feat: M1 foundation — compose stack, FastAPI, Google OAuth, encrypted tokens

- docker-compose with Postgres 16 + slim Python API image
- FastAPI app with session middleware, health endpoint, static login page
- Google OAuth (Authlib) with email invite-list whitelist; admin role support
- User + OAuthToken models; refresh tokens encrypted at rest (Fernet)
- Alembic migrations, run automatically on container startup
- Postgres backup/restore scripts for portability between machines

backend/app/auth.py

@@ -0,0 +1,108 @@
+from datetime import datetime, timezone
+
+from authlib.integrations.starlette_client import OAuth, OAuthError
+from fastapi import APIRouter, Depends, HTTPException, Request
+from fastapi.responses import JSONResponse, RedirectResponse
+from sqlalchemy.orm import Session
+
+from app.config import settings
+from app.db import get_db
+from app.models import OAuthToken, User
+from app.security import encrypt
+
+# Single YouTube scope that allows reading subscriptions/playlists AND writing
+# (unsubscribe, playlist export). openid/email/profile give us the account identity.
+SCOPES = "openid email profile https://www.googleapis.com/auth/youtube"
+
+router = APIRouter(prefix="/auth", tags=["auth"])
+
+oauth = OAuth()
+oauth.register(
+    name="google",
+    client_id=settings.google_client_id,
+    client_secret=settings.google_client_secret,
+    server_metadata_url="https://accounts.google.com/.well-known/openid-configuration",
+    client_kwargs={
+        "scope": SCOPES,
+        # access_type=offline + prompt=consent ensures we receive a refresh_token.
+        "access_type": "offline",
+        "prompt": "consent",
+    },
+)
+
+
+@router.get("/login")
+async def login(request: Request):
+    return await oauth.google.authorize_redirect(request, settings.oauth_redirect_url)
+
+
+@router.get("/callback")
+async def callback(request: Request, db: Session = Depends(get_db)):
+    try:
+        token = await oauth.google.authorize_access_token(request)
+    except OAuthError as exc:
+        raise HTTPException(status_code=400, detail=f"OAuth error: {exc.error}")
+
+    userinfo = token.get("userinfo")
+    if not userinfo or not userinfo.get("sub"):
+        raise HTTPException(status_code=400, detail="No user info returned by Google")
+
+    email = (userinfo.get("email") or "").lower()
+    if not email or email not in settings.allowed_email_set:
+        raise HTTPException(
+            status_code=403, detail="This Google account is not on the invite list."
+        )
+
+    user = db.query(User).filter(User.google_sub == userinfo["sub"]).one_or_none()
+    if user is None:
+        user = User(google_sub=userinfo["sub"], email=email)
+        db.add(user)
+    user.email = email
+    user.display_name = userinfo.get("name")
+    user.avatar_url = userinfo.get("picture")
+    user.role = "admin" if email in settings.admin_email_set else "user"
+    db.flush()
+
+    tok = user.token or OAuthToken(user=user)
+    # Google only returns a refresh_token on (re)consent; keep the previous one otherwise.
+    if token.get("refresh_token"):
+        tok.refresh_token_enc = encrypt(token["refresh_token"])
+    tok.access_token = token.get("access_token")
+    expires_at = token.get("expires_at")
+    tok.expiry = (
+        datetime.fromtimestamp(expires_at, tz=timezone.utc) if expires_at else None
+    )
+    tok.scopes = token.get("scope") or SCOPES
+    db.add(tok)
+    db.commit()
+
+    request.session["user_id"] = user.id
+    return RedirectResponse(url="/")
+
+
+@router.post("/logout")
+async def logout(request: Request):
+    request.session.clear()
+    return JSONResponse({"ok": True})
+
+
+def current_user(request: Request, db: Session = Depends(get_db)) -> User:
+    user_id = request.session.get("user_id")
+    if not user_id:
+        raise HTTPException(status_code=401, detail="Not authenticated")
+    user = db.get(User, user_id)
+    if user is None:
+        request.session.clear()
+        raise HTTPException(status_code=401, detail="Not authenticated")
+    return user
+
+
+@router.get("/me")
+async def me(user: User = Depends(current_user)) -> dict:
+    return {
+        "id": user.id,
+        "email": user.email,
+        "display_name": user.display_name,
+        "avatar_url": user.avatar_url,
+        "role": user.role,
+    }

backend/app/config.py

@@ -0,0 +1,36 @@
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class Settings(BaseSettings):
+    model_config = SettingsConfigDict(env_file=".env", extra="ignore")
+
+    app_name: str = "Subfeed"
+
+    database_url: str = "postgresql+psycopg://subfeed:subfeed@db:5432/subfeed"
+
+    # Session cookie signing key.
+    secret_key: str = "change-me-session-key"
+    # Fernet key (urlsafe base64, 32 bytes) for encrypting stored refresh tokens.
+    token_encryption_key: str = ""
+
+    google_client_id: str = ""
+    google_client_secret: str = ""
+    oauth_redirect_url: str = "http://localhost:8080/auth/callback"
+
+    # Comma-separated invite list / admin list of Google account emails.
+    allowed_emails: str = ""
+    admin_emails: str = ""
+
+    # Origin of a separately served frontend dev server (enables CORS). Empty in production.
+    frontend_origin: str = ""
+
+    @property
+    def allowed_email_set(self) -> set[str]:
+        return {e.strip().lower() for e in self.allowed_emails.split(",") if e.strip()}
+
+    @property
+    def admin_email_set(self) -> set[str]:
+        return {e.strip().lower() for e in self.admin_emails.split(",") if e.strip()}
+
+
+settings = Settings()

backend/app/db.py

@@ -0,0 +1,22 @@
+from collections.abc import Iterator
+
+from sqlalchemy import create_engine
+from sqlalchemy.orm import DeclarativeBase, Session, sessionmaker
+
+from app.config import settings
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+engine = create_engine(settings.database_url, pool_pre_ping=True, future=True)
+SessionLocal = sessionmaker(bind=engine, autoflush=False, expire_on_commit=False)
+
+
+def get_db() -> Iterator[Session]:
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()

backend/app/main.py

@@ -0,0 +1,40 @@
+from pathlib import Path
+
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+from fastapi.responses import FileResponse
+from fastapi.staticfiles import StaticFiles
+from starlette.middleware.sessions import SessionMiddleware
+
+from app import auth
+from app.config import settings
+from app.routes import health
+
+app = FastAPI(title=settings.app_name)
+
+app.add_middleware(
+    SessionMiddleware,
+    secret_key=settings.secret_key,
+    same_site="lax",
+    https_only=False,
+)
+
+if settings.frontend_origin:
+    app.add_middleware(
+        CORSMiddleware,
+        allow_origins=[settings.frontend_origin],
+        allow_credentials=True,
+        allow_methods=["*"],
+        allow_headers=["*"],
+    )
+
+app.include_router(health.router)
+app.include_router(auth.router)
+
+STATIC_DIR = Path(__file__).parent / "static"
+app.mount("/assets", StaticFiles(directory=STATIC_DIR / "assets"), name="assets")
+
+
+@app.get("/")
+async def index() -> FileResponse:
+    return FileResponse(STATIC_DIR / "index.html")

backend/app/models.py

@@ -0,0 +1,43 @@
+from datetime import datetime
+
+from sqlalchemy import DateTime, ForeignKey, String, func
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.db import Base
+
+
+class User(Base):
+    __tablename__ = "users"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    google_sub: Mapped[str] = mapped_column(String(64), unique=True, index=True)
+    email: Mapped[str] = mapped_column(String(320), unique=True, index=True)
+    display_name: Mapped[str | None] = mapped_column(String(255))
+    avatar_url: Mapped[str | None] = mapped_column(String(1024))
+    role: Mapped[str] = mapped_column(String(16), default="user", server_default="user")
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now()
+    )
+
+    token: Mapped["OAuthToken | None"] = relationship(
+        back_populates="user", uselist=False, cascade="all, delete-orphan"
+    )
+
+
+class OAuthToken(Base):
+    __tablename__ = "oauth_tokens"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    user_id: Mapped[int] = mapped_column(
+        ForeignKey("users.id", ondelete="CASCADE"), unique=True
+    )
+    # Refresh token encrypted at rest (Fernet). Access token is short-lived and low risk.
+    refresh_token_enc: Mapped[str | None] = mapped_column(String)
+    access_token: Mapped[str | None] = mapped_column(String)
+    expiry: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
+    scopes: Mapped[str | None] = mapped_column(String)
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), onupdate=func.now()
+    )
+
+    user: Mapped["User"] = relationship(back_populates="token")

backend/app/routes/health.py

@@ -0,0 +1,13 @@
+from fastapi import APIRouter, Depends
+from sqlalchemy import text
+from sqlalchemy.orm import Session
+
+from app.db import get_db
+
+router = APIRouter(tags=["health"])
+
+
+@router.get("/healthz")
+def healthz(db: Session = Depends(get_db)) -> dict:
+    db.execute(text("SELECT 1"))
+    return {"status": "ok", "db": "ok"}

backend/app/security.py

@@ -0,0 +1,25 @@
+from cryptography.fernet import Fernet
+
+from app.config import settings
+
+_fernet: Fernet | None = (
+    Fernet(settings.token_encryption_key.encode()) if settings.token_encryption_key else None
+)
+
+
+def _require_fernet() -> Fernet:
+    if _fernet is None:
+        raise RuntimeError("TOKEN_ENCRYPTION_KEY is not configured")
+    return _fernet
+
+
+def encrypt(value: str | None) -> str | None:
+    if value is None:
+        return None
+    return _require_fernet().encrypt(value.encode()).decode()
+
+
+def decrypt(value: str | None) -> str | None:
+    if value is None:
+        return None
+    return _require_fernet().decrypt(value.encode()).decode()

backend/app/static/index.html

@@ -0,0 +1,58 @@
+<!doctype html>
+<html lang="hu">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <title>Subfeed</title>
+    <style>
+      :root { color-scheme: dark; }
+      * { box-sizing: border-box; }
+      body {
+        margin: 0;
+        min-height: 100vh;
+        display: grid;
+        place-items: center;
+        font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
+        color: #f4f4f5;
+        background: radial-gradient(1200px 800px at 20% 10%, #1f2a44 0%, #0b0f1a 55%, #07090f 100%);
+      }
+      .card {
+        width: min(92vw, 420px);
+        padding: 40px 36px;
+        border-radius: 20px;
+        background: rgba(255, 255, 255, 0.06);
+        border: 1px solid rgba(255, 255, 255, 0.12);
+        backdrop-filter: blur(16px);
+        box-shadow: 0 24px 60px rgba(0, 0, 0, 0.45);
+        text-align: center;
+      }
+      .logo { font-size: 28px; font-weight: 700; letter-spacing: -0.02em; }
+      .logo span { color: #ff4d4f; }
+      p { color: #a1a1aa; line-height: 1.5; margin: 14px 0 28px; }
+      a.btn {
+        display: inline-flex; align-items: center; gap: 10px;
+        padding: 12px 20px; border-radius: 12px; text-decoration: none;
+        font-weight: 600; color: #0b0f1a; background: #f4f4f5;
+        transition: transform 0.12s ease, box-shadow 0.12s ease;
+      }
+      a.btn:hover { transform: translateY(-1px); box-shadow: 0 8px 24px rgba(0,0,0,0.35); }
+      .foot { margin-top: 24px; font-size: 12px; color: #71717a; }
+    </style>
+  </head>
+  <body>
+    <div class="card">
+      <div class="logo">Sub<span>feed</span></div>
+      <p>A te feliratkozásaid, a te szűrőid szerint.<br />Jelentkezz be a Google-fiókoddal.</p>
+      <a class="btn" href="/auth/login">
+        <svg width="18" height="18" viewBox="0 0 48 48" aria-hidden="true">
+          <path fill="#EA4335" d="M24 9.5c3.5 0 6.6 1.2 9.1 3.6l6.8-6.8C35.9 2.4 30.4 0 24 0 14.6 0 6.4 5.4 2.5 13.3l7.9 6.1C12.3 13.2 17.7 9.5 24 9.5z"/>
+          <path fill="#4285F4" d="M46.1 24.6c0-1.6-.1-3.1-.4-4.6H24v9.1h12.4c-.5 2.9-2.1 5.3-4.6 6.9l7.1 5.5c4.2-3.9 6.2-9.6 6.2-16.9z"/>
+          <path fill="#FBBC05" d="M10.4 28.6c-.5-1.4-.8-2.9-.8-4.6s.3-3.2.8-4.6l-7.9-6.1C.9 16.5 0 20.1 0 24s.9 7.5 2.5 10.7l7.9-6.1z"/>
+          <path fill="#34A853" d="M24 48c6.4 0 11.9-2.1 15.9-5.8l-7.1-5.5c-2 1.3-4.5 2.1-8.8 2.1-6.3 0-11.7-3.7-13.6-9.9l-7.9 6.1C6.4 42.6 14.6 48 24 48z"/>
+        </svg>
+        Bejelentkezés Google-fiókkal
+      </a>
+      <div class="foot">Csak meghívott fiókok léphetnek be.</div>
+    </div>
+  </body>
+</html>