feat: enhance organization management; add member registration and validation, update user registration flow, and improve enum handling

app/api/v1/auth.py

@@ -3,6 +3,7 @@ from __future__ import annotations
 
 from pydantic import BaseModel, EmailStr
 from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy import select
 from sqlalchemy.exc import IntegrityError
 
 from app.api.deps import get_auth_service, get_user_repository
@@ -19,7 +20,7 @@ class RegisterRequest(BaseModel):
     email: EmailStr
     password: str
     name: str
-    organization_name: str
+    organization_name: str | None = None
 
 
 router = APIRouter(prefix="/auth", tags=["auth"])
@@ -37,21 +38,33 @@ async def register_user(
     if existing is not None:
         raise HTTPException(status_code=status.HTTP_409_CONFLICT, detail="User already exists")
 
-    organization = Organization(name=payload.organization_name)
-    repo.session.add(organization)
-    await repo.session.flush()
+    organization: Organization | None = None
+    if payload.organization_name:
+        existing_org = await repo.session.scalar(
+            select(Organization).where(Organization.name == payload.organization_name)
+        )
+        if existing_org is not None:
+            raise HTTPException(
+                status_code=status.HTTP_409_CONFLICT,
+                detail="Organization already exists",
+            )
+
+        organization = Organization(name=payload.organization_name)
+        repo.session.add(organization)
+        await repo.session.flush()
 
     user_data = UserCreate(email=payload.email, password=payload.password, name=payload.name)
     hashed_password = password_hasher.hash(payload.password)
 
     try:
         user = await repo.create(data=user_data, hashed_password=hashed_password)
-        membership = OrganizationMember(
-            organization_id=organization.id,
-            user_id=user.id,
-            role=OrganizationRole.OWNER,
-        )
-        repo.session.add(membership)
+        if organization is not None:
+            membership = OrganizationMember(
+                organization_id=organization.id,
+                user_id=user.id,
+                role=OrganizationRole.OWNER,
+            )
+            repo.session.add(membership)
         await repo.session.commit()
     except IntegrityError as exc:
         await repo.session.rollback()