service with accrual interest and loan update tested

backend/ruff.toml

@@ -24,3 +24,4 @@ ignore = [
 [lint.extend-per-file-ignores]
 "test*.py" = ["S101", "S105", "S106", "PT011", "PLR2004"]
 "models*.py" = ["FA102"]
+"dto.py" = ["TC001", "TC003"]

backend/tests/test_crud.py

@@ -56,7 +56,9 @@ def make_exchange(session: Session, user_id: int, name: str = "NASDAQ") -> int:
     return cast("int", exchange.id)
 
 
-def make_cycle(session: Session, user_id: int, exchange_id: int, friendly_name: str = "Test Cycle") -> int:
+def make_cycle(
+    session: Session, user_id: int, exchange_id: int, friendly_name: str = "Test Cycle"
+) -> int:
     cycle = models.Cycles(
         user_id=user_id,
         friendly_name=friendly_name,
@@ -72,7 +74,9 @@ def make_cycle(session: Session, user_id: int, exchange_id: int, friendly_name:
     return cast("int", cycle.id)
 
 
-def make_trade(session: Session, user_id: int, cycle_id: int, friendly_name: str = "Test Trade") -> int:
+def make_trade(
+    session: Session, user_id: int, cycle_id: int, friendly_name: str = "Test Trade"
+) -> int:
     cycle: models.Cycles | None = session.get(models.Cycles, cycle_id)
     assert cycle is not None
     exchange_id = cycle.exchange_id
@@ -137,13 +141,17 @@ def _ensure_utc_aware(dt: datetime | None) -> datetime | None:
     return dt.astimezone(timezone.utc)
 
 
-def _validate_timestamp(actual: datetime, expected: datetime, tolerance: timedelta) -> None:
+def _validate_timestamp(
+    actual: datetime, expected: datetime, tolerance: timedelta
+) -> None:
     actual_utc = _ensure_utc_aware(actual)
     expected_utc = _ensure_utc_aware(expected)
     assert actual_utc is not None
     assert expected_utc is not None
     delta = abs(actual_utc - expected_utc)
-    assert delta <= tolerance, f"Timestamps differ by {delta}, which exceeds tolerance of {tolerance}"
+    assert delta <= tolerance, (
+        f"Timestamps differ by {delta}, which exceeds tolerance of {tolerance}"
+    )
 
 
 # Trades
@@ -470,7 +478,9 @@ def test_update_trade_friendly_name(session: Session) -> None:
     trade_id = make_trade(session, user_id, cycle_id)
 
     new_friendly_name = "Updated Trade Name"
-    updated_trade = crud.update_trade_friendly_name(session, trade_id, new_friendly_name)
+    updated_trade = crud.update_trade_friendly_name(
+        session, trade_id, new_friendly_name
+    )
     assert updated_trade is not None
     assert updated_trade.id == trade_id
     assert updated_trade.friendly_name == new_friendly_name
@@ -624,7 +634,9 @@ def test_get_cycles_by_user_id(session: Session) -> None:
 def test_update_cycle(session: Session) -> None:
     user_id = make_user(session)
     exchange_id = make_exchange(session, user_id)
-    cycle_id = make_cycle(session, user_id, exchange_id, friendly_name="Initial Cycle Name")
+    cycle_id = make_cycle(
+        session, user_id, exchange_id, friendly_name="Initial Cycle Name"
+    )
 
     update_data = {
         "friendly_name": "Updated Cycle Name",
@@ -646,14 +658,20 @@ def test_update_cycle(session: Session) -> None:
 def test_update_cycle_immutable_fields(session: Session) -> None:
     user_id = make_user(session)
     exchange_id = make_exchange(session, user_id)
-    cycle_id = make_cycle(session, user_id, exchange_id, friendly_name="Initial Cycle Name")
+    cycle_id = make_cycle(
+        session, user_id, exchange_id, friendly_name="Initial Cycle Name"
+    )
 
     # Attempt to update immutable fields
     update_data = {
         "id": cycle_id + 1,  # Trying to change the ID
         "user_id": user_id + 1,  # Trying to change the user_id
-        "start_date": datetime(2020, 1, 1, tzinfo=timezone.utc).date(),  # Trying to change start_date
-        "created_at": datetime(2020, 1, 1, tzinfo=timezone.utc),  # Trying to change created_at
+        "start_date": datetime(
+            2020, 1, 1, tzinfo=timezone.utc
+        ).date(),  # Trying to change start_date
+        "created_at": datetime(
+            2020, 1, 1, tzinfo=timezone.utc
+        ),  # Trying to change created_at
         "friendly_name": "Valid Update",  # Valid field to update
     }
 
@@ -685,7 +703,10 @@ def test_create_cycle_loan_event(session: Session) -> None:
     assert loan_event.id is not None
     assert loan_event.cycle_id == cycle_id
     assert loan_event.loan_amount_cents == loan_data["loan_amount_cents"]
-    assert loan_event.loan_interest_rate_tenth_bps == loan_data["loan_interest_rate_tenth_bps"]
+    assert (
+        loan_event.loan_interest_rate_tenth_bps
+        == loan_data["loan_interest_rate_tenth_bps"]
+    )
     assert loan_event.notes == loan_data["notes"]
     assert loan_event.effective_date == now.date()
     _validate_timestamp(loan_event.created_at, now, timedelta(seconds=1))
@@ -695,12 +716,41 @@ def test_create_cycle_loan_event(session: Session) -> None:
     assert actual_loan_event is not None
     assert actual_loan_event.cycle_id == cycle_id
     assert actual_loan_event.loan_amount_cents == loan_data["loan_amount_cents"]
-    assert actual_loan_event.loan_interest_rate_tenth_bps == loan_data["loan_interest_rate_tenth_bps"]
+    assert (
+        actual_loan_event.loan_interest_rate_tenth_bps
+        == loan_data["loan_interest_rate_tenth_bps"]
+    )
     assert actual_loan_event.notes == loan_data["notes"]
     assert actual_loan_event.effective_date == now.date()
     _validate_timestamp(actual_loan_event.created_at, now, timedelta(seconds=1))
 
 
+def test_create_cycle_loan_event_same_date_error(session: Session) -> None:
+    user_id = make_user(session)
+    exchange_id = make_exchange(session, user_id)
+    cycle_id = make_cycle(session, user_id, exchange_id)
+
+    loan_data_1 = {
+        "cycle_id": cycle_id,
+        "loan_amount_cents": 100000,
+        "loan_interest_rate_tenth_bps": 5000,
+        "effective_date": datetime(2023, 1, 1, tzinfo=timezone.utc).date(),
+        "notes": "First loan event",
+    }
+    loan_data_2 = {
+        "cycle_id": cycle_id,
+        "loan_amount_cents": 150000,
+        "loan_interest_rate_tenth_bps": 4500,
+        "effective_date": datetime(2023, 1, 1, tzinfo=timezone.utc).date(),
+        "notes": "Second loan event same date",
+    }
+
+    crud.create_cycle_loan_event(session, loan_data_1)
+    with pytest.raises(ValueError) as excinfo:
+        crud.create_cycle_loan_event(session, loan_data_2)
+    assert "create_cycle_loan_event integrity error" in str(excinfo.value)
+
+
 def test_get_cycle_loan_events_by_cycle_id(session: Session) -> None:
     user_id = make_user(session)
     exchange_id = make_exchange(session, user_id)
@@ -729,34 +779,77 @@ def test_get_cycle_loan_events_by_cycle_id(session: Session) -> None:
     notes = [event.notes for event in loan_events]
     assert loan_events[0].notes == loan_data_2["notes"]
     assert loan_events[0].effective_date == yesterday
-    assert notes == ["Second loan event", "First loan event"]  # Ordered by effective_date desc
+    assert notes == [
+        "Second loan event",
+        "First loan event",
+    ]  # Ordered by effective_date desc
 
 
-def test_get_cycle_loan_events_by_cycle_id_same_date(session: Session) -> None:
+def test_get_cycle_loan_event_by_cycle_id_and_effective_date(session: Session) -> None:
     user_id = make_user(session)
     exchange_id = make_exchange(session, user_id)
     cycle_id = make_cycle(session, user_id, exchange_id)
 
-    loan_data_1 = {
+    effective_date = datetime(2023, 1, 1, tzinfo=timezone.utc).date()
+    loan_data = {
         "cycle_id": cycle_id,
         "loan_amount_cents": 100000,
         "loan_interest_rate_tenth_bps": 5000,
-        "notes": "First loan event",
+        "effective_date": effective_date,
+        "notes": "Loan event for specific date",
     }
-    loan_data_2 = {
+
+    crud.create_cycle_loan_event(session, loan_data)
+    loan_event = crud.get_loan_event_by_cycle_id_and_effective_date(
+        session, cycle_id, effective_date
+    )
+    assert loan_event is not None
+    assert loan_event.cycle_id == cycle_id
+    assert loan_event.effective_date == effective_date
+    assert loan_event.notes == loan_data["notes"]
+
+
+def test_update_cycle_loan_event(session: Session) -> None:
+    user_id = make_user(session)
+    exchange_id = make_exchange(session, user_id)
+    cycle_id = make_cycle(session, user_id, exchange_id)
+
+    loan_data = {
         "cycle_id": cycle_id,
-        "loan_amount_cents": 150000,
-        "loan_interest_rate_tenth_bps": 4500,
-        "notes": "Second loan event",
+        "loan_amount_cents": 100000,
+        "loan_interest_rate_tenth_bps": 5000,
+        "notes": "Initial loan event",
     }
 
-    crud.create_cycle_loan_event(session, loan_data_1)
-    crud.create_cycle_loan_event(session, loan_data_2)
+    loan_event = crud.create_cycle_loan_event(session, loan_data)
+    assert loan_event is not None
 
-    loan_events = crud.get_loan_events_by_cycle_id(session, cycle_id)
-    assert len(loan_events) == 2
-    notes = [event.notes for event in loan_events]
-    assert notes == ["First loan event", "Second loan event"]  # Ordered by id desc when effective_date is same
+    update_data = {
+        "loan_amount_cents": 120000,
+        "loan_interest_rate_tenth_bps": 4500,
+        "notes": "Updated loan event",
+    }
+    event_id = loan_event.id or 0
+
+    updated_loan_event = crud.update_cycle_loan_event(session, event_id, update_data)
+    assert updated_loan_event is not None
+    assert updated_loan_event.id == loan_event.id
+    assert updated_loan_event.loan_amount_cents == update_data["loan_amount_cents"]
+    assert (
+        updated_loan_event.loan_interest_rate_tenth_bps
+        == update_data["loan_interest_rate_tenth_bps"]
+    )
+    assert updated_loan_event.notes == update_data["notes"]
+
+    session.refresh(updated_loan_event)
+    actual_loan_event = session.get(models.CycleLoanChangeEvents, loan_event.id)
+    assert actual_loan_event is not None
+    assert actual_loan_event.loan_amount_cents == update_data["loan_amount_cents"]
+    assert (
+        actual_loan_event.loan_interest_rate_tenth_bps
+        == update_data["loan_interest_rate_tenth_bps"]
+    )
+    assert actual_loan_event.notes == update_data["notes"]
 
 
 def test_create_cycle_loan_event_single_field(session: Session) -> None:
@@ -802,7 +895,12 @@ def test_create_cycle_daily_accrual(session: Session) -> None:
         "notes": "Daily interest accrual",
     }
 
-    accrual = crud.create_cycle_daily_accrual(session, cycle_id, accrual_data["accrual_date"], accrual_data["accrued_interest_cents"])
+    accrual = crud.create_cycle_daily_accrual(
+        session,
+        cycle_id,
+        accrual_data["accrual_date"],
+        accrual_data["accrued_interest_cents"],
+    )
     assert accrual.id is not None
     assert accrual.cycle_id == cycle_id
     assert accrual.accrual_date == accrual_data["accrual_date"]
@@ -835,8 +933,18 @@ def test_get_cycle_daily_accruals_by_cycle_id(session: Session) -> None:
         "accrued_interest_cents": 150,
     }
 
-    crud.create_cycle_daily_accrual(session, cycle_id, accrual_data_1["accrual_date"], accrual_data_1["accrued_interest_cents"])
-    crud.create_cycle_daily_accrual(session, cycle_id, accrual_data_2["accrual_date"], accrual_data_2["accrued_interest_cents"])
+    crud.create_cycle_daily_accrual(
+        session,
+        cycle_id,
+        accrual_data_1["accrual_date"],
+        accrual_data_1["accrued_interest_cents"],
+    )
+    crud.create_cycle_daily_accrual(
+        session,
+        cycle_id,
+        accrual_data_2["accrual_date"],
+        accrual_data_2["accrued_interest_cents"],
+    )
 
     accruals = crud.get_cycle_daily_accruals_by_cycle_id(session, cycle_id)
     assert len(accruals) == 2
@@ -863,18 +971,37 @@ def test_get_cycle_daily_accruals_by_cycle_id_and_date(session: Session) -> None
         "accrued_interest_cents": 150,
     }
 
-    crud.create_cycle_daily_accrual(session, cycle_id, accrual_data_1["accrual_date"], accrual_data_1["accrued_interest_cents"])
-    crud.create_cycle_daily_accrual(session, cycle_id, accrual_data_2["accrual_date"], accrual_data_2["accrued_interest_cents"])
+    crud.create_cycle_daily_accrual(
+        session,
+        cycle_id,
+        accrual_data_1["accrual_date"],
+        accrual_data_1["accrued_interest_cents"],
+    )
+    crud.create_cycle_daily_accrual(
+        session,
+        cycle_id,
+        accrual_data_2["accrual_date"],
+        accrual_data_2["accrued_interest_cents"],
+    )
 
-    accruals_today = crud.get_cycle_daily_accrual_by_cycle_id_and_date(session, cycle_id, today)
+    accruals_today = crud.get_cycle_daily_accrual_by_cycle_id_and_date(
+        session, cycle_id, today
+    )
     assert accruals_today is not None
     assert accruals_today.accrual_date == today
-    assert accruals_today.accrual_amount_cents == accrual_data_2["accrued_interest_cents"]
+    assert (
+        accruals_today.accrual_amount_cents == accrual_data_2["accrued_interest_cents"]
+    )
 
-    accruals_yesterday = crud.get_cycle_daily_accrual_by_cycle_id_and_date(session, cycle_id, yesterday)
+    accruals_yesterday = crud.get_cycle_daily_accrual_by_cycle_id_and_date(
+        session, cycle_id, yesterday
+    )
     assert accruals_yesterday is not None
     assert accruals_yesterday.accrual_date == yesterday
-    assert accruals_yesterday.accrual_amount_cents == accrual_data_1["accrued_interest_cents"]
+    assert (
+        accruals_yesterday.accrual_amount_cents
+        == accrual_data_1["accrued_interest_cents"]
+    )
 
 
 # Exchanges
@@ -1031,7 +1158,9 @@ def test_update_user_immutable_fields(session: Session) -> None:
     update_data = {
         "id": user_id + 1,  # Trying to change the ID
         "username": "newusername",  # Trying to change the username
-        "created_at": datetime(2020, 1, 1, tzinfo=timezone.utc),  # Trying to change created_at
+        "created_at": datetime(
+            2020, 1, 1, tzinfo=timezone.utc
+        ),  # Trying to change created_at
         "password_hash": "validupdate",  # Valid field to update
     }
 
@@ -1065,7 +1194,9 @@ def test_create_login_session_with_invalid_user(session: Session) -> None:
 def test_get_login_session_by_token_and_user_id(session: Session) -> None:
     now = datetime.now(timezone.utc)
     created_session = make_login_session(session, now)
-    fetched_session = crud.get_login_session_by_token_hash_and_user_id(session, created_session.session_token_hash, created_session.user_id)
+    fetched_session = crud.get_login_session_by_token_hash_and_user_id(
+        session, created_session.session_token_hash, created_session.user_id
+    )
     assert fetched_session is not None
     assert fetched_session.id == created_session.id
     assert fetched_session.user_id == created_session.user_id
@@ -1075,7 +1206,9 @@ def test_get_login_session_by_token_and_user_id(session: Session) -> None:
 def test_get_login_session_by_token(session: Session) -> None:
     now = datetime.now(timezone.utc)
     created_session = make_login_session(session, now)
-    fetched_session = crud.get_login_session_by_token_hash(session, created_session.session_token_hash)
+    fetched_session = crud.get_login_session_by_token_hash(
+        session, created_session.session_token_hash
+    )
     assert fetched_session is not None
     assert fetched_session.id == created_session.id
     assert fetched_session.user_id == created_session.user_id
@@ -1090,9 +1223,13 @@ def test_update_login_session(session: Session) -> None:
         "last_seen_at": now + timedelta(hours=1),
         "last_used_ip": "192.168.1.1",
     }
-    updated_session = crud.update_login_session(session, created_session.session_token_hash, update_data)
+    updated_session = crud.update_login_session(
+        session, created_session.session_token_hash, update_data
+    )
     assert updated_session is not None
-    assert _ensure_utc_aware(updated_session.last_seen_at) == update_data["last_seen_at"]
+    assert (
+        _ensure_utc_aware(updated_session.last_seen_at) == update_data["last_seen_at"]
+    )
     assert updated_session.last_used_ip == update_data["last_used_ip"]
 
 
@@ -1101,5 +1238,7 @@ def test_delete_login_session(session: Session) -> None:
     created_session = make_login_session(session, now)
 
     crud.delete_login_session(session, created_session.session_token_hash)
-    deleted_session = crud.get_login_session_by_token_hash_and_user_id(session, created_session.session_token_hash, created_session.user_id)
+    deleted_session = crud.get_login_session_by_token_hash_and_user_id(
+        session, created_session.session_token_hash, created_session.user_id
+    )
     assert deleted_session is None

backend/tests/test_service.py

@@ -147,8 +147,14 @@ def test_auth_middleware_rejects_expired_token() -> None:
     )
 
     with (
-        patch("trading_journal.security.hash_session_token_sha256", return_value=expired_session.session_token_hash) as mock_hash,
-        patch("trading_journal.crud.get_login_session_by_token_hash", return_value=expired_session),
+        patch(
+            "trading_journal.security.hash_session_token_sha256",
+            return_value=expired_session.session_token_hash,
+        ) as mock_hash,
+        patch(
+            "trading_journal.crud.get_login_session_by_token_hash",
+            return_value=expired_session,
+        ),
         patch("trading_journal.crud.delete_login_session") as mock_delete,
     ):
         response = asyncio.run(middleware.dispatch(request, call_next))
@@ -192,8 +198,14 @@ def test_auth_middleware_reject_inactive_user() -> None:
     )
 
     with (
-        patch("trading_journal.security.hash_session_token_sha256", return_value=valid_session.session_token_hash),
-        patch("trading_journal.crud.get_login_session_by_token_hash", return_value=valid_session),
+        patch(
+            "trading_journal.security.hash_session_token_sha256",
+            return_value=valid_session.session_token_hash,
+        ),
+        patch(
+            "trading_journal.crud.get_login_session_by_token_hash",
+            return_value=valid_session,
+        ),
     ):
         response = asyncio.run(middleware.dispatch(request, call_next))
 
@@ -210,7 +222,10 @@ def test_auth_middleware_allows_valid_token_and_no_update_expires() -> None:
         "type": "http",
         "method": "GET",
         "path": f"/{settings.api_base}/protected",
-        "headers": [(b"cookie", f"session_token={fake_token_orig}".encode()), (b"user-agent", b"test-agent")],
+        "headers": [
+            (b"cookie", f"session_token={fake_token_orig}".encode()),
+            (b"user-agent", b"test-agent"),
+        ],
         "client": ("testclient", 50000),
         "app": app,
     }
@@ -236,8 +251,14 @@ def test_auth_middleware_allows_valid_token_and_no_update_expires() -> None:
     )
 
     with (
-        patch("trading_journal.security.hash_session_token_sha256", return_value=valid_session.session_token_hash),
-        patch("trading_journal.crud.get_login_session_by_token_hash", return_value=valid_session),
+        patch(
+            "trading_journal.security.hash_session_token_sha256",
+            return_value=valid_session.session_token_hash,
+        ),
+        patch(
+            "trading_journal.crud.get_login_session_by_token_hash",
+            return_value=valid_session,
+        ),
         patch("trading_journal.crud.update_login_session") as mock_update,
     ):
         response = asyncio.run(middleware.dispatch(request, call_next))
@@ -259,7 +280,10 @@ def test_auth_middleware_allows_valid_token_and_updates_expires() -> None:
         "type": "http",
         "method": "GET",
         "path": f"/{settings.api_base}/protected",
-        "headers": [(b"cookie", f"session_token={fake_token_orig}".encode()), (b"user-agent", b"test-agent")],
+        "headers": [
+            (b"cookie", f"session_token={fake_token_orig}".encode()),
+            (b"user-agent", b"test-agent"),
+        ],
         "client": ("testclient", 50000),
         "app": app,
     }
@@ -285,8 +309,14 @@ def test_auth_middleware_allows_valid_token_and_updates_expires() -> None:
     )
 
     with (
-        patch("trading_journal.security.hash_session_token_sha256", return_value=valid_session.session_token_hash),
-        patch("trading_journal.crud.get_login_session_by_token_hash", return_value=valid_session),
+        patch(
+            "trading_journal.security.hash_session_token_sha256",
+            return_value=valid_session.session_token_hash,
+        ),
+        patch(
+            "trading_journal.crud.get_login_session_by_token_hash",
+            return_value=valid_session,
+        ),
         patch("trading_journal.crud.update_login_session") as mock_update,
     ):
         response = asyncio.run(middleware.dispatch(request, call_next))
@@ -315,7 +345,10 @@ def test_register_user_success() -> None:
             "trading_journal.crud.create_user",
             return_value=SimpleNamespace(id=1, username=user_in.username, is_active=True),
         ) as mock_create,
-        patch("trading_journal.security.hash_password", return_value=user_in_with_hashed_password["password_hash"]),
+        patch(
+            "trading_journal.security.hash_password",
+            return_value=user_in_with_hashed_password["password_hash"],
+        ),
     ):
         user_out = service.register_user_service(db, user_in)
         assert user_out.id is not None
@@ -353,8 +386,14 @@ def test_authenticate_user_success() -> None:
             return_value=stored_user,
         ) as mock_get,
         patch("trading_journal.security.verify_password", return_value=True) as mock_verify,
-        patch("trading_journal.security.generate_session_token", return_value="newsessiontoken") as mock_token,
-        patch("trading_journal.security.hash_session_token_sha256", return_value="newsessiontokenhash") as mock_hash_session_token,
+        patch(
+            "trading_journal.security.generate_session_token",
+            return_value="newsessiontoken",
+        ) as mock_token,
+        patch(
+            "trading_journal.security.hash_session_token_sha256",
+            return_value="newsessiontokenhash",
+        ) as mock_hash_session_token,
         patch(
             "trading_journal.crud.create_login_session",
             return_value=SimpleNamespace(user_id=stored_user.id, expires_at=expected_login_session.expires_at),
@@ -423,7 +462,12 @@ def test_create_exchange_duplicate_raises() -> None:
         ) as mock_get,
     ):
         with pytest.raises(service.ExchangeAlreadyExistsError) as exc_info:
-            service.create_exchange_service(db, user_id=exchange_in.user_id, name=exchange_in.name, notes=exchange_in.notes)
+            service.create_exchange_service(
+                db,
+                user_id=exchange_in.user_id,
+                name=exchange_in.name,
+                notes=exchange_in.notes,
+            )
         assert str(exc_info.value) == "Exchange with the same name already exists for this user"
         mock_get.assert_called_once_with(db, exchange_in.name, exchange_in.user_id)
 
@@ -438,10 +482,20 @@ def test_create_exchange_success() -> None:
         ) as mock_get,
         patch(
             "trading_journal.crud.create_exchange",
-            return_value=SimpleNamespace(id=2, user_id=exchange_in.user_id, name=exchange_in.name, notes=exchange_in.notes),
+            return_value=SimpleNamespace(
+                id=2,
+                user_id=exchange_in.user_id,
+                name=exchange_in.name,
+                notes=exchange_in.notes,
+            ),
         ) as mock_create,
     ):
-        exchange_out = service.create_exchange_service(db, user_id=exchange_in.user_id, name=exchange_in.name, notes=exchange_in.notes)
+        exchange_out = service.create_exchange_service(
+            db,
+            user_id=exchange_in.user_id,
+            name=exchange_in.name,
+            notes=exchange_in.notes,
+        )
         assert exchange_out.name == exchange_in.name
         assert exchange_out.notes == exchange_in.notes
         mock_get.assert_called_once_with(db, exchange_in.name, exchange_in.user_id)
@@ -489,7 +543,13 @@ def test_update_exchange_not_found() -> None:
         ) as mock_get,
     ):
         with pytest.raises(service.ExchangeNotFoundError) as exc_info:
-            service.update_exchanges_service(db, exchange_id=1, user_id=1, name=exchange_update.name, notes=exchange_update.notes)
+            service.update_exchanges_service(
+                db,
+                exchange_id=1,
+                user_id=1,
+                name=exchange_update.name,
+                notes=exchange_update.notes,
+            )
         assert str(exc_info.value) == "Exchange not found"
         mock_get.assert_called_once_with(db, 1)
 
@@ -505,7 +565,13 @@ def test_update_exchange_owner_mismatch_raises() -> None:
         ) as mock_get,
     ):
         with pytest.raises(service.ExchangeNotFoundError) as exc_info:
-            service.update_exchanges_service(db, exchange_id=1, user_id=1, name=exchange_update.name, notes=exchange_update.notes)
+            service.update_exchanges_service(
+                db,
+                exchange_id=1,
+                user_id=1,
+                name=exchange_update.name,
+                notes=exchange_update.notes,
+            )
         assert str(exc_info.value) == "Exchange not found"
         mock_get.assert_called_once_with(db, 1)
 
@@ -525,7 +591,13 @@ def test_update_exchange_duplication() -> None:
         ) as mock_get_by_name,
     ):
         with pytest.raises(service.ExchangeAlreadyExistsError) as exc_info:
-            service.update_exchanges_service(db, exchange_id=1, user_id=1, name=exchange_update.name, notes=exchange_update.notes)
+            service.update_exchanges_service(
+                db,
+                exchange_id=1,
+                user_id=1,
+                name=exchange_update.name,
+                notes=exchange_update.notes,
+            )
         assert str(exc_info.value) == "Another exchange with the same name already exists for this user"
         mock_get.assert_called_once_with(db, 1)
         mock_get_by_name.assert_called_once_with(db, "DuplicateName", 1)
@@ -549,7 +621,13 @@ def test_update_exchange_success() -> None:
             return_value=SimpleNamespace(id=1, user_id=1, name=exchange_update.name, notes=exchange_update.notes),
         ) as mock_update,
     ):
-        exchange_out = service.update_exchanges_service(db, exchange_id=1, user_id=1, name=exchange_update.name, notes=exchange_update.notes)
+        exchange_out = service.update_exchanges_service(
+            db,
+            exchange_id=1,
+            user_id=1,
+            name=exchange_update.name,
+            notes=exchange_update.notes,
+        )
         assert exchange_out.name == exchange_update.name
         assert exchange_out.notes == exchange_update.notes
         mock_get.assert_called_once_with(db, 1)
@@ -683,7 +761,12 @@ def test_update_cycle_closed_status_mismatch_raises() -> None:
 
 
 def test_update_cycle_open_status_mismatch_raises() -> None:
-    cycle_data = dto.CycleUpdate(id=1, friendly_name="Updated Cycle", status="OPEN", end_date=datetime.now(timezone.utc).date())
+    cycle_data = dto.CycleUpdate(
+        id=1,
+        friendly_name="Updated Cycle",
+        status="OPEN",
+        end_date=datetime.now(timezone.utc).date(),
+    )
     with (
         FakeDBFactory().get_session_ctx_manager() as db,
     ):
@@ -703,7 +786,13 @@ def test_update_cycle_invalid_capital_exposure_raises() -> None:
 
 
 def test_update_cycle_no_cash_no_loan_raises() -> None:
-    cycle_data = dto.CycleUpdate(id=1, friendly_name="Updated Cycle", status="OPEN", funding_source="LOAN", loan_amount_cents=None)
+    cycle_data = dto.CycleUpdate(
+        id=1,
+        friendly_name="Updated Cycle",
+        status="OPEN",
+        funding_source="LOAN",
+        loan_amount_cents=None,
+    )
     with (
         FakeDBFactory().get_session_ctx_manager() as db,
     ):
@@ -788,7 +877,16 @@ def test_update_cycle_owner_mismatch_raises() -> None:
 
 
 def test_update_cycle_success() -> None:
-    cycle_data = dto.CycleUpdate(id=1, friendly_name="Updated Cycle", status="OPEN", funding_source="CASH", capital_exposure_cents=5000)
+    today = datetime.now(timezone.utc).date()
+    cycle_data = dto.CycleUpdate(
+        id=1,
+        friendly_name="Updated Cycle",
+        status="OPEN",
+        funding_source="MIXED",
+        capital_exposure_cents=5000,
+        loan_amount_cents=2000,
+        loan_interest_rate_tenth_bps=50,
+    )
     existing_cycle = SimpleNamespace(
         id=1,
         user_id=1,
@@ -796,7 +894,7 @@ def test_update_cycle_success() -> None:
         symbol="AAPL",
         exchange_id=1,
         underlying_currency="USD",
-        start_date=datetime.now(timezone.utc).date(),
+        start_date=today,
         status="OPEN",
         funding_source="MIXED",
         capital_exposure_cents=10000,
@@ -814,13 +912,18 @@ def test_update_cycle_success() -> None:
         status=cycle_data.status,
         funding_source=cycle_data.funding_source,
         capital_exposure_cents=cycle_data.capital_exposure_cents,
-        loan_amount_cents=None,
-        loan_interest_rate_tenth_bps=None,
+        loan_amount_cents=cycle_data.loan_amount_cents,
+        loan_interest_rate_tenth_bps=cycle_data.loan_interest_rate_tenth_bps,
     )
     with (
         FakeDBFactory().get_session_ctx_manager() as db,
         patch("trading_journal.crud.get_cycle_by_id", return_value=existing_cycle) as mock_get,
         patch("trading_journal.crud.update_cycle", return_value=updated_cycle) as mock_update,
+        patch(
+            "trading_journal.crud.get_loan_event_by_cycle_id_and_effective_date",
+            return_value=None,
+        ) as mock_get_loan_event,
+        patch("trading_journal.crud.create_cycle_loan_event"),
     ):
         cycle_out = service.update_cycle_service(db, user_id=1, cycle_data=cycle_data)
         assert cycle_out.id == updated_cycle.id
@@ -828,8 +931,8 @@ def test_update_cycle_success() -> None:
         assert cycle_out.status == updated_cycle.status
         assert cycle_out.funding_source == updated_cycle.funding_source
         assert cycle_out.capital_exposure_cents == updated_cycle.capital_exposure_cents
-        assert cycle_out.loan_amount_cents is None
-        assert cycle_out.loan_interest_rate_tenth_bps is None
+        assert cycle_out.loan_amount_cents == updated_cycle.loan_amount_cents
+        assert cycle_out.loan_interest_rate_tenth_bps == updated_cycle.loan_interest_rate_tenth_bps
         mock_get.assert_called_once_with(db, cycle_data.id)
         update_cycle_base = dto.CycleBase(
             friendly_name=cycle_data.friendly_name,
@@ -841,6 +944,43 @@ def test_update_cycle_success() -> None:
             end_date=getattr(cycle_data, "end_date", None),
         )
         mock_update.assert_called_once_with(db, cycle_data.id, update_data=update_cycle_base)
+        mock_get_loan_event.assert_called_once_with(db, cycle_data.id, today)
+
+
+def test_accrual_interest_service_cycle_not_found() -> None:
+    with (
+        FakeDBFactory().get_session_ctx_manager() as db,
+        patch("trading_journal.crud.get_cycle_by_id", return_value=None) as mock_get_cycle,
+    ):
+        with pytest.raises(service.CycleNotFoundError) as exc_info:
+            service.accrual_interest_service(db, cycle_id=1)
+        assert str(exc_info.value) == "Cycle not found"
+        mock_get_cycle.assert_called_once_with(db, 1)
+
+
+def test_accrual_interest_service_success() -> None:
+    today = datetime.now(timezone.utc).date()
+    cycle = SimpleNamespace(
+        id=1,
+        user_id=1,
+        friendly_name="Test Cycle",
+        status="OPEN",
+        funding_source="LOAN",
+        loan_amount_cents=200000,
+        loan_interest_rate_tenth_bps=500,  # 0.5%
+        start_date=today - timedelta(days=10),
+    )
+    with (
+        FakeDBFactory().get_session_ctx_manager() as db,
+        patch("trading_journal.crud.get_cycle_by_id", return_value=cycle) as mock_get_cycle,
+        patch(
+            "trading_journal.crud.create_cycle_daily_accrual",
+            return_value=None,
+        ) as mock_accrual_interest,
+    ):
+        service.accrual_interest_service(db, cycle_id=1)
+        mock_get_cycle.assert_called_once_with(db, 1)
+        mock_accrual_interest.assert_called_once_with(db, cycle_id=1, accrual_date=today, accrual_amount_cents=3)
 
 
 # --- Trade services ----------------------------------------------------------
@@ -930,7 +1070,10 @@ def test_create_trade_success() -> None:
 
 
 def test_get_trade_by_id_not_found_when_missing() -> None:
-    with FakeDBFactory().get_session_ctx_manager() as db, patch("trading_journal.crud.get_trade_by_id", return_value=None) as mock_get:
+    with (
+        FakeDBFactory().get_session_ctx_manager() as db,
+        patch("trading_journal.crud.get_trade_by_id", return_value=None) as mock_get,
+    ):
         with pytest.raises(service.TradeNotFoundError) as exc_info:
             service.get_trade_by_id_service(db, user_id=1, trade_id=1)
         assert str(exc_info.value) == "Trade not found"
@@ -976,7 +1119,10 @@ def test_get_trade_by_id_success() -> None:
         notes="ok",
         cycle_id=None,
     )
-    with FakeDBFactory().get_session_ctx_manager() as db, patch("trading_journal.crud.get_trade_by_id", return_value=trade_obj) as mock_get:
+    with (
+        FakeDBFactory().get_session_ctx_manager() as db,
+        patch("trading_journal.crud.get_trade_by_id", return_value=trade_obj) as mock_get,
+    ):
         res = service.get_trade_by_id_service(db, user_id=1, trade_id=10)
         assert res.id == trade_obj.id
         assert res.user_id == trade_obj.user_id
@@ -986,7 +1132,10 @@ def test_get_trade_by_id_success() -> None:
 
 
 def test_update_trade_friendly_name_not_found() -> None:
-    with FakeDBFactory().get_session_ctx_manager() as db, patch("trading_journal.crud.get_trade_by_id", return_value=None) as mock_get:
+    with (
+        FakeDBFactory().get_session_ctx_manager() as db,
+        patch("trading_journal.crud.get_trade_by_id", return_value=None) as mock_get,
+    ):
         with pytest.raises(service.TradeNotFoundError) as exc_info:
             service.update_trade_friendly_name_service(db, user_id=1, trade_id=10, friendly_name="New Name")
         assert str(exc_info.value) == "Trade not found"
@@ -1035,7 +1184,10 @@ def test_update_trade_friendly_name_success() -> None:
     with (
         FakeDBFactory().get_session_ctx_manager() as db,
         patch("trading_journal.crud.get_trade_by_id", return_value=existing_trade) as mock_get,
-        patch("trading_journal.crud.update_trade_friendly_name", return_value=updated_trade) as mock_update,
+        patch(
+            "trading_journal.crud.update_trade_friendly_name",
+            return_value=updated_trade,
+        ) as mock_update,
     ):
         res = service.update_trade_friendly_name_service(db, user_id=1, trade_id=10, friendly_name="New Friendly")
         assert res.friendly_name == "New Friendly"
@@ -1044,7 +1196,10 @@ def test_update_trade_friendly_name_success() -> None:
 
 
 def test_update_trade_note_not_found() -> None:
-    with FakeDBFactory().get_session_ctx_manager() as db, patch("trading_journal.crud.get_trade_by_id", return_value=None) as mock_get:
+    with (
+        FakeDBFactory().get_session_ctx_manager() as db,
+        patch("trading_journal.crud.get_trade_by_id", return_value=None) as mock_get,
+    ):
         with pytest.raises(service.TradeNotFoundError) as exc_info:
             service.update_trade_note_service(db, user_id=1, trade_id=20, note="x")
         assert str(exc_info.value) == "Trade not found"

backend/trading_journal/crud.py

@@ -340,6 +340,37 @@ def get_loan_events_by_cycle_id(session: Session, cycle_id: int) -> list[models.
     return list(session.exec(statement).all())
 
 
+def get_loan_event_by_cycle_id_and_effective_date(session: Session, cycle_id: int, effective_date: date) -> models.CycleLoanChangeEvents | None:
+    statement = select(models.CycleLoanChangeEvents).where(
+        models.CycleLoanChangeEvents.cycle_id == cycle_id,
+        models.CycleLoanChangeEvents.effective_date == effective_date,
+    )
+    return session.exec(statement).first()
+
+
+def update_cycle_loan_event(session: Session, event_id: int, update_data: Mapping[str, Any] | BaseModel) -> models.CycleLoanChangeEvents:
+    event: models.CycleLoanChangeEvents | None = session.get(models.CycleLoanChangeEvents, event_id)
+    if event is None:
+        raise ValueError("event_id does not exist")
+    data = _data_to_dict(update_data)
+
+    allowed = _allowed_columns(models.CycleLoanChangeEvents)
+    for k, v in data.items():
+        if k in {"id", "cycle_id", "effective_date", "created_at"}:
+            raise ValueError(f"field {k!r} is immutable")
+        if k not in allowed:
+            continue
+        setattr(event, k, v)
+    session.add(event)
+    try:
+        session.flush()
+    except IntegrityError as e:
+        session.rollback()
+        raise ValueError("update_cycle_loan_event integrity error") from e
+    session.refresh(event)
+    return event
+
+
 def create_cycle_daily_accrual(session: Session, cycle_id: int, accrual_date: date, accrual_amount_cents: int) -> models.CycleDailyAccrual:
     cycle = session.get(models.Cycles, cycle_id)
     if cycle is None:
@@ -583,7 +614,11 @@ def get_login_session_by_token_hash(session: Session, session_token_hash: str) -
 IMMUTABLE_SESSION_FIELDS = {"id", "user_id", "session_token_hash", "created_at"}
 
 
-def update_login_session(session: Session, session_token_hashed: str, update_session: Mapping[str, Any] | BaseModel) -> models.Sessions | None:
+def update_login_session(
+    session: Session,
+    session_token_hashed: str,
+    update_session: Mapping[str, Any] | BaseModel,
+) -> models.Sessions | None:
     login_session: models.Sessions | None = session.exec(
         select(models.Sessions).where(
             models.Sessions.session_token_hash == session_token_hashed,

backend/trading_journal/dto.py

@@ -1,11 +1,15 @@
 from __future__ import annotations
 
-from datetime import date, datetime  # noqa: TC003
+from datetime import date, datetime
 
 from pydantic import BaseModel
 from sqlmodel import SQLModel
 
-from trading_journal.models import TradeStrategy, TradeType, UnderlyingCurrency  # noqa: TC001
+from trading_journal.models import (
+    TradeStrategy,
+    TradeType,
+    UnderlyingCurrency,
+)
 
 
 class UserBase(SQLModel):
@@ -90,6 +94,32 @@ class CycleRead(CycleCreate):
     id: int
 
 
+class CycleLoanChangeEventBase(SQLModel):
+    cycle_id: int
+    effective_date: date
+    loan_amount_cents: int | None = None
+    loan_interest_rate_tenth_bps: int | None = None
+    related_trade_id: int | None = None
+    notes: str | None = None
+    created_at: datetime
+
+
+class CycleLoanChangeEventCreate(CycleLoanChangeEventBase):
+    created_at: datetime
+
+
+class CycleLoanChangeEventRead(CycleLoanChangeEventBase):
+    id: int
+    created_at: datetime
+
+
+class CycleInterestAccrualBase(SQLModel):
+    cycle_id: int
+    accrual_date: date
+    accrual_amount_cents: int
+    created_at: datetime
+
+
 class TradeBase(SQLModel):
     friendly_name: str | None = None
     symbol: str

backend/trading_journal/models.py

@@ -69,33 +69,51 @@ class FundingSource(str, Enum):
 
 class Trades(SQLModel, table=True):
     __tablename__ = "trades"  # type: ignore[attr-defined]
-    __table_args__ = (UniqueConstraint("user_id", "friendly_name", name="uq_trades_user_friendly_name"),)
+    __table_args__ = (
+        UniqueConstraint(
+            "user_id", "friendly_name", name="uq_trades_user_friendly_name"
+        ),
+    )
 
     id: int | None = Field(default=None, primary_key=True)
     user_id: int = Field(foreign_key="users.id", nullable=False, index=True)
     # allow null while user may omit friendly_name; uniqueness enforced per-user by constraint
-    friendly_name: str | None = Field(default=None, sa_column=Column(Text, nullable=True))
+    friendly_name: str | None = Field(
+        default=None, sa_column=Column(Text, nullable=True)
+    )
     symbol: str = Field(sa_column=Column(Text, nullable=False))
     exchange_id: int = Field(foreign_key="exchanges.id", nullable=False, index=True)
     exchange: "Exchanges" = Relationship(back_populates="trades")
-    underlying_currency: UnderlyingCurrency = Field(sa_column=Column(Text, nullable=False))
+    underlying_currency: UnderlyingCurrency = Field(
+        sa_column=Column(Text, nullable=False)
+    )
     trade_type: TradeType = Field(sa_column=Column(Text, nullable=False))
     trade_strategy: TradeStrategy = Field(sa_column=Column(Text, nullable=False))
     trade_date: date = Field(sa_column=Column(Date, nullable=False))
-    trade_time_utc: datetime = Field(sa_column=Column(DateTime(timezone=True), nullable=False))
+    trade_time_utc: datetime = Field(
+        sa_column=Column(DateTime(timezone=True), nullable=False)
+    )
     expiry_date: date | None = Field(default=None, nullable=True)
     strike_price_cents: int | None = Field(default=None, nullable=True)
     quantity: int = Field(sa_column=Column(Integer, nullable=False))
-    quantity_multiplier: int = Field(sa_column=Column(Integer, nullable=False), default=1)
+    quantity_multiplier: int = Field(
+        sa_column=Column(Integer, nullable=False), default=1
+    )
     price_cents: int = Field(sa_column=Column(Integer, nullable=False))
     gross_cash_flow_cents: int = Field(sa_column=Column(Integer, nullable=False))
     commission_cents: int = Field(sa_column=Column(Integer, nullable=False))
     net_cash_flow_cents: int = Field(sa_column=Column(Integer, nullable=False))
     is_invalidated: bool = Field(default=False, nullable=False)
-    invalidated_at: datetime | None = Field(default=None, sa_column=Column(DateTime(timezone=True), nullable=True))
-    replaced_by_trade_id: int | None = Field(default=None, foreign_key="trades.id", nullable=True)
+    invalidated_at: datetime | None = Field(
+        default=None, sa_column=Column(DateTime(timezone=True), nullable=True)
+    )
+    replaced_by_trade_id: int | None = Field(
+        default=None, foreign_key="trades.id", nullable=True
+    )
     notes: str | None = Field(default=None, sa_column=Column(Text, nullable=True))
-    cycle_id: int | None = Field(default=None, foreign_key="cycles.id", nullable=True, index=True)
+    cycle_id: int | None = Field(
+        default=None, foreign_key="cycles.id", nullable=True, index=True
+    )
 
     cycle: "Cycles" = Relationship(back_populates="trades")
 
@@ -107,15 +125,23 @@ class Trades(SQLModel, table=True):
 
 class Cycles(SQLModel, table=True):
     __tablename__ = "cycles"  # type: ignore[attr-defined]
-    __table_args__ = (UniqueConstraint("user_id", "friendly_name", name="uq_cycles_user_friendly_name"),)
+    __table_args__ = (
+        UniqueConstraint(
+            "user_id", "friendly_name", name="uq_cycles_user_friendly_name"
+        ),
+    )
 
     id: int | None = Field(default=None, primary_key=True)
     user_id: int = Field(foreign_key="users.id", nullable=False, index=True)
-    friendly_name: str | None = Field(default=None, sa_column=Column(Text, nullable=True))
+    friendly_name: str | None = Field(
+        default=None, sa_column=Column(Text, nullable=True)
+    )
     symbol: str = Field(sa_column=Column(Text, nullable=False))
     exchange_id: int = Field(foreign_key="exchanges.id", nullable=False, index=True)
     exchange: "Exchanges" = Relationship(back_populates="cycles")
-    underlying_currency: UnderlyingCurrency = Field(sa_column=Column(Text, nullable=False))
+    underlying_currency: UnderlyingCurrency = Field(
+        sa_column=Column(Text, nullable=False)
+    )
     status: CycleStatus = Field(sa_column=Column(Text, nullable=False))
     funding_source: FundingSource = Field(sa_column=Column(Text, nullable=True))
     capital_exposure_cents: int | None = Field(default=None, nullable=True)
@@ -127,23 +153,51 @@ class Cycles(SQLModel, table=True):
     loan_amount_cents: int | None = Field(default=None, nullable=True)
     loan_interest_rate_tenth_bps: int | None = Field(default=None, nullable=True)
 
-    latest_interest_accrued_date: date | None = Field(default=None, sa_column=Column(Date, nullable=True))
-    total_accrued_amount_cents: int = Field(default=0, sa_column=Column(Integer, nullable=False))
+    latest_interest_accrued_date: date | None = Field(
+        default=None, sa_column=Column(Date, nullable=True)
+    )
+    total_accrued_amount_cents: int = Field(
+        default=0, sa_column=Column(Integer, nullable=False)
+    )
 
-    loan_change_events: list["CycleLoanChangeEvents"] = Relationship(back_populates="cycle")
+    loan_change_events: list["CycleLoanChangeEvents"] = Relationship(
+        back_populates="cycle"
+    )
     daily_accruals: list["CycleDailyAccrual"] = Relationship(back_populates="cycle")
 
 
 class CycleLoanChangeEvents(SQLModel, table=True):
     __tablename__ = "cycle_loan_change_events"  # type: ignore[attr-defined]
+    __table_args__ = (
+        UniqueConstraint(
+            "cycle_id", "effective_date", name="uq_cycle_loan_change_cycle_date"
+        ),
+    )
+
     id: int | None = Field(default=None, primary_key=True)
-    cycle_id: int = Field(sa_column=Column(Integer, ForeignKey("cycles.id", ondelete="CASCADE"), nullable=False, index=True))
+    cycle_id: int = Field(
+        sa_column=Column(
+            Integer,
+            ForeignKey("cycles.id", ondelete="CASCADE"),
+            nullable=False,
+            index=True,
+        )
+    )
     effective_date: date = Field(sa_column=Column(Date, nullable=False))
-    loan_amount_cents: int | None = Field(default=None, sa_column=Column(Integer, nullable=True))
-    loan_interest_rate_tenth_bps: int | None = Field(default=None, sa_column=Column(Integer, nullable=True))
-    related_trade_id: int | None = Field(default=None, sa_column=Column(Integer, ForeignKey("trades.id"), nullable=True, unique=True))
+    loan_amount_cents: int | None = Field(
+        default=None, sa_column=Column(Integer, nullable=True)
+    )
+    loan_interest_rate_tenth_bps: int | None = Field(
+        default=None, sa_column=Column(Integer, nullable=True)
+    )
+    related_trade_id: int | None = Field(
+        default=None,
+        sa_column=Column(Integer, ForeignKey("trades.id"), nullable=True, unique=True),
+    )  # Not used for now.
     notes: str | None = Field(default=None, sa_column=Column(Text, nullable=True))
-    created_at: datetime = Field(sa_column=Column(DateTime(timezone=True), nullable=False))
+    created_at: datetime = Field(
+        sa_column=Column(DateTime(timezone=True), nullable=False)
+    )
 
     cycle: "Cycles" = Relationship(back_populates="loan_change_events")
     trade: Optional["Trades"] = Relationship(back_populates="related_loan_change_event")
@@ -151,20 +205,35 @@ class CycleLoanChangeEvents(SQLModel, table=True):
 
 class CycleDailyAccrual(SQLModel, table=True):
     __tablename__ = "cycle_daily_accrual"  # type: ignore[attr-defined]
-    __table_args__ = (UniqueConstraint("cycle_id", "accrual_date", name="uq_cycle_daily_accruals_cycle_date"),)
+    __table_args__ = (
+        UniqueConstraint(
+            "cycle_id", "accrual_date", name="uq_cycle_daily_accruals_cycle_date"
+        ),
+    )
 
     id: int | None = Field(default=None, primary_key=True)
-    cycle_id: int = Field(sa_column=Column(Integer, ForeignKey("cycles.id", ondelete="CASCADE"), nullable=False, index=True))
+    cycle_id: int = Field(
+        sa_column=Column(
+            Integer,
+            ForeignKey("cycles.id", ondelete="CASCADE"),
+            nullable=False,
+            index=True,
+        )
+    )
     accrual_date: date = Field(sa_column=Column(Date, nullable=False))
     accrual_amount_cents: int = Field(sa_column=Column(Integer, nullable=False))
-    created_at: datetime = Field(sa_column=Column(DateTime(timezone=True), nullable=False))
+    created_at: datetime = Field(
+        sa_column=Column(DateTime(timezone=True), nullable=False)
+    )
 
     cycle: "Cycles" = Relationship(back_populates="daily_accruals")
 
 
 class Exchanges(SQLModel, table=True):
     __tablename__ = "exchanges"  # type: ignore[attr-defined]
-    __table_args__ = (UniqueConstraint("user_id", "name", name="uq_exchanges_user_name"),)
+    __table_args__ = (
+        UniqueConstraint("user_id", "name", name="uq_exchanges_user_name"),
+    )
     id: int | None = Field(default=None, primary_key=True)
     user_id: int = Field(foreign_key="users.id", nullable=False, index=True)
     name: str = Field(sa_column=Column(Text, nullable=False))
@@ -190,10 +259,18 @@ class Sessions(SQLModel, table=True):
     id: int | None = Field(default=None, primary_key=True)
     user_id: int = Field(foreign_key="users.id", nullable=False, index=True)
     session_token_hash: str = Field(sa_column=Column(Text, nullable=False, unique=True))
-    created_at: datetime = Field(sa_column=Column(DateTime(timezone=True), nullable=False))
-    expires_at: datetime = Field(sa_column=Column(DateTime(timezone=True), nullable=False, index=True))
-    last_seen_at: datetime | None = Field(sa_column=Column(DateTime(timezone=True), nullable=True))
-    last_used_ip: str | None = Field(default=None, sa_column=Column(Text, nullable=True))
+    created_at: datetime = Field(
+        sa_column=Column(DateTime(timezone=True), nullable=False)
+    )
+    expires_at: datetime = Field(
+        sa_column=Column(DateTime(timezone=True), nullable=False, index=True)
+    )
+    last_seen_at: datetime | None = Field(
+        sa_column=Column(DateTime(timezone=True), nullable=True)
+    )
+    last_used_ip: str | None = Field(
+        default=None, sa_column=Column(Text, nullable=True)
+    )
     user_agent: str | None = Field(default=None, sa_column=Column(Text, nullable=True))
     device_name: str | None = Field(default=None, sa_column=Column(Text, nullable=True))
     user: "Users" = Relationship(back_populates="sessions")

backend/trading_journal/models_v1.py

@@ -69,33 +69,51 @@ class FundingSource(str, Enum):
 
 class Trades(SQLModel, table=True):
     __tablename__ = "trades"  # type: ignore[attr-defined]
-    __table_args__ = (UniqueConstraint("user_id", "friendly_name", name="uq_trades_user_friendly_name"),)
+    __table_args__ = (
+        UniqueConstraint(
+            "user_id", "friendly_name", name="uq_trades_user_friendly_name"
+        ),
+    )
 
     id: int | None = Field(default=None, primary_key=True)
     user_id: int = Field(foreign_key="users.id", nullable=False, index=True)
     # allow null while user may omit friendly_name; uniqueness enforced per-user by constraint
-    friendly_name: str | None = Field(default=None, sa_column=Column(Text, nullable=True))
+    friendly_name: str | None = Field(
+        default=None, sa_column=Column(Text, nullable=True)
+    )
     symbol: str = Field(sa_column=Column(Text, nullable=False))
     exchange_id: int = Field(foreign_key="exchanges.id", nullable=False, index=True)
     exchange: "Exchanges" = Relationship(back_populates="trades")
-    underlying_currency: UnderlyingCurrency = Field(sa_column=Column(Text, nullable=False))
+    underlying_currency: UnderlyingCurrency = Field(
+        sa_column=Column(Text, nullable=False)
+    )
     trade_type: TradeType = Field(sa_column=Column(Text, nullable=False))
     trade_strategy: TradeStrategy = Field(sa_column=Column(Text, nullable=False))
     trade_date: date = Field(sa_column=Column(Date, nullable=False))
-    trade_time_utc: datetime = Field(sa_column=Column(DateTime(timezone=True), nullable=False))
+    trade_time_utc: datetime = Field(
+        sa_column=Column(DateTime(timezone=True), nullable=False)
+    )
     expiry_date: date | None = Field(default=None, nullable=True)
     strike_price_cents: int | None = Field(default=None, nullable=True)
     quantity: int = Field(sa_column=Column(Integer, nullable=False))
-    quantity_multiplier: int = Field(sa_column=Column(Integer, nullable=False), default=1)
+    quantity_multiplier: int = Field(
+        sa_column=Column(Integer, nullable=False), default=1
+    )
     price_cents: int = Field(sa_column=Column(Integer, nullable=False))
     gross_cash_flow_cents: int = Field(sa_column=Column(Integer, nullable=False))
     commission_cents: int = Field(sa_column=Column(Integer, nullable=False))
     net_cash_flow_cents: int = Field(sa_column=Column(Integer, nullable=False))
     is_invalidated: bool = Field(default=False, nullable=False)
-    invalidated_at: datetime | None = Field(default=None, sa_column=Column(DateTime(timezone=True), nullable=True))
-    replaced_by_trade_id: int | None = Field(default=None, foreign_key="trades.id", nullable=True)
+    invalidated_at: datetime | None = Field(
+        default=None, sa_column=Column(DateTime(timezone=True), nullable=True)
+    )
+    replaced_by_trade_id: int | None = Field(
+        default=None, foreign_key="trades.id", nullable=True
+    )
     notes: str | None = Field(default=None, sa_column=Column(Text, nullable=True))
-    cycle_id: int | None = Field(default=None, foreign_key="cycles.id", nullable=True, index=True)
+    cycle_id: int | None = Field(
+        default=None, foreign_key="cycles.id", nullable=True, index=True
+    )
 
     cycle: "Cycles" = Relationship(back_populates="trades")
 
@@ -107,15 +125,23 @@ class Trades(SQLModel, table=True):
 
 class Cycles(SQLModel, table=True):
     __tablename__ = "cycles"  # type: ignore[attr-defined]
-    __table_args__ = (UniqueConstraint("user_id", "friendly_name", name="uq_cycles_user_friendly_name"),)
+    __table_args__ = (
+        UniqueConstraint(
+            "user_id", "friendly_name", name="uq_cycles_user_friendly_name"
+        ),
+    )
 
     id: int | None = Field(default=None, primary_key=True)
     user_id: int = Field(foreign_key="users.id", nullable=False, index=True)
-    friendly_name: str | None = Field(default=None, sa_column=Column(Text, nullable=True))
+    friendly_name: str | None = Field(
+        default=None, sa_column=Column(Text, nullable=True)
+    )
     symbol: str = Field(sa_column=Column(Text, nullable=False))
     exchange_id: int = Field(foreign_key="exchanges.id", nullable=False, index=True)
     exchange: "Exchanges" = Relationship(back_populates="cycles")
-    underlying_currency: UnderlyingCurrency = Field(sa_column=Column(Text, nullable=False))
+    underlying_currency: UnderlyingCurrency = Field(
+        sa_column=Column(Text, nullable=False)
+    )
     status: CycleStatus = Field(sa_column=Column(Text, nullable=False))
     funding_source: FundingSource = Field(sa_column=Column(Text, nullable=True))
     capital_exposure_cents: int | None = Field(default=None, nullable=True)
@@ -127,23 +153,51 @@ class Cycles(SQLModel, table=True):
     loan_amount_cents: int | None = Field(default=None, nullable=True)
     loan_interest_rate_tenth_bps: int | None = Field(default=None, nullable=True)
 
-    latest_interest_accrued_date: date | None = Field(default=None, sa_column=Column(Date, nullable=True))
-    total_accrued_amount_cents: int = Field(default=0, sa_column=Column(Integer, nullable=False))
+    latest_interest_accrued_date: date | None = Field(
+        default=None, sa_column=Column(Date, nullable=True)
+    )
+    total_accrued_amount_cents: int = Field(
+        default=0, sa_column=Column(Integer, nullable=False)
+    )
 
-    loan_change_events: list["CycleLoanChangeEvents"] = Relationship(back_populates="cycle")
+    loan_change_events: list["CycleLoanChangeEvents"] = Relationship(
+        back_populates="cycle"
+    )
     daily_accruals: list["CycleDailyAccrual"] = Relationship(back_populates="cycle")
 
 
 class CycleLoanChangeEvents(SQLModel, table=True):
     __tablename__ = "cycle_loan_change_events"  # type: ignore[attr-defined]
+    __table_args__ = (
+        UniqueConstraint(
+            "cycle_id", "effective_date", name="uq_cycle_loan_change_cycle_date"
+        ),
+    )
+
     id: int | None = Field(default=None, primary_key=True)
-    cycle_id: int = Field(sa_column=Column(Integer, ForeignKey("cycles.id", ondelete="CASCADE"), nullable=False, index=True))
+    cycle_id: int = Field(
+        sa_column=Column(
+            Integer,
+            ForeignKey("cycles.id", ondelete="CASCADE"),
+            nullable=False,
+            index=True,
+        )
+    )
     effective_date: date = Field(sa_column=Column(Date, nullable=False))
-    loan_amount_cents: int | None = Field(default=None, sa_column=Column(Integer, nullable=True))
-    loan_interest_rate_tenth_bps: int | None = Field(default=None, sa_column=Column(Integer, nullable=True))
-    related_trade_id: int | None = Field(default=None, sa_column=Column(Integer, ForeignKey("trades.id"), nullable=True, unique=True))
+    loan_amount_cents: int | None = Field(
+        default=None, sa_column=Column(Integer, nullable=True)
+    )
+    loan_interest_rate_tenth_bps: int | None = Field(
+        default=None, sa_column=Column(Integer, nullable=True)
+    )
+    related_trade_id: int | None = Field(
+        default=None,
+        sa_column=Column(Integer, ForeignKey("trades.id"), nullable=True, unique=True),
+    )  # Not used for now.
     notes: str | None = Field(default=None, sa_column=Column(Text, nullable=True))
-    created_at: datetime = Field(sa_column=Column(DateTime(timezone=True), nullable=False))
+    created_at: datetime = Field(
+        sa_column=Column(DateTime(timezone=True), nullable=False)
+    )
 
     cycle: "Cycles" = Relationship(back_populates="loan_change_events")
     trade: Optional["Trades"] = Relationship(back_populates="related_loan_change_event")
@@ -151,20 +205,35 @@ class CycleLoanChangeEvents(SQLModel, table=True):
 
 class CycleDailyAccrual(SQLModel, table=True):
     __tablename__ = "cycle_daily_accrual"  # type: ignore[attr-defined]
-    __table_args__ = (UniqueConstraint("cycle_id", "accrual_date", name="uq_cycle_daily_accruals_cycle_date"),)
+    __table_args__ = (
+        UniqueConstraint(
+            "cycle_id", "accrual_date", name="uq_cycle_daily_accruals_cycle_date"
+        ),
+    )
 
     id: int | None = Field(default=None, primary_key=True)
-    cycle_id: int = Field(sa_column=Column(Integer, ForeignKey("cycles.id", ondelete="CASCADE"), nullable=False, index=True))
+    cycle_id: int = Field(
+        sa_column=Column(
+            Integer,
+            ForeignKey("cycles.id", ondelete="CASCADE"),
+            nullable=False,
+            index=True,
+        )
+    )
     accrual_date: date = Field(sa_column=Column(Date, nullable=False))
     accrual_amount_cents: int = Field(sa_column=Column(Integer, nullable=False))
-    created_at: datetime = Field(sa_column=Column(DateTime(timezone=True), nullable=False))
+    created_at: datetime = Field(
+        sa_column=Column(DateTime(timezone=True), nullable=False)
+    )
 
     cycle: "Cycles" = Relationship(back_populates="daily_accruals")
 
 
 class Exchanges(SQLModel, table=True):
     __tablename__ = "exchanges"  # type: ignore[attr-defined]
-    __table_args__ = (UniqueConstraint("user_id", "name", name="uq_exchanges_user_name"),)
+    __table_args__ = (
+        UniqueConstraint("user_id", "name", name="uq_exchanges_user_name"),
+    )
     id: int | None = Field(default=None, primary_key=True)
     user_id: int = Field(foreign_key="users.id", nullable=False, index=True)
     name: str = Field(sa_column=Column(Text, nullable=False))
@@ -190,10 +259,18 @@ class Sessions(SQLModel, table=True):
     id: int | None = Field(default=None, primary_key=True)
     user_id: int = Field(foreign_key="users.id", nullable=False, index=True)
     session_token_hash: str = Field(sa_column=Column(Text, nullable=False, unique=True))
-    created_at: datetime = Field(sa_column=Column(DateTime(timezone=True), nullable=False))
-    expires_at: datetime = Field(sa_column=Column(DateTime(timezone=True), nullable=False, index=True))
-    last_seen_at: datetime | None = Field(sa_column=Column(DateTime(timezone=True), nullable=True))
-    last_used_ip: str | None = Field(default=None, sa_column=Column(Text, nullable=True))
+    created_at: datetime = Field(
+        sa_column=Column(DateTime(timezone=True), nullable=False)
+    )
+    expires_at: datetime = Field(
+        sa_column=Column(DateTime(timezone=True), nullable=False, index=True)
+    )
+    last_seen_at: datetime | None = Field(
+        sa_column=Column(DateTime(timezone=True), nullable=True)
+    )
+    last_used_ip: str | None = Field(
+        default=None, sa_column=Column(Text, nullable=True)
+    )
     user_agent: str | None = Field(default=None, sa_column=Column(Text, nullable=True))
     device_name: str | None = Field(default=None, sa_column=Column(Text, nullable=True))
     user: "Users" = Relationship(back_populates="sessions")

backend/trading_journal/service.py

@@ -13,6 +13,7 @@ from trading_journal import crud, security
 from trading_journal.dto import (
     CycleBase,
     CycleCreate,
+    CycleLoanChangeEventBase,
     CycleRead,
     CycleUpdate,
     ExchangesBase,
@@ -26,6 +27,17 @@ from trading_journal.dto import (
     UserLogin,
     UserRead,
 )
+from trading_journal.service_error import (
+    CycleLoanEventExistsError,
+    CycleNotFoundError,
+    ExchangeAlreadyExistsError,
+    ExchangeNotFoundError,
+    InvalidCycleDataError,
+    InvalidTradeDataError,
+    ServiceError,
+    TradeNotFoundError,
+    UserAlreadyExistsError,
+)
 
 if TYPE_CHECKING:
     from sqlmodel import Session
@@ -62,20 +74,32 @@ class AuthMiddleWare(BaseHTTPMiddleware):
 
         db_factory: Database | None = getattr(request.app.state, "db_factory", None)
         if db_factory is None:
-            return JSONResponse(status_code=status.HTTP_500_INTERNAL_SERVER_ERROR, content={"detail": "db factory not configured"})
+            return JSONResponse(
+                status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
+                content={"detail": "db factory not configured"},
+            )
         try:
             with db_factory.get_session_ctx_manager() as request_session:
                 hashed_token = security.hash_session_token_sha256(token)
                 request.state.db_session = request_session
                 login_session: Sessions | None = crud.get_login_session_by_token_hash(request_session, hashed_token)
                 if not login_session:
-                    return JSONResponse(status_code=status.HTTP_401_UNAUTHORIZED, content={"detail": "Unauthorized"})
+                    return JSONResponse(
+                        status_code=status.HTTP_401_UNAUTHORIZED,
+                        content={"detail": "Unauthorized"},
+                    )
                 session_expires_utc = login_session.expires_at.replace(tzinfo=timezone.utc)
                 if session_expires_utc < datetime.now(timezone.utc):
                     crud.delete_login_session(request_session, login_session.session_token_hash)
-                    return JSONResponse(status_code=status.HTTP_401_UNAUTHORIZED, content={"detail": "Unauthorized"})
+                    return JSONResponse(
+                        status_code=status.HTTP_401_UNAUTHORIZED,
+                        content={"detail": "Unauthorized"},
+                    )
                 if login_session.user.is_active is False:
-                    return JSONResponse(status_code=status.HTTP_401_UNAUTHORIZED, content={"detail": "Unauthorized"})
+                    return JSONResponse(
+                        status_code=status.HTTP_401_UNAUTHORIZED,
+                        content={"detail": "Unauthorized"},
+                    )
                 if session_expires_utc - datetime.now(timezone.utc) < timedelta(seconds=3600):
                     updated_expiry = datetime.now(timezone.utc) + timedelta(seconds=settings.settings.session_expiry_seconds)
                 else:
@@ -91,43 +115,14 @@ class AuthMiddleWare(BaseHTTPMiddleware):
                 crud.update_login_session(request_session, hashed_token, update_session=updated_session)
         except Exception:
             logger.exception("Failed to authenticate user: \n")
-            return JSONResponse(status_code=status.HTTP_500_INTERNAL_SERVER_ERROR, content={"detail": "Internal server error"})
+            return JSONResponse(
+                status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
+                content={"detail": "Internal server error"},
+            )
 
         return await call_next(request)
 
 
-class ServiceError(Exception):
-    pass
-
-
-class UserAlreadyExistsError(ServiceError):
-    pass
-
-
-class ExchangeAlreadyExistsError(ServiceError):
-    pass
-
-
-class ExchangeNotFoundError(ServiceError):
-    pass
-
-
-class CycleNotFoundError(ServiceError):
-    pass
-
-
-class TradeNotFoundError(ServiceError):
-    pass
-
-
-class InvalidTradeDataError(ServiceError):
-    pass
-
-
-class InvalidCycleDataError(ServiceError):
-    pass
-
-
 # User service
 def register_user_service(db_session: Session, user_in: UserCreate) -> UserRead:
     if crud.get_user_by_username(db_session, user_in.username):
@@ -203,7 +198,13 @@ def get_exchanges_by_user_service(db_session: Session, user_id: int) -> list[Exc
     return [ExchangesRead.model_validate(exchange) for exchange in exchanges]
 
 
-def update_exchanges_service(db_session: Session, user_id: int, exchange_id: int, name: str | None, notes: str | None) -> ExchangesBase:
+def update_exchanges_service(
+    db_session: Session,
+    user_id: int,
+    exchange_id: int,
+    name: str | None,
+    notes: str | None,
+) -> ExchangesBase:
     existing_exchange = crud.get_exchange_by_id(db_session, exchange_id)
     if not existing_exchange:
         raise ExchangeNotFoundError("Exchange not found")
@@ -263,7 +264,10 @@ def _validate_cycle_update_data(cycle_data: CycleUpdate) -> tuple[bool, str]:  #
         and cycle_data.funding_source != "CASH"
         and (cycle_data.loan_amount_cents is None or cycle_data.loan_interest_rate_tenth_bps is None)
     ):
-        return False, "loan_amount_cents and loan_interest_rate_tenth_bps are required when funding_source is not CASH"
+        return (
+            False,
+            "loan_amount_cents and loan_interest_rate_tenth_bps are required when funding_source is not CASH",
+        )
     if cycle_data.loan_amount_cents is not None and cycle_data.loan_amount_cents < 0:
         return False, "loan_amount_cents must be non-negative"
     if cycle_data.loan_interest_rate_tenth_bps is not None and cycle_data.loan_interest_rate_tenth_bps < 0:
@@ -271,6 +275,31 @@ def _validate_cycle_update_data(cycle_data: CycleUpdate) -> tuple[bool, str]:  #
     return True, ""
 
 
+def _create_cycle_loan_event(
+    db_session: Session,
+    cycle_id: int,
+    loan_amount_cents: int | None,
+    loan_interest_rate_tenth_bps: int | None,
+) -> None:
+    now = datetime.now(timezone.utc)
+    today = now.date()
+    existing_loan_event = crud.get_loan_event_by_cycle_id_and_effective_date(db_session, cycle_id, today)
+    if existing_loan_event:
+        raise CycleLoanEventExistsError("A loan event with the same effective_date already exists for this cycle.")
+    loan_event_data = CycleLoanChangeEventBase(
+        cycle_id=cycle_id,
+        effective_date=today,
+        loan_amount_cents=loan_amount_cents,
+        loan_interest_rate_tenth_bps=loan_interest_rate_tenth_bps,
+        created_at=now,
+    )
+    try:
+        crud.create_cycle_loan_event(db_session, loan_event_data)
+    except Exception as e:
+        logger.exception("Failed to create cycle loan event: \n")
+        raise ServiceError("Failed to create cycle loan event") from e
+
+
 def update_cycle_service(db_session: Session, user_id: int, cycle_data: CycleUpdate) -> CycleRead:
     is_valid, err_msg = _validate_cycle_update_data(cycle_data)
     if not is_valid:
@@ -281,6 +310,13 @@ def update_cycle_service(db_session: Session, user_id: int, cycle_data: CycleUpd
         raise CycleNotFoundError("Cycle not found")
     if existing_cycle.user_id != user_id:
         raise CycleNotFoundError("Cycle not found")
+    if cycle_data.loan_amount_cents is not None or cycle_data.loan_interest_rate_tenth_bps is not None:
+        _create_cycle_loan_event(
+            db_session,
+            cycle_id,
+            cycle_data.loan_amount_cents,
+            cycle_data.loan_interest_rate_tenth_bps,
+        )
 
     provided_data_dict = cycle_data.model_dump(exclude_unset=True)
     cycle_data_with_user_id: CycleBase = CycleBase.model_validate(provided_data_dict)
@@ -293,10 +329,42 @@ def update_cycle_service(db_session: Session, user_id: int, cycle_data: CycleUpd
     return CycleRead.model_validate(updated_cycle)
 
 
+def accrual_interest_service(db_session: Session, cycle_id: int) -> None:
+    cycle = crud.get_cycle_by_id(db_session, cycle_id)
+    if not cycle:
+        logger.exception("Cycle not found for interest accrual")
+        raise CycleNotFoundError("Cycle not found")
+    if cycle.loan_amount_cents is None or cycle.loan_interest_rate_tenth_bps is None:
+        logger.info("Cycle has no loan, skipping interest accrual")
+        return
+    today = datetime.now(timezone.utc).date()
+    amount_cents = round(cycle.loan_amount_cents * cycle.loan_interest_rate_tenth_bps / 100000 / 365)
+    try:
+        crud.create_cycle_daily_accrual(
+            db_session,
+            cycle_id=cycle_id,
+            accrual_date=today,
+            accrual_amount_cents=amount_cents,
+        )
+    except Exception as e:
+        logger.exception("Failed to create cycle interest accrual: \n")
+        raise ServiceError("Failed to create cycle interest accrual") from e
+
+
+def flush_interest_accruals_service(db_session: Session) -> None:
+    pass
+
+
 # Trades service
 def _append_cashflows(trade_data: TradeCreate) -> TradeCreate:
     sign_multipler: int
-    if trade_data.trade_type in ("SELL_PUT", "SELL_CALL", "EXERCISE_CALL", "CLOSE_LONG_SPOT", "SHORT_SPOT"):
+    if trade_data.trade_type in (
+        "SELL_PUT",
+        "SELL_CALL",
+        "EXERCISE_CALL",
+        "CLOSE_LONG_SPOT",
+        "SHORT_SPOT",
+    ):
         sign_multipler = 1
     else:
         sign_multipler = -1

backend/trading_journal/service_error.py

@@ -0,0 +1,34 @@
+class ServiceError(Exception):
+    pass
+
+
+class UserAlreadyExistsError(ServiceError):
+    pass
+
+
+class ExchangeAlreadyExistsError(ServiceError):
+    pass
+
+
+class ExchangeNotFoundError(ServiceError):
+    pass
+
+
+class CycleNotFoundError(ServiceError):
+    pass
+
+
+class TradeNotFoundError(ServiceError):
+    pass
+
+
+class InvalidTradeDataError(ServiceError):
+    pass
+
+
+class InvalidCycleDataError(ServiceError):
+    pass
+
+
+class CycleLoanEventExistsError(ServiceError):
+    pass