diff --git a/app/api/v1/auth.py b/app/api/v1/auth.py
index a44b86d..ce6ac79 100644
--- a/app/api/v1/auth.py
+++ b/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()
diff --git a/app/api/v1/organizations.py b/app/api/v1/organizations.py
index 52d2dbc..70e679b 100644
--- a/app/api/v1/organizations.py
+++ b/app/api/v1/organizations.py
@@ -1,16 +1,36 @@
 """Organization-related API endpoints."""
 from __future__ import annotations
 
-from fastapi import APIRouter, Depends
+from fastapi import APIRouter, Depends, HTTPException, status
+from pydantic import BaseModel, EmailStr
 
-from app.api.deps import get_current_user, get_organization_repository
+from app.api.deps import (
+    get_current_user,
+    get_organization_context,
+    get_organization_repository,
+    get_organization_service,
+    get_user_repository,
+)
 from app.models.organization import OrganizationRead
+from app.models.organization_member import OrganizationMemberRead, OrganizationRole
 from app.models.user import User
 from app.repositories.org_repo import OrganizationRepository
+from app.repositories.user_repo import UserRepository
+from app.services.organization_service import (
+    OrganizationContext,
+    OrganizationForbiddenError,
+    OrganizationMemberAlreadyExistsError,
+    OrganizationService,
+)
 
 router = APIRouter(prefix="/organizations", tags=["organizations"])
 
 
+class AddMemberPayload(BaseModel):
+    email: EmailStr
+    role: OrganizationRole = OrganizationRole.MEMBER
+
+
 @router.get("/me", response_model=list[OrganizationRead])
 async def list_user_organizations(
     current_user: User = Depends(get_current_user),
@@ -20,3 +40,26 @@ async def list_user_organizations(
 
     organizations = await repo.list_for_user(current_user.id)
     return [OrganizationRead.model_validate(org) for org in organizations]
+
+
+@router.post("/members", response_model=OrganizationMemberRead, status_code=status.HTTP_201_CREATED)
+async def add_member_to_organization(
+    payload: AddMemberPayload,
+    context: OrganizationContext = Depends(get_organization_context),
+    service: OrganizationService = Depends(get_organization_service),
+    user_repo: UserRepository = Depends(get_user_repository),
+) -> OrganizationMemberRead:
+    """Allow owners/admins to add existing users to their organization."""
+
+    user = await user_repo.get_by_email(payload.email)
+    if user is None:
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="User not found")
+
+    try:
+        membership = await service.add_member(context=context, user_id=user.id, role=payload.role)
+    except OrganizationMemberAlreadyExistsError as exc:
+        raise HTTPException(status_code=status.HTTP_409_CONFLICT, detail=str(exc)) from exc
+    except OrganizationForbiddenError as exc:
+        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail=str(exc)) from exc
+
+    return OrganizationMemberRead.model_validate(membership)
diff --git a/app/models/activity.py b/app/models/activity.py
index 89daa10..b3d16dd 100644
--- a/app/models/activity.py
+++ b/app/models/activity.py
@@ -11,7 +11,7 @@ from sqlalchemy.dialects.postgresql import JSONB
 from sqlalchemy.types import JSON as GenericJSON, TypeDecorator
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
-from app.models.base import Base
+from app.models.base import Base, enum_values
 
 
 class ActivityType(StrEnum):
@@ -46,7 +46,9 @@ class Activity(Base):
     author_id: Mapped[int | None] = mapped_column(
         ForeignKey("users.id", ondelete="SET NULL"), nullable=True
     )
-    type: Mapped[ActivityType] = mapped_column(SqlEnum(ActivityType, name="activity_type"), nullable=False)
+    type: Mapped[ActivityType] = mapped_column(
+        SqlEnum(ActivityType, name="activity_type", values_callable=enum_values), nullable=False
+    )
     payload: Mapped[dict[str, Any]] = mapped_column(
         JSONBCompat().with_variant(GenericJSON(), "sqlite"),
         nullable=False,
diff --git a/app/models/base.py b/app/models/base.py
index 6e65077..3eb91e7 100644
--- a/app/models/base.py
+++ b/app/models/base.py
@@ -1,6 +1,13 @@
 """Declarative base for SQLAlchemy models."""
+from __future__ import annotations
+
+from enum import StrEnum
+from typing import TypeVar
+
 from sqlalchemy.orm import DeclarativeBase, declared_attr
 
+EnumT = TypeVar("EnumT", bound=StrEnum)
+
 
 class Base(DeclarativeBase):
     """Base class that configures naming conventions."""
@@ -8,3 +15,9 @@ class Base(DeclarativeBase):
     @declared_attr.directive
     def __tablename__(cls) -> str:  # type: ignore[misc]
         return cls.__name__.lower()
+
+
+def enum_values(enum_cls: type[EnumT]) -> list[str]:
+    """Return enum member values to keep DB representation stable."""
+
+    return [member.value for member in enum_cls]
diff --git a/app/models/deal.py b/app/models/deal.py
index 628ea8e..b142589 100644
--- a/app/models/deal.py
+++ b/app/models/deal.py
@@ -9,7 +9,7 @@ from pydantic import BaseModel, ConfigDict
 from sqlalchemy import DateTime, Enum as SqlEnum, ForeignKey, Integer, Numeric, String, func
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
-from app.models.base import Base
+from app.models.base import Base, enum_values
 
 
 class DealStatus(StrEnum):
@@ -39,10 +39,14 @@ class Deal(Base):
     amount: Mapped[Decimal | None] = mapped_column(Numeric(12, 2), nullable=True)
     currency: Mapped[str | None] = mapped_column(String(8), nullable=True)
     status: Mapped[DealStatus] = mapped_column(
-        SqlEnum(DealStatus, name="deal_status"), nullable=False, default=DealStatus.NEW
+        SqlEnum(DealStatus, name="deal_status", values_callable=enum_values),
+        nullable=False,
+        default=DealStatus.NEW,
     )
     stage: Mapped[DealStage] = mapped_column(
-        SqlEnum(DealStage, name="deal_stage"), nullable=False, default=DealStage.QUALIFICATION
+        SqlEnum(DealStage, name="deal_stage", values_callable=enum_values),
+        nullable=False,
+        default=DealStage.QUALIFICATION,
     )
     created_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=True), server_default=func.now(), nullable=False
diff --git a/app/models/organization_member.py b/app/models/organization_member.py
index ec434d3..ab67c21 100644
--- a/app/models/organization_member.py
+++ b/app/models/organization_member.py
@@ -8,7 +8,7 @@ from pydantic import BaseModel, ConfigDict
 from sqlalchemy import DateTime, Enum as SqlEnum, ForeignKey, Integer, UniqueConstraint, func
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
-from app.models.base import Base
+from app.models.base import Base, enum_values
 
 
 class OrganizationRole(StrEnum):
@@ -30,7 +30,11 @@ class OrganizationMember(Base):
     organization_id: Mapped[int] = mapped_column(ForeignKey("organizations.id", ondelete="CASCADE"))
     user_id: Mapped[int] = mapped_column(ForeignKey("users.id", ondelete="CASCADE"))
     role: Mapped[OrganizationRole] = mapped_column(
-        SqlEnum(OrganizationRole, name="organization_role"),
+        SqlEnum(
+            OrganizationRole,
+            name="organization_role",
+            values_callable=enum_values,
+        ),
         nullable=False,
         default=OrganizationRole.MEMBER,
     )
diff --git a/app/services/organization_service.py b/app/services/organization_service.py
index c2ddafc..6d8354a 100644
--- a/app/services/organization_service.py
+++ b/app/services/organization_service.py
@@ -24,6 +24,10 @@ class OrganizationForbiddenError(OrganizationServiceError):
     """Raised when a user does not have enough privileges."""
 
 
+class OrganizationMemberAlreadyExistsError(OrganizationServiceError):
+    """Raised when attempting to add a duplicate organization member."""
+
+
 @dataclass(slots=True, frozen=True)
 class OrganizationContext:
     """Resolved organization and membership information for a request."""
@@ -84,4 +88,29 @@ class OrganizationService:
         """Members can only mutate entities they own (contacts/deals/tasks)."""
 
         if context.role == OrganizationRole.MEMBER and owner_id != context.user_id:
-            raise OrganizationForbiddenError("Members can only modify their own records")
\ No newline at end of file
+            raise OrganizationForbiddenError("Members can only modify their own records")
+
+    async def add_member(
+        self,
+        *,
+        context: OrganizationContext,
+        user_id: int,
+        role: OrganizationRole,
+    ) -> OrganizationMember:
+        """Add a user to the current organization enforced by permissions."""
+
+        self.ensure_can_manage_settings(context)
+
+        existing = await self._repository.get_membership(context.organization_id, user_id)
+        if existing is not None:
+            raise OrganizationMemberAlreadyExistsError("User already belongs to this organization")
+
+        membership = OrganizationMember(
+            organization_id=context.organization_id,
+            user_id=user_id,
+            role=role,
+        )
+        self._repository.session.add(membership)
+        await self._repository.session.commit()
+        await self._repository.session.refresh(membership)
+        return membership
\ No newline at end of file
diff --git a/test_db_filling.sql b/test_db_filling.sql
new file mode 100644
index 0000000..1f458d3
--- /dev/null
+++ b/test_db_filling.sql
@@ -0,0 +1,65 @@
+TRUNCATE TABLE activities CASCADE;
+TRUNCATE TABLE contacts CASCADE;
+TRUNCATE TABLE deals CASCADE;
+TRUNCATE TABLE organization_members CASCADE;
+TRUNCATE TABLE organizations CASCADE;
+TRUNCATE TABLE tasks CASCADE;
+TRUNCATE TABLE users CASCADE;
+
+-- Пользователи
+INSERT INTO users (id, email, hashed_password, name, is_active, created_at)
+VALUES
+    (1, 'owner@example.com', 'pbkdf2_sha256$260000$demo$Tk5YEtPJj6..', 'Alice Owner', TRUE, now()),
+    (2, 'manager@example.com', 'pbkdf2_sha256$260000$demo$Tk5YEtPJj6..', 'Bob Manager', TRUE, now()),
+    (3, 'member@example.com',  'pbkdf2_sha256$260000$demo$Tk5YEtPJj6..', 'Carol Member', TRUE, now());
+
+-- Организации
+INSERT INTO organizations (id, name, created_at)
+VALUES
+    (1, 'Acme Corp', now()),
+    (2, 'Beta LLC', now());
+
+-- Участники организаций
+INSERT INTO organization_members (id, organization_id, user_id, role, created_at)
+VALUES
+    (1, 1, 1, 'owner', now()),
+    (2, 1, 2, 'manager', now()),
+    (3, 1, 3, 'member', now()),
+    (4, 2, 2, 'owner', now());
+
+-- Контакты (в рамках орг. 1)
+INSERT INTO contacts (id, organization_id, owner_id, name, email, phone, created_at)
+VALUES
+    (1, 1, 2, 'John Doe', 'john.doe@acme.com', '+1-202-555-0101', now()),
+    (2, 1, 3, 'Jane Smith', 'jane.smith@acme.com', '+1-202-555-0102', now());
+
+-- Сделки
+INSERT INTO deals (
+    id, organization_id, contact_id, owner_id, title, amount, currency,
+    status, stage, created_at, updated_at
+) VALUES
+    (1, 1, 1, 2, 'Website Redesign', 15000.00, 'USD', 'in_progress', 'proposal', now(), now()),
+    (2, 1, 2, 3, 'Support Contract', 5000.00, 'USD', 'new', 'qualification', now(), now());
+
+-- Задачи
+INSERT INTO tasks (
+    id, deal_id, title, description, due_date, is_done, created_at
+) VALUES
+    (1, 1, 'Prepare proposal', 'Draft technical scope', now() + interval '5 days', FALSE, now()),
+    (2, 2, 'Call client', 'Discuss onboarding plan', now() + interval '3 days', FALSE, now());
+
+-- Активности
+INSERT INTO activities (
+    id, deal_id, author_id, type, payload, created_at
+) VALUES
+    (1, 1, 2, 'comment', '{"text": "Kickoff meeting scheduled"}', now()),
+    (2, 1, 2, 'status_changed', '{"old_status": "new", "new_status": "in_progress"}', now()),
+    (3, 2, 3, 'task_created', '{"task_id": 2, "title": "Call client"}', now());
+
+SELECT setval('users_id_seq', COALESCE((SELECT MAX(id) FROM users), 0), (SELECT MAX(id) FROM users) IS NOT NULL);
+SELECT setval('organizations_id_seq', COALESCE((SELECT MAX(id) FROM organizations), 0), (SELECT MAX(id) FROM organizations) IS NOT NULL);
+SELECT setval('organization_members_id_seq', COALESCE((SELECT MAX(id) FROM organization_members), 0), (SELECT MAX(id) FROM organization_members) IS NOT NULL);
+SELECT setval('contacts_id_seq', COALESCE((SELECT MAX(id) FROM contacts), 0), (SELECT MAX(id) FROM contacts) IS NOT NULL);
+SELECT setval('deals_id_seq', COALESCE((SELECT MAX(id) FROM deals), 0), (SELECT MAX(id) FROM deals) IS NOT NULL);
+SELECT setval('tasks_id_seq', COALESCE((SELECT MAX(id) FROM tasks), 0), (SELECT MAX(id) FROM tasks) IS NOT NULL);
+SELECT setval('activities_id_seq', COALESCE((SELECT MAX(id) FROM activities), 0), (SELECT MAX(id) FROM activities) IS NOT NULL);
\ No newline at end of file
diff --git a/tests/api/v1/test_auth.py b/tests/api/v1/test_auth.py
index 37eb090..2369747 100644
--- a/tests/api/v1/test_auth.py
+++ b/tests/api/v1/test_auth.py
@@ -51,6 +51,57 @@ async def test_register_user_creates_organization_membership(
         assert membership.role == OrganizationRole.OWNER
 
 
+@pytest.mark.asyncio
+async def test_register_user_without_organization_succeeds(
+    session_factory: async_sessionmaker[AsyncSession],
+    client: AsyncClient,
+) -> None:
+    payload = {
+        "email": "solo-user@example.com",
+        "password": "StrongPass123!",
+        "name": "Solo User",
+    }
+
+    response = await client.post("/api/v1/auth/register", json=payload)
+
+    assert response.status_code == 201
+
+    async with session_factory() as session:
+        user = await session.scalar(select(User).where(User.email == payload["email"]))
+        assert user is not None
+
+        membership = await session.scalar(
+            select(OrganizationMember).where(OrganizationMember.user_id == user.id)
+        )
+        assert membership is None
+
+
+@pytest.mark.asyncio
+async def test_register_fails_when_organization_exists(
+    client: AsyncClient,
+) -> None:
+    payload = {
+        "email": "owner-one@example.com",
+        "password": "StrongPass123!",
+        "name": "Owner One",
+        "organization_name": "Duplicate Org",
+    }
+    response = await client.post("/api/v1/auth/register", json=payload)
+    assert response.status_code == 201
+
+    duplicate_payload = {
+        "email": "owner-two@example.com",
+        "password": "StrongPass123!",
+        "name": "Owner Two",
+        "organization_name": "Duplicate Org",
+    }
+
+    duplicate_response = await client.post("/api/v1/auth/register", json=duplicate_payload)
+
+    assert duplicate_response.status_code == 409
+    assert duplicate_response.json()["detail"] == "Organization already exists"
+
+
 @pytest.mark.asyncio
 async def test_login_endpoint_returns_token_for_valid_credentials(
     session_factory: async_sessionmaker[AsyncSession],
diff --git a/tests/api/v1/test_organizations.py b/tests/api/v1/test_organizations.py
index 13a97c3..c078ddd 100644
--- a/tests/api/v1/test_organizations.py
+++ b/tests/api/v1/test_organizations.py
@@ -7,6 +7,7 @@ from typing import AsyncGenerator, Sequence, cast
 import pytest
 import pytest_asyncio
 from httpx import ASGITransport, AsyncClient
+from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
 from sqlalchemy.schema import Table
 
@@ -101,3 +102,188 @@ async def test_list_user_organizations_returns_memberships(
 async def test_list_user_organizations_requires_token(client: AsyncClient) -> None:
     response = await client.get("/api/v1/organizations/me")
     assert response.status_code == 401
+
+
+@pytest.mark.asyncio
+async def test_owner_can_add_member_to_organization(
+    session_factory: async_sessionmaker[AsyncSession],
+    client: AsyncClient,
+) -> None:
+    async with session_factory() as session:
+        owner = User(email="owner-add@example.com", hashed_password="hashed", name="Owner", is_active=True)
+        invitee = User(email="new-member@example.com", hashed_password="hashed", name="Member", is_active=True)
+        session.add_all([owner, invitee])
+        await session.flush()
+
+        organization = Organization(name="Membership LLC")
+        session.add(organization)
+        await session.flush()
+
+        membership = OrganizationMember(
+            organization_id=organization.id,
+            user_id=owner.id,
+            role=OrganizationRole.OWNER,
+        )
+        session.add(membership)
+        await session.commit()
+
+    token = jwt_service.create_access_token(
+        subject=str(owner.id),
+        expires_delta=timedelta(minutes=30),
+        claims={"email": owner.email},
+    )
+
+    response = await client.post(
+        "/api/v1/organizations/members",
+        headers={
+            "Authorization": f"Bearer {token}",
+            "X-Organization-Id": str(organization.id),
+        },
+        json={"email": invitee.email, "role": OrganizationRole.MANAGER.value},
+    )
+
+    assert response.status_code == 201
+    payload = response.json()
+    assert payload["organization_id"] == organization.id
+    assert payload["user_id"] == invitee.id
+    assert payload["role"] == OrganizationRole.MANAGER.value
+
+    async with session_factory() as session:
+        new_membership = await session.scalar(
+            select(OrganizationMember).where(
+                OrganizationMember.organization_id == organization.id,
+                OrganizationMember.user_id == invitee.id,
+            )
+        )
+        assert new_membership is not None
+        assert new_membership.role == OrganizationRole.MANAGER
+
+
+@pytest.mark.asyncio
+async def test_add_member_requires_existing_user(
+    session_factory: async_sessionmaker[AsyncSession],
+    client: AsyncClient,
+) -> None:
+    async with session_factory() as session:
+        owner = User(email="owner-missing@example.com", hashed_password="hashed", name="Owner", is_active=True)
+        session.add(owner)
+        await session.flush()
+
+        organization = Organization(name="Missing LLC")
+        session.add(organization)
+        await session.flush()
+
+        membership = OrganizationMember(
+            organization_id=organization.id,
+            user_id=owner.id,
+            role=OrganizationRole.OWNER,
+        )
+        session.add(membership)
+        await session.commit()
+
+    token = jwt_service.create_access_token(
+        subject=str(owner.id),
+        expires_delta=timedelta(minutes=30),
+        claims={"email": owner.email},
+    )
+
+    response = await client.post(
+        "/api/v1/organizations/members",
+        headers={
+            "Authorization": f"Bearer {token}",
+            "X-Organization-Id": str(organization.id),
+        },
+        json={"email": "ghost@example.com"},
+    )
+
+    assert response.status_code == 404
+    assert response.json()["detail"] == "User not found"
+
+
+@pytest.mark.asyncio
+async def test_member_role_cannot_add_users(
+    session_factory: async_sessionmaker[AsyncSession],
+    client: AsyncClient,
+) -> None:
+    async with session_factory() as session:
+        member_user = User(email="member@example.com", hashed_password="hashed", name="Member", is_active=True)
+        invitee = User(email="invitee@example.com", hashed_password="hashed", name="Invitee", is_active=True)
+        session.add_all([member_user, invitee])
+        await session.flush()
+
+        organization = Organization(name="Members Only LLC")
+        session.add(organization)
+        await session.flush()
+
+        membership = OrganizationMember(
+            organization_id=organization.id,
+            user_id=member_user.id,
+            role=OrganizationRole.MEMBER,
+        )
+        session.add(membership)
+        await session.commit()
+
+    token = jwt_service.create_access_token(
+        subject=str(member_user.id),
+        expires_delta=timedelta(minutes=30),
+        claims={"email": member_user.email},
+    )
+
+    response = await client.post(
+        "/api/v1/organizations/members",
+        headers={
+            "Authorization": f"Bearer {token}",
+            "X-Organization-Id": str(organization.id),
+        },
+        json={"email": invitee.email},
+    )
+
+    assert response.status_code == 403
+    assert response.json()["detail"] == "Only owner/admin can modify organization settings"
+
+
+@pytest.mark.asyncio
+async def test_cannot_add_duplicate_member(
+    session_factory: async_sessionmaker[AsyncSession],
+    client: AsyncClient,
+) -> None:
+    async with session_factory() as session:
+        owner = User(email="dup-owner@example.com", hashed_password="hashed", name="Owner", is_active=True)
+        invitee = User(email="dup-member@example.com", hashed_password="hashed", name="Invitee", is_active=True)
+        session.add_all([owner, invitee])
+        await session.flush()
+
+        organization = Organization(name="Duplicate LLC")
+        session.add(organization)
+        await session.flush()
+
+        owner_membership = OrganizationMember(
+            organization_id=organization.id,
+            user_id=owner.id,
+            role=OrganizationRole.OWNER,
+        )
+        invitee_membership = OrganizationMember(
+            organization_id=organization.id,
+            user_id=invitee.id,
+            role=OrganizationRole.MEMBER,
+        )
+        session.add_all([owner_membership, invitee_membership])
+        await session.commit()
+
+    token = jwt_service.create_access_token(
+        subject=str(owner.id),
+        expires_delta=timedelta(minutes=30),
+        claims={"email": owner.email},
+    )
+
+    response = await client.post(
+        "/api/v1/organizations/members",
+        headers={
+            "Authorization": f"Bearer {token}",
+            "X-Organization-Id": str(organization.id),
+        },
+        json={"email": invitee.email},
+    )
+
+    assert response.status_code == 409
+    assert response.json()["detail"] == "User already belongs to this organization"
diff --git a/tests/models/test_enums.py b/tests/models/test_enums.py
new file mode 100644
index 0000000..9c4021f
--- /dev/null
+++ b/tests/models/test_enums.py
@@ -0,0 +1,32 @@
+"""Regression tests ensuring Enum mappings store lowercase values."""
+from __future__ import annotations
+
+from enum import StrEnum
+
+from app.models.activity import Activity, ActivityType
+from app.models.deal import Deal, DealStage, DealStatus
+from app.models.organization_member import OrganizationMember, OrganizationRole
+
+
+def _values(enum_cls: type[StrEnum]) -> list[str]:
+    return [member.value for member in enum_cls]
+
+
+def test_organization_role_column_uses_value_strings() -> None:
+    role_type = OrganizationMember.__table__.c.role.type  # noqa: SLF001 - runtime inspection
+    assert role_type.enums == _values(OrganizationRole)
+
+
+def test_deal_status_column_uses_value_strings() -> None:
+    status_type = Deal.__table__.c.status.type  # noqa: SLF001 - runtime inspection
+    assert status_type.enums == _values(DealStatus)
+
+
+def test_deal_stage_column_uses_value_strings() -> None:
+    stage_type = Deal.__table__.c.stage.type  # noqa: SLF001 - runtime inspection
+    assert stage_type.enums == _values(DealStage)
+
+
+def test_activity_type_column_uses_value_strings() -> None:
+    activity_type = Activity.__table__.c.type.type  # noqa: SLF001 - runtime inspection
+    assert activity_type.enums == _values(ActivityType)