Phase 1: auth, room CRUD, WebSocket chat, PWA frontend

Invite-only FastAPI + SQLAlchemy(async) + Postgres backend (session-cookie
auth via CLI-provisioned accounts, open-room CRUD, single-instance /ws/chat)
and a React + Vite PWA frontend (login, room list, chat view). Backend tests
pass against a local Postgres DB. See README.md and backend/README.md for
setup, and ARCHITECTURE.md for the full phased design.

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

backend/app/services/auth_service.py

@@ -0,0 +1,46 @@
+from sqlalchemy import or_, select
+from sqlalchemy.exc import IntegrityError
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models import User
+from app.schemas.user import UserCreate
+from app.security import hash_password, verify_password
+
+
+class DuplicateUserError(Exception):
+    pass
+
+
+class InvalidCredentialsError(Exception):
+    pass
+
+
+async def register_user(db: AsyncSession, data: UserCreate) -> User:
+    user = User(
+        username=data.username,
+        email=data.email,
+        password_hash=hash_password(data.password),
+    )
+    db.add(user)
+    try:
+        await db.commit()
+    except IntegrityError as exc:
+        await db.rollback()
+        raise DuplicateUserError() from exc
+
+    await db.refresh(user)
+    return user
+
+
+async def authenticate_user(
+    db: AsyncSession, username_or_email: str, password: str
+) -> User:
+    result = await db.execute(
+        select(User).where(
+            or_(User.username == username_or_email, User.email == username_or_email)
+        )
+    )
+    user = result.scalar_one_or_none()
+    if user is None or not verify_password(password, user.password_hash):
+        raise InvalidCredentialsError()
+    return user

backend/app/services/message_service.py

@@ -0,0 +1,30 @@
+import uuid
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models import Message
+
+
+async def create_message(
+    db: AsyncSession, room_id: uuid.UUID, user_id: uuid.UUID, content: str
+) -> Message:
+    message = Message(room_id=room_id, user_id=user_id, content=content)
+    db.add(message)
+    await db.commit()
+    await db.refresh(message)
+    return message
+
+
+async def list_recent_messages(
+    db: AsyncSession, room_id: uuid.UUID, limit: int = 50
+) -> list[Message]:
+    result = await db.execute(
+        select(Message)
+        .where(Message.room_id == room_id)
+        .order_by(Message.created_at.desc())
+        .limit(limit)
+    )
+    messages = list(result.scalars().all())
+    messages.reverse()
+    return messages

backend/app/services/room_service.py

@@ -0,0 +1,77 @@
+import uuid
+
+from sqlalchemy import select
+from sqlalchemy.exc import IntegrityError
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy.orm import selectinload
+
+from app.models import Room, RoomMembership, RoomRole
+from app.schemas.room import RoomCreate
+
+
+class DuplicateRoomError(Exception):
+    pass
+
+
+class RoomNotFoundError(Exception):
+    pass
+
+
+class RoomIsPrivateError(Exception):
+    pass
+
+
+async def create_room(db: AsyncSession, owner_id: uuid.UUID, data: RoomCreate) -> Room:
+    room = Room(name=data.name, description=data.description, owner_id=owner_id)
+    db.add(room)
+    try:
+        await db.flush()
+    except IntegrityError as exc:
+        await db.rollback()
+        raise DuplicateRoomError() from exc
+
+    db.add(RoomMembership(room_id=room.id, user_id=owner_id, role=RoomRole.owner))
+    await db.commit()
+    await db.refresh(room)
+    return room
+
+
+async def list_open_rooms(db: AsyncSession, user_id: uuid.UUID) -> list[tuple[Room, bool]]:
+    result = await db.execute(
+        select(Room)
+        .where(Room.is_private.is_(False))
+        .options(selectinload(Room.memberships))
+        .order_by(Room.created_at)
+    )
+    rooms = result.scalars().all()
+    return [
+        (room, any(m.user_id == user_id for m in room.memberships)) for room in rooms
+    ]
+
+
+async def get_room(db: AsyncSession, room_id: uuid.UUID) -> Room:
+    room = await db.get(Room, room_id)
+    if room is None:
+        raise RoomNotFoundError()
+    return room
+
+
+async def join_room(db: AsyncSession, room_id: uuid.UUID, user_id: uuid.UUID) -> RoomMembership:
+    room = await get_room(db, room_id)
+    if room.is_private:
+        raise RoomIsPrivateError()
+
+    result = await db.execute(
+        select(RoomMembership).where(
+            RoomMembership.room_id == room_id, RoomMembership.user_id == user_id
+        )
+    )
+    membership = result.scalar_one_or_none()
+    if membership is not None:
+        return membership
+
+    membership = RoomMembership(room_id=room_id, user_id=user_id, role=RoomRole.member)
+    db.add(membership)
+    await db.commit()
+    await db.refresh(membership)
+    return membership