Fix remaining critical review issue: list_worlds visibility filter bypass

Requesting an explicit ?visibility=PRIVATE (or FRIENDS_ONLY) skipped the
ownership check entirely — any authenticated user could list every other
user's private worlds just by passing the filter. Only the no-filter
default path enforced ownership. Now the ownership check applies whenever
a non-PUBLIC visibility is requested, explicit or not.

Also fixed current_user: CurrentUser = Depends() in assets.py (redundant
empty Depends() on an already-Annotated dependency, inconsistent with
every other endpoint) to plain current_user: CurrentUser per the review
feedback, and reordered params since that made it a non-default arg
following a defaulted one (SyntaxError otherwise).

Verified: py_compile clean, full app imports and loads in a clean venv.

.gitignore

@@ -0,0 +1,2 @@
+# Godot 4 editor cache/import directory
+.godot/

backend/.env.example

@@ -1,5 +1,5 @@
-# Database
-DATABASE_URL=postgresql://agp_user:agp_password@localhost:5432/agp_db
+# Database (async driver)
+DATABASE_URL=postgresql+asyncpg://agp_user:agp_password@localhost:5432/agp_db
 
 # Redis
 REDIS_URL=redis://localhost:6379/0
@@ -10,5 +10,11 @@ ALGORITHM=HS256
 ACCESS_TOKEN_EXPIRE_MINUTES=30
 
 # 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/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 +1,126 @@
+"""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"
+            ),
+            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",
+            ),
+            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/app/config.py

@@ -1,8 +1,9 @@
 """Application configuration via pydantic-settings."""
 
-from pydantic_settings import BaseSettings
 from functools import lru_cache
 
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
 
 class Settings(BaseSettings):
     # App
@@ -17,6 +18,8 @@ class Settings(BaseSettings):
     REDIS_URL: str = "redis://localhost:6379/0"
 
     # JWT / Auth
+    # NOTE: production must override SECRET_KEY with a secure random value
+    # (e.g. `python -c "import secrets; print(secrets.token_urlsafe(32))"`)
     SECRET_KEY: str = "change-me-to-a-secure-random-string"
     ALGORITHM: str = "HS256"
     ACCESS_TOKEN_EXPIRE_MINUTES: int = 30
@@ -28,15 +31,16 @@ class Settings(BaseSettings):
     UPLOAD_DIR: str = "uploads"
     MAX_UPLOAD_SIZE_MB: int = 100
 
+    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(",")]
 
-    class Config:
-        env_file = ".env"
-        env_file_encoding = "utf-8"
-        case_sensitive = True
-
 
 @lru_cache()
 def get_settings() -> Settings:

backend/app/database.py

@@ -10,7 +10,7 @@ from sqlalchemy.orm import DeclarativeBase
 from app.config import settings
 
 engine = create_async_engine(
-    settings.database_url,
+    settings.DATABASE_URL,
     echo=settings.DEBUG,
     pool_size=10,
     max_overflow=20,
@@ -28,11 +28,15 @@ class Base(DeclarativeBase):
 
 
 async def get_db() -> AsyncSession:
-    """Dependency that yields an async database session."""
+    """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
-            await session.commit()
         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.SECRET_KEY, 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

@@ -3,6 +3,7 @@
 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
@@ -17,12 +18,21 @@ async def lifespan(app: FastAPI):
 
 
 app = FastAPI(
-    title=settings.app_name,
-    version=settings.app_version,
+    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"])
@@ -33,4 +43,4 @@ 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}
+    return {"status": "ok", "app": settings.APP_NAME}

backend/app/models/asset.py

@@ -1,4 +1,5 @@
-from sqlalchemy import Column, Integer, String, ForeignKey, Text, DateTime, Enum as SAEnum
+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
@@ -21,14 +22,17 @@ class Asset(Base):
     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)
+    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(Integer, default=0, 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())
 

backend/app/models/session.py

@@ -1,4 +1,6 @@
-from sqlalchemy import Column, String, DateTime, ForeignKey, Boolean
+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
@@ -7,8 +9,8 @@ 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)
+    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)

backend/app/models/world.py

@@ -1,4 +1,5 @@
-from sqlalchemy import Column, Integer, String, Text, DateTime, ForeignKey, Enum
+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
@@ -19,7 +20,10 @@ class World(Base):
     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)
+    visibility = Column(
+        ENUM(WorldVisibility, name="world_visibility", create_type=False),
+        default=WorldVisibility.PUBLIC,
+    )
     created_at = Column(DateTime(timezone=True), server_default=func.now())
     updated_at = Column(DateTime(timezone=True), onupdate=func.now())
 

backend/app/routers/assets.py

@@ -1,17 +1,18 @@
 """Asset management router."""
 
+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 sqlalchemy.orm import selectinload
 
+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.user import User
 from app.models.world import World
-from app.routers.worlds import get_current_user
 from pydantic import BaseModel, Field
 
 router = APIRouter()
@@ -42,8 +43,7 @@ class AssetResponse(BaseModel):
     created_at: str
     updated_at: str
 
-    class Config:
-        from_attributes = True
+    model_config = {"from_attributes": True}
 
 
 class AssetUpdate(BaseModel):
@@ -53,13 +53,24 @@ class AssetUpdate(BaseModel):
     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"
+
+
 # --- Endpoints ---
 
 @router.post("/", response_model=AssetResponse, status_code=201)
 async def create_asset(
     payload: AssetCreate,
+    current_user: CurrentUser,
     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
@@ -87,12 +98,12 @@ async def create_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),
-    current_user: User = Depends(get_current_user),
 ):
     """List assets with optional filters."""
     stmt = select(Asset).where(Asset.owner_id == current_user.id)
@@ -111,8 +122,8 @@ async def list_assets(
 @router.get("/{asset_id}", response_model=AssetResponse)
 async def get_asset(
     asset_id: int,
+    current_user: CurrentUser,
     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)
@@ -125,8 +136,8 @@ async def get_asset(
 async def update_asset(
     asset_id: int,
     payload: AssetUpdate,
+    current_user: CurrentUser,
     db: AsyncSession = Depends(get_db),
-    current_user: User = Depends(get_current_user),
 ):
     """Update an asset."""
     asset = await db.get(Asset, asset_id)
@@ -145,8 +156,8 @@ async def update_asset(
 @router.delete("/{asset_id}", status_code=204)
 async def delete_asset(
     asset_id: int,
+    current_user: CurrentUser,
     db: AsyncSession = Depends(get_db),
-    current_user: User = Depends(get_current_user),
 ):
     """Delete an asset."""
     asset = await db.get(Asset, asset_id)
@@ -157,25 +168,42 @@ async def delete_asset(
     await db.commit()
 
 
-@router.post("/{asset_id}/upload")
+@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),
-    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
+    # Sanitize filename to prevent path traversal.
+    safe_filename = _sanitize_filename(file.filename or f"asset_{asset_id}")
+
+    # Validate file size against configured maximum.
+    max_bytes = settings.MAX_UPLOAD_SIZE_MB * 1024 * 1024
+    content = await file.read()
+    file_size = len(content)
+    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)
+
+    asset.file_path = str(file_path)
     asset.mime_type = file.content_type
-    asset.file_size = 0  # Will be updated after actual write
+    asset.file_size = file_size
 
     await db.commit()
     await db.refresh(asset)
-
-    return {"message": "File upload endpoint", "asset_id": asset_id, "file_path": file_path}
+    return asset

backend/app/routers/auth.py

@@ -3,13 +3,15 @@
 from datetime import datetime, timedelta, timezone
 
 from fastapi import APIRouter, Depends, HTTPException, status
+from fastapi.security import OAuth2PasswordRequestForm
 from pydantic import BaseModel, EmailStr
 
-from jose import JWTError, jwt
+from jose import jwt
 from passlib.context import CryptContext
 
 from app.config import settings
 from app.database import get_db
+from app.dependencies import CurrentUser
 from app.models.user import User
 from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy import select
@@ -32,9 +34,14 @@ class RegisterRequest(BaseModel):
     password: str
 
 
-class LoginRequest(BaseModel):
+class UserResponse(BaseModel):
+    id: int
     username: str
-    password: str
+    email: str
+    is_active: bool
+    created_at: datetime | None = None
+
+    model_config = {"from_attributes": True}
 
 
 # --- Helpers ---
@@ -93,12 +100,16 @@ async def register(req: RegisterRequest, db: AsyncSession = Depends(get_db)):
 
 
 @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))
+async def login(form: OAuth2PasswordRequestForm = Depends(), db: AsyncSession = Depends(get_db)):
+    """Authenticate user and return an access token.
+
+    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(req.password, user.hashed_password):
+    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",
@@ -114,20 +125,7 @@ async def login(req: LoginRequest, db: AsyncSession = Depends(get_db)):
     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,
-    }
+@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

@@ -8,18 +8,13 @@ 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 UserCreate(BaseModel):
-    username: str
-    email: EmailStr
-    password: str
-
+# ─── Pydantic schemas ────────────────────────────────────────────────────────
 
 class UserResponse(BaseModel):
     id: int
@@ -35,62 +30,32 @@ class UserUpdate(BaseModel):
     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
-
+# ─── Endpoints ───────────────────────────────────────────────────────────────
 
 @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
+async def get_current_user_profile(
+    current_user: CurrentUser,
 ):
-    """Get the currently authenticated user (placeholder)."""
-    raise HTTPException(status_code=501, detail="Not implemented")
+    """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."""
+    """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
 
 
@@ -98,14 +63,19 @@ async def get_user(
 async def update_user(
     user_id: int,
     user_update: UserUpdate,
+    current_user: CurrentUser,
     db: Annotated[AsyncSession, Depends(get_db)],
 ):
-    """Update a user."""
+    """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:
@@ -119,12 +89,18 @@ async def update_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."""
+    """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

@@ -3,110 +3,133 @@
 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()
 
-
-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"}
+DbDep = Annotated[AsyncSession, Depends(get_db)]
 
 
-@router.get("/")
+# --- 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: str | 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,
-    db: Annotated[AsyncSession, Depends(get_db)] = Depends(),
 ):
-    """List worlds with optional visibility filter."""
+    """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 [
-        {
-            "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
-    ]
+    return worlds
 
 
-@router.get("/{world_id}")
+@router.get("/{world_id}", response_model=WorldResponse)
 async def get_world(
     world_id: int,
-    db: Annotated[AsyncSession, Depends(get_db)] = Depends(),
+    current_user: CurrentUser,
+    db: DbDep,
 ):
-    """Get a single world by ID."""
+    """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")
-    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,
-    }
+
+    # 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("/")
+@router.post("/", response_model=WorldResponse, status_code=201)
 async def create_world(
-    world_data: dict,
-    current_user=Depends(get_current_user),
-    db: Annotated[AsyncSession, Depends(get_db)] = Depends(),
+    world_data: WorldCreate,
+    current_user: CurrentUser,
+    db: DbDep,
 ):
     """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")
-        ),
+        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 {
-        "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,
-    }
+    return world
 
 
-@router.put("/{world_id}")
+@router.put("/{world_id}", response_model=WorldResponse)
 async def update_world(
     world_id: int,
-    world_data: dict,
-    current_user=Depends(get_current_user),
-    db: Annotated[AsyncSession, Depends(get_db)] = Depends(),
+    world_data: WorldUpdate,
+    current_user: CurrentUser,
+    db: DbDep,
 ):
     """Update an existing world."""
     result = await db.execute(select(World).where(World.id == world_id))
@@ -114,31 +137,23 @@ async def update_world(
     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"])
+    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 {
-        "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,
-    }
+    return world
 
 
-@router.delete("/{world_id}")
+@router.delete("/{world_id}", status_code=204)
 async def delete_world(
     world_id: int,
-    current_user=Depends(get_current_user),
-    db: Annotated[AsyncSession, Depends(get_db)] = Depends(),
+    current_user: CurrentUser,
+    db: DbDep,
 ):
     """Delete a world."""
     result = await db.execute(select(World).where(World.id == world_id))
@@ -146,6 +161,8 @@ async def delete_world(
     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()
-    return {"detail": "World deleted"}

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:
+      - "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:
+      - "6379:6379"
+    volumes:
+      - redis_data:/data
+    healthcheck:
+      test: ["CMD", "redis-cli", "ping"]
+      interval: 5s
+      timeout: 5s
+      retries: 5
+
+volumes:
+  postgres_data:
+  redis_data:

backend/requirements.txt

@@ -3,6 +3,7 @@ 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

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"

scenes/main_menu.tscn

@@ -0,0 +1,43 @@
+[gd_scene load_steps=2 format=3]
+
+[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="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"]

scripts/main_menu.gd

@@ -0,0 +1,14 @@
+extends Control
+
+
+func _ready():
+	pass
+
+
+func _on_play_button_pressed():
+	# No gameplay scene exists yet — wire this to the real scene once one lands.
+	print("Play pressed — no gameplay scene yet")
+
+
+func _on_quit_button_pressed():
+	get_tree().quit()