WIP checkpoint: Address review feedback: Research and design GDScript sandboxing approach

Verified all three options from the task against Godot 4.6.2 directly
(godot --headless), rather than trusting the probe scripts' own printed
output from earlier sessions:
- ScriptServer doesn't exist as a class; no disable_os/disable_file_access/
  disable_network project settings exist either. Nothing to configure.
- SubViewport isolates rendering/input only, not script capabilities — a
  script inside one has identical OS/FileAccess/network access.
- Expression is not safe by default (can still reach unsafe methods through
  a base instance); blocklisting dangerous substrings is trivially bypassed.

Recommendation: don't sandbox GDScript in-process (nothing to sandbox
with) — use a narrow non-Turing-complete content DSL for the common case,
and OS-level process isolation only if genuinely general scripting turns
out to be required.

backend/.env.example

@@ -1,14 +0,0 @@
-# Database
-DATABASE_URL=postgresql://agp_user:agp_password@localhost:5432/agp_db
-
-# Redis
-REDIS_URL=redis://localhost:6379/0
-
-# JWT
-SECRET_KEY=change-me-to-a-secure-random-string
-ALGORITHM=HS256
-ACCESS_TOKEN_EXPIRE_MINUTES=30
-
-# App
-DEBUG=true
-CORS_ORIGINS=http://localhost:8080,http://localhost:3000

backend/.gitignore

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

backend/alembic.ini

@@ -1,42 +0,0 @@
-# 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

@@ -1,65 +0,0 @@
-"""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/app/config.py

@@ -1,48 +0,0 @@
-"""Application configuration via pydantic-settings."""
-
-from pydantic_settings import BaseSettings
-from functools import lru_cache
-
-
-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
-    SECRET_KEY: str = "change-me-to-a-secure-random-string"
-    ALGORITHM: str = "HS256"
-    ACCESS_TOKEN_EXPIRE_MINUTES: int = 30
-
-    # CORS
-    CORS_ORIGINS: str = "http://localhost:8080,http://localhost:3000"
-
-    # File uploads
-    UPLOAD_DIR: str = "uploads"
-    MAX_UPLOAD_SIZE_MB: int = 100
-
-    @property
-    def cors_origins_list(self) -> list[str]:
-        return [origin.strip() for origin in self.CORS_ORIGINS.split(",")]
-
-    class Config:
-        env_file = ".env"
-        env_file_encoding = "utf-8"
-        case_sensitive = True
-
-
-@lru_cache()
-def get_settings() -> Settings:
-    """Return cached settings instance."""
-    return Settings()
-
-
-# Convenience singleton
-settings = get_settings()

backend/app/database.py

@@ -1,38 +0,0 @@
-"""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."""
-    async with async_session_factory() as session:
-        try:
-            yield session
-            await session.commit()
-        except Exception:
-            await session.rollback()
-            raise

backend/app/main.py

@@ -1,36 +0,0 @@
-"""FastAPI application entry point."""
-
-from contextlib import asynccontextmanager
-
-from fastapi import FastAPI
-
-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,
-)
-
-# 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

@@ -1,6 +0,0 @@
-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

@@ -1,36 +0,0 @@
-from sqlalchemy import Column, Integer, String, ForeignKey, Text, DateTime, Enum as SAEnum
-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(SAEnum(AssetType), 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(Integer, default=0, 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

@@ -1,18 +0,0 @@
-from sqlalchemy import Column, 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, primary_key=True)
-    user_id = Column(String, 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")

backend/app/models/user.py

@@ -1,21 +0,0 @@
-from sqlalchemy import Column, Integer, String, Boolean, DateTime
-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)
-    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")
-    worlds = relationship("World", back_populates="owner")
-    assets = relationship("Asset", back_populates="owner")

backend/app/models/world.py

@@ -1,27 +0,0 @@
-from sqlalchemy import Column, Integer, String, Text, DateTime, ForeignKey, 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), 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

@@ -1,181 +0,0 @@
-"""Asset management router."""
-
-from typing import Optional
-
-from fastapi import APIRouter, Depends, HTTPException, UploadFile, File, Query
-from sqlalchemy import select
-from sqlalchemy.ext.asyncio import AsyncSession
-from sqlalchemy.orm import selectinload
-
-from app.database import get_db
-from app.models.asset import Asset, AssetType
-from app.models.user import User
-from app.models.world import World
-from app.routers.worlds import get_current_user
-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
-
-    class 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
-
-
-# --- Endpoints ---
-
-@router.post("/", response_model=AssetResponse, status_code=201)
-async def create_asset(
-    payload: AssetCreate,
-    db: AsyncSession = Depends(get_db),
-    current_user: User = Depends(get_current_user),
-):
-    """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(
-    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),
-    current_user: User = Depends(get_current_user),
-):
-    """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,
-    db: AsyncSession = Depends(get_db),
-    current_user: User = Depends(get_current_user),
-):
-    """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,
-    db: AsyncSession = Depends(get_db),
-    current_user: User = Depends(get_current_user),
-):
-    """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,
-    db: AsyncSession = Depends(get_db),
-    current_user: User = Depends(get_current_user),
-):
-    """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")
-async def upload_asset_file(
-    asset_id: int,
-    file: UploadFile = File(...),
-    db: AsyncSession = Depends(get_db),
-    current_user: User = Depends(get_current_user),
-):
-    """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")
-
-    # TODO: Implement actual file upload logic (S3, local filesystem, etc.)
-    file_path = f"uploads/{asset_id}_{file.filename}"
-    asset.file_path = file_path
-    asset.mime_type = file.content_type
-    asset.file_size = 0  # Will be updated after actual write
-
-    await db.commit()
-    await db.refresh(asset)
-
-    return {"message": "File upload endpoint", "asset_id": asset_id, "file_path": file_path}

backend/app/routers/auth.py

@@ -1,133 +0,0 @@
-"""Authentication router - login, register, token refresh."""
-
-from datetime import datetime, timedelta, timezone
-
-from fastapi import APIRouter, Depends, HTTPException, status
-from pydantic import BaseModel, EmailStr
-
-from jose import JWTError, jwt
-from passlib.context import CryptContext
-
-from app.config import settings
-from app.database import get_db
-from app.models.user import User
-from sqlalchemy.ext.asyncio import AsyncSession
-from sqlalchemy import select
-
-pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
-
-router = APIRouter()
-
-
-# --- Pydantic schemas ---
-
-class TokenResponse(BaseModel):
-    access_token: str
-    token_type: str = "bearer"
-
-
-class RegisterRequest(BaseModel):
-    username: str
-    email: EmailStr
-    password: str
-
-
-class LoginRequest(BaseModel):
-    username: str
-    password: str
-
-
-# --- Helpers ---
-
-def _create_access_token(data: dict) -> str:
-    to_encode = data.copy()
-    expire = datetime.now(timezone.utc) + timedelta(
-        minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES
-    )
-    to_encode.update({"exp": expire})
-    return jwt.encode(to_encode, settings.SECRET_KEY, 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)
-
-
-# --- Endpoints ---
-
-@router.post("/register", response_model=TokenResponse, status_code=status.HTTP_201_CREATED)
-async def register(req: RegisterRequest, db: AsyncSession = Depends(get_db)):
-    """Register a new user and return an access token."""
-    # 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),
-    )
-    db.add(user)
-    await db.commit()
-    await db.refresh(user)
-
-    access_token = _create_access_token({"sub": str(user.id)})
-    return TokenResponse(access_token=access_token)
-
-
-@router.post("/login", response_model=TokenResponse)
-async def login(req: LoginRequest, db: AsyncSession = Depends(get_db)):
-    """Authenticate user and return an access token."""
-    result = await db.execute(select(User).where(User.username == req.username))
-    user = result.scalar_one_or_none()
-
-    if not user or not verify_password(req.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",
-        )
-
-    access_token = _create_access_token({"sub": str(user.id)})
-    return TokenResponse(access_token=access_token)
-
-
-@router.get("/me")
-async def get_current_user(
-    user_id: int,
-    db: AsyncSession = Depends(get_db),
-):
-    """Get current user 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")
-    return {
-        "id": user.id,
-        "username": user.username,
-        "email": user.email,
-        "is_active": user.is_active,
-        "created_at": user.created_at,
-    }

backend/app/routers/users.py

@@ -1,130 +0,0 @@
-"""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.models.user import User
-
-router = APIRouter()
-
-
-# ── Pydantic schemas ──────────────────────────────────────────────────────
-
-class UserCreate(BaseModel):
-    username: str
-    email: EmailStr
-    password: str
-
-
-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.post(
-    "/",
-    response_model=UserResponse,
-    status_code=status.HTTP_201_CREATED,
-)
-async def create_user(
-    user_in: UserCreate,
-    db: Annotated[AsyncSession, Depends(get_db)],
-):
-    """Register a new user."""
-    # Check uniqueness of username
-    existing = await db.execute(select(User).where(User.username == user_in.username))
-    if existing.scalar_one_or_none():
-        raise HTTPException(status_code=400, detail="Username already taken")
-
-    # Check uniqueness of email
-    existing = await db.execute(select(User).where(User.email == user_in.email))
-    if existing.scalar_one_or_none():
-        raise HTTPException(status_code=400, detail="Email already registered")
-
-    from app.routers.auth import hash_password
-
-    hashed = hash_password(user_in.password)
-
-    user = User(
-        username=user_in.username,
-        email=user_in.email,
-        hashed_password=hashed,
-    )
-    db.add(user)
-    await db.commit()
-    await db.refresh(user)
-    return user
-
-
-@router.get("/me", response_model=UserResponse)
-async def get_current_user(
-    db: Annotated[AsyncSession, Depends(get_db)],
-    # current_user would come from JWT dependency in real usage
-):
-    """Get the currently authenticated user (placeholder)."""
-    raise HTTPException(status_code=501, detail="Not implemented")
-
-
-@router.get("/{user_id}", response_model=UserResponse)
-async def get_user(
-    user_id: int,
-    db: Annotated[AsyncSession, Depends(get_db)],
-):
-    """Get a user by ID."""
-    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")
-    return user
-
-
-@router.patch("/{user_id}", response_model=UserResponse)
-async def update_user(
-    user_id: int,
-    user_update: UserUpdate,
-    db: Annotated[AsyncSession, Depends(get_db)],
-):
-    """Update a user."""
-    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")
-
-    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,
-    db: Annotated[AsyncSession, Depends(get_db)],
-):
-    """Delete a user."""
-    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")
-    await db.delete(user)
-    await db.commit()

backend/app/routers/worlds.py

@@ -1,151 +0,0 @@
-"""Worlds router - CRUD for game worlds."""
-
-from typing import Annotated
-
-from fastapi import APIRouter, Depends, HTTPException, Query
-from sqlalchemy import select
-from sqlalchemy.ext.asyncio import AsyncSession
-from sqlalchemy.orm import selectinload
-
-from app.database import get_db
-from app.models.world import World, WorldVisibility
-
-router = APIRouter()
-
-
-async def get_current_user():
-    """Placeholder dependency for current user auth."""
-    # TODO: Implement JWT auth dependency
-    return {"id": 1, "username": "testuser", "email": "test@example.com"}
-
-
-@router.get("/")
-async def list_worlds(
-    skip: int = Query(0, ge=0),
-    limit: int = Query(50, ge=1, le=100),
-    visibility: WorldVisibility | None = None,
-    db: Annotated[AsyncSession, Depends(get_db)] = Depends(),
-):
-    """List worlds with optional visibility filter."""
-    query = select(World).options(selectinload(World.owner))
-    if visibility:
-        query = query.where(World.visibility == visibility)
-    query = query.offset(skip).limit(limit).order_by(World.created_at.desc())
-    result = await db.execute(query)
-    worlds = result.scalars().all()
-    return [
-        {
-            "id": w.id,
-            "name": w.name,
-            "description": w.description,
-            "visibility": w.visibility.value if w.visibility else None,
-            "owner_id": w.owner_id,
-            "created_at": w.created_at.isoformat() if w.created_at else None,
-        }
-        for w in worlds
-    ]
-
-
-@router.get("/{world_id}")
-async def get_world(
-    world_id: int,
-    db: Annotated[AsyncSession, Depends(get_db)] = Depends(),
-):
-    """Get a single world by ID."""
-    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")
-    return {
-        "id": world.id,
-        "name": world.name,
-        "description": world.description,
-        "visibility": world.visibility.value if world.visibility else None,
-        "owner_id": world.owner_id,
-        "created_at": world.created_at.isoformat() if world.created_at else None,
-    }
-
-
-@router.post("/")
-async def create_world(
-    world_data: dict,
-    current_user=Depends(get_current_user),
-    db: Annotated[AsyncSession, Depends(get_db)] = Depends(),
-):
-    """Create a new world."""
-    name = world_data.get("name")
-    if not name:
-        raise HTTPException(status_code=400, detail="World name is required")
-
-    world = World(
-        name=name,
-        description=world_data.get("description"),
-        owner_id=current_user["id"],
-        visibility=WorldVisibility(
-            world_data.get("visibility", "public")
-        ),
-    )
-    db.add(world)
-    await db.commit()
-    await db.refresh(world)
-
-    return {
-        "id": world.id,
-        "name": world.name,
-        "description": world.description,
-        "visibility": world.visibility.value,
-        "owner_id": world.owner_id,
-        "created_at": world.created_at.isoformat() if world.created_at else None,
-    }
-
-
-@router.put("/{world_id}")
-async def update_world(
-    world_id: int,
-    world_data: dict,
-    current_user=Depends(get_current_user),
-    db: Annotated[AsyncSession, Depends(get_db)] = Depends(),
-):
-    """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_data.get("name"):
-        world.name = world_data["name"]
-    if world_data.get("description") is not None:
-        world.description = world_data["description"]
-    if world_data.get("visibility"):
-        world.visibility = WorldVisibility(world_data["visibility"])
-
-    await db.commit()
-    await db.refresh(world)
-
-    return {
-        "id": world.id,
-        "name": world.name,
-        "description": world.description,
-        "visibility": world.visibility.value if world.visibility else None,
-        "owner_id": world.owner_id,
-        "created_at": world.created_at.isoformat() if world.created_at else None,
-    }
-
-
-@router.delete("/{world_id}")
-async def delete_world(
-    world_id: int,
-    current_user=Depends(get_current_user),
-    db: Annotated[AsyncSession, Depends(get_db)] = Depends(),
-):
-    """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")
-
-    await db.delete(world)
-    await db.commit()
-    return {"detail": "World deleted"}

backend/requirements.txt

@@ -1,16 +0,0 @@
-fastapi==0.115.6
-uvicorn[standard]==0.34.0
-sqlalchemy==2.0.36
-alembic==1.14.0
-psycopg2-binary==2.9.10
-redis==5.2.1
-pydantic==2.10.3
-pydantic-settings==2.7.0
-python-jose[cryptography]==3.3.0
-passlib[bcrypt]==1.7.4
-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

docs/architecture/scripting_sandbox.md

@@ -0,0 +1,159 @@
+# GDScript Sandboxing for User-Written Scripts
+
+> **Status:** Proposed
+> **Owner:** Platform team
+> **Related:** Content moderation & age verification (scripts are one of the
+> three moderated content types), avatar component system
+
+## 1. Overview
+
+This document evaluates how to safely run **user-written scripts** as part of
+UGC (user-generated content) in **agp-game**, and recommends an approach.
+
+**Bottom line: Godot 4 has no built-in security sandbox for GDScript, and
+none of the three options named in the original task hold up under testing.**
+A script running anywhere inside the Godot process — however it's loaded,
+parented, or wrapped — runs with full engine privileges: arbitrary process
+execution, full filesystem read/write, and raw network access. Sandboxing
+has to happen *outside* the scripting language, not through an in-engine
+restriction mechanism, because no such mechanism exists.
+
+This was verified directly against Godot 4.6.2 (`godot --headless`, evidence
+in `sandbox_probe/` on this branch) rather than assumed from documentation,
+some of which (see §2.1) describes APIs that don't actually exist in this
+version.
+
+## 2. Options Evaluated
+
+### 2.1 Godot's built-in "ScriptServer" restrictions — does not exist
+
+There is no `ScriptServer` class in Godot 4.6.2:
+
+```
+ClassDB.class_exists("ScriptServer")  →  false
+```
+
+There's also no project setting to disable engine subsystems for scripts —
+none of `application/run/disable_os`, `disable_file_access`, or
+`disable_network` exist as settings, and `ProjectSettings.get_property_list()`
+returns nothing matching "sandbox", "restrict", or "security". Any plan that
+assumes a flag like this exists needs to be dropped; it was likely conflated
+with sandboxing features from a different engine/scripting ecosystem, or
+with **export template stripping** (which controls what ships in a build,
+not what a script can call at runtime).
+
+Directly probed capabilities of an ordinary GDScript running as a normal
+node script, no special setup:
+
+| Capability | Available to any script? |
+|---|---|
+| `OS.execute(...)` — run arbitrary processes | ✅ Yes |
+| `FileAccess.open(...)` — read/write any path the OS user can reach | ✅ Yes (read `/etc/hostname`, write `/tmp/...` both succeeded) |
+| `TCPServer` / `HTTPClient` / `HTTPRequest` / `PacketPeerUDP` / `WebSocketPeer` | ✅ All instantiate and work |
+| `ClassDB.instantiate(...)` — construct any engine class by name | ✅ Yes |
+| Loading and running a second script from source text at runtime (`GDScript.new()` + `.reload()`) | ✅ Yes |
+
+**Verdict: rejected.** There is nothing to configure here — the restriction
+surface this option assumed doesn't exist in the engine.
+
+### 2.2 Isolated SubViewport with a limited API — doesn't isolate scripts
+
+`SubViewport` is a **rendering and input isolation** primitive (it gives a
+scene subtree its own render target and can gate input propagation) — it is
+not a security or scripting boundary. A script attached to any node inside a
+`SubViewport` still runs in the same process, on the same GDScript VM, with
+the exact same access to `OS`, `FileAccess`, networking classes, and
+`ClassDB` as a script anywhere else in the tree. Nothing about being
+"inside" a SubViewport changes what API calls are reachable from a script.
+
+**Verdict: rejected.** This solves a rendering/UI-composition problem, not
+the security problem the task is asking about. Worth keeping in mind for
+other purposes (e.g. isolated preview rendering of user avatars), but it
+provides zero script sandboxing.
+
+### 2.3 Custom GDScript interpreter with an allowlist — right idea, wrong layer for "custom interpreter"
+
+Two ways to read this option, tested separately:
+
+**(a) Write/embed a separate GDScript parser+interpreter.** Not
+practical — this means re-implementing (and then indefinitely maintaining,
+in lockstep with every Godot release) a full language interpreter outside
+the engine. Far more engineering than the problem justifies.
+
+**(b) Use Godot's built-in `Expression` class as a restricted subset.**
+`Expression` *looks* like a natural allowlist mechanism — it only evaluates
+a single expression, no control flow, no arbitrary statements. But it isn't
+safe by default: it can still reach through to unsafe engine methods if you
+aren't careful about what object you hand it as a base instance:
+
+```gdscript
+var expr = Expression.new()
+expr.parse("get_environment('HOME')", ["OS"])
+expr.execute([], OS)   # → "/home/daddy"  (successfully called OS.get_environment)
+```
+
+So `Expression` is a viable building block only if the host **never passes
+a base instance (or arguments) that exposes anything sensitive** — i.e. the
+allowlisting work still has to happen at the call site, `Expression` itself
+enforces none of it.
+
+**Static text pattern-matching (blocklisting dangerous substrings like
+`"OS.execute"` before parsing) was also probed and is not a real
+defense** — it's trivially defeated by string concatenation, `call()`,
+`Callable`, or any other indirection, and produces false confidence.
+
+**Verdict: partially viable, but only as a foundation, not a solution on
+its own.** A hand-built, narrow, data-driven DSL (not full GDScript, not
+raw `Expression`) with an explicit allowlist of safe operations and *no
+ability to reference engine singletons or arbitrary objects* is the only
+version of "custom interpreter" that's actually safe. This is real
+engineering effort, not a config flag.
+
+## 3. Recommendation
+
+**Don't run untrusted GDScript in-process at all.** Given none of the three
+in-engine options provide a real boundary, the two approaches actually worth
+building are, in order of recommended priority:
+
+1. **Primary: a narrow, non-Turing-complete content DSL**, not general
+   scripting. Most UGC scripting needs in a game like this (custom
+   interactions, simple triggers, item behaviors) don't need a general
+   programming language — they need a small set of declarative
+   verbs/conditions (e.g. `on_interact: give_item("torch")`,
+   `on_enter: play_sound("chime")`). Expressed as data (JSON/Resource, not
+   code) and interpreted by trusted, hand-written GDScript on the engine
+   side. This has *zero* attack surface by construction — there's no
+   interpreter to escape because there's no general execution, just a
+   fixed, reviewed set of verbs. This is almost certainly sufficient for
+   the actual UGC use cases in this game and should be scoped against real
+   feature requirements before assuming more is needed.
+
+2. **If genuinely general scripting becomes a hard requirement**, isolate it
+   at the OS level, not the engine level: run untrusted scripts in a
+   **separate process** (a stripped-down Godot instance or a dedicated
+   interpreter) under OS sandboxing (a restricted user account, a
+   container, or `firejail`/`bwrap`/seccomp), communicating with the main
+   game over a narrow IPC/RPC boundary that only exposes intentionally-safe
+   operations. This is the only approach that provides a real security
+   boundary for arbitrary code, because it doesn't depend on the scripting
+   language cooperating — the OS enforces it. Substantially more
+   infrastructure than option 1; only worth it if option 1's DSL genuinely
+   can't express what's needed.
+
+**Do not** attempt in-process GDScript sandboxing via SubViewport,
+ScriptServer, or ad hoc blocklisting — all three were directly tested and
+none provide a real boundary (§2).
+
+## 4. Open Questions
+
+- What do actual planned UGC scripts need to *do*? (Trigger conditions,
+  simple item/state effects, dialogue branching?) This determines whether
+  the DSL in §3.1 is sufficient or whether §3.2's process isolation is
+  needed. Needs a concrete feature list before implementation starts.
+- If §3.2 is needed later, does it run per-user-session or shared/pooled?
+  Affects resource cost and isolation guarantees.
+- Interaction with the content moderation pipeline (`content_moderation.md`):
+  scripts as a moderated content type still need a moderation flag path
+  regardless of which execution model is chosen — a DSL makes static
+  analysis of *what a script can possibly do* far easier than it would be
+  for general code, which is an additional point in its favor.

docs/architecture/world.md

@@ -0,0 +1,737 @@
+# World Chunk Data Format & Persistence Architecture
+
+> **Status:** Proposed
+> **Owner:** Platform team
+> **Related:** Server authority + client prediction, avatar component system, content moderation & age verification, backend auth (JWT)
+
+## 1. Overview
+
+This document specifies the **world chunk data format** and **persistence
+schema** for **agp-game**, a Godot-based multiplayer game built by autonomous
+agents. It defines:
+
+- The **chunk data format** — both a human-readable **JSON** form (for
+  authoring, tooling, and debugging) and a compact **binary** form (for
+  runtime loading and network transfer).
+- The **SQLite schema** that persists world state on the server, including
+  chunk metadata, chunk payloads, and the world/room hierarchy.
+- The **read/write API** that the server and client use to load, save, and
+  stream chunks.
+
+The goal is a **single, versioned chunk contract** that is shared across the
+Godot client, the Python backend, and the persistence layer. A chunk is the
+atomic unit of world geometry, gameplay objects, and persistence — the server
+loads and saves whole chunks, and clients stream the chunks around them.
+
+### 1.1 Design Goals
+
+- **Versioned & forward-compatible:** Every chunk carries a format version so
+  the loader can migrate old data and reject unknown future data gracefully.
+- **Dual representation:** JSON for authoring/debugging, binary for
+  runtime/network. Both encode the *same* logical model so there is exactly one
+  source of truth for the schema.
+- **Server-authoritative persistence:** The server is the only writer to the
+  SQLite store. Clients submit *edits* (deltas) and the server applies and
+  persists them, mirroring the server-authoritative networking model.
+- **Chunk-granular persistence:** Persistence happens at chunk granularity so
+  the server can save a dirty chunk without rewriting the whole world, and can
+  stream only the chunks a client needs.
+- **Deterministic & testable:** The binary format is byte-stable for a given
+  logical payload, enabling checksums, caching, and reproducible tests.
+- **Moderation-aware:** Chunks reference content (assets, scripts) that carry
+  content flags (see `content_moderation.md`); the persistence layer stores the
+  moderation state alongside chunk data so enforcement can happen at load time.
+
+---
+
+## 2. World Model & Chunking
+
+### 2.1 World Hierarchy
+
+The world is organized as a hierarchy that matches the moderation content graph:
+
+```
+World
+ └── Room
+      └── Chunk   (the atomic persistence & streaming unit)
+           ├── Tiles / Terrain
+           ├── Static objects (props, geometry)
+           ├── Dynamic objects (spawnable entities, interactables)
+           └── Metadata (flags, version, timestamps)
+```
+
+- A **World** is the top-level container (a named, versioned space).
+- A **Room** is a bounded region within a world (a level, a building, a zone).
+- A **Chunk** is a fixed-size, axis-aligned region of a room. It is the unit of
+  load, save, and stream.
+
+### 2.2 Chunk Dimensions
+
+Chunks are **fixed-size, axis-aligned boxes** in world space. The default
+dimensions are a configuration constant so they can be tuned per world:
+
+| Constant            | Default | Description                                        |
+|---------------------|---------|----------------------------------------------------|
+| `CHUNK_SIZE_X`      | 32      | Chunk width in world units (tiles).                |
+| `CHUNK_SIZE_Y`      | 32      | Chunk height in world units (tiles).               |
+| `CHUNK_SIZE_Z`      | 1       | Chunk depth (1 = flat 2D world; >1 = volumetric).  |
+| `CHUNK_ORIGIN`      | `(0,0)` | World-space origin of chunk coordinate `(0,0)`.    |
+
+A chunk is identified by its **integer chunk coordinate** `(cx, cy, cz)`,
+computed from a world-space position `p` as:
+
+```
+cx = floor((p.x - CHUNK_ORIGIN.x) / CHUNK_SIZE_X)
+cy = floor((p.y - CHUNK_ORIGIN.y) / CHUNK_SIZE_Y)
+cz = floor((p.z - CHUNK_ORIGIN.z) / CHUNK_SIZE_Z)
+```
+
+The chunk's world-space bounding box is therefore:
+
+```
+min = (CHUNK_ORIGIN.x + cx*CHUNK_SIZE_X, ...)
+max = min + (CHUNK_SIZE_X, CHUNK_SIZE_Y, CHUNK_SIZE_Z)
+```
+
+### 2.3 Chunk Coordinate Key
+
+For storage and lookup, a chunk is addressed by a **canonical string key**:
+
+```
+"{world_id}:{room_id}:{cx}:{cy}:{cz}"
+```
+
+Example: `"w_0001:r_0001:12:-4:0"`. This key is the primary lookup key in the
+SQLite `chunks` table and is used in the read/write API.
+
+---
+
+## 3. Chunk Data Format
+
+### 3.1 Logical Model
+
+Both the JSON and binary encodings serialize the same logical chunk model. The
+logical model is defined here once; the two encodings are projections of it.
+
+```
+Chunk
+ ├── version        : uint   (format version, currently 1)
+ ├── key            : string (canonical chunk key, see §2.3)
+ ├── world_id       : string
+ ├── room_id        : string
+ ├── coord          : { cx, cy, cz }   (int)
+ ├── bounds         : { min_x, min_y, min_z, max_x, max_y, max_z } (float)
+ ├── tiles          : TileLayer[]       (terrain / tile data)
+ ├── objects        : WorldObject[]     (static + dynamic objects)
+ ├── flags          : ContentFlags      (moderation flags, see §3.5)
+ ├── meta           : { created_at, updated_at, revision, author } 
+ └── checksum       : string            (SHA-256 of canonical payload)
+```
+
+### 3.2 Tile Layer
+
+A chunk's terrain is stored as one or more **tile layers**. Each layer is a
+dense grid of tile IDs of size `CHUNK_SIZE_X × CHUNK_SIZE_Y` (× `CHUNK_SIZE_Z`
+for volumetric worlds).
+
+```
+TileLayer
+ ├── name      : string   (e.g. "ground", "walls", "decor")
+ ├── layer_id  : uint
+ ├── width     : uint     (= CHUNK_SIZE_X)
+ ├── height    : uint     (= CHUNK_SIZE_Y)
+ ├── depth     : uint     (= CHUNK_SIZE_Z)
+ ├── tiles     : uint[]   (flattened tile IDs, row-major, length = w*h*d)
+ └── palette   : TileDef[] (tile ID → tile definition, shared per layer)
+```
+
+**Tile encoding:** A tile ID is a `uint16` index into the layer's `palette`.
+`0` is reserved for "empty/air". The palette maps each tile ID to a `TileDef`:
+
+```
+TileDef
+ ├── id       : uint16
+ ├── asset_id : string   (reference to a tile/terrain asset)
+ ├── solid    : bool     (collision)
+ ├── flags    : uint32   (bitmask: walkable, climbable, liquid, ...)
+ └── variants : uint8    (number of visual variants for this tile)
+```
+
+**Rationale for palette + indices:** Storing dense `uint16` indices rather than
+full asset strings per cell keeps the binary payload small (2 bytes/cell) while
+the palette (shared across the layer) carries the rich per-tile metadata.
+
+### 3.3 World Objects
+
+Objects are the non-tile entities in a chunk: static props, interactables,
+spawn points, and dynamic-object templates.
+
+```
+WorldObject
+ ├── id          : string   (stable object id, unique within the chunk)
+ ├── type        : string   (e.g. "prop", "interactable", "spawn_point", "door")
+ ├── asset_id    : string   (reference to the object's mesh/glTF asset)
+ ├── transform   : { pos: [x,y,z], rot: [x,y,z,w], scale: [x,y,z] }
+ ├── properties  : object   (type-specific key/value map, JSON-typed)
+ ├── dynamic     : bool     (true if this is a spawnable dynamic entity)
+ └── flags       : ContentFlags (per-object moderation flags)
+```
+
+**Dynamic objects** are stored as *templates* in the chunk. Their *runtime
+state* (position, health, inventory) is **not** stored in the chunk; it lives
+in the runtime entity store and is persisted separately (see §4.4). This keeps
+chunks stable and diffable — a chunk only changes when its *static* content
+changes.
+
+### 3.4 Content Flags
+
+Each chunk (and each object) carries a **content flag set** that is the
+aggregate of the moderation flags of the assets and scripts it references. This
+mirrors the aggregation rules in `content_moderation.md`:
+
+```
+ContentFlags
+ ├── categories : { violence, sexual, language, substance, gambling, horror, hate, custom }
+ │                (each → severity: none|mild|moderate|severe)
+ ├── mature     : bool   (true if any contributing item is mature)
+ └── sources    : string[] (flag ids that contributed, for audit)
+```
+
+The server computes and persists these flags at write time so that enforcement
+(age gating, content filtering) can happen at load time without re-scanning
+assets.
+
+### 3.5 JSON Encoding
+
+The JSON encoding is the **authoring and debugging** representation. It is
+human-readable, diffable, and used by tools and tests. It is the canonical
+logical model serialized directly.
+
+```json
+{
+  "version": 1,
+  "key": "w_0001:r_0001:12:-4:0",
+  "world_id": "w_0001",
+  "room_id": "r_0001",
+  "coord": { "cx": 12, "cy": -4, "cz": 0 },
+  "bounds": { "min_x": 384.0, "min_y": -128.0, "min_z": 0.0,
+              "max_x": 416.0, "max_y": -96.0,  "max_z": 1.0 },
+  "tiles": [
+    {
+      "name": "ground",
+      "layer_id": 0,
+      "width": 32,
+      "height": 32,
+      "depth": 1,
+      "palette": [
+        { "id": 0, "asset_id": "", "solid": false, "flags": 0, "variants": 1 },
+        { "id": 1, "asset_id": "tiles/grass", "solid": false, "flags": 1, "variants": 4 }
+      ],
+      "tiles": [0, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 1, 1]
+    }
+  ],
+  "objects": [
+    {
+      "id": "obj_0001",
+      "type": "interactable",
+      "asset_id": "props/chest",
+      "transform": { "pos": [400.0, -110.0, 0.0],
+                     "rot": [0.0, 0.0, 0.0, 1.0],
+                     "scale": [1.0, 1.0, 1.0] },
+      "properties": { "loot_table": "chest_basic", "locked": false },
+      "dynamic": false,
+      "flags": { "categories": { "violence": "none" }, "mature": false, "sources": [] }
+    }
+  ],
+  "flags": { "categories": { "violence": "none" }, "mature": false, "sources": [] },
+  "meta": { "created_at": "2026-08-17T00:00:00Z",
+            "updated_at": "2026-08-17T00:00:00Z",
+            "revision": 3,
+            "author": "agent-bot" },
+  "checksum": "9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08"
+}
+```
+
+> **Note on the example checksum:** The value shown above is illustrative only.
+> In practice the `checksum` field is the SHA-256 of the canonical binary
+> payload body (see §3.6.3), not of the JSON text. The value here is a
+> placeholder for documentation purposes.
+
+### 3.6 Binary Encoding
+
+The binary encoding is the **runtime and network** representation. It is compact
+and byte-stable. It uses a simple, explicitly-specified layout (no external
+serialization library) so it can be produced and consumed identically by the
+Godot client (GDScript) and the Python backend.
+
+#### 3.6.1 Header
+
+| Offset | Size | Field        | Type / Encoding                          |
+|--------|------|--------------|------------------------------------------|
+| 0      | 4    | magic        | ASCII `"AGPC"` (0x41 0x47 0x50 0x43)     |
+| 4      | 2    | version      | `uint16` LE (currently `1`)              |
+| 6      | 2    | header_len   | `uint16` LE (bytes of header after this) |
+| 8      | 4    | flags        | `uint32` LE (bitmask, reserved)          |
+| 12     | 4    | payload_len  | `uint32` LE (bytes of payload body)      |
+| 16     | 32   | checksum     | SHA-256 of payload body (hex, 32 bytes)  |
+
+Total header size: **48 bytes**.
+
+#### 3.6.2 Payload Body
+
+The payload body is a sequence of typed sections. Each section has a small
+header:
+
+| Offset | Size | Field      | Type / Encoding            |
+|--------|------|------------|----------------------------|
+| 0      | 1    | section_id | `uint8` (see table below)  |
+| 1      | 4    | section_len| `uint32` LE (bytes of section data) |
+| 5      | ...  | data       | section-specific           |
+
+Section IDs:
+
+| section_id | Section        | Data layout                                                       |
+|------------|----------------|-------------------------------------------------------------------|
+| `0x01`     | metadata       | world_id, room_id (length-prefixed strings), coord (3×int32), bounds (6×float32) |
+| `0x02`     | tile layer     | name, layer_id, dims (3×uint16), palette, dense tile indices      |
+| `0x03`     | object         | one `WorldObject` (repeated; one section per object)              |
+| `0x04`     | content flags  | category severities (8×uint8), mature (uint8), sources (string list) |
+| `0x05`     | meta           | created_at, updated_at (int64 unix), revision (uint32), author (string) |
+
+**String encoding:** length-prefixed UTF-8 — `uint16` LE byte length followed by
+the UTF-8 bytes.
+
+**Tile layer data layout (section `0x02`):**
+
+```
+name        : string
+layer_id    : uint16 LE
+width       : uint16 LE
+height      : uint16 LE
+depth       : uint16 LE
+palette_count : uint16 LE
+palette     : palette_count × TileDef
+tile_count  : uint32 LE
+tiles       : tile_count × uint16 LE   (dense, row-major)
+```
+
+```
+TileDef:
+  id        : uint16 LE
+  asset_id  : string
+  solid     : uint8
+  flags     : uint32 LE
+  variants  : uint8
+```
+
+**Object data layout (section `0x03`):**
+
+```
+id          : string
+type        : string
+asset_id    : string
+pos         : 3 × float32
+rot         : 4 × float32
+scale       : 3 × float32
+dynamic     : uint8
+properties  : JSON string (length-prefixed)
+flags       : ContentFlags (see 0x04 layout)
+```
+
+**Content flags layout (section `0x04`):**
+
+```
+violence, sexual, language, substance, gambling, horror, hate, custom
+            : 8 × uint8   (severity enum: 0=none,1=mild,2=moderate,3=severe)
+mature      : uint8
+source_count: uint16 LE
+sources     : source_count × string
+```
+
+#### 3.6.3 Byte-Stability
+
+For a given logical payload, the binary encoding is **deterministic**:
+
+- All integers are little-endian.
+- All strings are UTF-8, length-prefixed, and never null-terminated.
+- Maps (e.g. `properties`) are serialized as a **canonical JSON string** with
+  keys sorted lexicographically.
+- The `checksum` is the SHA-256 of the payload body bytes.
+
+This guarantees that two encoders produce identical bytes, enabling content
+addressing, caching, and reproducible tests.
+
+---
+
+## 4. SQLite Persistence Schema
+
+The server persists world state in a **SQLite** database. SQLite is chosen for
+its zero-configuration, single-file, transactional, and embedded nature — ideal
+for a server that owns the world store and needs ACID guarantees without a
+separate database process.
+
+### 4.1 Database Layout
+
+The database file is `world.db` (path configurable). It contains the following
+tables:
+
+```
+worlds
+rooms
+chunks
+chunk_objects
+content_flags
+revisions
+```
+
+### 4.2 `worlds`
+
+Top-level world containers.
+
+```sql
+CREATE TABLE worlds (
+    id          TEXT PRIMARY KEY,          -- e.g. 'w_0001'
+    name        TEXT NOT NULL,
+    description TEXT,
+    chunk_size_x INTEGER NOT NULL DEFAULT 32,
+    chunk_size_y INTEGER NOT NULL DEFAULT 32,
+    chunk_size_z INTEGER NOT NULL DEFAULT 1,
+    origin_x    REAL NOT NULL DEFAULT 0,
+    origin_y    REAL NOT NULL DEFAULT 0,
+    origin_z    REAL NOT NULL DEFAULT 0,
+    created_at  TEXT NOT NULL,             -- ISO-8601 UTC
+    updated_at  TEXT NOT NULL
+);
+```
+
+### 4.3 `rooms`
+
+Rooms within a world.
+
+```sql
+CREATE TABLE rooms (
+    id          TEXT PRIMARY KEY,          -- e.g. 'r_0001'
+    world_id    TEXT NOT NULL REFERENCES worlds(id) ON DELETE CASCADE,
+    name        TEXT NOT NULL,
+    bounds_min_x REAL NOT NULL,
+    bounds_min_y REAL NOT NULL,
+    bounds_min_z REAL NOT NULL DEFAULT 0,
+    bounds_max_x REAL NOT NULL,
+    bounds_max_y REAL NOT NULL,
+    bounds_max_z REAL NOT NULL DEFAULT 1,
+    created_at  TEXT NOT NULL,
+    updated_at  TEXT NOT NULL,
+    UNIQUE (world_id, name)
+);
+CREATE INDEX idx_rooms_world ON rooms(world_id);
+```
+
+### 4.4 `chunks`
+
+The core persistence table. One row per chunk. The **payload** is stored as a
+BLOB in the **binary format** (§3.6); the JSON form is derived on demand for
+authoring/debugging and is not stored (to avoid dual-write drift).
+
+```sql
+CREATE TABLE chunks (
+    key         TEXT PRIMARY KEY,          -- canonical key 'world:room:cx:cy:cz'
+    world_id    TEXT NOT NULL REFERENCES worlds(id) ON DELETE CASCADE,
+    room_id     TEXT NOT NULL REFERENCES rooms(id) ON DELETE CASCADE,
+    cx          INTEGER NOT NULL,
+    cy          INTEGER NOT NULL,
+    cz          INTEGER NOT NULL DEFAULT 0,
+    format_version INTEGER NOT NULL DEFAULT 1,
+    payload     BLOB NOT NULL,             -- binary chunk encoding (§3.6)
+    payload_len INTEGER NOT NULL,
+    checksum    TEXT NOT NULL,             -- SHA-256 of payload
+    revision    INTEGER NOT NULL DEFAULT 0,
+    dirty       INTEGER NOT NULL DEFAULT 0, -- 1 = needs flush to disk
+    created_at  TEXT NOT NULL,
+    updated_at  TEXT NOT NULL,
+    UNIQUE (world_id, room_id, cx, cy, cz)
+);
+CREATE INDEX idx_chunks_world_room ON chunks(world_id, room_id);
+CREATE INDEX idx_chunks_coord ON chunks(cx, cy, cz);
+```
+
+**Design notes:**
+
+- The `payload` BLOB is the single source of truth for chunk content. The
+  `checksum` guards against corruption and enables content addressing.
+- `revision` increments on every write; it is used for optimistic concurrency
+  and change detection (see §5.4).
+- `dirty` marks chunks that have been modified in memory but not yet flushed,
+  enabling a write-behind persistence strategy (see §5.5).
+
+### 4.5 `chunk_objects`
+
+A denormalized, queryable index of the objects inside each chunk. This is
+**derived** from the chunk payload and kept in sync by the write path. It exists
+so the server can answer queries like "which chunks contain a door?" without
+parsing every payload BLOB.
+
+```sql
+CREATE TABLE chunk_objects (
+    id          TEXT NOT NULL,             -- object id (unique within chunk)
+    chunk_key   TEXT NOT NULL REFERENCES chunks(key) ON DELETE CASCADE,
+    type        TEXT NOT NULL,             -- 'prop', 'interactable', ...
+    asset_id    TEXT,
+    dynamic     INTEGER NOT NULL DEFAULT 0,
+    pos_x       REAL NOT NULL,
+    pos_y       REAL NOT NULL,
+    pos_z       REAL NOT NULL DEFAULT 0,
+    PRIMARY KEY (chunk_key, id)
+);
+CREATE INDEX idx_chunk_objects_type ON chunk_objects(type);
+CREATE INDEX idx_chunk_objects_asset ON chunk_objects(asset_id);
+```
+
+**Sync mechanism:** `chunk_objects` is maintained **explicitly by the write
+path** — it is not a SQL trigger. Whenever `put_chunk` (or `delete_chunk`)
+commits a chunk, the service layer performs a **delete-and-reinsert** of that
+chunk's object rows in the same transaction: it deletes all rows for
+`chunk_key`, then inserts fresh rows parsed from the new payload. This keeps the
+index transactionally consistent with the payload and avoids the complexity and
+fragility of SQL triggers over a binary BLOB. Because the index is derived, it
+can always be rebuilt from `chunks.payload` if it ever drifts (a `rebuild_index`
+utility is provided for this).
+
+### 4.6 `content_flags`
+
+Persists the aggregated moderation flags per chunk (and optionally per object).
+This lets the server enforce age/content gates at load time without parsing
+payloads.
+
+```sql
+CREATE TABLE content_flags (
+    chunk_key   TEXT NOT NULL REFERENCES chunks(key) ON DELETE CASCADE,
+    object_id   TEXT NOT NULL DEFAULT '',  -- '' = chunk-level flag (sentinel)
+    violence    INTEGER NOT NULL DEFAULT 0,
+    sexual      INTEGER NOT NULL DEFAULT 0,
+    language    INTEGER NOT NULL DEFAULT 0,
+    substance   INTEGER NOT NULL DEFAULT 0,
+    gambling    INTEGER NOT NULL DEFAULT 0,
+    horror      INTEGER NOT NULL DEFAULT 0,
+    hate        INTEGER NOT NULL DEFAULT 0,
+    custom      INTEGER NOT NULL DEFAULT 0,
+    mature      INTEGER NOT NULL DEFAULT 0,
+    sources     TEXT NOT NULL DEFAULT '[]', -- JSON array of flag ids
+    PRIMARY KEY (chunk_key, object_id)
+);
+CREATE INDEX idx_content_flags_mature ON content_flags(mature);
+```
+
+Severity is stored as `0=none, 1=mild, 2=moderate, 3=severe`.
+
+**Chunk-level vs. object-level flags:** Chunk-level flags use the **sentinel
+value `''` (empty string)** in `object_id` rather than `NULL`. This is
+deliberate: in SQLite, `NULL` values in a composite primary key are **not**
+unique-constrained, so two rows with the same `chunk_key` and `object_id = NULL`
+could be inserted accidentally. Using `''` as the sentinel means the composite
+`PRIMARY KEY (chunk_key, object_id)` enforces that there is **exactly one**
+chunk-level flag row per chunk. Object-level flags use the object's actual `id`
+(which is never empty). The application layer treats `object_id = ''` as
+"chunk-level" and any non-empty value as "object-level".
+
+### 4.7 `revisions`
+
+An append-only audit log of chunk writes. Enables rollback, auditing, and
+replication of changes.
+
+```sql
+CREATE TABLE revisions (
+    id          INTEGER PRIMARY KEY AUTOINCREMENT,
+    chunk_key   TEXT NOT NULL,             -- NOT a FK: survives chunk deletion
+    revision    INTEGER NOT NULL,
+    actor       TEXT NOT NULL,             -- user / agent id
+    action      TEXT NOT NULL,             -- 'create' | 'update' | 'delete'
+    checksum    TEXT NOT NULL,             -- SHA-256 of payload
+    payload     BLOB,                      -- full binary payload at this revision
+    created_at  TEXT NOT NULL
+);
+CREATE INDEX idx_revisions_chunk ON revisions(chunk_key);
+```
+
+**Rollback support:** The `payload` BLOB stores the **full binary chunk payload**
+at each revision. This is what makes rollback possible: to restore a chunk to a
+previous revision, the server reads the `payload` of the target revision and
+writes it back to `chunks.payload` (incrementing `revision` and appending a new
+`revisions` row). Without the payload, only the checksum would be available,
+which is insufficient to reconstruct the chunk.
+
+**Audit trail preservation:** `chunk_key` is **not** a foreign key to `chunks`.
+This means deleting a chunk does **not** cascade-delete its revision history —
+the audit trail is preserved even after a chunk is removed. (The `chunk_key`
+string is still stored so the history can be correlated to a chunk that existed
+at that time.) If a chunk is later recreated with the same key, its history is
+still intact.
+
+### 4.8 Schema Versioning & Migrations
+
+The database carries a schema version in a `meta` table:
+
+```sql
+CREATE TABLE meta (
+    key   TEXT PRIMARY KEY,
+    value TEXT NOT NULL
+);
+-- seed: INSERT INTO meta(key, value) VALUES ('schema_version', '1');
+```
+
+Migrations are applied in order at startup. Each migration is a numbered SQL
+script; the server tracks the applied version in `meta` and applies any pending
+migrations transactionally. This keeps the schema forward-compatible as the
+chunk format evolves.
+
+---
+
+## 5. Read/Write API
+
+The API is exposed as a **Python service layer** on the backend (the same
+process that owns the SQLite store) and consumed by the Godot client over the
+network transport (see `networking.md`). The service layer is the **only**
+writer to the database; clients never touch SQLite directly.
+
+### 5.1 Service Interface (Python)
+
+```python
+class WorldStore:
+    """Owns the SQLite connection and chunk read/write operations."""
+
+    def get_chunk(self, key: str) -> Chunk | None: ...
+    def get_chunk_binary(self, key: str) -> bytes | None: ...
+    def put_chunk(self, chunk: Chunk, actor: str) -> Chunk: ...
+    def delete_chunk(self, key: str, actor: str) -> None: ...
+    def list_chunks(self, world_id: str, room_id: str | None = None,
+                    bounds: Bounds | None = None) -> list[str]: ...
+    def get_chunk_flags(self, key: str) -> ContentFlags: ...
+    def flush_dirty(self) -> int: ...
+    def rollback_chunk(self, key: str, revision: int, actor: str) -> Chunk: ...
+    def rebuild_index(self, chunk_key: str | None = None) -> int: ...
+    def migrate(self) -> None: ...
+```
+
+### 5.2 Encoding Helpers
+
+The service layer provides symmetric encode/decode functions shared by the
+client and server:
+
+```python
+def encode_binary(chunk: Chunk) -> bytes: ...
+def decode_binary(data: bytes) -> Chunk: ...
+def encode_json(chunk: Chunk) -> str: ...
+def decode_json(text: str) -> Chunk: ...
+def checksum(payload: bytes) -> str: ...
+```
+
+These are the single implementation of the format spec (§3), so the Godot
+client and Python backend never drift.
+
+### 5.3 Network RPCs
+
+The chunk API is exposed to the client via RPCs (matching the networking
+architecture). All chunk traffic is **reliable** (chunks are discrete,
+must-arrive data).
+
+| RPC                        | Direction | Payload                                   | Notes |
+|----------------------------|-----------|-------------------------------------------|-------|
+| `request_chunk`            | C → S     | `{ key }`                                 | Client asks for a chunk |
+| `chunk_data`               | S → C     | `{ key, binary_payload, checksum }`       | Server streams a chunk |
+| `request_chunk_edit`       | C → S     | `{ key, base_revision, delta }`           | Client submits an edit |
+| `chunk_edit_result`        | S → C     | `{ key, success, new_revision, error? }`  | Acknowledges an edit |
+| `chunk_invalidated`        | S → C     | `{ key, new_revision }`                   | Server pushes a change |
+| `request_chunk_flags`      | C → S     | `{ key }`                                 | Age/content gate check |
+
+### 5.4 Edit & Concurrency Model
+
+- **Read:** Client requests a chunk; server returns the binary payload and its
+  `revision`.
+- **Edit:** Client submits a **delta** against a known `base_revision`. The
+  server applies the delta, increments `revision`, persists, and returns the new
+  revision.
+- **Optimistic concurrency:** If the chunk's current revision differs from the
+  client's `base_revision`, the server rejects the edit with a conflict error
+  and the client re-fetches and re-applies. This prevents lost updates when two
+  clients edit the same chunk.
+- **Deltas:** A delta is a JSON patch (RFC 6902 style) applied to the chunk's
+  logical model. The server validates the patched chunk (schema, bounds,
+  moderation) before persisting.
+
+### 5.5 Write-Behind Persistence
+
+To amortize disk I/O, the server keeps a **dirty set** of chunks modified in
+memory and flushes them to SQLite in batches:
+
+1. `put_chunk` updates the in-memory chunk and marks it `dirty`.
+2. A background flusher periodically calls `flush_dirty()`, which writes all
+   dirty chunks in a single transaction and clears the `dirty` flag.
+3. On graceful shutdown, `flush_dirty()` is called to ensure durability.
+
+This keeps the hot path (in-memory chunk access) fast while guaranteeing
+durability at shutdown and on a configurable interval.
+
+**Recovery after unclean shutdown:** The `dirty` column in the `chunks` table
+exists specifically to support recovery if the process crashes before a flush
+completes. On startup, the server scans for rows where `dirty = 1` and treats
+them as **unflushed in-memory state that was lost** — it re-reads the last
+persisted payload from `chunks.payload` (the last durable state) and clears the
+`dirty` flag. In other words, `dirty = 1` at startup means "the last write was
+not durable; discard the in-memory delta and fall back to the persisted
+payload." This guarantees that the on-disk state is always a consistent,
+previously-committed snapshot, never a partially-written chunk. (The in-memory
+dirty set is authoritative during normal operation; the `dirty` column is only a
+recovery marker.)
+
+### 5.6 Streaming & Caching
+
+- The server streams only the chunks a client needs (those within the client's
+  view radius), using `list_chunks` with a bounds query.
+- Chunks are cached in memory (LRU) keyed by `key`; the cache is invalidated on
+  write.
+- The binary payload is content-addressed by `checksum`, so unchanged chunks can
+  be served from cache without re-reading SQLite.
+
+---
+
+## 6. Format Versioning & Migration
+
+- The chunk format `version` field (currently `1`) is checked on decode. A
+  decoder that encounters a higher version than it supports **rejects** the
+  chunk with a clear error rather than misreading it.
+- The SQLite `schema_version` in `meta` drives database migrations (§4.8).
+- Chunk payloads are migrated **lazily**: when a chunk is read and its
+  `format_version` is older than the current one, the server migrates it to the
+  current version in memory and marks it dirty so it is rewritten on the next
+  flush. This avoids a costly full-world migration at startup.
+
+---
+
+## 7. Security & Integrity
+
+- **Server-authoritative writes:** Only the `WorldStore` writes to SQLite;
+  clients submit deltas that are validated before application.
+- **Checksum verification:** Every chunk payload is checksummed (SHA-256) on
+  write and verified on read. Corruption is detected and the chunk is re-fetched
+  or flagged.
+- **Bounds validation:** Chunk coordinates and object positions are validated
+  against the world's chunk dimensions and room bounds before persistence.
+- **Moderation enforcement:** `content_flags` are checked at load time; mature
+  chunks are gated behind the age-verification flow (see `content_moderation.md`).
+- **Input validation:** All string fields are length-limited and validated
+  against allowed character sets to prevent injection and oversized payloads.
+
+---
+
+## 8. Open Questions / Future Work
+
+- **Volumetric worlds:** The schema and format already support `CHUNK_SIZE_Z >
+  1`, but the tooling and streaming for 3D chunks are not yet specified.
+- **Chunk compression:** For very large worlds, the binary payload could be
+  compressed (e.g. zstd) before storage/transfer. The header reserves a `flags`
+  bitmask for a compression flag.
+- **Multi-server sharding:** If a single SQLite file becomes a bottleneck, the
+  `chunks` table could be sharded by `world_id` across multiple databases. The
+  key design already supports this (world_id is a leading key component).
+- **Delta compression for streaming:** Instead of sending full chunks, the
+  server could send only the delta between revisions to reduce bandwidth for
+  frequently-updated chunks.

project.godot

@@ -0,0 +1,24 @@
+; 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="AGP-Game"
+run/main_scene="res://scenes/main_menu.tscn"
+config/features=PackedStringArray("4.6.2")
+
+[autoload]
+
+[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/.godot/.gdignore

@@ -0,0 +1 @@
+

sandbox_probe/probe6.gd

@@ -0,0 +1,174 @@
+extends Node
+
+func _ready():
+	print("=== SANDBOX PROBE 6: Corrected Evidence Gathering (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_allowlist()
+	print("=== SANDBOX PROBE 6 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"))
+
+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)
+	print("ClassDB has 'class_get_singleton': ", ClassDB.has_method("class_get_singleton"))
+
+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())
+
+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_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)

sandbox_probe/probe6.tscn

@@ -0,0 +1,6 @@
+[gd_scene load_steps=2 format=3]
+
+[ext_resource type="Script" path="res://probe6.gd" id="1"]
+
+[node name="Probe6" type="Node"]
+script = ExtResource("1")

sandbox_probe/project.godot

@@ -0,0 +1,8 @@
+; Engine configuration file.
+config_version=5
+
+[application]
+
+config/name="sandbox_probe"
+run/main_scene="res://probe6.tscn"
+config/features=PackedStringArray("4.6")

sandbox_probe/test_script.gd

@@ -0,0 +1,4 @@
+extends RefCounted
+
+func hello():
+	return "from test_script.gd"