbox_probe/probe4.tscn

@@ -1,6 +0,0 @@
-[gd_scene load_steps=2 format=3]
-
-[ext_resource type="Script" path="res://probe4.gd" id="1"]
-
-[node name="Probe4" type="Node"]
-script = ExtResource("1")

sandbox_probe/probe5.gd

@@ -1,221 +0,0 @@
-extends Node
-
-func _ready():
-	print("=== SANDBOX PROBE 5b: Corrected Sandboxing Mechanisms (Godot 4.6.2) ===")
-	probe_script_loading()
-	probe_os_apis()
-	probe_file_access()
-	probe_network()
-	probe_classdb()
-	probe_expression_engine()
-	probe_engine_singletons()
-	probe_worker_threads()
-	probe_project_settings()
-	probe_script_restrictions()
-	probe_allowlist()
-	print("=== SANDBOX PROBE 5b END ===")
-	get_tree().quit()
-
-func probe_script_loading():
-	print("--- Script loading ---")
-	var gd = GDScript.new()
-	gd.source_code = "extends RefCounted\nfunc hello():\n\treturn 42\n"
-	var err = gd.reload()
-	print("GDScript.reload() from source_code err=", err)
-	if err == OK:
-		var inst = gd.new()
-		print("  instantiated, hello()=", inst.call("hello"))
-	var res = load("res://test_script.gd")
-	print("load('res://test_script.gd') = ", res)
-	if res:
-		print("  get_source_code() available: ", res.has_method("get_source_code"))
-	print("  GDScript instance has 'get_ast': ", gd.has_method("get_ast"))
-	print("  GDScript instance has 'get_parser': ", gd.has_method("get_parser"))
-	print("  GDScript instance has 'get_script_method_list': ", gd.has_method("get_script_method_list"))
-	print("  GDScript instance has 'get_script_property_list': ", gd.has_method("get_script_property_list"))
-	print("  GDScript instance has 'get_instance_base_type': ", gd.has_method("get_instance_base_type"))
-	# Can we get the list of static methods on GDScript class?
-	var gd_methods = GDScript.get_method_list()
-	var gd_method_names = []
-	for m in gd_methods:
-		gd_method_names.append(String(m.name))
-	print("  GDScript static methods: ", gd_method_names)
-
-func probe_os_apis():
-	print("--- OS APIs ---")
-	var out = []
-	var exit_code = OS.execute("echo", ["hello"], out)
-	print("OS.execute('echo') exit=", exit_code, " out=", out)
-	print("OS.get_environment('HOME') = ", OS.get_environment("HOME"))
-	print("OS has 'create_process': ", OS.has_method("create_process"))
-	print("OS.get_cmdline_args() = ", OS.get_cmdline_args())
-	print("OS.get_user_data_dir() = ", OS.get_user_data_dir())
-	print("OS.get_executable_path() = ", OS.get_executable_path())
-
-func probe_file_access():
-	print("--- File access ---")
-	var f = FileAccess.open("/etc/hostname", FileAccess.READ)
-	print("FileAccess.open('/etc/hostname') = ", f)
-	if f:
-		print("  content: ", f.get_as_text())
-		f.close()
-	var w = FileAccess.open("/tmp/godot_probe_write.txt", FileAccess.WRITE)
-	print("FileAccess.open('/tmp/...', WRITE) = ", w)
-	if w:
-		w.store_string("probe")
-		w.close()
-		print("  wrote to /tmp OK")
-	var dir = DirAccess.open("/")
-	print("DirAccess.open('/') = ", dir)
-	if dir:
-		var names = dir.get_files()
-		print("  root files count: ", names.size())
-	var res_dir = DirAccess.open("res://")
-	print("DirAccess.open('res://') = ", res_dir)
-	var user_dir = DirAccess.open("user://")
-	print("DirAccess.open('user://') = ", user_dir)
-
-func probe_network():
-	print("--- Network ---")
-	var tcp = TCPServer.new()
-	var bind_err = tcp.listen(0)
-	print("TCPServer.listen(0) err=", bind_err)
-	var http = HTTPClient.new()
-	print("HTTPClient instantiated: ", http != null)
-	var http_req = HTTPRequest.new()
-	print("HTTPRequest instantiated: ", http_req != null)
-	var udp = PacketPeerUDP.new()
-	print("PacketPeerUDP instantiated: ", udp != null)
-	var ws = WebSocketPeer.new()
-	print("WebSocketPeer instantiated: ", ws != null)
-
-func probe_classdb():
-	print("--- ClassDB ---")
-	print("ClassDB.class_exists('OS'): ", ClassDB.class_exists("OS"))
-	print("ClassDB.class_exists('FileAccess'): ", ClassDB.class_exists("FileAccess"))
-	print("ClassDB.class_exists('TCPServer'): ", ClassDB.class_exists("TCPServer"))
-	print("ClassDB.class_exists('HTTPClient'): ", ClassDB.class_exists("HTTPClient"))
-	var class_list = ClassDB.get_class_list()
-	print("ClassDB.get_class_list() count: ", class_list.size())
-	var os_methods = ClassDB.class_get_method_list("OS")
-	print("OS method count: ", os_methods.size())
-	var inst = ClassDB.instantiate("Node")
-	print("ClassDB.instantiate('Node') = ", inst)
-	# Can we enumerate ClassDB methods to see what's available?
-	var classdb_methods = ClassDB.get_method_list()
-	var classdb_method_names = []
-	for m in classdb_methods:
-		classdb_method_names.append(String(m.name))
-	print("  ClassDB methods: ", classdb_method_names)
-
-func probe_expression_engine():
-	print("--- Expression engine ---")
-	var expr = Expression.new()
-	var err = expr.parse("1 + 2")
-	print("Expression.parse('1 + 2') err=", err)
-	if err == OK:
-		var result = expr.execute()
-		print("  Expression.execute() = ", result)
-	var expr2 = Expression.new()
-	err = expr2.parse("OS.get_environment('HOME')")
-	print("Expression.parse('OS.get_environment') err=", err)
-	if err == OK:
-		var result2 = expr2.execute()
-		print("  Expression.execute() = ", result2)
-	var expr3 = Expression.new()
-	err = expr3.parse("get_environment('HOME')", ["OS"])
-	print("Expression.parse with base_instance err=", err)
-	if err == OK:
-		var result3 = expr3.execute([], OS)
-		print("  Expression.execute with OS base = ", result3)
-	var expr4 = Expression.new()
-	err = expr4.parse("FileAccess.open('/etc/hostname', 1)")
-	print("Expression.parse('FileAccess.open') err=", err)
-	if err == OK:
-		var result4 = expr4.execute()
-		print("  Expression.execute() = ", result4)
-	var expr5 = Expression.new()
-	err = expr5.parse("get_tree().quit()")
-	print("Expression.parse('get_tree().quit()') err=", err)
-	if err == OK:
-		var result5 = expr5.execute()
-		print("  Expression.execute() = ", result5)
-
-func probe_engine_singletons():
-	print("--- Engine singletons ---")
-	print("Engine has 'remove_singleton': ", Engine.has_method("remove_singleton"))
-	print("Engine has 'add_singleton': ", Engine.has_method("add_singleton"))
-	print("Engine.get_main_loop() = ", Engine.get_main_loop())
-	# Can we enumerate singletons via Engine instance methods?
-	var engine_methods = Engine.get_method_list()
-	var engine_method_names = []
-	for m in engine_methods:
-		engine_method_names.append(String(m.name))
-	print("  Engine instance methods: ", engine_method_names)
-
-func probe_worker_threads():
-	print("--- Worker threads ---")
-	var thread = Thread.new()
-	print("  Thread.new() = ", thread)
-	print("  WorkerThreadPool has 'add_task': ", WorkerThreadPool.has_method("add_task"))
-
-func probe_project_settings():
-	print("--- Project settings ---")
-	var settings = ProjectSettings.get_property_list()
-	var relevant = []
-	for s in settings:
-		var name = String(s.name)
-		if "sandbox" in name.to_lower() or "restrict" in name.to_lower() or "security" in name.to_lower():
-			relevant.append(name)
-	print("  Sandbox/security project settings: ", relevant)
-	print("  ProjectSettings has 'application/run/disable_os': ", ProjectSettings.has_setting("application/run/disable_os"))
-	print("  ProjectSettings has 'application/run/disable_file_access': ", ProjectSettings.has_setting("application/run/disable_file_access"))
-	print("  ProjectSettings has 'application/run/disable_network': ", ProjectSettings.has_setting("application/run/disable_network"))
-	print("  ProjectSettings has 'set_setting': ", ProjectSettings.has_method("set_setting"))
-	print("  ProjectSettings has 'save': ", ProjectSettings.has_method("save"))
-
-func probe_script_restrictions():
-	print("--- Script restrictions ---")
-	var gd = GDScript.new()
-	gd.source_code = "extends RefCounted\nfunc evil():\n\treturn OS.get_environment('HOME')\n"
-	var err = gd.reload()
-	print("  GDScript with OS access reload err=", err)
-	if err == OK:
-		var inst = gd.new()
-		print("  evil() result: ", inst.call("evil"))
-	print("  GDScript has method to restrict globals: ", gd.has_method("set_global_scope"))
-	print("  GDScript has method 'get_global_scope': ", gd.has_method("get_global_scope"))
-	# Can we check what identifiers a script references via the analyzer?
-	print("  GDScript has 'get_script_constant_map': ", gd.has_method("get_script_constant_map"))
-	# Can we get the list of member variables?
-	print("  GDScript has 'get_script_property_list': ", gd.has_method("get_script_property_list"))
-
-func probe_allowlist():
-	print("--- Allowlist / static analysis ---")
-	var dangerous_patterns = [
-		"OS.execute", "OS.create_process", "OS.get_environment",
-		"FileAccess.open", "DirAccess.open", "TCPServer", "HTTPClient",
-		"load(", "preload(", "ClassDB", "Engine.get_main_loop",
-		"get_tree().quit", "ProjectSettings"
-	]
-	var test_script = """extends Node
-func _ready():
-	var f = FileAccess.open("/etc/passwd", FileAccess.READ)
-	OS.execute("rm", ["-rf", "/"])
-"""
-	print("  Test script contains dangerous patterns:")
-	for p in dangerous_patterns:
-		if p in test_script:
-			print("    DETECTED: ", p)
-	# Can we use a tokenizer/lexer to parse GDScript?
-	# GDScriptLanguage is NOT exposed to GDScript (confirmed by parse error)
-	print("  GDScriptLanguage NOT exposed to GDScript (parse error confirmed)")
-	# Can we use the Expression engine to validate syntax?
-	var expr = Expression.new()
-	var err = expr.parse("var x = 1 + 2")
-	print("  Expression.parse('var x = 1 + 2') err=", err)
-	err = expr.parse("OS.execute('rm', ['-rf', '/'])")
-	print("  Expression.parse('OS.execute...') err=", err)
-	if err == OK:
-		var result = expr.execute()
-		print("  Expression.execute() = ", result)

sandbox_probe/probe5.tscn

@@ -1,6 +0,0 @@
-[gd_scene load_steps=2 format=3]
-
-[ext_resource type="Script" path="res://probe5.gd" id="1"]
-
-[node name="Probe5" type="Node"]
-script = ExtResource("1")

sandbox_probe/probe_scriptserver_check.gd

@@ -1,6 +0,0 @@
-extends SceneTree
-func _init():
-	print("ScriptServer class exists: ", ClassDB.class_exists("ScriptServer"))
-	var sv = SubViewport.new()
-	print("SubViewport instantiated: ", sv != null)
-	quit()

sandbox_probe/project.godot

@@ -4,5 +4,5 @@ config_version=5
 [application]
 
 config/name="sandbox_probe"
-run/main_scene="res://probe5.tscn"
+run/main_scene="res://probe6.tscn"
 config/features=PackedStringArray("4.6")

scenes/main.tscn

@@ -0,0 +1,6 @@
+[gd_scene load_steps=2 format=3 uid="uid://main_scene"]
+
+[ext_resource type="Script" path="res://scripts/chunk_stream_manager.gd" id="1_chunk_stream"]
+
+[node name="Main" type="Node3D"]
+script = ExtResource("1_chunk_stream")

scenes/main_menu.tscn

@@ -0,0 +1,114 @@
+[gd_scene load_steps=2 format=3 uid="uid://main_menu_scene"]
+
+[ext_resource type="Script" path="res://scripts/main_menu.gd" id="1_main"]
+
+[node name="MainMenu" type="Control"]
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+script = ExtResource("1_main")
+
+[node name="CenterContainer" type="CenterContainer" parent="."]
+layout_mode = 3
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+
+[node name="VBoxContainer" type="VBoxContainer" parent="CenterContainer"]
+layout_mode = 1
+theme_override_constants/separation = 16
+size_flags_horizontal = 4
+
+[node name="TitleLabel" type="Label" parent="CenterContainer/VBoxContainer"]
+layout_mode = 1
+text = "AGP Game"
+horizontal_alignment = 1
+theme_override_font_sizes/font_size = 72
+
+[node name="AuthPanel" type="PanelContainer" parent="CenterContainer/VBoxContainer"]
+layout_mode = 1
+visible = false
+
+[node name="MarginContainer" type="MarginContainer" parent="CenterContainer/VBoxContainer/AuthPanel"]
+layout_mode = 1
+theme_override_constants/margin_left = 24
+theme_override_constants/margin_top = 24
+theme_override_constants/margin_right = 24
+theme_override_constants/margin_bottom = 24
+
+[node name="AuthVBox" type="VBoxContainer" parent="CenterContainer/VBoxContainer/AuthPanel/MarginContainer"]
+layout_mode = 1
+theme_override_constants/separation = 8
+size_flags_horizontal = 3
+
+[node name="AuthModeLabel" type="Label" parent="CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox"]
+layout_mode = 1
+text = "Login"
+horizontal_alignment = 1
+theme_override_font_sizes/font_size = 24
+
+[node name="UsernameEdit" type="LineEdit" parent="CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox"]
+layout_mode = 1
+placeholder_text = "Username"
+size_flags_horizontal = 3
+
+[node name="PasswordEdit" type="LineEdit" parent="CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox"]
+layout_mode = 1
+placeholder_text = "Password"
+size_flags_horizontal = 3
+echo_password = true
+
+[node name="EmailEdit" type="LineEdit" parent="CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox"]
+layout_mode = 1
+visible = false
+placeholder_text = "Email"
+size_flags_horizontal = 3
+
+[node name="DOBEdit" type="LineEdit" parent="CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox"]
+layout_mode = 1
+visible = false
+placeholder_text = "Date of Birth (YYYY-MM-DD)"
+size_flags_horizontal = 3
+
+[node name="ModeToggle" type="CheckButton" parent="CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox"]
+layout_mode = 1
+text = "Register"
+
+[node name="AuthButton" type="Button" parent="CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox"]
+layout_mode = 1
+text = "Login"
+size_flags_horizontal = 3
+
+[node name="AuthStatusLabel" type="Label" parent="CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox"]
+layout_mode = 1
+text = ""
+horizontal_alignment = 1
+autowrap_mode = 2
+visible = false
+
+[node name="WelcomeLabel" type="Label" parent="CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox"]
+layout_mode = 1
+visible = false
+text = ""
+horizontal_alignment = 1
+
+[node name="PlayButton" type="Button" parent="CenterContainer/VBoxContainer"]
+layout_mode = 1
+text = "Play"
+size_flags_horizontal = 4
+
+[node name="QuitButton" type="Button" parent="CenterContainer/VBoxContainer"]
+layout_mode = 1
+text = "Quit"
+size_flags_horizontal = 4
+
+[connection signal="pressed" from="CenterContainer/VBoxContainer/PlayButton" to="." method="_on_play_button_pressed"]
+[connection signal="pressed" from="CenterContainer/VBoxContainer/QuitButton" to="." method="_on_quit_button_pressed"]
+[connection signal="toggled" from="CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/ModeToggle" to="." method="_on_mode_toggle_toggled"]
+[connection signal="pressed" from="CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/AuthButton" to="." method="_on_auth_button_pressed"]
+[connection signal="text_submitted" from="CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/UsernameEdit" to="." method="_on_auth_button_pressed"]
+[connection signal="text_submitted" from="CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/PasswordEdit" to="." method="_on_auth_button_pressed"]

scenes/world_list.tscn

@@ -0,0 +1,76 @@
+[gd_scene load_steps=2 format=3]
+
+[ext_resource type="Script" path="res://scripts/world_list.gd" id="1_wl"]
+
+[node name="WorldList" type="Control"]
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+script = ExtResource("1_wl")
+
+[node name="VBoxContainer" type="VBoxContainer" parent="."]
+layout_mode = 3
+theme_override_constants/separation = 8
+size_flags_horizontal = 4
+size_flags_vertical = 4
+
+[node name="HeaderHBox" type="HBoxContainer" parent="VBoxContainer"]
+layout_mode = 3
+size_flags_horizontal = 4
+theme_override_constants/separation = 16
+
+[node name="BackButton" type="Button" parent="VBoxContainer/HeaderHBox"]
+layout_mode = 3
+text = "< Back"
+size_flags_horizontal = 0
+
+[node name="TitleLabel" type="Label" parent="VBoxContainer/HeaderHBox"]
+layout_mode = 3
+text = "Browse Worlds"
+horizontal_alignment = 1
+size_flags_horizontal = 4
+theme_override_font_sizes/font_size = 28
+
+[node name="RefreshButton" type="Button" parent="VBoxContainer/HeaderHBox"]
+layout_mode = 3
+text = "Refresh"
+size_flags_horizontal = 0
+
+[node name="ScrollContainer" type="ScrollContainer" parent="VBoxContainer"]
+layout_mode = 3
+size_flags_horizontal = 4
+size_flags_vertical = 4
+horizontal_mode = 2
+vertical_mode = 2
+
+[node name="WorldList" type="VBoxContainer" parent="VBoxContainer/ScrollContainer"]
+layout_mode = 3
+size_flags_horizontal = 4
+size_flags_vertical = 4
+theme_override_constants/separation = 8
+
+[node name="LoadingLabel" type="Label" parent="VBoxContainer"]
+layout_mode = 3
+text = "Loading worlds..."
+visible = false
+horizontal_alignment = 1
+theme_override_font_sizes/font_size = 18
+
+[node name="ErrorLabel" type="Label" parent="VBoxContainer"]
+layout_mode = 3
+text = ""
+visible = false
+horizontal_alignment = 1
+theme_override_font_sizes/font_size = 18
+
+[node name="EmptyLabel" type="Label" parent="VBoxContainer"]
+layout_mode = 3
+text = ""
+visible = false
+horizontal_alignment = 1
+theme_override_font_sizes/font_size = 18
+
+[connection signal="pressed" from="VBoxContainer/HeaderHBox/BackButton" to="." method="_on_back_button_pressed"]
+[connection signal="pressed" from="VBoxContainer/HeaderHBox/RefreshButton" to="." method="_on_refresh_button_pressed"]

scripts/api_client.gd

@@ -0,0 +1,292 @@
+extends Node
+## Central HTTP client singleton (autoload name: "ApiClient").
+##
+## Every network call in the game flows through this class. Callers use the
+## high-level helpers ([method login], [method register], [method get_worlds],
+## [method health_check], [method get_me]) or the generic [method request]
+## primitive. All results conform to the result-dictionary contract below.
+##
+## [b]Result Dictionary Contract[/b]
+## Every public method returns (after `await`) a Dictionary with this shape:
+##
+##     {
+##         "ok":     bool,     # true for HTTP 2xx, false otherwise
+##         "status": int,      # HTTP status code (0 on network failure)
+##         "data":   Variant,  # parsed JSON body on success (null otherwise)
+##         "detail": String,   # human-readable message
+##     }
+##
+## Network failures (timeout / DNS / refused connection) return `status == 0`
+## with a `detail` describing the transport failure. Non-2xx responses return
+## the real HTTP status and the backend's `detail` field from the JSON error
+## body when present. No caller can crash on a failed request.
+##
+## [b]Token storage[/b]
+## JWTs are kept in memory. [method set_token] is the single seam for future
+## disk persistence (override it to save to `user://`).
+##
+## [b]Usage[/b]
+##     var result: Dictionary = await ApiClient.login("alice", "secret")
+##     if result.ok:
+##         print("Logged in!")
+##     else:
+##         print("Error: ", result.detail)
+
+# ---------------------------------------------------------------------------
+# Token storage
+# ---------------------------------------------------------------------------
+
+var _access_token: String = ""
+var _token_type: String = "Bearer"
+
+## Full Authorization header value, e.g. "Bearer eyJ...". Empty if no token.
+var bearer_token: String:
+	get:
+		return _token_type + " " + _access_token if _access_token != "" else ""
+
+
+## Whether an access token is currently stored.
+func has_token() -> bool:
+	return _access_token != ""
+
+
+## Set the access token (called after login / register / token refresh).
+## This is the persistence seam: override to also write to disk.
+func set_token(access_token: String, token_type: String = "Bearer") -> void:
+	_access_token = access_token
+	_token_type = token_type
+
+
+## Clear stored tokens.
+func clear_token() -> void:
+	_access_token = ""
+	_token_type = "Bearer"
+
+
+# ---------------------------------------------------------------------------
+# Configuration
+# ---------------------------------------------------------------------------
+
+var _base_url: String = "http://127.0.0.1:8000"
+
+## Request timeout in seconds. 0 disables the timeout.
+var timeout_seconds: float = 10.0
+
+
+func _ready() -> void:
+	# Environment variable override (e.g. for headless smoke tests against a
+	# backend on a non-default port). Falls back to the ProjectSetting, then
+	# to the documented default.
+	var env_url := OS.get_environment("AGP_API_BASE_URL")
+	if env_url != "":
+		_base_url = env_url.rstrip("/")
+	else:
+		_base_url = str(ProjectSettings.get_setting(
+			"application/agp/api_base_url",
+			"http://127.0.0.1:8000"
+		)).rstrip("/")
+
+
+# ---------------------------------------------------------------------------
+# Core request primitive
+# ---------------------------------------------------------------------------
+
+## Generic request primitive. Awaitable via `await`.
+##
+## Uses a dedicated HTTPRequest node per call so concurrent requests can never
+## cross-talk, and so the result maps 1:1 to the awaiting caller.
+##
+## @param method       HTTPClient.Method enum value (GET/POST/PUT/PATCH/DELETE).
+## @param path         URL path, e.g. "/api/health".
+## @param body         Request body string (JSON or form-encoded).
+## @param content_type "application/json" or "application/x-www-form-urlencoded".
+## @param require_auth If true, attach the stored bearer token when present.
+## @return Result dictionary conforming to the contract.
+func request(
+	method: HTTPClient.Method,
+	path: String,
+	body: String = "",
+	content_type: String = "application/json",
+	require_auth: bool = false
+) -> Dictionary:
+	var http := HTTPRequest.new()
+	http.timeout = timeout_seconds
+	http.max_redirects = 8
+	http.accept_gzip = true
+	add_child(http)
+
+	var headers := PackedStringArray()
+	headers.append("Accept: application/json")
+	if content_type != "":
+		headers.append("Content-Type: " + content_type)
+	if require_auth and has_token():
+		headers.append("Authorization: " + bearer_token)
+
+	var url := _base_url + path
+	var err := http.request(url, headers, method, body)
+	if err != OK:
+		http.queue_free()
+		return _make_result(false, 0, null, "Failed to start request: " + _error_string(err))
+
+	# request_completed emits (result, response_code, headers, body).
+	var args: Array = await http.request_completed
+	var result_code: int = args[0]
+	var response_code: int = args[1]
+	var response_body: PackedByteArray = args[3]
+	http.queue_free()
+
+	# Transport-level failure (timeout / DNS / refused / TLS, etc.).
+	if result_code != HTTPRequest.RESULT_SUCCESS:
+		return _make_result(false, 0, null, _transport_error_detail(result_code))
+
+	# Server accepted the connection but returned no HTTP status line.
+	if response_code == 0:
+		return _make_result(false, 0, null, "No response received from server.")
+
+	var json_string := response_body.get_string_from_utf8()
+	var ok := response_code >= 200 and response_code < 300
+
+	if ok:
+		var data: Variant = _parse_json(json_string)
+		return _make_result(true, response_code, data, "OK")
+
+	# Non-2xx: surface the backend's "detail" message when available.
+	var detail := "HTTP error %d" % response_code
+	var parsed: Variant = _parse_json(json_string)
+	if parsed is Dictionary and (parsed as Dictionary).has("detail"):
+		detail = str((parsed as Dictionary)["detail"])
+	return _make_result(false, response_code, null, detail)
+
+
+# ---------------------------------------------------------------------------
+# High-level helpers
+# ---------------------------------------------------------------------------
+
+## Log in with username/password (OAuth2PasswordRequestForm).
+## On success stores the returned access token.
+func login(username: String, password: String) -> Dictionary:
+	var form := "username=" + username.uri_encode() + "&password=" + password.uri_encode()
+	var result := await request(
+		HTTPClient.METHOD_POST,
+		"/api/auth/login",
+		form,
+		"application/x-www-form-urlencoded",
+		false
+	)
+	_store_token_from_result(result)
+	return result
+
+
+## Register a new user. On success stores the returned access token.
+## @param date_of_birth ISO date string "YYYY-MM-DD".
+func register(
+	username: String,
+	email: String,
+	password: String,
+	date_of_birth: String
+) -> Dictionary:
+	var payload := {
+		"username": username,
+		"email": email,
+		"password": password,
+		"date_of_birth": date_of_birth,
+	}
+	var result := await request(
+		HTTPClient.METHOD_POST,
+		"/api/auth/register",
+		JSON.stringify(payload),
+		"application/json",
+		false
+	)
+	_store_token_from_result(result)
+	return result
+
+
+## List worlds visible to the current user (requires auth).
+## @param visibility Optional filter: "public", "private", "friends_only".
+func get_worlds(skip: int = 0, limit: int = 50, visibility: String = "") -> Dictionary:
+	var path := "/api/worlds/?skip=%d&limit=%d" % [skip, limit]
+	if visibility != "":
+		path += "&visibility=" + visibility.uri_encode()
+	return await request(HTTPClient.METHOD_GET, path, "", "application/json", true)
+
+
+## Ping the backend health endpoint (no auth).
+func health_check() -> Dictionary:
+	return await request(HTTPClient.METHOD_GET, "/api/health", "", "application/json", false)
+
+
+## Fetch the current user's profile from the stored JWT (requires auth).
+func get_me() -> Dictionary:
+	return await request(HTTPClient.METHOD_GET, "/api/users/me", "", "application/json", true)
+
+
+# ---------------------------------------------------------------------------
+# Internals
+# ---------------------------------------------------------------------------
+
+func _store_token_from_result(result: Dictionary) -> void:
+	if result.ok and result.data is Dictionary:
+		var token: String = str((result.data as Dictionary).get("access_token", ""))
+		if token != "":
+			set_token(token)
+
+
+func _parse_json(text: String) -> Variant:
+	if text == "":
+		return null
+	var parsed: Variant = JSON.parse_string(text)
+	if parsed == null:
+		# null is ambiguous (valid JSON "null" vs parse failure). Fall back to
+		# the raw string so callers never lose the body entirely.
+		return text if text != "null" else null
+	return parsed
+
+
+func _make_result(ok: bool, status: int, data: Variant, detail: String) -> Dictionary:
+	return {
+		"ok": ok,
+		"status": status,
+		"data": data,
+		"detail": detail,
+	}
+
+
+func _transport_error_detail(result_code: int) -> String:
+	match result_code:
+		HTTPRequest.RESULT_CANT_CONNECT:
+			return "Could not connect to server. Is it running?"
+		HTTPRequest.RESULT_CANT_RESOLVE:
+			return "Could not resolve server hostname."
+		HTTPRequest.RESULT_CONNECTION_ERROR:
+			return "Connection error."
+		HTTPRequest.RESULT_TLS_HANDSHAKE_ERROR:
+			return "TLS handshake failed."
+		HTTPRequest.RESULT_NO_RESPONSE:
+			return "No response from server."
+		HTTPRequest.RESULT_BODY_SIZE_LIMIT_EXCEEDED:
+			return "Response body too large."
+		HTTPRequest.RESULT_BODY_DECOMPRESS_FAILED:
+			return "Failed to decompress response body."
+		HTTPRequest.RESULT_REQUEST_FAILED:
+			return "Request failed."
+		HTTPRequest.RESULT_TIMEOUT:
+			return "Request timed out."
+		_:
+			return "Network error (code %d)." % result_code
+
+
+func _error_string(err_code: int) -> String:
+	match err_code:
+		OK:
+			return "OK"
+		ERR_UNCONFIGURED:
+			return "HTTPRequest not configured (not in tree)."
+		ERR_BUSY:
+			return "HTTPRequest is busy with a previous request."
+		ERR_INVALID_PARAMETER:
+			return "Invalid URL format."
+		ERR_CANT_CONNECT:
+			return "Cannot connect to host."
+		_:
+			return "Unknown error (%d)." % err_code

scripts/api_client.gd.uid

@@ -0,0 +1 @@
+uid://cjd0uhll7iylj

scripts/build.sh

@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+# Headless CI export for Linux and Windows.
+#
+# Requires:
+#   - Godot 4.6.2 (the exact version this project + export_presets.cfg were
+#     built against; a different Godot minor version's export templates are
+#     not guaranteed compatible)
+#   - The matching export templates installed at
+#     ~/.local/share/godot/export_templates/4.6.2.stable/
+#     (download: https://godotengine.org/download/archive/4.6.2-stable/,
+#     "Export templates" -- NOT the same as the editor download)
+#   - godot on PATH (or set GODOT_BIN below)
+#
+# Usage: scripts/build.sh
+# Output: export/linux/agp-game.x86_64, export/windows/agp-game.exe
+
+set -euo pipefail
+cd "$(dirname "$0")/.."
+
+GODOT_BIN="${GODOT_BIN:-godot}"
+if ! command -v "$GODOT_BIN" >/dev/null 2>&1; then
+    if [ -x "$HOME/godot/godot" ]; then
+        GODOT_BIN="$HOME/godot/godot"
+    else
+        echo "godot binary not found (checked PATH and ~/godot/godot)." >&2
+        exit 1
+    fi
+fi
+
+echo "Godot version: $("$GODOT_BIN" --version)"
+
+mkdir -p export/linux export/windows
+
+echo "=== Exporting Linux/X11 ==="
+"$GODOT_BIN" --headless --path . --export-release "Linux" export/linux/agp-game.x86_64
+
+echo "=== Exporting Windows Desktop ==="
+"$GODOT_BIN" --headless --path . --export-release "Windows Desktop" export/windows/agp-game.exe
+
+echo ""
+echo "Build artifacts:"
+ls -la export/linux export/windows

scripts/chunk.gd

@@ -0,0 +1,105 @@
+class_name Chunk
+extends Node3D
+## A single world chunk. Holds the chunk coordinate, bounds, and the
+## visual/gameplay content for that region of the world.
+##
+## Chunks are the atomic unit of world geometry, gameplay objects, and
+## persistence (see docs/architecture/world.md). The server loads and saves
+## whole chunks; clients stream the chunks around them.
+
+## Default chunk dimensions in world units (tiles). Matches the constants in
+## docs/architecture/world.md section 2.2.
+const CHUNK_SIZE_X: int = 32
+const CHUNK_SIZE_Y: int = 32
+const CHUNK_SIZE_Z: int = 1
+
+## World-space origin of chunk coordinate (0,0).
+const CHUNK_ORIGIN := Vector3(0.0, 0.0, 0.0)
+
+## Chunk coordinate (cx, cy, cz) in chunk space.
+var coord := Vector3i.ZERO
+
+## The canonical chunk key: "{world_id}:{room_id}:{cx}:{cy}:{cz}".
+var key: String = ""
+
+## World and room identifiers this chunk belongs to.
+var world_id: String = ""
+var room_id: String = ""
+
+## Format version of the chunk payload (currently 1).
+var format_version: int = 1
+
+## Revision counter, incremented on every write. Used for optimistic
+## concurrency and change detection.
+var revision: int = 0
+
+## Whether this chunk has been modified in memory but not yet flushed.
+var dirty: bool = false
+
+## Container for static objects (props, geometry) in this chunk.
+var objects: Array[Node3D] = []
+
+## Container for dynamic object templates (spawnable entities).
+var dynamic_templates: Array[Node3D] = []
+
+## The world-space bounding box of this chunk.
+var bounds: AABB
+
+
+func _init(p_coord: Vector3i = Vector3i.ZERO, p_world_id: String = "", p_room_id: String = "") -> void:
+	coord = p_coord
+	world_id = p_world_id
+	room_id = p_room_id
+	key = build_key(world_id, room_id, coord)
+	bounds = compute_bounds(coord)
+
+
+## Build the canonical chunk key from its components.
+static func build_key(p_world_id: String, p_room_id: String, p_coord: Vector3i) -> String:
+	return "%s:%s:%d:%d:%d" % [p_world_id, p_room_id, p_coord.x, p_coord.y, p_coord.z]
+
+
+## Compute the world-space bounding box for a chunk coordinate.
+static func compute_bounds(p_coord: Vector3i) -> AABB:
+	var min_pos := Vector3(
+		CHUNK_ORIGIN.x + p_coord.x * CHUNK_SIZE_X,
+		CHUNK_ORIGIN.y + p_coord.y * CHUNK_SIZE_Y,
+		CHUNK_ORIGIN.z + p_coord.z * CHUNK_SIZE_Z
+	)
+	return AABB(min_pos, Vector3(CHUNK_SIZE_X, CHUNK_SIZE_Y, CHUNK_SIZE_Z))
+
+
+## Compute the chunk coordinate that contains a world-space position.
+static func coord_for_position(p_pos: Vector3) -> Vector3i:
+	return Vector3i(
+		int(floor((p_pos.x - CHUNK_ORIGIN.x) / CHUNK_SIZE_X)),
+		int(floor((p_pos.y - CHUNK_ORIGIN.y) / CHUNK_SIZE_Y)),
+		int(floor((p_pos.z - CHUNK_ORIGIN.z) / CHUNK_SIZE_Z))
+	)
+
+
+## Add a static object to this chunk.
+func add_object(p_object: Node3D) -> void:
+	objects.append(p_object)
+	add_child(p_object)
+
+
+## Add a dynamic object template to this chunk.
+func add_dynamic_template(p_template: Node3D) -> void:
+	dynamic_templates.append(p_template)
+	add_child(p_template)
+
+
+## Remove all objects from this chunk.
+func clear_objects() -> void:
+	for obj in objects:
+		if is_instance_valid(obj):
+			obj.queue_free()
+	objects.clear()
+	dynamic_templates.clear()
+
+
+## Mark this chunk as dirty (modified but not yet persisted).
+func mark_dirty() -> void:
+	dirty = true
+	revision += 1

scripts/chunk.gd.uid

@@ -0,0 +1 @@
+uid://dc6j7kqjitc6g

scripts/chunk_data_decoder.gd

@@ -0,0 +1,667 @@
+class_name ChunkDataDecoder
+extends RefCounted
+## Decodes chunk binary payloads (and JSON) into logical chunk data.
+##
+## Implements the binary format spec from docs/architecture/world.md §3.6.
+## Both the Godot client and Python backend use this class to ensure
+## identical encoding/decoding behavior.
+##
+## ## Binary Format Overview
+##
+## ```
+## Header (48 bytes):
+##   [0:4]   magic "AGPC"
+##   [4:6]   version (uint16 LE)
+##   [6:8]   header_len (uint16 LE)
+##   [8:12]  flags (uint32 LE)
+##   [12:16] payload_len (uint32 LE)
+##   [16:48] checksum (SHA-256 hex, 32 bytes)
+##
+## Payload Body (sections):
+##   [section_id:1][section_len:4][data:section_len]
+## ```
+
+
+## Content flags parsed from a chunk.
+class ContentFlags:
+	## Severity levels: 0=none, 1=mild, 2=moderate, 3=severe
+	var violence: int = 0
+	var sexual: int = 0
+	var language: int = 0
+	var substance: int = 0
+	var gambling: int = 0
+	var horror: int = 0
+	var hate: int = 0
+	var custom: int = 0
+	var mature: bool = false
+	var sources: Array[String] = []
+
+	func is_mature() -> bool:
+		return mature
+
+	func has_severe_content() -> bool:
+		return (violence >= 3 or sexual >= 3 or language >= 3 or
+		        substance >= 3 or gambling >= 3 or horror >= 3 or
+		        hate >= 3 or custom >= 3)
+
+	func get_max_severity() -> int:
+		return maxi(
+			violence, maxi(sexual, maxi(language, maxi(substance,
+			maxi(gambling, maxi(horror, maxi(hate, custom)))))))
+
+	func to_dict() -> Dictionary:
+		return {
+			"categories": {
+				"violence": violence,
+				"sexual": sexual,
+				"language": language,
+				"substance": substance,
+				"gambling": gambling,
+				"horror": horror,
+				"hate": hate,
+				"custom": custom,
+			},
+			"mature": mature,
+			"sources": sources,
+		}
+
+	func from_dict(d: Dictionary) -> void:
+		if d.has("categories"):
+			violence = d["categories"].get("violence", 0)
+			sexual = d["categories"].get("sexual", 0)
+			language = d["categories"].get("language", 0)
+			substance = d["categories"].get("substance", 0)
+			gambling = d["categories"].get("gambling", 0)
+			horror = d["categories"].get("horror", 0)
+			hate = d["categories"].get("hate", 0)
+			custom = d["categories"].get("custom", 0)
+		mature = d.get("mature", false)
+		sources = d.get("sources", [])
+
+
+## A tile layer definition (palette + dense tile indices).
+class TileLayerData:
+	var name: String = ""
+	var layer_id: int = 0
+	var width: int = 0
+	var height: int = 0
+	var depth: int = 1
+	var palette: Array[TileDef] = []
+	var tiles: PackedInt32Array = PackedInt32Array()
+
+	func tile_count() -> int:
+		return width * height * depth
+
+	func get_tile(x: int, y: int, z: int = 0) -> int:
+		if x < 0 or x >= width or y < 0 or y >= height or z < 0 or z >= depth:
+			return 0  # Out of bounds returns empty tile
+		var idx := (z * height + y) * width + x
+		if idx < tiles.size():
+			return tiles[idx]
+		return 0
+
+	func get_tile_def(tile_id: int) -> TileDef:
+		for def in palette:
+			if def.id == tile_id:
+				return def
+		return null
+
+
+## A world object parsed from chunk data.
+class WorldObjectData:
+	var id: String = ""
+	var type: String = ""
+	var asset_id: String = ""
+	var position: Vector3 = Vector3.ZERO
+	var rotation: Vector4 = Vector4(0, 0, 0, 1)
+	var scale: Vector3 = Vector3.ONE
+	var properties: Dictionary = {}
+	var dynamic: bool = false
+	var flags: ContentFlags = ContentFlags.new()
+
+
+## The complete decoded chunk payload.
+class ChunkPayload:
+	var version: int = 1
+	var key: String = ""
+	var world_id: String = ""
+	var room_id: String = ""
+	var coord: Vector3i = Vector3i.ZERO
+	var bounds: AABB = AABB()
+	var tile_layers: Array[TileLayerData] = []
+	var objects: Array[WorldObjectData] = []
+	var flags: ContentFlags = ContentFlags.new()
+	var created_at: int = 0  # Unix timestamp
+	var updated_at: int = 0  # Unix timestamp
+	var revision: int = 0
+	var author: String = ""
+	var checksum: String = ""
+
+
+# ───────────────── Binary Decoding ─────────────────
+
+static var MAGIC := PackedByteArray([0x41, 0x47, 0x50, 0x43])  # "AGPC"
+const HEADER_SIZE: int = 48
+const SECTION_META: int = 0x01
+const SECTION_TILE: int = 0x02
+const SECTION_OBJECT: int = 0x03
+const SECTION_FLAGS: int = 0x04
+const SECTION_REVISION_META: int = 0x05
+
+
+## Decode a binary chunk payload into a ChunkPayload.
+## Returns null if the data is invalid or version is unsupported.
+static func decode_binary(data: PackedByteArray) -> ChunkPayload:
+	if data.size() < HEADER_SIZE:
+		push_error("ChunkDataDecoder: Data too short for header (%d bytes)" % data.size())
+		return null
+
+	# Verify magic
+	var magic := PackedByteArray(data.slice(0, 4))
+	if magic != MAGIC:
+		push_error("ChunkDataDecoder: Invalid magic bytes")
+		return null
+
+	# Read header fields
+	var version := _read_uint16(data, 4)
+	if version != 1:
+		push_error("ChunkDataDecoder: Unsupported chunk version %d" % version)
+		return null
+
+	var header_len := _read_uint16(data, 6)
+	var flags := _read_uint32(data, 8)
+	var payload_len := _read_uint32(data, 12)
+	var checksum := _read_hex_string(data, 16, 32)
+
+	# Verify payload length
+	if data.size() < HEADER_SIZE + payload_len:
+		push_error("ChunkDataDecoder: Payload too short")
+		return null
+
+	var payload := data.slice(HEADER_SIZE, HEADER_SIZE + payload_len)
+
+	# Verify checksum
+	var computed_checksum := _sha256_hex(payload)
+	if computed_checksum != checksum:
+		push_error("ChunkDataDecoder: Checksum mismatch")
+		# Continue anyway for resilience
+
+	var result := ChunkPayload.new()
+	result.version = version
+	result.checksum = checksum
+
+	# Parse sections
+	var offset := 0
+	while offset < payload.size():
+		if offset + 5 > payload.size():
+			break
+
+		var section_id := payload[offset]
+		var section_len := _read_uint32(payload, offset + 1)
+
+		if offset + 5 + section_len > payload.size():
+			break
+
+		var section_data := payload.slice(offset + 5, offset + 5 + section_len)
+
+		match section_id:
+			SECTION_META:
+				_parse_metadata_section(section_data, result)
+			SECTION_TILE:
+				_parse_tile_section(section_data, result)
+			SECTION_OBJECT:
+				_parse_object_section(section_data, result)
+			SECTION_FLAGS:
+				_parse_flags_section(section_data, result.flags)
+			SECTION_REVISION_META:
+				_parse_revision_meta_section(section_data, result)
+
+		offset += 5 + section_len
+
+	return result
+
+
+## Encode a ChunkPayload into binary format.
+static func encode_binary(payload: ChunkPayload) -> PackedByteArray:
+	var sections := PackedByteArray()
+
+	# Build metadata section
+	sections.append_array(_build_metadata_section(payload))
+	# Build tile sections
+	for layer in payload.tile_layers:
+		sections.append_array(_build_tile_section(layer))
+	# Build object sections
+	for obj in payload.objects:
+		sections.append_array(_build_object_section(obj))
+	# Build flags section
+	sections.append_array(_build_flags_section(payload.flags))
+	# Build revision meta section
+	sections.append_array(_build_revision_meta_section(payload))
+
+	var payload_bytes := PackedByteArray(sections)
+	var checksum := _sha256_hex(payload_bytes)
+
+	# Build header
+	var header := PackedByteArray()
+	header.append_array(MAGIC)
+	header.append_array(_write_uint16(1))  # version
+	header.append_array(_write_uint16(0))  # header_len (after this field)
+	header.append_array(_write_uint32(0))  # flags
+	header.append_array(_write_uint32(payload_bytes.size()))
+	header.append_array(_hex_to_bytes(checksum))
+
+	return header + payload_bytes
+
+
+# ───────────────── Section Parsers ─────────────────
+
+static func _parse_metadata_section(data: PackedByteArray, result: ChunkPayload) -> void:
+	var offset := 0
+
+	# world_id (length-prefixed string)
+	var world_id_len := _read_uint16(data, offset)
+	offset += 2
+	result.world_id = data.slice(offset, offset + world_id_len).get_string_from_utf8()
+	offset += world_id_len
+
+	# room_id (length-prefixed string)
+	var room_id_len := _read_uint16(data, offset)
+	offset += 2
+	result.room_id = data.slice(offset, offset + room_id_len).get_string_from_utf8()
+	offset += room_id_len
+
+	# coord (3 × int32)
+	result.coord = Vector3i(
+		_read_int32(data, offset),
+		_read_int32(data, offset + 4),
+		_read_int32(data, offset + 8)
+	)
+	offset += 12
+
+	# bounds (6 × float32)
+	var min_pos := Vector3(
+		_read_float32(data, offset),
+		_read_float32(data, offset + 4),
+		_read_float32(data, offset + 8)
+	)
+	var max_pos := Vector3(
+		_read_float32(data, offset + 12),
+		_read_float32(data, offset + 16),
+		_read_float32(data, offset + 20)
+	)
+	result.bounds = AABB(min_pos, max_pos - min_pos)
+
+
+static func _parse_tile_section(data: PackedByteArray, result: ChunkPayload) -> void:
+	var layer := TileLayerData.new()
+	var offset := 0
+
+	# name (length-prefixed string)
+	var name_len := _read_uint16(data, offset)
+	offset += 2
+	layer.name = data.slice(offset, offset + name_len).get_string_from_utf8()
+	offset += name_len
+
+	# layer_id (uint16)
+	layer.layer_id = _read_uint16(data, offset)
+	offset += 2
+
+	# dimensions (3 × uint16)
+	layer.width = _read_uint16(data, offset)
+	offset += 2
+	layer.height = _read_uint16(data, offset)
+	offset += 2
+	layer.depth = _read_uint16(data, offset)
+	offset += 2
+
+	# palette
+	var palette_count := _read_uint16(data, offset)
+	offset += 2
+	for _i in range(palette_count):
+		var tile_def := TileDef.new()
+		tile_def.id = _read_uint16(data, offset)
+		offset += 2
+
+		var asset_id_len := _read_uint16(data, offset)
+		offset += 2
+		tile_def.asset_id = data.slice(offset, offset + asset_id_len).get_string_from_utf8()
+		offset += asset_id_len
+
+		tile_def.solid = data[offset] != 0
+		offset += 1
+
+		tile_def.flags = _read_uint32(data, offset)
+		offset += 4
+
+		tile_def.variants = data[offset]
+		offset += 1
+
+		layer.palette.append(tile_def)
+
+	# tiles
+	var tile_count := _read_uint32(data, offset)
+	offset += 4
+	for i in range(tile_count):
+		layer.tiles.append(_read_uint16(data, offset))
+		offset += 2
+
+	result.tile_layers.append(layer)
+
+
+static func _parse_object_section(data: PackedByteArray, result: ChunkPayload) -> void:
+	var obj := WorldObjectData.new()
+	var offset := 0
+
+	# id (length-prefixed string)
+	var id_len := _read_uint16(data, offset)
+	offset += 2
+	obj.id = data.slice(offset, offset + id_len).get_string_from_utf8()
+	offset += id_len
+
+	# type (length-prefixed string)
+	var type_len := _read_uint16(data, offset)
+	offset += 2
+	obj.type = data.slice(offset, offset + type_len).get_string_from_utf8()
+	offset += type_len
+
+	# asset_id (length-prefixed string)
+	var asset_id_len := _read_uint16(data, offset)
+	offset += 2
+	obj.asset_id = data.slice(offset, offset + asset_id_len).get_string_from_utf8()
+	offset += asset_id_len
+
+	# position (3 × float32)
+	obj.position = Vector3(
+		_read_float32(data, offset),
+		_read_float32(data, offset + 4),
+		_read_float32(data, offset + 8)
+	)
+	offset += 12
+
+	# rotation (4 × float32)
+	obj.rotation = Vector4(
+		_read_float32(data, offset),
+		_read_float32(data, offset + 4),
+		_read_float32(data, offset + 8),
+		_read_float32(data, offset + 12)
+	)
+	offset += 16
+
+	# scale (3 × float32)
+	obj.scale = Vector3(
+		_read_float32(data, offset),
+		_read_float32(data, offset + 4),
+		_read_float32(data, offset + 8)
+	)
+	offset += 12
+
+	# dynamic (uint8)
+	obj.dynamic = data[offset] != 0
+	offset += 1
+
+	# properties (length-prefixed JSON string)
+	var props_len := _read_uint16(data, offset)
+	offset += 2
+	var props_str := data.slice(offset, offset + props_len).get_string_from_utf8()
+	offset += props_len
+	obj.properties = JSON.parse_string(props_str) or {}
+
+	# flags (ContentFlags)
+	obj.flags.violence = data[offset]
+	offset += 1
+	obj.flags.sexual = data[offset]
+	offset += 1
+	obj.flags.language = data[offset]
+	offset += 1
+	obj.flags.substance = data[offset]
+	offset += 1
+	obj.flags.gambling = data[offset]
+	offset += 1
+	obj.flags.horror = data[offset]
+	offset += 1
+	obj.flags.hate = data[offset]
+	offset += 1
+	obj.flags.custom = data[offset]
+	offset += 1
+	obj.flags.mature = data[offset] != 0
+	offset += 1
+
+	var source_count := _read_uint16(data, offset)
+	offset += 2
+	for _i in range(source_count):
+		var src_len := _read_uint16(data, offset)
+		offset += 2
+		obj.flags.sources.append(data.slice(offset, offset + src_len).get_string_from_utf8())
+		offset += src_len
+
+	result.objects.append(obj)
+
+
+static func _parse_flags_section(data: PackedByteArray, flags: ContentFlags) -> void:
+	flags.violence = data[0]
+	flags.sexual = data[1]
+	flags.language = data[2]
+	flags.substance = data[3]
+	flags.gambling = data[4]
+	flags.horror = data[5]
+	flags.hate = data[6]
+	flags.custom = data[7]
+	flags.mature = data[8] != 0
+
+	var offset := 9
+	var source_count := _read_uint16(data, offset)
+	offset += 2
+	for _i in range(source_count):
+		var src_len := _read_uint16(data, offset)
+		offset += 2
+		flags.sources.append(data.slice(offset, offset + src_len).get_string_from_utf8())
+		offset += src_len
+
+
+static func _parse_revision_meta_section(data: PackedByteArray, result: ChunkPayload) -> void:
+	var offset := 0
+	# created_at (int64 unix)
+	result.created_at = _read_int64(data, offset)
+	offset += 8
+	# updated_at (int64 unix)
+	result.updated_at = _read_int64(data, offset)
+	offset += 8
+	# revision (uint32)
+	result.revision = _read_uint32(data, offset)
+	offset += 4
+	# author (length-prefixed string)
+	var author_len := _read_uint16(data, offset)
+	offset += 2
+	result.author = data.slice(offset, offset + author_len).get_string_from_utf8()
+
+
+# ───────────────── Section Builders ─────────────────
+
+static func _build_metadata_section(payload: ChunkPayload) -> PackedByteArray:
+	var data := PackedByteArray()
+	data.append_array(_write_string(payload.world_id))
+	data.append_array(_write_string(payload.room_id))
+	data.append_array(_write_int32(payload.coord.x))
+	data.append_array(_write_int32(payload.coord.y))
+	data.append_array(_write_int32(payload.coord.z))
+	data.append_array(_write_float32(payload.bounds.position.x))
+	data.append_array(_write_float32(payload.bounds.position.y))
+	data.append_array(_write_float32(payload.bounds.position.z))
+	data.append_array(_write_float32(payload.bounds.size.x))
+	data.append_array(_write_float32(payload.bounds.size.y))
+	data.append_array(_write_float32(payload.bounds.size.z))
+	return data
+
+
+static func _build_tile_section(layer: TileLayerData) -> PackedByteArray:
+	var data := PackedByteArray()
+	data.append_array(_write_string(layer.name))
+	data.append_array(_write_uint16(layer.layer_id))
+	data.append_array(_write_uint16(layer.width))
+	data.append_array(_write_uint16(layer.height))
+	data.append_array(_write_uint16(layer.depth))
+	data.append_array(_write_uint16(layer.palette.size()))
+
+	for tile_def in layer.palette:
+		data.append_array(_write_uint16(tile_def.id))
+		data.append_array(_write_string(tile_def.asset_id))
+		data.append(tile_def.solid as int)
+		data.append_array(_write_uint32(tile_def.flags))
+		data.append(tile_def.variants)
+
+	data.append_array(_write_uint32(layer.tiles.size()))
+	for tile_id in layer.tiles:
+		data.append_array(_write_uint16(tile_id))
+
+	return _wrap_section(data, SECTION_TILE)
+
+
+static func _build_object_section(obj: WorldObjectData) -> PackedByteArray:
+	var data := PackedByteArray()
+	data.append_array(_write_string(obj.id))
+	data.append_array(_write_string(obj.type))
+	data.append_array(_write_string(obj.asset_id))
+	data.append_array(_write_float32(obj.position.x))
+	data.append_array(_write_float32(obj.position.y))
+	data.append_array(_write_float32(obj.position.z))
+	data.append_array(_write_float32(obj.rotation.x))
+	data.append_array(_write_float32(obj.rotation.y))
+	data.append_array(_write_float32(obj.rotation.z))
+	data.append_array(_write_float32(obj.rotation.w))
+	data.append_array(_write_float32(obj.scale.x))
+	data.append_array(_write_float32(obj.scale.y))
+	data.append_array(_write_float32(obj.scale.z))
+	data.append(obj.dynamic as int)
+
+	var props_json := JSON.stringify(obj.properties, "  ")
+	data.append_array(_write_string(props_json))
+
+	data.append(obj.flags.violence)
+	data.append(obj.flags.sexual)
+	data.append(obj.flags.language)
+	data.append(obj.flags.substance)
+	data.append(obj.flags.gambling)
+	data.append(obj.flags.horror)
+	data.append(obj.flags.hate)
+	data.append(obj.flags.custom)
+	data.append(obj.flags.mature as int)
+	data.append_array(_write_uint16(obj.flags.sources.size()))
+	for src in obj.flags.sources:
+		data.append_array(_write_string(src))
+
+	return _wrap_section(data, SECTION_OBJECT)
+
+
+static func _build_flags_section(flags: ContentFlags) -> PackedByteArray:
+	var data := PackedByteArray()
+	data.append(flags.violence)
+	data.append(flags.sexual)
+	data.append(flags.language)
+	data.append(flags.substance)
+	data.append(flags.gambling)
+	data.append(flags.horror)
+	data.append(flags.hate)
+	data.append(flags.custom)
+	data.append(flags.mature as int)
+	data.append_array(_write_uint16(flags.sources.size()))
+	for src in flags.sources:
+		data.append_array(_write_string(src))
+	return _wrap_section(data, SECTION_FLAGS)
+
+
+static func _build_revision_meta_section(payload: ChunkPayload) -> PackedByteArray:
+	var data := PackedByteArray()
+	data.append_array(_write_int64(payload.created_at))
+	data.append_array(_write_int64(payload.updated_at))
+	data.append_array(_write_uint32(payload.revision))
+	data.append_array(_write_string(payload.author))
+	return _wrap_section(data, SECTION_REVISION_META)
+
+
+static func _wrap_section(data: PackedByteArray, section_id: int) -> PackedByteArray:
+	var wrapped := PackedByteArray()
+	wrapped.append(section_id)
+	wrapped.append_array(_write_uint32(data.size()))
+	wrapped.append_array(data)
+	return wrapped
+
+
+# ───────────────── Binary Helpers ─────────────────
+
+static func _read_uint16(data: PackedByteArray, offset: int) -> int:
+	return data[offset] | (data[offset + 1] << 8)
+
+static func _read_uint32(data: PackedByteArray, offset: int) -> int:
+	return (data[offset] | (data[offset + 1] << 8) |
+	        (data[offset + 2] << 16) | (data[offset + 3] << 24))
+
+static func _read_int32(data: PackedByteArray, offset: int) -> int:
+	var val := _read_uint32(data, offset)
+	if val >= 0x80000000:
+		return val - 0x100000000
+	return val
+
+static func _read_int64(data: PackedByteArray, offset: int) -> int:
+	var lo := _read_uint32(data, offset)
+	var hi := _read_uint32(data, offset + 4)
+	return hi * 0x100000000 + lo
+
+static func _read_float32(data: PackedByteArray, offset: int) -> float:
+	var bits := _read_uint32(data, offset)
+	return bits as float  # GDScript float is 64-bit; bits repr works for IEEE 754
+
+static func _read_hex_string(data: PackedByteArray, offset: int, length: int) -> String:
+	var hex_chars := "0123456789abcdef"
+	var result := ""
+	for i in range(length):
+		var byte_val := data[offset + i]
+		result += hex_chars[byte_val >> 4]
+		result += hex_chars[byte_val & 0x0F]
+	return result
+
+
+static func _write_uint16(val: int) -> PackedByteArray:
+	return PackedByteArray([(val & 0xFF), (val >> 8) & 0xFF])
+
+static func _write_uint32(val: int) -> PackedByteArray:
+	return PackedByteArray([
+		val & 0xFF, (val >> 8) & 0xFF, (val >> 16) & 0xFF, (val >> 24) & 0xFF
+	])
+
+static func _write_int32(val: int) -> PackedByteArray:
+	return _write_uint32(val)
+
+static func _write_int64(val: int) -> PackedByteArray:
+	var lo := val & 0xFFFFFFFF
+	var hi := (val >> 32) & 0xFFFFFFFF
+	return _write_uint32(lo) + _write_uint32(hi)
+
+static func _write_float32(val: float) -> PackedByteArray:
+	var bits := val as int
+	return _write_uint32(bits)
+
+static func _write_string(s: String) -> PackedByteArray:
+	var bytes := s.to_utf8_buffer()
+	return _write_uint16(bytes.size()) + bytes
+
+static func _hex_to_bytes(hex_str: String) -> PackedByteArray:
+	var result := PackedByteArray()
+	for i in range(0, hex_str.length(), 2):
+		var byte_val := ("0x" + hex_str.substr(i, 2)).hex_to_int()
+		result.append(byte_val)
+	return result
+
+
+# ───────────────── SHA-256 ─────────────────
+
+static func _sha256_hex(data: PackedByteArray) -> String:
+	var ctx := HashingContext.new()
+	ctx.start(HashingContext.HASH_SHA256)
+	ctx.update(data)
+	var hash := ctx.finish()
+	var hex_chars := "0123456789abcdef"
+	var result := ""
+	for byte_val in hash:
+		result += hex_chars[(byte_val >> 4) & 0x0F]
+		result += hex_chars[byte_val & 0x0F]
+	return result

scripts/chunk_data_decoder.gd.uid

@@ -0,0 +1 @@
+uid://bv445xrd6f5tk

scripts/chunk_scene.gd

@@ -0,0 +1,170 @@
+class_name ChunkScene
+extends Node3D
+## A visual representation of a single loaded world chunk.
+##
+## This node is instantiated by [ChunkStreamManager] when a chunk is loaded.
+## It holds the tile layers, world objects, and metadata for one chunk of the
+## world. The scene is responsible for rendering the chunk's visual content
+## and exposing its gameplay objects to the rest of the game.
+##
+## ## Structure
+##
+## ```
+## ChunkScene (Node3D)
+##  ├── TileLayer (Node3D)  # one per tile layer (ground, walls, decor, ...)
+##  ├── StaticObject (Node3D)  # props, geometry, interactables
+##  └── DynamicObject (Node3D)  # spawnable entities (templates)
+## ```
+##
+## ## Lifecycle
+##
+## 1. [ChunkStreamManager] requests chunk data from the server.
+## 2. Server responds with binary payload.
+## 3. [ChunkStreamManager] decodes the payload and creates a [ChunkScene].
+## 4. [ChunkScene] populates itself with tile layers and objects.
+## 5. When the player moves out of range, [ChunkStreamManager] calls
+##    [method ChunkScene.queue_free] to unload it.
+
+## The chunk coordinate this scene represents.
+var coord: Vector3i = Vector3i.ZERO
+
+## The canonical chunk key.
+var key: String = ""
+
+## World-space bounding box of this chunk.
+var bounds: AABB = AABB()
+
+## Format version of the chunk data.
+var format_version: int = 1
+
+## Revision counter from the server.
+var revision: int = 0
+
+## List of tile layers in this chunk.
+var tile_layers: Array[TileLayer] = []
+
+## List of world objects (static + dynamic) in this chunk.
+var world_objects: Array[WorldObject] = []
+
+## Content moderation flags for this chunk.
+var content_flags: ChunkDataDecoder.ContentFlags = ChunkDataDecoder.ContentFlags.new()
+
+## Whether this chunk has been modified locally (not yet synced to server).
+var is_dirty: bool = false
+
+
+func _ready() -> void:
+	# Position this chunk scene at its world-space origin
+	global_position = bounds.position
+	# Set up collision shape for the chunk bounds
+	_setup_collision()
+
+
+func _setup_collision() -> void:
+	# Add a collision shape for the chunk's bounding box
+	var collision := CollisionShape3D.new()
+	var shape := BoxShape3D.new()
+	shape.size = bounds.size
+	collision.shape = shape
+	collision.name = "ChunkBounds"
+	add_child(collision)
+
+
+## Add a tile layer to this chunk scene.
+func add_tile_layer(layer: TileLayer) -> void:
+	tile_layers.append(layer)
+	var layer_node := TileLayerNode.new()
+	layer_node.tile_layer = layer
+	layer_node.chunk_coord = coord
+	add_child(layer_node)
+
+
+## Add a world object to this chunk scene.
+func add_object(obj: WorldObject) -> void:
+	world_objects.append(obj)
+	if obj.is_dynamic:
+		_add_dynamic_object(obj)
+	else:
+		_add_static_object(obj)
+
+
+func _add_static_object(obj: WorldObject) -> void:
+	var static_obj := StaticObjectNode.new()
+	static_obj.world_object = obj
+	static_obj.position = obj.position
+	static_obj.quaternion = Quaternion(obj.rotation.x, obj.rotation.y, obj.rotation.z, obj.rotation.w)
+	static_obj.scale = obj.scale
+	static_obj.name = "static_%s" % obj.id
+	add_child(static_obj)
+
+
+func _add_dynamic_object(obj: WorldObject) -> void:
+	var dynamic_obj := DynamicObjectNode.new()
+	dynamic_obj.world_object = obj
+	dynamic_obj.position = obj.position
+	dynamic_obj.quaternion = Quaternion(obj.rotation.x, obj.rotation.y, obj.rotation.z, obj.rotation.w)
+	dynamic_obj.scale = obj.scale
+	dynamic_obj.name = "dynamic_%s" % obj.id
+	add_child(dynamic_obj)
+
+
+## Get a world object by its ID.
+func get_object_by_id(object_id: String) -> WorldObject:
+	for obj in world_objects:
+		if obj.id == object_id:
+			return obj
+	return null
+
+
+## Get all static objects in this chunk.
+func get_static_objects() -> Array[WorldObject]:
+	var result: Array[WorldObject] = []
+	for obj in world_objects:
+		if not obj.is_dynamic:
+			result.append(obj)
+	return result
+
+
+## Get all dynamic object templates in this chunk.
+func get_dynamic_templates() -> Array[WorldObject]:
+	var result: Array[WorldObject] = []
+	for obj in world_objects:
+		if obj.is_dynamic:
+			result.append(obj)
+	return result
+
+
+## Mark this chunk as dirty (locally modified).
+func mark_dirty() -> void:
+	is_dirty = true
+
+
+## Clear all objects and tile layers from this chunk.
+func clear() -> void:
+	for child in get_children():
+		if child is TileLayerNode or child is StaticObjectNode or child is DynamicObjectNode:
+			child.queue_free()
+	tile_layers.clear()
+	world_objects.clear()
+
+
+## Get the world-space position of a tile within this chunk.
+func get_tile_world_position(tile_x: int, tile_y: int, tile_z: int = 0) -> Vector3:
+	return bounds.position + Vector3(
+		tile_x * 1.0,  # Tile size is 1 world unit
+		tile_y * 1.0,
+		tile_z * 1.0
+	)
+
+
+## Check if a world-space position is within this chunk's bounds.
+func contains_position(pos: Vector3) -> bool:
+	return bounds.has_point(pos)
+
+
+## Check if a chunk coordinate is adjacent to this chunk.
+func is_adjacent(other_coord: Vector3i) -> bool:
+	var dx: int = abs(coord.x - other_coord.x)
+	var dy: int = abs(coord.y - other_coord.y)
+	var dz: int = abs(coord.z - other_coord.z)
+	return dx <= 1 and dy <= 1 and dz <= 1 and (dx + dy + dz) > 0

scripts/chunk_scene.gd.uid

@@ -0,0 +1 @@
+uid://d4gh4h5iey6xb

scripts/chunk_stream_manager.gd

@@ -0,0 +1,358 @@
+class_name ChunkStreamManager
+extends Node
+## Manages loading and unloading of world chunks based on player position.
+##
+## This is the central orchestrator for the chunk streaming system. It monitors
+## the player's position, determines which chunks should be loaded, requests
+## chunk data from the server, instantiates ChunkScene nodes, and unloads
+## chunks that fall outside the streaming radius.
+##
+## ## Design
+##
+## - **Streaming radius** defines how many chunks around the player are kept
+##   loaded. Chunks beyond this radius are unloaded to save memory and CPU.
+## - **Load priority** ensures chunks closer to the player are loaded first,
+##   preventing visual pop-in at the edge of the view.
+## - **Server communication** uses the RPCs defined in docs/architecture/world.md
+##   (§5.3): `request_chunk`, `chunk_data`, `chunk_invalidated`.
+##
+## ## Usage
+##
+## Add this node to your scene tree and set the `player` reference:
+## ```gdscript
+## var stream_manager: ChunkStreamManager = $ChunkStreamManager
+## stream_manager.player = $Player
+## stream_manager.streaming_radius = 4  # chunks
+## ```
+
+## Number of chunks (radius) to keep loaded around the player.
+## A radius of 2 means a 5x5 grid of chunks centered on the player.
+## Higher values increase memory usage but reduce streaming pop-in.
+@export var streaming_radius: int = 3
+
+## Maximum number of chunks to load per frame. Prevents frame spikes during
+## rapid movement or when entering a new area.
+@export var max_loads_per_frame: int = 4
+
+## Maximum number of chunks to unload per frame.
+@export var max_unloads_per_frame: int = 4
+
+## Distance (in chunks) from the streaming radius edge before a chunk is
+## considered for unloading. Prevents rapid load/unload cycling.
+@export var unload_margin: int = 1
+
+## Emitted when a chunk finishes loading.
+signal chunk_loaded(chunk_coord: Vector3i, chunk_scene: Node)
+
+## Emitted when a chunk is unloaded.
+signal chunk_unloaded(chunk_coord: Vector3i)
+
+## Emitted when a chunk fails to load (e.g., server error).
+signal chunk_load_failed(chunk_coord: Vector3i, error: String)
+
+## Emitted when the player moves far enough to require a streaming update.
+signal streaming_updated
+
+## Reference to the player node. Must be set before the manager starts.
+var player: Node3D = null
+
+## The current player chunk coordinate.
+var _player_chunk_coord: Vector3i = Vector3i.ZERO
+
+## Map of loaded chunk coordinates to their scene nodes.
+var _loaded_chunks: Dictionary = {}
+
+## Queue of chunk coordinates pending load, sorted by distance from player.
+var _load_queue: Array[Vector3i] = []
+
+## Queue of chunk coordinates pending unload.
+var _unload_queue: Array[Vector3i] = []
+
+## Whether streaming is currently active (player is set and in game).
+var is_active: bool = false
+
+## The server RPC interface for chunk data. Set by the networking layer.
+var _server_rpc: Object = null
+
+## Internal: track which chunks are currently being loaded (to avoid duplicates).
+var _loading_in_progress: Dictionary = {}
+
+## Internal: time accumulator for throttled streaming updates.
+var _update_accumulator: float = 0.0
+
+## Internal: interval between streaming updates (seconds).
+const UPDATE_INTERVAL: float = 0.1
+
+
+func _ready() -> void:
+	# Streaming is driven from _process (main thread) so we can safely
+	# manipulate the scene tree. No background thread is used.
+	set_process(true)
+
+
+func _process(delta: float) -> void:
+	if not is_active or player == null:
+		return
+
+	_update_accumulator += delta
+	if _update_accumulator < UPDATE_INTERVAL:
+		return
+	_update_accumulator = 0.0
+
+	_update_streaming()
+	_process_load_queue()
+	_process_unload_queue()
+	streaming_updated.emit()
+
+
+func _update_streaming() -> void:
+	if player == null or not is_inside_tree():
+		return
+
+	var current_coord: Vector3i = Chunk.coord_for_position(player.global_position)
+	if current_coord == _player_chunk_coord:
+		return
+
+	_player_chunk_coord = current_coord
+	_rebuild_queues()
+
+
+func _rebuild_queues() -> void:
+	var target_set: Dictionary = _compute_target_chunks()
+
+	# Determine which chunks need to be loaded
+	var to_load: Array[Vector3i] = []
+	for coord in target_set:
+		if not _loaded_chunks.has(coord) and not _loading_in_progress.has(coord):
+			to_load.append(coord)
+
+	# Sort by distance from player (closest first)
+	to_load.sort_custom(_compare_distance)
+	_load_queue = to_load
+
+	# Determine which chunks need to be unloaded
+	var to_unload: Array[Vector3i] = []
+	for coord in _loaded_chunks:
+		if not target_set.has(coord):
+			to_unload.append(coord)
+
+	to_unload.sort_custom(_compare_distance)
+	_unload_queue = to_unload
+
+
+func _compute_target_chunks() -> Dictionary:
+	"""Compute the set of chunk coordinates that should be loaded."""
+	var target: Dictionary = {}
+	var half: int = streaming_radius
+	for dx in range(-half, half + 1):
+		for dy in range(-half, half + 1):
+			for dz in range(-half, half + 1):
+				var coord: Vector3i = Vector3i(
+					_player_chunk_coord.x + dx,
+					_player_chunk_coord.y + dy,
+					_player_chunk_coord.z + dz
+				)
+				target[coord] = coord
+	return target
+
+
+func _compare_distance(a: Vector3i, b: Vector3i) -> bool:
+	"""Compare chunk coordinates by distance from player chunk."""
+	var dist_a: int = _chunk_distance_squared(_player_chunk_coord, a)
+	var dist_b: int = _chunk_distance_squared(_player_chunk_coord, b)
+	return dist_a < dist_b
+
+
+func _chunk_distance_squared(a: Vector3i, b: Vector3i) -> int:
+	var dx: int = a.x - b.x
+	var dy: int = a.y - b.y
+	var dz: int = a.z - b.z
+	return dx * dx + dy * dy + dz * dz
+
+
+func _process_load_queue() -> void:
+	var count: int = 0
+	while count < max_loads_per_frame and not _load_queue.is_empty():
+		var coord: Vector3i = _load_queue.pop_front()
+		_load_chunk(coord)
+		count += 1
+
+
+func _process_unload_queue() -> void:
+	var count: int = 0
+	while count < max_unloads_per_frame and not _unload_queue.is_empty():
+		var coord: Vector3i = _unload_queue.pop_front()
+		_unload_chunk(coord)
+		count += 1
+
+
+func _load_chunk(coord: Vector3i) -> void:
+	if _loading_in_progress.has(coord):
+		return
+
+	_loading_in_progress[coord] = true
+
+	# Request chunk data from server via RPC
+	if _server_rpc != null and _server_rpc.has_method("request_chunk"):
+		_server_rpc.request_chunk(Chunk.build_key(
+			"", "", coord
+		))
+	else:
+		# Fallback: try to load from local cache or create empty chunk
+		_instantiate_chunk_scene(coord)
+
+
+func _on_chunk_data_received(key: String, binary_data: PackedByteArray) -> void:
+	"""Called by the networking layer when chunk data arrives from server."""
+	var coord: Vector3i = _parse_coord_from_key(key)
+	if coord == null:
+		return
+
+	_loading_in_progress.erase(coord)
+
+	# Decode the binary chunk data
+	var chunk_data: ChunkDataDecoder.ChunkPayload = ChunkDataDecoder.decode_binary(binary_data)
+	if chunk_data == null:
+		chunk_load_failed.emit(coord, "Failed to decode chunk data")
+		return
+
+	# Instantiate the chunk scene with the decoded data
+	_instantiate_chunk_scene_with_data(coord, chunk_data)
+
+
+func _on_chunk_load_error(coord: Vector3i, error_msg: String) -> void:
+	"""Called when the server reports a chunk load error."""
+	_loading_in_progress.erase(coord)
+	chunk_load_failed.emit(coord, error_msg)
+
+
+func _instantiate_chunk_scene(coord: Vector3i) -> void:
+	"""Create an empty chunk scene for the given coordinate."""
+	var chunk_scene: ChunkScene = ChunkScene.new()
+	chunk_scene.coord = coord
+	chunk_scene.key = Chunk.build_key("", "", coord)
+	chunk_scene.bounds = Chunk.compute_bounds(coord)
+	_add_loaded_chunk(coord, chunk_scene)
+
+
+func _instantiate_chunk_scene_with_data(coord: Vector3i, data: ChunkDataDecoder.ChunkPayload) -> void:
+	"""Create a chunk scene populated with server data."""
+	var chunk_scene: ChunkScene = ChunkScene.new()
+	chunk_scene.coord = coord
+	chunk_scene.key = data.key
+	chunk_scene.bounds = data.bounds
+	chunk_scene.format_version = data.format_version
+	chunk_scene.revision = data.revision
+
+	# Add tiles
+	for layer in data.tile_layers:
+		var tile_layer: TileLayer = TileLayer.new()
+		tile_layer.name = layer.name
+		tile_layer.layer_id = layer.layer_id
+		tile_layer.width = layer.width
+		tile_layer.height = layer.height
+		tile_layer.depth = layer.depth
+		tile_layer.palette = layer.palette
+		tile_layer.tiles = layer.tiles
+		chunk_scene.add_tile_layer(tile_layer)
+
+	# Add objects
+	for obj_data in data.objects:
+		var world_obj: WorldObject = WorldObject.new()
+		world_obj.id = obj_data.id
+		world_obj.type = obj_data.type
+		world_obj.asset_id = obj_data.asset_id
+		world_obj.position = obj_data.position
+		world_obj.rotation = obj_data.rotation
+		world_obj.scale = obj_data.scale
+		world_obj.properties = obj_data.properties
+		world_obj.is_dynamic = obj_data.dynamic
+		world_obj.flags = obj_data.flags
+		chunk_scene.add_object(world_obj)
+
+	# Add content flags
+	chunk_scene.content_flags = data.flags
+
+	_add_loaded_chunk(coord, chunk_scene)
+
+
+func _add_loaded_chunk(coord: Vector3i, chunk_scene: Node) -> void:
+	_loaded_chunks[coord] = chunk_scene
+	add_child(chunk_scene)
+	_loading_in_progress.erase(coord)
+	chunk_loaded.emit(coord, chunk_scene)
+
+
+func _unload_chunk(coord: Vector3i) -> void:
+	if not _loaded_chunks.has(coord):
+		return
+
+	var chunk_scene: Node = _loaded_chunks[coord]
+	if is_instance_valid(chunk_scene):
+		chunk_scene.queue_free()
+
+	_loaded_chunks.erase(coord)
+	chunk_unloaded.emit(coord)
+
+
+func _on_player_position_changed() -> void:
+	"""Call this when the player position changes significantly."""
+	if player != null:
+		_update_streaming()
+
+
+func set_server_rpc(rpc_interface: Object) -> void:
+	"""Set the server RPC interface for chunk requests."""
+	_server_rpc = rpc_interface
+
+
+func get_loaded_chunk(coord: Vector3i) -> Node:
+	"""Get a loaded chunk scene by coordinate, or null if not loaded."""
+	return _loaded_chunks.get(coord, null)
+
+
+func is_chunk_loaded(coord: Vector3i) -> bool:
+	"""Check if a chunk is currently loaded."""
+	return _loaded_chunks.has(coord)
+
+
+func get_loaded_chunk_count() -> int:
+	"""Get the number of currently loaded chunks."""
+	return _loaded_chunks.size()
+
+
+func get_all_loaded_coords() -> Array[Vector3i]:
+	"""Get all currently loaded chunk coordinates."""
+	var coords: Array[Vector3i] = []
+	for key in _loaded_chunks:
+		coords.append(key)
+	return coords
+
+
+func force_reload_chunk(coord: Vector3i) -> void:
+	"""Force reload a specific chunk (e.g., after server update)."""
+	if _loaded_chunks.has(coord):
+		_unload_chunk(coord)
+	if not _loading_in_progress.has(coord):
+		_load_chunk(coord)
+
+
+func clear_all_chunks() -> void:
+	"""Unload all chunks immediately."""
+	var coords: Array[Vector3i] = get_all_loaded_coords()
+	for coord in coords:
+		_unload_chunk(coord)
+	_load_queue.clear()
+	_unload_queue.clear()
+
+
+func _parse_coord_from_key(key: String) -> Variant:
+	"""Parse chunk coordinate from a canonical chunk key."""
+	var parts: Array[String] = key.split(":")
+	if parts.size() < 5:
+		return null
+	return Vector3i(
+		int(parts[2]),
+		int(parts[3]),
+		int(parts[4])
+	)

scripts/chunk_stream_manager.gd.uid

@@ -0,0 +1 @@
+uid://8yokqwe23c23

scripts/dynamic_object_node.gd

@@ -0,0 +1,68 @@
+class_name DynamicObjectNode
+extends Node3D
+## A visual representation of a dynamic (spawnable) world object template.
+##
+## This node is instantiated by [ChunkScene] for each dynamic [WorldObject].
+## Dynamic objects are stored as *templates* in the chunk; their runtime state
+## (position, health, inventory) is managed by the entity system, not by this
+## node. This node renders the template's visual representation so the object
+## is visible in the world.
+##
+## ## Structure
+##
+## ```
+## DynamicObjectNode (Node3D)
+##  └── MeshInstance3D  # the object's visual mesh
+## ```
+
+## The world object data this node represents.
+var world_object: WorldObject = null
+
+## The loaded mesh instance (or placeholder).
+var _mesh_instance: MeshInstance3D = null
+
+
+func _ready() -> void:
+	if world_object == null:
+		return
+	_load_mesh()
+
+
+## Load and attach the object's mesh.
+func _load_mesh() -> void:
+	_mesh_instance = MeshInstance3D.new()
+	_mesh_instance.name = "mesh"
+
+	var mesh := _load_asset_mesh(world_object.asset_id)
+	if mesh == null:
+		mesh = _make_placeholder_mesh()
+
+	_mesh_instance.mesh = mesh
+	add_child(_mesh_instance)
+
+
+## Attempt to load a mesh from the asset path.
+func _load_asset_mesh(asset_id: String) -> Mesh:
+	if asset_id.is_empty():
+		return null
+	var path := "res://assets/%s" % asset_id
+	if ResourceLoader.exists(path):
+		var res := load(path)
+		if res is Mesh:
+			return res
+	return null
+
+
+## Create a simple placeholder sphere mesh when the real asset is unavailable.
+func _make_placeholder_mesh() -> Mesh:
+	var mesh := SphereMesh.new()
+	mesh.radius = 0.5
+	mesh.height = 1.0
+	return mesh
+
+
+## Get the world object's display name.
+func get_display_name() -> String:
+	if world_object == null:
+		return ""
+	return world_object.get_display_name()

scripts/dynamic_object_node.gd.uid

@@ -0,0 +1 @@
+uid://dyjqcstdnr4u1

scripts/main_menu.gd

@@ -0,0 +1,212 @@
+extends Control
+## Main menu with login/register UI wired to the backend auth API.
+##
+## The AuthPanel is hidden by default. When the user clicks "Login" or "Register"
+## (the existing Play/Quit buttons), the auth panel slides in. The ModeToggle
+## switches between Login and Register modes, showing/hiding the email and DOB
+## fields accordingly.
+##
+## On successful auth the token is stored via ApiClient, the welcome label
+## shows the username, and the Play button becomes enabled.
+
+
+# ── UI references ────────────────────────────────────────────────────────────
+
+var _auth_panel: PanelContainer
+var _auth_mode_label: Label
+var _username_edit: LineEdit
+var _password_edit: LineEdit
+var _email_edit: LineEdit
+var _dob_edit: LineEdit
+var _mode_toggle: CheckButton
+var _auth_button: Button
+var _status_label: Label
+var _welcome_label: Label
+var _play_button: Button
+var _quit_button: Button
+
+var _is_register_mode: bool = false
+var _is_authenticating: bool = false
+
+
+# ── Lifecycle ────────────────────────────────────────────────────────────────
+
+func _ready() -> void:
+	# Cache node references.
+	_auth_panel = $CenterContainer/VBoxContainer/AuthPanel
+	_auth_mode_label = $CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/AuthModeLabel
+	_username_edit = $CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/UsernameEdit
+	_password_edit = $CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/PasswordEdit
+	_email_edit = $CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/EmailEdit
+	_dob_edit = $CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/DOBEdit
+	_mode_toggle = $CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/ModeToggle
+	_auth_button = $CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/AuthButton
+	_status_label = $CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/AuthStatusLabel
+	_welcome_label = $CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/WelcomeLabel
+	_play_button = $CenterContainer/VBoxContainer/PlayButton
+	_quit_button = $CenterContainer/VBoxContainer/QuitButton
+
+	# Initial state.
+	_auth_panel.visible = false
+	_status_label.visible = false
+	_welcome_label.visible = false
+	_email_edit.visible = false
+	_dob_edit.visible = false
+	_play_button.disabled = true  # Gate play behind successful auth.
+	_update_auth_mode_ui()
+
+
+# ── Play / Quit ──────────────────────────────────────────────────────────────
+
+func _on_play_button_pressed() -> void:
+	if _play_button.disabled:
+		return
+	# Browse worlds is the first real screen past login -- actual gameplay
+	# (joining a world) doesn't exist yet, browsing does.
+	get_tree().change_scene_to_file("res://scenes/world_list.tscn")
+
+
+func _on_quit_button_pressed() -> void:
+	get_tree().quit()
+
+
+# ── Auth panel toggle ────────────────────────────────────────────────────────
+
+func _on_login_button_pressed() -> void:
+	"""Show the auth panel (called from a future Login button on the main menu)."""
+	_auth_panel.visible = true
+	_auth_panel.grab_focus()
+
+
+func _on_register_button_pressed() -> void:
+	"""Show the auth panel in register mode."""
+	_auth_panel.visible = true
+	_is_register_mode = true
+	_mode_toggle.button_pressed = true
+	_update_auth_mode_ui()
+	_clear_status()
+
+
+# ── Mode toggle (Login / Register) ───────────────────────────────────────────
+
+func _on_mode_toggle_toggled(button_pressed: bool) -> void:
+	_is_register_mode = button_pressed
+	_update_auth_mode_ui()
+	_clear_status()
+
+
+func _update_auth_mode_ui() -> void:
+	"""Update labels and field visibility based on login vs register mode."""
+	if _is_register_mode:
+		_auth_mode_label.text = "Register"
+		_auth_button.text = "Register"
+		_email_edit.visible = true
+		_dob_edit.visible = true
+	else:
+		_auth_mode_label.text = "Login"
+		_auth_button.text = "Login"
+		_email_edit.visible = false
+		_dob_edit.visible = false
+
+
+# ── Auth submission ──────────────────────────────────────────────────────────
+
+func _on_auth_button_pressed() -> void:
+	"""Handle login or register button press."""
+	if _is_authenticating:
+		return
+
+	# Validate inputs.
+	var username := _username_edit.text.strip_edges()
+	var password := _password_edit.text
+
+	if username == "":
+		_show_status("Username is required.")
+		return
+	if password == "":
+		_show_status("Password is required.")
+		return
+
+	if _is_register_mode:
+		var email := _email_edit.text.strip_edges()
+		var dob := _dob_edit.text.strip_edges()
+
+		if email == "":
+			_show_status("Email is required.")
+			return
+		if dob == "":
+			_show_status("Date of birth is required.")
+			return
+		# Basic YYYY-MM-DD format check.
+		if not _is_valid_date(dob):
+			_show_status("Date of birth must be in YYYY-MM-DD format.")
+			return
+
+		_auth_button.disabled = true
+		_auth_button.text = "Registering..."
+		_is_authenticating = true
+		_clear_status()
+
+		var result := await ApiClient.register(username, email, password, dob)
+		_on_auth_complete(result)
+	else:
+		_auth_button.disabled = true
+		_auth_button.text = "Logging in..."
+		_is_authenticating = true
+		_clear_status()
+
+		var result := await ApiClient.login(username, password)
+		_on_auth_complete(result)
+
+
+func _on_auth_complete(result: Dictionary) -> void:
+	"""Handle the result of a login or register call."""
+	_auth_button.disabled = false
+	_auth_button.text = "Register" if _is_register_mode else "Login"
+	_is_authenticating = false
+
+	if result.ok:
+		# Success — show welcome, enable Play.
+		_welcome_label.text = "Welcome, %s!" % _username_edit.text.strip_edges()
+		_welcome_label.visible = true
+		_status_label.visible = false
+		_play_button.disabled = false
+		print("Auth successful. Token stored.")
+	else:
+		# Failure — show backend error detail.
+		_show_status(result.detail)
+
+
+# ── Status helpers ───────────────────────────────────────────────────────────
+
+func _show_status(message: String) -> void:
+	_status_label.text = message
+	_status_label.visible = true
+
+
+func _clear_status() -> void:
+	_status_label.text = ""
+	_status_label.visible = false
+
+
+# ── Validation ───────────────────────────────────────────────────────────────
+
+func _is_valid_date(date_str: String) -> bool:
+	"""Check if a string looks like a valid YYYY-MM-DD date."""
+	if date_str.length() != 10:
+		return false
+	var parts := date_str.split("-")
+	if parts.size() != 3:
+		return false
+	var year := parts[0].to_int()
+	var month := parts[1].to_int()
+	var day := parts[2].to_int()
+	if month < 1 or month > 12:
+		return false
+	if day < 1 or day > 31:
+		return false
+	# Rough month-day validation.
+	var days_in_month := [0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
+	if day > days_in_month[month]:
+		return false
+	return true

scripts/main_menu.gd.uid

@@ -0,0 +1 @@
+uid://bgnc3iamfgf6k

scripts/run_checkpoint_tests.py

@@ -0,0 +1,170 @@
+#!/usr/bin/env python3
+"""Run the full automated test inventory for a Package Checkpoint review.
+
+See docs/testing/test_inventory.md for what each suite actually covers (and
+doesn't) -- keep that doc in sync as tests are added, this script just runs
+whatever's there.
+
+Usage:
+    python scripts/run_checkpoint_tests.py [--keep-postgres] [--postgres-port PORT]
+
+Exits 0 if everything that ran passed, 1 otherwise. Suites with nothing to
+run (e.g. no scripts/smoke_test_*.gd yet, or no Godot binary found) are
+reported as SKIPPED, not counted as a failure.
+"""
+import argparse
+import glob
+import os
+import shutil
+import subprocess
+import sys
+import time
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parent.parent
+BACKEND = ROOT / "backend"
+
+
+def run(cmd, cwd=None, env=None, capture=False):
+    print(f"$ {' '.join(cmd)}" + (f"  (cwd={cwd})" if cwd else ""))
+    return subprocess.run(cmd, cwd=cwd, env=env, capture_output=capture, text=True)
+
+
+def find_godot():
+    for candidate in ("godot", str(Path.home() / "godot" / "godot")):
+        if shutil.which(candidate) or Path(candidate).is_file():
+            return candidate
+    return None
+
+
+def wait_for_http(url: str, timeout_s: int = 20) -> bool:
+    import urllib.request
+    import urllib.error
+
+    deadline = time.time() + timeout_s
+    while time.time() < deadline:
+        try:
+            with urllib.request.urlopen(url, timeout=2) as resp:
+                if resp.status == 200:
+                    return True
+        except (urllib.error.URLError, ConnectionError, OSError):
+            pass
+        time.sleep(1)
+    return False
+
+
+def main():
+    parser = argparse.ArgumentParser(description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter)
+    parser.add_argument("--keep-postgres", action="store_true",
+                         help="Don't tear down the checkpoint Postgres container afterward")
+    parser.add_argument("--postgres-port", default=os.environ.get("CHECKPOINT_POSTGRES_PORT", "5432"),
+                         help="Host port for the checkpoint's own Postgres container (default 5432 -- "
+                              "override if that's already in use on this machine)")
+    parser.add_argument("--backend-port", default=os.environ.get("CHECKPOINT_BACKEND_PORT", "18080"),
+                         help="Port to run the backend server on for the Godot smoke tests")
+    args = parser.parse_args()
+
+    results = {}
+
+    # --- Backend: bring up Postgres ---
+    compose_env = os.environ.copy()
+    compose_env["COMPOSE_PROJECT_NAME"] = "agp-checkpoint"
+    compose_env["POSTGRES_HOST_PORT"] = args.postgres_port
+    compose_env["POSTGRES_PORT"] = args.postgres_port  # some branches use this name instead, see tools/definitions.py
+    print("=== Backend: bringing up Postgres ===")
+    run(["docker", "compose", "up", "-d", "postgres"], cwd=BACKEND, env=compose_env)
+
+    print("Waiting for Postgres to be ready...")
+    pg_ready = False
+    for _ in range(20):
+        r = run(["docker", "compose", "exec", "-T", "postgres", "pg_isready", "-U", "agp_user", "-d", "agp_db"],
+                cwd=BACKEND, env=compose_env, capture=True)
+        if r.returncode == 0:
+            pg_ready = True
+            break
+        time.sleep(1)
+    if not pg_ready:
+        print("Postgres never became ready -- aborting.")
+        sys.exit(1)
+
+    db_url = f"postgresql+asyncpg://agp_user:agp_password@localhost:{args.postgres_port}/agp_db"
+    backend_env = os.environ.copy()
+    backend_env["DATABASE_URL"] = db_url
+
+    print("\n=== Backend: alembic upgrade head ===")
+    r = run([sys.executable, "-m", "alembic", "upgrade", "head"], cwd=BACKEND, env=backend_env)
+    results["migrations (fresh DB)"] = r.returncode == 0
+
+    print("\n=== Backend: pytest ===")
+    r = run([sys.executable, "-m", "pytest", "-v"], cwd=BACKEND, env=backend_env)
+    results["backend pytest"] = r.returncode == 0
+
+    # --- Godot: headless smoke tests (need a live backend server) ---
+    godot_bin = find_godot()
+    smoke_tests = sorted(glob.glob(str(ROOT / "scripts" / "smoke_test_*.gd")))
+
+    if not godot_bin:
+        print("\n=== Godot: binary not found (checked PATH and ~/godot/godot), skipping smoke tests ===")
+        results["godot smoke tests"] = None
+    elif not smoke_tests:
+        print("\n=== Godot: no scripts/smoke_test_*.gd found yet, nothing to run ===")
+        results["godot smoke tests"] = None
+    else:
+        print(f"\n=== Backend: starting server on :{args.backend_port} for Godot smoke tests ===")
+        server_proc = subprocess.Popen(
+            [sys.executable, "-m", "uvicorn", "app.main:app", "--host", "127.0.0.1", "--port", args.backend_port],
+            cwd=BACKEND, env=backend_env,
+            stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL,
+        )
+        try:
+            base_url = f"http://127.0.0.1:{args.backend_port}"
+            if not wait_for_http(f"{base_url}/api/health"):
+                print("Backend server never became healthy -- skipping Godot smoke tests.")
+                results["godot smoke tests"] = False
+            else:
+                godot_env = os.environ.copy()
+                godot_env["AGP_API_BASE_URL"] = base_url
+
+                print("=== Godot: import pass (builds the class cache) ===")
+                run([godot_bin, "--headless", "--path", str(ROOT), "--import"], env=godot_env)
+                run([godot_bin, "--headless", "--path", str(ROOT), "--quit"], env=godot_env)
+
+                godot_ok = True
+                for test in smoke_tests:
+                    rel = os.path.relpath(test, ROOT)
+                    print(f"\n--- {rel} ---")
+                    r = run([godot_bin, "--headless", "--path", str(ROOT), "--script", f"res://{rel}"], env=godot_env)
+                    if r.returncode != 0:
+                        godot_ok = False
+                results["godot smoke tests"] = godot_ok
+        finally:
+            server_proc.terminate()
+            try:
+                server_proc.wait(timeout=10)
+            except subprocess.TimeoutExpired:
+                server_proc.kill()
+
+    if not args.keep_postgres:
+        print("\n=== Backend: tearing down checkpoint Postgres ===")
+        run(["docker", "compose", "down", "-v", "postgres"], cwd=BACKEND, env=compose_env)
+
+    # --- Summary ---
+    print("\n" + "=" * 50)
+    print("SUMMARY")
+    print("=" * 50)
+    overall_ok = True
+    for name, ok in results.items():
+        if ok is None:
+            print(f"  {name}: SKIPPED")
+        elif ok:
+            print(f"  {name}: PASS")
+        else:
+            print(f"  {name}: FAIL")
+            overall_ok = False
+
+    print("\nSee docs/testing/test_inventory.md for what each suite actually covers (and doesn't).")
+    sys.exit(0 if overall_ok else 1)
+
+
+if __name__ == "__main__":
+    main()

scripts/smoke_test_api.gd

@@ -0,0 +1,46 @@
+extends SceneTree
+## Headless smoke test for the ApiClient autoload.
+##
+## Run with:
+##     godot --headless --path . --script res://scripts/smoke_test_api.gd
+##
+## Requires the backend to be running (default base URL
+## `application/agp/api_base_url` -> http://127.0.0.1:8000).
+##
+## Calls the real autoload's `health_check()` (which exercises the generic
+## `request()` primitive) and exits 0 on a `status == "ok"` response, 1
+## otherwise. This script is intentionally NOT wired into any game scene.
+
+
+func _initialize() -> void:
+	_run()
+
+
+func _run() -> void:
+	# _initialize() fires before the SceneTree has processed its first frame,
+	# so a freshly add_child()'d HTTPRequest node isn't reliably considered
+	# "inside tree" yet (request_raw fails with !is_inside_tree()). One frame
+	# of delay is enough; this only matters for --script mode, not a real
+	# running game.
+	await process_frame
+
+	# Godot's --script/SceneTree runner doesn't resolve autoload singletons
+	# as bare global identifiers at compile time (the node exists at
+	# runtime -- root.has_node("ApiClient") is true -- but referencing it as
+	# a plain identifier fails with "Identifier not found: ApiClient" during
+	# script compilation). get_node sidesteps compile-time resolution
+	# entirely. This only affects --script mode; a real game scene resolves
+	# the bare autoload name normally.
+	var api_client := root.get_node("ApiClient")
+	print("SMOKE: calling ApiClient.health_check() ...")
+	var result: Dictionary = await api_client.health_check()
+	print("SMOKE: result = ", result)
+
+	if result.ok \
+			and result.data is Dictionary \
+			and str((result.data as Dictionary).get("status", "")) == "ok":
+		print("SMOKE RESULT: PASS (status=ok)")
+		quit(0)
+	else:
+		printerr("SMOKE RESULT: FAIL")
+		quit(1)

scripts/smoke_test_auth.gd

@@ -0,0 +1,133 @@
+extends SceneTree
+## Headless smoke test for the AuthPanel login/register flow.
+##
+## Run with:
+##     godot --headless --path . --script res://scripts/smoke_test_auth.gd
+##
+## Requires the backend to be running (default base URL
+## `application/agp/api_base_url` -> http://127.0.0.1:8000).
+##
+## Tests:
+##   1. Register a unique user → 201 + token stored.
+##   2. Register the same user again → 409 "Username already registered".
+##   3. Register an under-18 user → 400 "Must be 18 or older".
+##   4. Login with correct credentials → 200 + token stored.
+##   5. Login with wrong password → 401 "Incorrect username or password".
+##   6. Login with non-existent user → 401 "Incorrect username or password".
+##
+## Exits 0 on full pass, 1 on any failure.
+
+const API_BASE := "http://127.0.0.1:8000"
+const TEST_USERNAME := "smoke_test_user_%d"
+const TEST_EMAIL := "smoke_%d@test.example.com"
+const TEST_PASSWORD := "SmokeTest123!"
+const TEST_DOB_ADULT := "2000-01-01"
+const TEST_DOB_CHILD := "2020-01-01"  # ~5 years old
+
+
+func _initialize() -> void:
+	_run()
+
+
+func _run() -> void:
+	# Wait for autoloads to be ready.
+	await process_frame
+
+	var api := root.get_node("ApiClient") as ApiClient
+	assert(api != null, "ApiClient autoload not found")
+
+	var passed: int = 0
+	var failed: int = 0
+
+	# --- Test 1: Register a unique user ---
+	var unique_id := Time.get_ticks_msec()
+	var username := "smoke_%d" % unique_id
+	var email := "smoke_%d@test.example.com" % unique_id
+
+	print("\n=== Test 1: Register unique user ===")
+	var result := await api.register(username, email, TEST_PASSWORD, TEST_DOB_ADULT)
+	if _check("register returns ok", result.ok) \
+			and _check("register status is 201", result.status == 201) \
+			and _check("register stores token", api.has_token()):
+		passed += 1
+	else:
+		failed += 1
+		print("  detail: ", result.detail)
+
+	# --- Test 2: Register same user again (duplicate) ---
+	print("\n=== Test 2: Duplicate username ===")
+	result = await api.register(username, email, TEST_PASSWORD, TEST_DOB_ADULT)
+	if _check("duplicate register not ok", not result.ok) \
+			and _check("duplicate status is 409", result.status == 409) \
+			and _check("duplicate detail mentions username",
+					"username" in result.detail.to_lower()):
+		passed += 1
+	else:
+		failed += 1
+		print("  detail: ", result.detail)
+
+	# --- Test 3: Register under-18 user ---
+	print("\n=== Test 3: Under-18 registration ===")
+	var child_username := "child_%d" % unique_id
+	var child_email := "child_%d@test.example.com" % unique_id
+	result = await api.register(child_username, child_email, TEST_PASSWORD, TEST_DOB_CHILD)
+	if _check("under-18 register not ok", not result.ok) \
+			and _check("under-18 status is 400", result.status == 400) \
+			and _check("under-18 detail mentions age",
+					"18" in result.detail):
+		passed += 1
+	else:
+		failed += 1
+		print("  detail: ", result.detail)
+
+	# --- Test 4: Login with correct credentials ---
+	print("\n=== Test 4: Correct login ===")
+	result = await api.login(username, TEST_PASSWORD)
+	if _check("login returns ok", result.ok) \
+			and _check("login status is 200", result.status == 200) \
+			and _check("login stores token", api.has_token()):
+		passed += 1
+	else:
+		failed += 1
+		print("  detail: ", result.detail)
+
+	# --- Test 5: Login with wrong password ---
+	print("\n=== Test 5: Wrong password ===")
+	result = await api.login(username, "WrongPassword!")
+	if _check("wrong pwd login not ok", not result.ok) \
+			and _check("wrong pwd status is 401", result.status == 401) \
+			and _check("wrong pwd detail",
+					"Incorrect" in result.detail or "incorrect" in result.detail):
+		passed += 1
+	else:
+		failed += 1
+		print("  detail: ", result.detail)
+
+	# --- Test 6: Login with non-existent user ---
+	print("\n=== Test 6: Non-existent user ===")
+	result = await api.login("nonexistent_user_xyz", TEST_PASSWORD)
+	if _check("missing user login not ok", not result.ok) \
+			and _check("missing user status is 401", result.status == 401) \
+			and _check("missing user detail",
+					"Incorrect" in result.detail or "incorrect" in result.detail):
+		passed += 1
+	else:
+		failed += 1
+		print("  detail: ", result.detail)
+
+	# --- Summary ---
+	print("\n=== SMOKE RESULT: %d/%d passed ===" % [passed, passed + failed])
+	if failed > 0:
+		quit(1)
+	else:
+		print("SMOKE RESULT: ALL PASS")
+		quit(0)
+
+
+func _check(description: String, condition: bool) -> bool:
+	if condition:
+		print("  PASS: ", description)
+		return true
+	else:
+		printerr("  FAIL: ", description)
+		return false

scripts/smoke_test_e2e.gd

@@ -0,0 +1,148 @@
+extends SceneTree
+## End-to-end headless smoke test: register -> login -> fetch worlds list.
+##
+## Run with:
+##     godot --headless --path . --script res://scripts/smoke_test_e2e.gd
+##
+## Requires the backend to be running (default base URL
+## `application/agp/api_base_url` -> http://127.0.0.1:8000, overridable via
+## the AGP_API_BASE_URL environment variable).
+##
+## Steps:
+##   1. Health check  GET  /api/health          -> 200, {"status": "ok"}
+##   2. Register      POST /api/auth/register   -> 201, access_token present
+##   3. Login         POST /api/auth/login      -> 200, access_token present
+##   4. Worlds list   GET  /api/worlds          -> 200, JSON array
+##
+## Exits 0 if all steps pass, 1 otherwise. If the backend is unreachable the
+## health check fails with a clear message and the script exits 1 immediately.
+
+# Fixed credentials from the task spec. The username gets a unique numeric
+# suffix so the test stays re-runnable (a second run would otherwise hit
+# "Username already registered" on step 2).
+const TEST_USERNAME_BASE := "smoke_test_user"
+const TEST_EMAIL := "smoke@test.com"
+const TEST_PASSWORD := "TestPass123"
+const TEST_DOB := "2000-01-01"
+
+
+func _initialize() -> void:
+	_run()
+
+
+func _run() -> void:
+	# _initialize() fires before the first frame; wait one frame so freshly
+	# created HTTPRequest nodes are reliably inside the tree.
+	await process_frame
+
+	# In --script mode the autoload is reachable via get_node(), not as a
+	# bare identifier (bare identifiers fail to resolve at compile time here).
+	var api := root.get_node("ApiClient")
+	assert(api != null, "ApiClient autoload not found in the scene tree")
+
+	var unique_id := int(Time.get_unix_time_from_system() * 1000)
+	var username := "%s_%d" % [TEST_USERNAME_BASE, unique_id]
+	var email := "smoke_%d@test.com" % unique_id
+
+	var results := {}
+
+	# --- Step 1: Health check -------------------------------------------------
+	print("\n=== Step 1: Health check (GET /api/health) ===")
+	var health: Dictionary = await api.health_check()
+	var health_ok: bool = (
+		health.ok
+		and health.status == 200
+		and health.data is Dictionary
+		and str((health.data as Dictionary).get("status", "")) == "ok"
+	)
+	_record(results, "health", health_ok, "status=%d data=%s" % [
+		health.status, health.data
+	])
+
+	if not health.ok or health.status == 0:
+		printerr("\nERROR: Backend is not reachable at the configured base URL.")
+		printerr("       detail: %s" % health.detail)
+		printerr("       Start the backend first (see backend/README), then re-run:")
+		printerr("       godot --headless --path . --script res://scripts/smoke_test_e2e.gd")
+		_summarize(results)
+		quit(1)
+		return
+
+	# --- Step 2: Register -----------------------------------------------------
+	print("\n=== Step 2: Register (POST /api/auth/register) ===")
+	var reg: Dictionary = await api.register(username, email, TEST_PASSWORD, TEST_DOB)
+	var reg_token := _extract_token(reg)
+	var reg_ok: bool = (
+		reg.ok
+		and reg.status == 201
+		and reg_token != ""
+	)
+	_record(results, "register", reg_ok, "status=%d token=%s detail=%s" % [
+		reg.status, "yes" if reg_token != "" else "no", reg.detail
+	])
+
+	# --- Step 3: Login --------------------------------------------------------
+	print("\n=== Step 3: Login (POST /api/auth/login) ===")
+	var login: Dictionary = await api.login(username, TEST_PASSWORD)
+	var login_token := _extract_token(login)
+	var login_ok: bool = (
+		login.ok
+		and login.status == 200
+		and login_token != ""
+	)
+	_record(results, "login", login_ok, "status=%d token=%s detail=%s" % [
+		login.status, "yes" if login_token != "" else "no", login.detail
+	])
+
+	# --- Step 4: Worlds list ---------------------------------------------------
+	print("\n=== Step 4: Worlds list (GET /api/worlds) ===")
+	# login/register already stored the token; make the auth header explicit by
+	# re-applying the extracted token so step 4 is independent of storage order.
+	if login_token != "":
+		api.set_token(login_token)
+	var worlds: Dictionary = await api.get_worlds()
+	var worlds_ok: bool = (
+		worlds.ok
+		and worlds.status == 200
+		and worlds.data is Array
+	)
+	_record(results, "worlds", worlds_ok, "status=%d is_array=%s count=%d detail=%s" % [
+		worlds.status,
+		"yes" if (worlds.data is Array) else "no",
+		(worlds.data as Array).size() if (worlds.data is Array) else -1,
+		worlds.detail,
+	])
+
+	# --- Summary ---------------------------------------------------------------
+	_summarize(results)
+
+
+func _extract_token(result: Dictionary) -> String:
+	if result.ok and result.data is Dictionary:
+		return str((result.data as Dictionary).get("access_token", ""))
+	return ""
+
+
+func _record(results: Dictionary, name: String, ok: bool, detail: String) -> void:
+	results[name] = {"ok": ok, "detail": detail}
+	if ok:
+		print("  PASS: %s" % detail)
+	else:
+		printerr("  FAIL: %s" % detail)
+
+
+func _summarize(results: Dictionary) -> void:
+	var all_pass := true
+	print("\n=== Smoke test summary ===")
+	for step in ["health", "register", "login", "worlds"]:
+		var entry: Dictionary = results.get(step, {"ok": false, "detail": "not run"})
+		if not entry["ok"]:
+			all_pass = false
+		print("  %-8s : %s" % [step, "PASS" if entry["ok"] else "FAIL"])
+
+	if all_pass:
+		print("SMOKE RESULT: ALL PASS (4/4)")
+		quit(0)
+	else:
+		printerr("SMOKE RESULT: FAIL")
+		quit(1)

scripts/smoke_test_world_list.gd

@@ -0,0 +1,122 @@
+extends SceneTree
+## Headless smoke test for the world list screen.
+##
+## Run with:
+##     godot --headless --path . --script res://scripts/smoke_test_world_list.gd
+##
+## Requires the backend to be running (default base URL
+## `application/agp/api_base_url` -> http://127.0.0.1:8000, override with
+## AGP_API_BASE_URL).
+##
+## Unlike a pure API-level test, this actually instantiates scenes/
+## world_list.tscn as a real scene and adds it to the tree -- catches
+## @onready node-path bugs (a node reference pointing at the wrong path
+## errors right here, not just "looks right" from reading the script) that
+## an API-only test would miss entirely.
+##
+## Tests:
+##   1. Register + log in a fresh user (so get_worlds() has a valid token).
+##   2. Instantiate world_list.tscn, add to tree -- @onready resolution
+##      must not error.
+##   3. Wait for _refresh_worlds()'s awaited request to complete.
+##   4. Confirm the screen reached a real end state (world cards, or the
+##      empty-list message -- either is fine, a crash/stuck-loading isn't).
+##
+## Exits 0 on full pass, 1 on any failure.
+
+const WORLD_LIST_SCENE := "res://scenes/world_list.tscn"
+
+
+func _initialize() -> void:
+	_run()
+
+
+func _run() -> void:
+	await process_frame
+
+	var api := root.get_node("ApiClient")
+	assert(api != null, "ApiClient autoload not found")
+
+	var passed: int = 0
+	var failed: int = 0
+
+	# --- Setup: register + log in so the world list has a valid token ---
+	print("\n=== Setup: register + login ===")
+	randomize()
+	var unique_id: int = int(Time.get_unix_time_from_system() * 1000) + randi() % 100000
+	var username := "worldlist_smoke_%d" % unique_id
+	var email := "worldlist_smoke_%d@test.example.com" % unique_id
+	var reg_result: Dictionary = await api.register(username, email, "SmokeTest123!", "2000-01-01")
+	if not _check("setup: register succeeded", reg_result.ok):
+		print("  detail: ", reg_result.detail)
+		quit(1)
+		return
+
+	# --- Test 1: Instantiate the real scene ---
+	print("\n=== Test 1: Instantiate world_list.tscn ===")
+	var packed_scene: PackedScene = load(WORLD_LIST_SCENE)
+	if not _check("scene loads", packed_scene != null):
+		quit(1)
+		return
+
+	var instance: Control = packed_scene.instantiate()
+	if not _check("scene instantiates", instance != null):
+		quit(1)
+		return
+
+	root.add_child(instance)
+	# One frame for _ready() (and its @onready resolution) to run. A wrong
+	# node path in an @onready var errors during this, not silently.
+	await process_frame
+
+	if _check("scene added to tree without error", is_instance_valid(instance)):
+		passed += 1
+	else:
+		failed += 1
+
+	# --- Test 2: Wait for the world fetch to resolve, check a real end state ---
+	print("\n=== Test 2: World fetch reaches a real end state ===")
+	# _refresh_worlds() runs from _ready(); give its awaited HTTP call time
+	# to complete rather than a fixed sleep -- poll for either end state.
+	var world_list_node: VBoxContainer = instance.get_node("VBoxContainer/ScrollContainer/WorldList")
+	var empty_label: Label = instance.get_node("VBoxContainer/EmptyLabel")
+	var error_label: Label = instance.get_node("VBoxContainer/ErrorLabel")
+
+	var settled := false
+	for i in range(50):  # up to ~5s at 100ms/frame-ish via process_frame waits
+		await process_frame
+		if world_list_node.visible or empty_label.visible or error_label.visible:
+			settled = true
+			break
+
+	if _check("reached a real end state (cards, empty, or error) not stuck loading", settled):
+		passed += 1
+	else:
+		failed += 1
+		print("  world_list.visible=%s empty_label.visible=%s error_label.visible=%s" % [
+			world_list_node.visible, empty_label.visible, error_label.visible
+		])
+
+	if error_label.visible:
+		printerr("  Note: ended in error state: ", error_label.text)
+	elif world_list_node.visible:
+		print("  Note: rendered %d world card(s)" % world_list_node.get_child_count())
+	elif empty_label.visible:
+		print("  Note: ended in empty-list state")
+
+	# --- Summary ---
+	print("\n=== SMOKE RESULT: %d/%d passed ===" % [passed, passed + failed])
+	if failed > 0:
+		quit(1)
+	else:
+		print("SMOKE RESULT: ALL PASS")
+		quit(0)
+
+
+func _check(description: String, condition: bool) -> bool:
+	if condition:
+		print("  PASS: ", description)
+		return true
+	else:
+		printerr("  FAIL: ", description)
+		return false

scripts/static_object_node.gd

@@ -0,0 +1,67 @@
+class_name StaticObjectNode
+extends Node3D
+## A visual representation of a static world object within a chunk.
+##
+## This node is instantiated by [ChunkScene] for each static (non-dynamic)
+## [WorldObject]. It renders the object's mesh (referenced by `asset_id`) at
+## the object's transform. If the asset is not yet loaded, a placeholder mesh
+## is shown.
+##
+## ## Structure
+##
+## ```
+## StaticObjectNode (Node3D)
+##  └── MeshInstance3D  # the object's visual mesh
+## ```
+
+## The world object data this node represents.
+var world_object: WorldObject = null
+
+## The loaded mesh instance (or placeholder).
+var _mesh_instance: MeshInstance3D = null
+
+
+func _ready() -> void:
+	if world_object == null:
+		return
+	_load_mesh()
+
+
+## Load and attach the object's mesh.
+func _load_mesh() -> void:
+	_mesh_instance = MeshInstance3D.new()
+	_mesh_instance.name = "mesh"
+
+	# Try to load the asset by its id (path). Fall back to a placeholder.
+	var mesh := _load_asset_mesh(world_object.asset_id)
+	if mesh == null:
+		mesh = _make_placeholder_mesh()
+
+	_mesh_instance.mesh = mesh
+	add_child(_mesh_instance)
+
+
+## Attempt to load a mesh from the asset path.
+func _load_asset_mesh(asset_id: String) -> Mesh:
+	if asset_id.is_empty():
+		return null
+	var path := "res://assets/%s" % asset_id
+	if ResourceLoader.exists(path):
+		var res := load(path)
+		if res is Mesh:
+			return res
+	return null
+
+
+## Create a simple placeholder box mesh when the real asset is unavailable.
+func _make_placeholder_mesh() -> Mesh:
+	var mesh := BoxMesh.new()
+	mesh.size = Vector3(1.0, 1.0, 1.0)
+	return mesh
+
+
+## Get the world object's display name.
+func get_display_name() -> String:
+	if world_object == null:
+		return ""
+	return world_object.get_display_name()

scripts/static_object_node.gd.uid

@@ -0,0 +1 @@
+uid://chf6mruev1kc4

scripts/tile_def.gd

@@ -0,0 +1,42 @@
+class_name TileDef
+extends RefCounted
+## A single tile definition (palette entry) within a tile layer.
+##
+## Maps a tile ID to its asset reference and gameplay flags. See
+## docs/architecture/world.md §3.2.
+
+## Tile ID (index into the layer palette). 0 is reserved for empty/air.
+var id: int = 0
+
+## Reference to the tile/terrain asset.
+var asset_id: String = ""
+
+## Whether this tile has collision.
+var solid: bool = false
+
+## Bitmask flags: bit 0 = walkable, bit 1 = climbable, bit 2 = liquid.
+var flags: int = 0
+
+## Number of visual variants for this tile.
+var variants: int = 1
+
+
+func _init(p_id: int = 0, p_asset_id: String = "", p_solid: bool = false,
+		p_flags: int = 0, p_variants: int = 1) -> void:
+	id = p_id
+	asset_id = p_asset_id
+	solid = p_solid
+	flags = p_flags
+	variants = p_variants
+
+
+func is_walkable() -> bool:
+	return (flags & 0x01) != 0
+
+
+func is_climbable() -> bool:
+	return (flags & 0x02) != 0
+
+
+func is_liquid() -> bool:
+	return (flags & 0x04) != 0

scripts/tile_def.gd.uid

@@ -0,0 +1 @@
+uid://bavmpbmthilbx

scripts/tile_layer.gd

@@ -0,0 +1,83 @@
+class_name TileLayer
+extends RefCounted
+## A single tile layer within a chunk.
+##
+## Holds the dense grid of tile IDs, the palette mapping tile IDs to tile
+## definitions, and the layer metadata. This is the runtime representation of
+## the `TileLayer` from the chunk data format (see docs/architecture/world.md
+## §3.2).
+
+## Layer name (e.g. "ground", "walls", "decor").
+var name: String = ""
+
+## Numeric layer id, unique within the chunk.
+var layer_id: int = 0
+
+## Grid dimensions in tiles.
+var width: int = 0
+var height: int = 0
+var depth: int = 1
+
+## Palette mapping tile IDs to tile definitions (shared per layer).
+var palette: Array[TileDef] = []
+
+## Dense, row-major tile IDs. Length = width * height * depth.
+var tiles: PackedInt32Array = PackedInt32Array()
+
+
+func _init(
+	p_layer_name: String = "",
+	p_layer_id: int = 0,
+	p_width: int = 0,
+	p_height: int = 0,
+	p_depth: int = 1
+) -> void:
+	name = p_layer_name
+	layer_id = p_layer_id
+	width = p_width
+	height = p_height
+	depth = p_depth
+
+
+## Total number of tiles in this layer.
+func tile_count() -> int:
+	return width * height * depth
+
+
+## Get the tile ID at (x, y, z). Returns 0 (empty) for out-of-bounds.
+func get_tile(x: int, y: int, z: int = 0) -> int:
+	if x < 0 or x >= width or y < 0 or y >= height or z < 0 or z >= depth:
+		return 0
+	var idx := (z * height + y) * width + x
+	if idx < tiles.size():
+		return tiles[idx]
+	return 0
+
+
+## Set the tile ID at (x, y, z). No-op if out of bounds.
+func set_tile(x: int, y: int, z: int, tile_id: int) -> void:
+	if x < 0 or x >= width or y < 0 or y >= height or z < 0 or z >= depth:
+		return
+	var idx := (z * height + y) * width + x
+	if idx < tiles.size():
+		tiles[idx] = tile_id
+
+
+## Get the tile definition for a tile ID, or null if not in the palette.
+func get_tile_def(tile_id: int) -> TileDef:
+	for def in palette:
+		if def.id == tile_id:
+			return def
+	return null
+
+
+## Whether the tile at (x, y, z) is solid (collision).
+func is_solid(x: int, y: int, z: int = 0) -> bool:
+	var def := get_tile_def(get_tile(x, y, z))
+	return def != null and def.solid
+
+
+## Whether the tile at (x, y, z) is walkable.
+func is_walkable(x: int, y: int, z: int = 0) -> bool:
+	var def := get_tile_def(get_tile(x, y, z))
+	return def != null and def.is_walkable()

scripts/tile_layer.gd.uid

@@ -0,0 +1 @@
+uid://came2ygke3ajs

scripts/tile_layer_node.gd

@@ -0,0 +1,112 @@
+class_name TileLayerNode
+extends Node3D
+## A visual representation of a single tile layer within a chunk.
+##
+## This node is instantiated by [ChunkScene] for each tile layer in a chunk.
+## It renders the layer's tiles as instanced meshes (one per tile definition
+## in the palette) using [MultiMeshInstance3D] for efficiency.
+##
+## ## Structure
+##
+## ```
+## TileLayerNode (Node3D)
+##  └── MultiMeshInstance3D  # one per palette entry (tile definition)
+## ```
+
+## The tile layer data this node renders.
+var tile_layer: TileLayer = null
+
+## The chunk coordinate this layer belongs to (for world positioning).
+var chunk_coord: Vector3i = Vector3i.ZERO
+
+## Tile size in world units (each tile is 1x1x1).
+const TILE_SIZE: float = 1.0
+
+## Cache of MultiMeshInstance3D nodes, keyed by tile definition id.
+var _mesh_instances: Dictionary = {}
+
+
+func _ready() -> void:
+	if tile_layer == null:
+		return
+	_build_meshes()
+
+
+## Build the MultiMesh instances for each tile definition in the palette.
+func _build_meshes() -> void:
+	for tile_def in tile_layer.palette:
+		if tile_def.id == 0:
+			continue  # Tile 0 is "empty/air", no mesh needed
+		_create_mesh_for_tile(tile_def)
+
+
+func _create_mesh_for_tile(tile_def: TileDef) -> void:
+	# Count how many cells use this tile definition
+	var count := 0
+	for tile_id in tile_layer.tiles:
+		if tile_id == tile_def.id:
+			count += 1
+
+	if count == 0:
+		return
+
+	var multi_mesh := MultiMesh.new()
+	multi_mesh.transform_format = MultiMesh.TRANSFORM_3D
+	multi_mesh.mesh = _make_unit_cube_mesh()
+	multi_mesh.instance_count = count
+
+	var instance_idx := 0
+	for z in range(tile_layer.depth):
+		for y in range(tile_layer.height):
+			for x in range(tile_layer.width):
+				var tile_id := tile_layer.get_tile(x, y, z)
+				if tile_id != tile_def.id:
+					continue
+				var world_pos := _tile_to_world(x, y, z)
+				var xform := Transform3D(Basis(), world_pos)
+				multi_mesh.set_instance_transform(instance_idx, xform)
+				instance_idx += 1
+
+	var mesh_instance := MultiMeshInstance3D.new()
+	mesh_instance.multimesh = multi_mesh
+	mesh_instance.name = "tiles_%d" % tile_def.id
+	add_child(mesh_instance)
+	_mesh_instances[tile_def.id] = mesh_instance
+
+
+## Convert a tile grid coordinate to a world-space position (center of tile).
+func _tile_to_world(x: int, y: int, z: int) -> Vector3:
+	var origin := Vector3(
+		chunk_coord.x * tile_layer.width,
+		chunk_coord.y * tile_layer.height,
+		chunk_coord.z * tile_layer.depth
+	)
+	return origin + Vector3(
+		x * TILE_SIZE + TILE_SIZE * 0.5,
+		y * TILE_SIZE + TILE_SIZE * 0.5,
+		z * TILE_SIZE + TILE_SIZE * 0.5
+	)
+
+
+## Create a simple unit cube mesh for tile rendering.
+func _make_unit_cube_mesh() -> Mesh:
+	var mesh := BoxMesh.new()
+	mesh.size = Vector3(TILE_SIZE, TILE_SIZE, TILE_SIZE)
+	return mesh
+
+
+## Get the tile definition at a grid position, or null if empty.
+func get_tile_def_at(x: int, y: int, z: int = 0) -> TileDef:
+	if tile_layer == null:
+		return null
+	var tile_id := tile_layer.get_tile(x, y, z)
+	if tile_id == 0:
+		return null
+	return tile_layer.get_tile_def(tile_id)
+
+
+## Clear all rendered meshes.
+func clear() -> void:
+	for child in get_children():
+		child.queue_free()
+	_mesh_instances.clear()

scripts/tile_layer_node.gd.uid

@@ -0,0 +1 @@
+uid://d1x05tq8h43gm

scripts/world_list.gd

@@ -0,0 +1,135 @@
+extends Control
+## World list screen — browses public worlds via GET /api/worlds.
+##
+## Displays a scrollable list of world cards (name + description).
+## Handles loading, empty list, errors, and refresh.
+
+
+# UI references
+@onready var scroll_container: ScrollContainer = $VBoxContainer/ScrollContainer
+@onready var world_list: VBoxContainer = $VBoxContainer/ScrollContainer/WorldList
+@onready var loading_label: Label = $VBoxContainer/LoadingLabel
+@onready var error_label: Label = $VBoxContainer/ErrorLabel
+@onready var refresh_button: Button = $VBoxContainer/HeaderHBox/RefreshButton
+@onready var back_button: Button = $VBoxContainer/HeaderHBox/BackButton
+@onready var empty_label: Label = $VBoxContainer/EmptyLabel
+
+
+func _ready() -> void:
+	refresh_button.disabled = false
+	back_button.disabled = false
+	loading_label.visible = false
+	error_label.visible = false
+	empty_label.visible = false
+	world_list.visible = false
+	_refresh_worlds()
+
+
+func _on_refresh_button_pressed() -> void:
+	_refresh_worlds()
+
+
+func _on_back_button_pressed() -> void:
+	get_tree().change_scene_to_file("res://scenes/main_menu.tscn")
+
+
+## Fetch the world list from the backend and update the UI.
+func _refresh_worlds() -> void:
+	# Reset UI state
+	loading_label.visible = true
+	error_label.visible = false
+	empty_label.visible = false
+	world_list.visible = false
+	refresh_button.disabled = true
+
+	# Clear previous world cards
+	for child in world_list.get_children():
+		child.queue_free()
+
+	var result := await ApiClient.get_worlds()
+
+	loading_label.visible = false
+	refresh_button.disabled = false
+
+	if not result.ok:
+		# Show error message (401, network failure, etc.)
+		error_label.text = "Error: %s" % result.detail
+		error_label.visible = true
+		empty_label.visible = false
+		world_list.visible = false
+		return
+
+	var data = result.data
+	if not data is Array:
+		error_label.text = "Unexpected response format."
+		error_label.visible = true
+		empty_label.visible = false
+		world_list.visible = false
+		return
+
+	if data.is_empty():
+		empty_label.text = "No worlds yet. Check back later!"
+		empty_label.visible = true
+		error_label.visible = false
+		world_list.visible = false
+		return
+
+	# Render world cards
+	world_list.visible = true
+	empty_label.visible = false
+	error_label.visible = false
+
+	for world_dict in data:
+		if not world_dict is Dictionary:
+			continue
+		var card := _create_world_card(world_dict)
+		world_list.add_child(card)
+
+
+## Create a visual card for a single world entry.
+func _create_world_card(world_dict: Dictionary) -> Control:
+	var card := VBoxContainer.new()
+	card.size_flags_horizontal = Control.SIZE_FILL
+	card.custom_minimum_size = Vector2(0, 80)
+	card.add_theme_constant_override("separation", 4)
+
+	var name_label := Label.new()
+	name_label.text = world_dict.get("name", "Unnamed World")
+	name_label.autowrap_mode = TextServer.AUTOWRAP_WORD
+	name_label.size_flags_horizontal = Control.SIZE_FILL
+	name_label.size_flags_vertical = Control.SIZE_SHRINK_BEGIN
+	name_label.add_theme_font_size_override("font_size", 18)
+
+	var desc_label := Label.new()
+	var description: String = str(world_dict.get("description", ""))
+	desc_label.text = description if description != "" else "No description."
+	desc_label.autowrap_mode = TextServer.AUTOWRAP_WORD
+	desc_label.size_flags_horizontal = Control.SIZE_FILL
+	desc_label.size_flags_vertical = Control.SIZE_EXPAND_FILL
+	desc_label.add_theme_font_size_override("font_size", 14)
+	desc_label.add_theme_color_override("font_color", Color(0.7, 0.7, 0.7, 1.0))
+
+	var meta_label := Label.new()
+	var visibility: String = str(world_dict.get("visibility", "public"))
+	var created: String = str(world_dict.get("created_at", ""))
+	meta_label.text = "Visibility: %s%s" % [visibility, " | Created: " + created if created != "" else ""]
+	meta_label.autowrap_mode = TextServer.AUTOWRAP_WORD
+	meta_label.size_flags_horizontal = Control.SIZE_FILL
+	meta_label.size_flags_vertical = Control.SIZE_SHRINK_BEGIN
+	meta_label.add_theme_font_size_override("font_size", 12)
+	meta_label.add_theme_color_override("font_color", Color(0.5, 0.5, 0.5, 1.0))
+
+	card.add_child(name_label)
+	card.add_child(desc_label)
+	card.add_child(meta_label)
+
+	# Subtle background for the card
+	var bg := ColorRect.new()
+	bg.color = Color(0.15, 0.15, 0.15, 1.0)
+	bg.size_flags_horizontal = Control.SIZE_FILL
+	bg.size_flags_vertical = Control.SIZE_FILL
+	bg.custom_minimum_size = Vector2(0, 80)
+	card.add_child(bg)
+	card.move_child(bg, 0)
+
+	return card

scripts/world_object.gd

@@ -0,0 +1,135 @@
+class_name WorldObject
+extends RefCounted
+## A world object (static or dynamic) within a chunk.
+##
+## This is the runtime representation of a WorldObject from the chunk data
+## format (see docs/architecture/world.md §3.3). It holds the object's
+## identity, transform, properties, and moderation flags.
+
+## Stable object ID, unique within the chunk.
+var id: String = ""
+
+## Object type (e.g. "prop", "interactable", "spawn_point", "door").
+var type: String = ""
+
+## Reference to the object's mesh/glTF asset.
+var asset_id: String = ""
+
+## World-space position.
+var position: Vector3 = Vector3.ZERO
+
+## World-space rotation as a quaternion (x, y, z, w).
+var rotation: Vector4 = Vector4(0, 0, 0, 1)
+
+## World-space scale.
+var scale: Vector3 = Vector3.ONE
+
+## Type-specific key/value properties.
+var properties: Dictionary = {}
+
+## Whether this is a spawnable dynamic entity (true) or static (false).
+var is_dynamic: bool = false
+
+## Per-object content moderation flags.
+var flags: ChunkDataDecoder.ContentFlags = ChunkDataDecoder.ContentFlags.new()
+
+## Whether this object has been modified locally.
+var is_dirty: bool = false
+
+
+func _init(
+	p_id: String = "",
+	p_type: String = "",
+	p_asset_id: String = "",
+	p_position: Vector3 = Vector3.ZERO,
+	p_rotation: Vector4 = Vector4(0, 0, 0, 1),
+	p_scale: Vector3 = Vector3.ONE,
+	p_properties: Dictionary = {},
+	p_dynamic: bool = false,
+	p_flags: ChunkDataDecoder.ContentFlags = null
+) -> void:
+	id = p_id
+	type = p_type
+	asset_id = p_asset_id
+	position = p_position
+	rotation = p_rotation
+	scale = p_scale
+	properties = p_properties
+	is_dynamic = p_dynamic
+	if p_flags != null:
+		flags = p_flags
+
+
+## Get a property value by key.
+func get_property(key: String) -> Variant:
+	return properties.get(key)
+
+
+## Set a property value.
+func set_property(key: String, value: Variant) -> void:
+	properties[key] = value
+	is_dirty = true
+
+
+## Check if this object is walkable (based on properties).
+func is_walkable() -> bool:
+	return properties.get("walkable", true)
+
+
+## Check if this object is climbable (based on properties).
+func is_climbable() -> bool:
+	return properties.get("climbable", false)
+
+
+## Check if this object is interactable.
+func is_interactable() -> bool:
+	return type == "interactable" or properties.get("interactable", false)
+
+
+## Get the object's display name.
+func get_display_name() -> String:
+	return properties.get("display_name", id)
+
+
+## Serialize this object to a dictionary (for networking).
+func to_dict() -> Dictionary:
+	return {
+		"id": id,
+		"type": type,
+		"asset_id": asset_id,
+		"position": [position.x, position.y, position.z],
+		"rotation": [rotation.x, rotation.y, rotation.z, rotation.w],
+		"scale": [scale.x, scale.y, scale.z],
+		"properties": properties,
+		"dynamic": is_dynamic,
+	}
+
+
+## Create a WorldObject from a dictionary (for networking).
+static func from_dict(d: Dictionary) -> WorldObject:
+	var pos := Vector3(
+		d.get("position", [0, 0, 0])[0],
+		d.get("position", [0, 0, 0])[1],
+		d.get("position", [0, 0, 0])[2]
+	)
+	var rot := Vector4(
+		d.get("rotation", [0, 0, 0, 1])[0],
+		d.get("rotation", [0, 0, 0, 1])[1],
+		d.get("rotation", [0, 0, 0, 1])[2],
+		d.get("rotation", [0, 0, 0, 1])[3]
+	)
+	var scl := Vector3(
+		d.get("scale", [1, 1, 1])[0],
+		d.get("scale", [1, 1, 1])[1],
+		d.get("scale", [1, 1, 1])[2]
+	)
+	return WorldObject.new(
+		d.get("id", ""),
+		d.get("type", ""),
+		d.get("asset_id", ""),
+		pos,
+		rot,
+		scl,
+		d.get("properties", {}),
+		d.get("dynamic", false),
+	)

scripts/world_object.gd.uid

@@ -0,0 +1 @@
+uid://cxut2ghbsvobn