diff --git a/app/core/database.py b/app/core/database.py
index be4cf83..e0d2820 100644
--- a/app/core/database.py
+++ b/app/core/database.py
@@ -14,4 +14,9 @@ AsyncSessionMaker = async_sessionmaker(bind=engine, expire_on_commit=False)
 async def get_session() -> AsyncGenerator[AsyncSession, None]:
     """Yield an async database session for request scope."""
     async with AsyncSessionMaker() as session:
-        yield session
+        try:
+            yield session
+            await session.commit()
+        except Exception:  # pragma: no cover - defensive cleanup
+            await session.rollback()
+            raise
diff --git a/app/repositories/deal_repo.py b/app/repositories/deal_repo.py
index 1f03ae0..a944716 100644
--- a/app/repositories/deal_repo.py
+++ b/app/repositories/deal_repo.py
@@ -108,6 +108,7 @@ class DealRepository:
 			if hasattr(deal, field):
 				setattr(deal, field, value)
 		await self._session.flush()
+		await self._session.refresh(deal)
 		return deal
 
 	def _apply_filters(
diff --git a/tests/api/v1/conftest.py b/tests/api/v1/conftest.py
index 61c6611..8c8fcb6 100644
--- a/tests/api/v1/conftest.py
+++ b/tests/api/v1/conftest.py
@@ -3,15 +3,31 @@ from __future__ import annotations
 
 from collections.abc import AsyncGenerator
 
+import pytest
 import pytest_asyncio
 from httpx import ASGITransport, AsyncClient
 from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
 
 from app.api.deps import get_db_session
+from app.core.security import password_hasher
 from app.main import create_app
 from app.models import Base
 
 
+@pytest.fixture(autouse=True)
+def stub_password_hasher(monkeypatch: pytest.MonkeyPatch) -> None:
+    """Replace bcrypt-dependent hashing with deterministic helpers for tests."""
+
+    def fake_hash(password: str) -> str:
+        return f"hashed-{password}"
+
+    def fake_verify(password: str, hashed_password: str) -> bool:
+        return hashed_password == f"hashed-{password}"
+
+    monkeypatch.setattr(password_hasher, "hash", fake_hash)
+    monkeypatch.setattr(password_hasher, "verify", fake_verify)
+
+
 @pytest_asyncio.fixture()
 async def session_factory() -> AsyncGenerator[async_sessionmaker[AsyncSession], None]:
     engine = create_async_engine("sqlite+aiosqlite:///:memory:", future=True)
@@ -30,7 +46,12 @@ async def client(
 
     async def _get_session_override() -> AsyncGenerator[AsyncSession, None]:
         async with session_factory() as session:
-            yield session
+            try:
+                yield session
+                await session.commit()
+            except Exception:
+                await session.rollback()
+                raise
 
     app.dependency_overrides[get_db_session] = _get_session_override
     transport = ASGITransport(app=app)
diff --git a/tests/api/v1/test_auth.py b/tests/api/v1/test_auth.py
new file mode 100644
index 0000000..b81c66d
--- /dev/null
+++ b/tests/api/v1/test_auth.py
@@ -0,0 +1,100 @@
+"""API tests for authentication endpoints."""
+from __future__ import annotations
+
+import pytest
+from httpx import AsyncClient
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker
+
+from app.core.security import password_hasher
+from app.models.organization import Organization
+from app.models.organization_member import OrganizationMember, OrganizationRole
+from app.models.user import User
+
+
+@pytest.mark.asyncio
+async def test_register_user_creates_organization_membership(
+    session_factory: async_sessionmaker[AsyncSession],
+    client: AsyncClient,
+) -> None:
+    payload = {
+        "email": "new-owner@example.com",
+        "password": "StrongPass123!",
+        "name": "Alice Owner",
+        "organization_name": "Rocket LLC",
+    }
+
+    response = await client.post("/api/v1/auth/register", json=payload)
+
+    assert response.status_code == 201
+    body = response.json()
+    assert body["token_type"] == "bearer"
+    assert "access_token" in body
+
+    async with session_factory() as session:
+        user = await session.scalar(select(User).where(User.email == payload["email"]))
+        assert user is not None
+
+        organization = await session.scalar(
+            select(Organization).where(Organization.name == payload["organization_name"])
+        )
+        assert organization is not None
+
+        membership = await session.scalar(
+            select(OrganizationMember).where(
+                OrganizationMember.organization_id == organization.id,
+                OrganizationMember.user_id == user.id,
+            )
+        )
+        assert membership is not None
+        assert membership.role == OrganizationRole.OWNER
+
+
+@pytest.mark.asyncio
+async def test_login_endpoint_returns_token_for_valid_credentials(
+    session_factory: async_sessionmaker[AsyncSession],
+    client: AsyncClient,
+) -> None:
+    async with session_factory() as session:
+        user = User(
+            email="login-user@example.com",
+            hashed_password=password_hasher.hash("Secret123!"),
+            name="Login User",
+            is_active=True,
+        )
+        session.add(user)
+        await session.commit()
+
+    response = await client.post(
+        "/api/v1/auth/login",
+        json={"email": "login-user@example.com", "password": "Secret123!"},
+    )
+
+    assert response.status_code == 200
+    body = response.json()
+    assert body["token_type"] == "bearer"
+    assert "access_token" in body
+
+
+@pytest.mark.asyncio
+async def test_token_endpoint_rejects_invalid_credentials(
+    session_factory: async_sessionmaker[AsyncSession],
+    client: AsyncClient,
+) -> None:
+    async with session_factory() as session:
+        user = User(
+            email="token-user@example.com",
+            hashed_password=password_hasher.hash("SuperSecret123"),
+            name="Token User",
+            is_active=True,
+        )
+        session.add(user)
+        await session.commit()
+
+    response = await client.post(
+        "/api/v1/auth/token",
+        json={"email": "token-user@example.com", "password": "wrong-pass"},
+    )
+
+    assert response.status_code == 401
+    assert response.json()["detail"] == "Invalid email or password"
diff --git a/tests/api/v1/test_deals.py b/tests/api/v1/test_deals.py
new file mode 100644
index 0000000..535b4a6
--- /dev/null
+++ b/tests/api/v1/test_deals.py
@@ -0,0 +1,113 @@
+"""API tests for deal endpoints."""
+from __future__ import annotations
+
+from decimal import Decimal
+
+import pytest
+from httpx import AsyncClient
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker
+
+from app.models.activity import Activity, ActivityType
+from app.models.deal import Deal, DealStage, DealStatus
+
+from tests.api.v1.task_activity_shared import auth_headers, make_token, prepare_scenario
+
+
+@pytest.mark.asyncio
+async def test_create_deal_endpoint_uses_context_owner(
+    session_factory: async_sessionmaker[AsyncSession],
+    client: AsyncClient,
+) -> None:
+    scenario = await prepare_scenario(session_factory)
+    token = make_token(scenario.user_id, scenario.user_email)
+
+    response = await client.post(
+        "/api/v1/deals/",
+        json={
+            "contact_id": scenario.contact_id,
+            "title": "Upsell Subscription",
+            "amount": 2500.0,
+            "currency": "USD",
+        },
+        headers=auth_headers(token, scenario),
+    )
+
+    assert response.status_code == 201
+    payload = response.json()
+    assert payload["owner_id"] == scenario.user_id
+    assert payload["organization_id"] == scenario.organization_id
+    assert payload["title"] == "Upsell Subscription"
+
+
+@pytest.mark.asyncio
+async def test_list_deals_endpoint_filters_by_status(
+    session_factory: async_sessionmaker[AsyncSession],
+    client: AsyncClient,
+) -> None:
+    scenario = await prepare_scenario(session_factory)
+    token = make_token(scenario.user_id, scenario.user_email)
+
+    async with session_factory() as session:
+        base_deal = await session.get(Deal, scenario.deal_id)
+        assert base_deal is not None
+        base_deal.status = DealStatus.NEW
+
+        won_deal = Deal(
+            organization_id=scenario.organization_id,
+            contact_id=scenario.contact_id,
+            owner_id=scenario.user_id,
+            title="Enterprise Upgrade",
+            amount=Decimal("8000"),
+            currency="USD",
+            status=DealStatus.WON,
+            stage=DealStage.CLOSED,
+        )
+        session.add(won_deal)
+        await session.commit()
+
+    response = await client.get(
+        "/api/v1/deals/?status=won",
+        headers=auth_headers(token, scenario),
+    )
+
+    assert response.status_code == 200
+    data = response.json()
+    assert len(data) == 1
+    assert data[0]["title"] == "Enterprise Upgrade"
+    assert data[0]["status"] == DealStatus.WON.value
+
+
+@pytest.mark.asyncio
+async def test_update_deal_endpoint_updates_stage_and_logs_activity(
+    session_factory: async_sessionmaker[AsyncSession],
+    client: AsyncClient,
+) -> None:
+    scenario = await prepare_scenario(session_factory)
+    token = make_token(scenario.user_id, scenario.user_email)
+
+    response = await client.patch(
+        f"/api/v1/deals/{scenario.deal_id}",
+        json={
+            "stage": DealStage.PROPOSAL.value,
+            "status": DealStatus.WON.value,
+            "amount": 5000.0,
+            "currency": "USD",
+        },
+        headers=auth_headers(token, scenario),
+    )
+
+    assert response.status_code == 200
+    body = response.json()
+    assert body["stage"] == DealStage.PROPOSAL.value
+    assert body["status"] == DealStatus.WON.value
+    assert Decimal(body["amount"]) == Decimal("5000")
+
+    async with session_factory() as session:
+        activity_types = await session.scalars(
+            select(Activity.type).where(Activity.deal_id == scenario.deal_id)
+        )
+        collected = set(activity_types.all())
+
+    assert ActivityType.STAGE_CHANGED in collected
+    assert ActivityType.STATUS_CHANGED in collected
diff --git a/tests/api/v1/test_users.py b/tests/api/v1/test_users.py
new file mode 100644
index 0000000..447f52d
--- /dev/null
+++ b/tests/api/v1/test_users.py
@@ -0,0 +1,88 @@
+"""API tests for user endpoints."""
+from __future__ import annotations
+
+import pytest
+from httpx import AsyncClient
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker
+
+from app.core.security import password_hasher
+from app.models.user import User
+
+
+async def _seed_user(
+    session_factory: async_sessionmaker[AsyncSession],
+    *,
+    email: str,
+    name: str,
+) -> int:
+    async with session_factory() as session:
+        user = User(
+            email=email,
+            hashed_password=password_hasher.hash("SeedPass123!"),
+            name=name,
+            is_active=True,
+        )
+        session.add(user)
+        await session.commit()
+        return user.id
+
+
+@pytest.mark.asyncio
+async def test_create_user_endpoint_persists_user(
+    session_factory: async_sessionmaker[AsyncSession],
+    client: AsyncClient,
+) -> None:
+    payload = {
+        "email": "api-user@example.com",
+        "name": "API User",
+        "password": "UserPass123!",
+    }
+
+    response = await client.post("/api/v1/users/", json=payload)
+
+    assert response.status_code == 201
+    body = response.json()
+    assert body["email"] == payload["email"]
+
+    async with session_factory() as session:
+        user = await session.get(User, body["id"])
+        assert user is not None
+        assert user.email == payload["email"]
+        assert user.hashed_password != payload["password"]
+
+
+@pytest.mark.asyncio
+async def test_list_users_endpoint_returns_existing_users(
+    session_factory: async_sessionmaker[AsyncSession],
+    client: AsyncClient,
+) -> None:
+    await _seed_user(session_factory, email="list-a@example.com", name="List A")
+    await _seed_user(session_factory, email="list-b@example.com", name="List B")
+
+    response = await client.get("/api/v1/users/")
+
+    assert response.status_code == 200
+    data = response.json()
+    emails = {item["email"] for item in data}
+    assert {"list-a@example.com", "list-b@example.com"}.issubset(emails)
+
+
+@pytest.mark.asyncio
+async def test_get_user_endpoint_returns_single_user(
+    session_factory: async_sessionmaker[AsyncSession],
+    client: AsyncClient,
+) -> None:
+    user_id = await _seed_user(session_factory, email="detail@example.com", name="Detail User")
+
+    response = await client.get(f"/api/v1/users/{user_id}")
+
+    assert response.status_code == 200
+    payload = response.json()
+    assert payload["id"] == user_id
+    assert payload["email"] == "detail@example.com"
+
+
+@pytest.mark.asyncio
+async def test_get_user_endpoint_returns_404_for_missing_user(client: AsyncClient) -> None:
+    response = await client.get("/api/v1/users/999")
+    assert response.status_code == 404
\ No newline at end of file