fix: force auto-begin in create_db_dependency so lock_tables always uses savepoints (#176)

.pre-commit-config.yaml

@@ -0,0 +1,34 @@
+# See https://pre-commit.com for more information
+# See https://pre-commit.com/hooks.html for more hooks
+repos:
+    - repo: https://github.com/pre-commit/pre-commit-hooks
+      rev: v6.0.0
+      hooks:
+          - id: check-added-large-files
+            args: ["--maxkb=750"]
+            exclude: ^uv.lock$
+          - id: end-of-file-fixer
+          - id: trailing-whitespace
+
+    - repo: local
+      hooks:
+          - id: local-ruff-check
+            name: ruff check
+            entry: uv run ruff check --force-exclude --fix --exit-non-zero-on-fix .
+            require_serial: true
+            language: unsupported
+            types: [python]
+
+          - id: local-ruff-format
+            name: ruff format
+            entry: uv run ruff format --force-exclude --exit-non-zero-on-format .
+            require_serial: true
+            language: unsupported
+            types: [python]
+
+          - id: local-ty
+            name: ty check
+            entry: uv run ty check
+            require_serial: true
+            language: unsupported
+            pass_filenames: false

docs/module/models.md

@@ -138,6 +138,23 @@ Server-side defaults (e.g. `id`, `created_at`) are fully populated in all callba
 | `@watch("status", "role")` | Only fires when `status` or `role` changes |
 | *(no decorator)* | Fires when **any** mapped field changes |
 
+`@watch` is inherited through the class hierarchy. If a subclass does not declare its own `@watch`, it uses the filter from the nearest decorated parent. Applying `@watch` on the subclass overrides the parent's filter:
+
+```python
+@watch("status")
+class Order(Base, UUIDMixin, WatchedFieldsMixin):
+    ...
+
+class UrgentOrder(Order):
+    # inherits @watch("status") — on_update fires only for status changes
+    ...
+
+@watch("priority")
+class PriorityOrder(Order):
+    # overrides parent — on_update fires only for priority changes
+    ...
+```
+
 #### Option 1 — catch-all with `on_event`
 
 Override `on_event` to handle all event types in one place. The specific methods delegate here by default:
@@ -197,6 +214,25 @@ The `changes` dict maps each watched field that changed to `{"old": ..., "new":
 
 !!! warning "Callbacks fire only for ORM-level changes. Rows updated via raw SQL (`UPDATE ... SET ...`) are not detected."
 
+!!! warning "Callbacks fire when the **outermost active context** (savepoint or transaction) commits."
+    If you create several related objects using `CrudFactory.create` and need
+    callbacks to see all of them (including associations), wrap the whole
+    operation in a single [`get_transaction`](db.md) or [`lock_tables`](db.md)
+    block. Without it, each `create` call commits its own savepoint and
+    `on_create` fires before the remaining objects exist.
+
+    ```python
+    from fastapi_toolsets.db import get_transaction
+
+    async with get_transaction(session):
+        order = await OrderCrud.create(session, order_data)
+        item  = await ItemCrud.create(session, item_data)
+        await session.refresh(order, attribute_names=["items"])
+        order.items.append(item)
+    # on_create fires here for both order and item,
+    # with the full association already committed.
+    ```
+
 ## Composing mixins
 
 All mixins can be combined in any order. The only constraint is that exactly one primary key must be defined — either via `UUIDMixin` or directly on the model.

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "fastapi-toolsets"
-version = "2.4.1"
+version = "2.4.2"
 description = "Production-ready utilities for FastAPI applications"
 readme = "README.md"
 license = "MIT"
@@ -67,6 +67,7 @@ dev = [
     {include-group = "tests"},
     {include-group = "docs"},
     "fastapi-toolsets[all]",
+    "prek>=0.3.8",
     "ruff>=0.1.0",
     "ty>=0.0.1a0",
 ]

src/fastapi_toolsets/__init__.py

@@ -21,4 +21,4 @@ Example usage:
         return Response(data={"user": user.username}, message="Success")
 """
 
-__version__ = "2.4.1"
+__version__ = "2.4.2"

src/fastapi_toolsets/db.py

@@ -56,6 +56,7 @@ def create_db_dependency(
 
     async def get_db() -> AsyncGenerator[AsyncSession, None]:
         async with session_maker() as session:
+            await session.connection()
             yield session
             if session.in_transaction():
                 await session.commit()

src/fastapi_toolsets/models/watched.py

@@ -1,6 +1,7 @@
 """Field-change monitoring via SQLAlchemy session events."""
 
 import asyncio
+import inspect
 import weakref
 from collections.abc import Awaitable
 from enum import Enum
@@ -25,6 +26,7 @@ _SESSION_PENDING_NEW = "_ft_pending_new"
 _SESSION_CREATES = "_ft_creates"
 _SESSION_DELETES = "_ft_deletes"
 _SESSION_UPDATES = "_ft_updates"
+_SESSION_SAVEPOINT_DEPTH = "_ft_sp_depth"
 
 
 class ModelEvent(str, Enum):
@@ -65,6 +67,14 @@ def _snapshot_column_attrs(obj: Any) -> dict[str, Any]:
     }
 
 
+def _get_watched_fields(cls: type) -> list[str] | None:
+    """Return the watched fields for *cls*, walking the MRO to inherit from parents."""
+    for klass in cls.__mro__:
+        if klass in _WATCHED_FIELDS:
+            return _WATCHED_FIELDS[klass]
+    return None
+
+
 def _upsert_changes(
     pending: dict[int, tuple[Any, dict[str, dict[str, Any]]]],
     obj: Any,
@@ -83,6 +93,22 @@ def _upsert_changes(
         pending[key] = (obj, changes)
 
 
+@event.listens_for(AsyncSession.sync_session_class, "after_transaction_create")
+def _after_transaction_create(session: Any, transaction: Any) -> None:
+    if transaction.nested:
+        session.info[_SESSION_SAVEPOINT_DEPTH] = (
+            session.info.get(_SESSION_SAVEPOINT_DEPTH, 0) + 1
+        )
+
+
+@event.listens_for(AsyncSession.sync_session_class, "after_transaction_end")
+def _after_transaction_end(session: Any, transaction: Any) -> None:
+    if transaction.nested:
+        depth = session.info.get(_SESSION_SAVEPOINT_DEPTH, 0)
+        if depth > 0:  # pragma: no branch
+            session.info[_SESSION_SAVEPOINT_DEPTH] = depth - 1
+
+
 @event.listens_for(AsyncSession.sync_session_class, "after_flush")
 def _after_flush(session: Any, flush_context: Any) -> None:
     # New objects: capture references while session.new is still populated.
@@ -102,7 +128,7 @@ def _after_flush(session: Any, flush_context: Any) -> None:
             continue
 
         # None = not in dict = watch all fields; list = specific fields only
-        watched = _WATCHED_FIELDS.get(type(obj))
+        watched = _get_watched_fields(type(obj))
         changes: dict[str, dict[str, Any]] = {}
 
         attrs = (
@@ -169,7 +195,7 @@ def _schedule_with_snapshot(
             _sa_set_committed_value(obj, key, value)
         try:
             result = fn(*args)
-            if asyncio.iscoroutine(result):
+            if inspect.isawaitable(result):
                 await result
         except Exception as exc:
             _logger.error(_CALLBACK_ERROR_MSG, exc_info=exc)
@@ -180,12 +206,24 @@ def _schedule_with_snapshot(
 
 @event.listens_for(AsyncSession.sync_session_class, "after_commit")
 def _after_commit(session: Any) -> None:
+    if session.info.get(_SESSION_SAVEPOINT_DEPTH, 0) > 0:
+        return
+
     creates: list[Any] = session.info.pop(_SESSION_CREATES, [])
     deletes: list[Any] = session.info.pop(_SESSION_DELETES, [])
     field_changes: dict[int, tuple[Any, dict[str, dict[str, Any]]]] = session.info.pop(
         _SESSION_UPDATES, {}
     )
 
+    if creates and deletes:
+        transient_ids = {id(o) for o in creates} & {id(o) for o in deletes}
+        if transient_ids:
+            creates = [o for o in creates if id(o) not in transient_ids]
+            deletes = [o for o in deletes if id(o) not in transient_ids]
+            field_changes = {
+                k: v for k, v in field_changes.items() if k not in transient_ids
+            }
+
     if not creates and not deletes and not field_changes:
         return
 

tests/conftest.py

@@ -321,30 +321,3 @@ async def db_session(engine):
         # Drop tables after test
         async with engine.begin() as conn:
             await conn.run_sync(Base.metadata.drop_all)
-
-
-@pytest.fixture
-def sample_role_data() -> RoleCreate:
-    """Sample role creation data."""
-    return RoleCreate(name="admin")
-
-
-@pytest.fixture
-def sample_user_data() -> UserCreate:
-    """Sample user creation data."""
-    return UserCreate(
-        username="testuser",
-        email="test@example.com",
-        is_active=True,
-    )
-
-
-@pytest.fixture
-def sample_post_data() -> PostCreate:
-    """Sample post creation data."""
-    return PostCreate(
-        title="Test Post",
-        content="Test content",
-        is_published=True,
-        author_id=uuid.uuid4(),
-    )

tests/test_db.py

@@ -68,6 +68,55 @@ class TestCreateDbDependency:
                 await conn.run_sync(Base.metadata.drop_all)
             await engine.dispose()
 
+    @pytest.mark.anyio
+    async def test_in_transaction_on_yield(self):
+        """Session is already in a transaction when the endpoint body starts."""
+        engine = create_async_engine(DATABASE_URL, echo=False)
+        session_factory = async_sessionmaker(engine, expire_on_commit=False)
+        get_db = create_db_dependency(session_factory)
+
+        async for session in get_db():
+            assert session.in_transaction()
+            break
+
+        await engine.dispose()
+
+    @pytest.mark.anyio
+    async def test_update_after_lock_tables_is_persisted(self):
+        """Changes made after lock_tables exits (before endpoint returns) are committed.
+
+        Regression: without the auto-begin fix, lock_tables would start and commit a
+        real outer transaction, leaving the session idle. Any modifications after that
+        point were silently dropped.
+        """
+        engine = create_async_engine(DATABASE_URL, echo=False)
+        session_factory = async_sessionmaker(engine, expire_on_commit=False)
+
+        async with engine.begin() as conn:
+            await conn.run_sync(Base.metadata.create_all)
+
+        try:
+            get_db = create_db_dependency(session_factory)
+
+            async for session in get_db():
+                async with lock_tables(session, [Role]):
+                    role = Role(name="lock_then_update")
+                    session.add(role)
+                    await session.flush()
+                # lock_tables has exited — outer transaction must still be open
+                assert session.in_transaction()
+                role.name = "updated_after_lock"
+
+            async with session_factory() as verify:
+                result = await RoleCrud.first(
+                    verify, [Role.name == "updated_after_lock"]
+                )
+                assert result is not None
+        finally:
+            async with engine.begin() as conn:
+                await conn.run_sync(Base.metadata.drop_all)
+            await engine.dispose()
+
 
 class TestCreateDbContext:
     """Tests for create_db_context."""

tests/test_example_pagination_search.py

@@ -10,12 +10,13 @@ import datetime
 import pytest
 from fastapi import FastAPI
 from httpx import ASGITransport, AsyncClient
-from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
+from sqlalchemy.ext.asyncio import AsyncSession
 
 from docs_src.examples.pagination_search.db import get_db
 from docs_src.examples.pagination_search.models import Article, Base, Category
 from docs_src.examples.pagination_search.routes import router
 from fastapi_toolsets.exceptions import init_exceptions_handlers
+from fastapi_toolsets.pytest import create_db_session
 
 from .conftest import DATABASE_URL
 
@@ -35,20 +36,8 @@ def build_app(session: AsyncSession) -> FastAPI:
 @pytest.fixture(scope="function")
 async def ex_db_session():
     """Isolated session for the example models (separate tables from conftest)."""
-    engine = create_async_engine(DATABASE_URL, echo=False)
-    async with engine.begin() as conn:
-        await conn.run_sync(Base.metadata.create_all)
-
-    session_factory = async_sessionmaker(engine, expire_on_commit=False)
-    session = session_factory()
-
-    try:
+    async with create_db_session(DATABASE_URL, Base) as session:
         yield session
-    finally:
-        await session.close()
-        async with engine.begin() as conn:
-            await conn.run_sync(Base.metadata.drop_all)
-        await engine.dispose()
 
 
 @pytest.fixture

tests/test_fixtures.py

@@ -16,7 +16,7 @@ from fastapi_toolsets.fixtures import (
 
 from fastapi_toolsets.fixtures.utils import _get_primary_key
 
-from .conftest import IntRole, Permission, Role, User
+from .conftest import IntRole, Permission, Role, RoleCrud, User, UserCrud
 
 
 class TestContext:
@@ -447,8 +447,6 @@ class TestLoadFixtures:
         assert "roles" in result
         assert len(result["roles"]) == 2
 
-        from .conftest import RoleCrud
-
         count = await RoleCrud.count(db_session)
         assert count == 2
 
@@ -479,8 +477,6 @@ class TestLoadFixtures:
         assert "roles" in result
         assert "users" in result
 
-        from .conftest import RoleCrud, UserCrud
-
         assert await RoleCrud.count(db_session) == 1
         assert await UserCrud.count(db_session) == 1
 
@@ -497,8 +493,6 @@ class TestLoadFixtures:
         await load_fixtures(db_session, registry, "roles", strategy=LoadStrategy.MERGE)
         await load_fixtures(db_session, registry, "roles", strategy=LoadStrategy.MERGE)
 
-        from .conftest import RoleCrud
-
         count = await RoleCrud.count(db_session)
         assert count == 1
 
@@ -526,8 +520,6 @@ class TestLoadFixtures:
             db_session, registry, "roles", strategy=LoadStrategy.SKIP_EXISTING
         )
 
-        from .conftest import RoleCrud
-
         role = await RoleCrud.first(db_session, [Role.id == role_id])
         assert role is not None
         assert role.name == "original"
@@ -553,8 +545,6 @@ class TestLoadFixtures:
         assert "roles" in result
         assert len(result["roles"]) == 2
 
-        from .conftest import RoleCrud
-
         count = await RoleCrud.count(db_session)
         assert count == 2
 
@@ -594,8 +584,6 @@ class TestLoadFixtures:
         assert "roles" in result
         assert "other_roles" in result
 
-        from .conftest import RoleCrud
-
         count = await RoleCrud.count(db_session)
         assert count == 2
 
@@ -660,8 +648,6 @@ class TestLoadFixturesByContext:
 
         await load_fixtures_by_context(db_session, registry, Context.BASE)
 
-        from .conftest import RoleCrud
-
         count = await RoleCrud.count(db_session)
         assert count == 1
 
@@ -688,8 +674,6 @@ class TestLoadFixturesByContext:
             db_session, registry, Context.BASE, Context.TESTING
         )
 
-        from .conftest import RoleCrud
-
         count = await RoleCrud.count(db_session)
         assert count == 2
 
@@ -717,8 +701,6 @@ class TestLoadFixturesByContext:
 
         await load_fixtures_by_context(db_session, registry, Context.TESTING)
 
-        from .conftest import RoleCrud, UserCrud
-
         assert await RoleCrud.count(db_session) == 1
         assert await UserCrud.count(db_session) == 1
 

tests/test_imports.py

@@ -171,8 +171,15 @@ class TestPytestImportGuard:
 class TestCliImportGuard:
     """Tests for CLI module import guard when typer is missing."""
 
-    def test_import_raises_without_typer(self):
-        """Importing cli.app raises when typer is missing."""
+    @pytest.mark.parametrize(
+        "expected_match",
+        [
+            "typer",
+            r"pip install fastapi-toolsets\[cli\]",
+        ],
+    )
+    def test_import_raises_without_typer(self, expected_match):
+        """Importing cli.app raises when typer is missing, with an informative error message."""
         saved, blocking_import = _reload_without_package(
             "fastapi_toolsets.cli.app", ["typer"]
         )
@@ -186,33 +193,7 @@ class TestCliImportGuard:
 
         try:
             with patch("builtins.__import__", side_effect=blocking_import):
-                with pytest.raises(ImportError, match="typer"):
-                    importlib.import_module("fastapi_toolsets.cli.app")
-        finally:
-            for key in list(sys.modules):
-                if key.startswith("fastapi_toolsets.cli.app") or key.startswith(
-                    "fastapi_toolsets.cli.config"
-                ):
-                    sys.modules.pop(key, None)
-            sys.modules.update(saved)
-
-    def test_error_message_suggests_cli_extra(self):
-        """Error message suggests installing the cli extra."""
-        saved, blocking_import = _reload_without_package(
-            "fastapi_toolsets.cli.app", ["typer"]
-        )
-        config_keys = [
-            k for k in sys.modules if k.startswith("fastapi_toolsets.cli.config")
-        ]
-        for key in config_keys:
-            if key not in saved:
-                saved[key] = sys.modules.pop(key)
-
-        try:
-            with patch("builtins.__import__", side_effect=blocking_import):
-                with pytest.raises(
-                    ImportError, match=r"pip install fastapi-toolsets\[cli\]"
-                ):
+                with pytest.raises(ImportError, match=expected_match):
                     importlib.import_module("fastapi_toolsets.cli.app")
         finally:
             for key in list(sys.modules):

tests/test_metrics.py

@@ -1,6 +1,5 @@
 """Tests for fastapi_toolsets.metrics module."""
 
-import os
 import tempfile
 from unittest.mock import AsyncMock, MagicMock
 
@@ -287,6 +286,16 @@ class TestIncludeRegistry:
 class TestInitMetrics:
     """Tests for init_metrics function."""
 
+    @pytest.fixture
+    def metrics_client(self):
+        """Create a FastAPI app with MetricsRegistry and return a TestClient."""
+        app = FastAPI()
+        registry = MetricsRegistry()
+        init_metrics(app, registry)
+        client = TestClient(app)
+        yield client
+        client.close()
+
     def test_returns_app(self):
         """Returns the FastAPI app."""
         app = FastAPI()
@@ -294,26 +303,14 @@ class TestInitMetrics:
         result = init_metrics(app, registry)
         assert result is app
 
-    def test_metrics_endpoint_responds(self):
+    def test_metrics_endpoint_responds(self, metrics_client):
         """The /metrics endpoint returns 200."""
-        app = FastAPI()
-        registry = MetricsRegistry()
-        init_metrics(app, registry)
-
-        client = TestClient(app)
-        response = client.get("/metrics")
-
+        response = metrics_client.get("/metrics")
         assert response.status_code == 200
 
-    def test_metrics_endpoint_content_type(self):
+    def test_metrics_endpoint_content_type(self, metrics_client):
         """The /metrics endpoint returns prometheus content type."""
-        app = FastAPI()
-        registry = MetricsRegistry()
-        init_metrics(app, registry)
-
-        client = TestClient(app)
-        response = client.get("/metrics")
-
+        response = metrics_client.get("/metrics")
         assert "text/plain" in response.headers["content-type"]
 
     def test_custom_path(self):
@@ -445,11 +442,10 @@ class TestInitMetrics:
 class TestMultiProcessMode:
     """Tests for multi-process Prometheus mode."""
 
-    def test_multiprocess_with_env_var(self):
+    def test_multiprocess_with_env_var(self, monkeypatch):
         """Multi-process mode works when PROMETHEUS_MULTIPROC_DIR is set."""
         with tempfile.TemporaryDirectory() as tmpdir:
-            os.environ["PROMETHEUS_MULTIPROC_DIR"] = tmpdir
-            try:
+            monkeypatch.setenv("PROMETHEUS_MULTIPROC_DIR", tmpdir)
             # Use a separate registry to avoid conflicts with default
             prom_registry = CollectorRegistry()
             app = FastAPI()
@@ -469,12 +465,10 @@ class TestMultiProcessMode:
             response = client.get("/metrics")
 
             assert response.status_code == 200
-            finally:
-                del os.environ["PROMETHEUS_MULTIPROC_DIR"]
 
-    def test_single_process_without_env_var(self):
+    def test_single_process_without_env_var(self, monkeypatch):
         """Single-process mode when PROMETHEUS_MULTIPROC_DIR is not set."""
-        os.environ.pop("PROMETHEUS_MULTIPROC_DIR", None)
+        monkeypatch.delenv("PROMETHEUS_MULTIPROC_DIR", raising=False)
 
         app = FastAPI()
         registry = MetricsRegistry()

tests/test_models.py

@@ -6,27 +6,28 @@ from contextlib import suppress
 from types import SimpleNamespace
 from unittest.mock import patch
 
-import fastapi_toolsets.models.watched as _watched_module
 import pytest
 from sqlalchemy import String
-from sqlalchemy.ext.asyncio import async_sessionmaker, create_async_engine
 from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column
 
+from fastapi_toolsets.pytest import create_db_session
+
+import fastapi_toolsets.models.watched as _watched_module
 from fastapi_toolsets.models import (
     CreatedAtMixin,
     ModelEvent,
     TimestampMixin,
+    UpdatedAtMixin,
     UUIDMixin,
     UUIDv7Mixin,
-    UpdatedAtMixin,
     WatchedFieldsMixin,
     watch,
 )
 from fastapi_toolsets.models.watched import (
     _SESSION_CREATES,
     _SESSION_DELETES,
-    _SESSION_UPDATES,
     _SESSION_PENDING_NEW,
+    _SESSION_UPDATES,
     _after_commit,
     _after_flush,
     _after_flush_postexec,
@@ -81,8 +82,6 @@ class FullMixinModel(MixinBase, UUIDMixin, UpdatedAtMixin):
     name: Mapped[str] = mapped_column(String(50))
 
 
-# --- WatchedFieldsMixin test models ---
-
 _test_events: list[dict] = []
 
 
@@ -145,6 +144,66 @@ class NonWatchedModel(MixinBase):
     value: Mapped[str] = mapped_column(String(50))
 
 
+_poly_events: list[dict] = []
+
+
+class PolyAnimal(MixinBase, UUIDMixin, WatchedFieldsMixin):
+    """Base class for STI polymorphism tests."""
+
+    __tablename__ = "mixin_poly_animals"
+    __mapper_args__ = {"polymorphic_on": "kind", "polymorphic_identity": "animal"}
+
+    kind: Mapped[str] = mapped_column(String(50))
+    name: Mapped[str] = mapped_column(String(50))
+
+    async def on_create(self) -> None:
+        _poly_events.append(
+            {"event": "create", "type": type(self).__name__, "obj_id": self.id}
+        )
+
+    async def on_delete(self) -> None:
+        _poly_events.append(
+            {"event": "delete", "type": type(self).__name__, "obj_id": self.id}
+        )
+
+
+class PolyDog(PolyAnimal):
+    """STI subclass — shares the same table as PolyAnimal."""
+
+    __mapper_args__ = {"polymorphic_identity": "dog"}
+
+
+_watch_inherit_events: list[dict] = []
+
+
+@watch("status")
+class WatchParent(MixinBase, UUIDMixin, WatchedFieldsMixin):
+    """Base class with @watch("status") — subclasses should inherit this filter."""
+
+    __tablename__ = "mixin_watch_parent"
+    __mapper_args__ = {"polymorphic_on": "kind", "polymorphic_identity": "parent"}
+
+    kind: Mapped[str] = mapped_column(String(50))
+    status: Mapped[str] = mapped_column(String(50))
+    other: Mapped[str] = mapped_column(String(50))
+
+    async def on_update(self, changes: dict) -> None:
+        _watch_inherit_events.append({"type": type(self).__name__, "changes": changes})
+
+
+class WatchChild(WatchParent):
+    """STI subclass that does NOT redeclare @watch — should inherit parent's filter."""
+
+    __mapper_args__ = {"polymorphic_identity": "child"}
+
+
+@watch("other")
+class WatchOverride(WatchParent):
+    """STI subclass that overrides @watch with a different field."""
+
+    __mapper_args__ = {"polymorphic_identity": "override"}
+
+
 _attr_access_events: list[dict] = []
 
 
@@ -172,6 +231,7 @@ class AttrAccessModel(MixinBase, UUIDMixin, WatchedFieldsMixin):
 
 
 _sync_events: list[dict] = []
+_future_events: list[str] = []
 
 
 @watch("status")
@@ -192,41 +252,33 @@ class SyncCallbackModel(MixinBase, UUIDMixin, WatchedFieldsMixin):
         _sync_events.append({"event": "update", "changes": changes})
 
 
+class FutureCallbackModel(MixinBase, UUIDMixin, WatchedFieldsMixin):
+    """Model whose on_create returns an asyncio.Task (awaitable, not a coroutine)."""
+
+    __tablename__ = "mixin_future_callback_models"
+
+    name: Mapped[str] = mapped_column(String(50))
+
+    def on_create(self) -> "asyncio.Task[None]":
+        async def _work() -> None:
+            _future_events.append("created")
+
+        return asyncio.ensure_future(_work())
+
+
 @pytest.fixture(scope="function")
 async def mixin_session():
-    engine = create_async_engine(DATABASE_URL, echo=False)
-    async with engine.begin() as conn:
-        await conn.run_sync(MixinBase.metadata.create_all)
-
-    session_factory = async_sessionmaker(engine, expire_on_commit=False)
-    session = session_factory()
-
-    try:
+    async with create_db_session(DATABASE_URL, MixinBase) as session:
         yield session
-    finally:
-        await session.close()
-        async with engine.begin() as conn:
-            await conn.run_sync(MixinBase.metadata.drop_all)
-        await engine.dispose()
 
 
 @pytest.fixture(scope="function")
 async def mixin_session_expire():
     """Session with expire_on_commit=True (the default) to exercise attribute access after commit."""
-    engine = create_async_engine(DATABASE_URL, echo=False)
-    async with engine.begin() as conn:
-        await conn.run_sync(MixinBase.metadata.create_all)
-
-    session_factory = async_sessionmaker(engine, expire_on_commit=True)
-    session = session_factory()
-
-    try:
+    async with create_db_session(
+        DATABASE_URL, MixinBase, expire_on_commit=True
+    ) as session:
         yield session
-    finally:
-        await session.close()
-        async with engine.begin() as conn:
-            await conn.run_sync(MixinBase.metadata.drop_all)
-        await engine.dispose()
 
 
 class TestUUIDMixin:
@@ -473,6 +525,67 @@ class TestWatchDecorator:
             watch()
 
 
+class TestWatchInheritance:
+    @pytest.fixture(autouse=True)
+    def clear_events(self):
+        _watch_inherit_events.clear()
+        yield
+        _watch_inherit_events.clear()
+
+    @pytest.mark.anyio
+    async def test_child_inherits_parent_watch_filter(self, mixin_session):
+        """Subclass without @watch inherits the parent's field filter."""
+        obj = WatchChild(status="initial", other="x")
+        mixin_session.add(obj)
+        await mixin_session.commit()
+        await asyncio.sleep(0)
+
+        obj.other = "changed"  # not watched by parent's @watch("status")
+        await mixin_session.commit()
+        await asyncio.sleep(0)
+
+        assert _watch_inherit_events == []
+
+    @pytest.mark.anyio
+    async def test_child_triggers_on_watched_field(self, mixin_session):
+        """Subclass without @watch triggers on_update for the parent's watched field."""
+        obj = WatchChild(status="initial", other="x")
+        mixin_session.add(obj)
+        await mixin_session.commit()
+        await asyncio.sleep(0)
+
+        obj.status = "updated"
+        await mixin_session.commit()
+        await asyncio.sleep(0)
+
+        assert len(_watch_inherit_events) == 1
+        assert _watch_inherit_events[0]["type"] == "WatchChild"
+        assert "status" in _watch_inherit_events[0]["changes"]
+
+    @pytest.mark.anyio
+    async def test_subclass_override_takes_precedence(self, mixin_session):
+        """Subclass @watch overrides the parent's field filter."""
+        obj = WatchOverride(status="initial", other="x")
+        mixin_session.add(obj)
+        await mixin_session.commit()
+        await asyncio.sleep(0)
+
+        obj.status = (
+            "changed"  # watched by parent but overridden by child's @watch("other")
+        )
+        await mixin_session.commit()
+        await asyncio.sleep(0)
+
+        assert _watch_inherit_events == []
+
+        obj.other = "changed"
+        await mixin_session.commit()
+        await asyncio.sleep(0)
+
+        assert len(_watch_inherit_events) == 1
+        assert "other" in _watch_inherit_events[0]["changes"]
+
+
 class TestUpsertChanges:
     def test_inserts_new_entry(self):
         """New key is inserted with the full changes dict."""
@@ -871,6 +984,119 @@ class TestWatchedFieldsMixin:
         }
 
 
+class TestTransientObject:
+    """Create + delete within the same transaction should fire no events."""
+
+    @pytest.fixture(autouse=True)
+    def clear_events(self):
+        _test_events.clear()
+        yield
+        _test_events.clear()
+
+    @pytest.mark.anyio
+    async def test_no_events_when_created_and_deleted_in_same_transaction(
+        self, mixin_session
+    ):
+        """Neither on_create nor on_delete fires when the object never survives a commit."""
+        obj = WatchedModel(status="active", other="x")
+        mixin_session.add(obj)
+        await mixin_session.flush()
+        await mixin_session.delete(obj)
+        await mixin_session.commit()
+        await asyncio.sleep(0)
+
+        assert _test_events == []
+
+    @pytest.mark.anyio
+    async def test_other_objects_unaffected(self, mixin_session):
+        """on_create still fires for objects that are not deleted in the same transaction."""
+        survivor = WatchedModel(status="active", other="x")
+        transient = WatchedModel(status="gone", other="y")
+        mixin_session.add(survivor)
+        mixin_session.add(transient)
+        await mixin_session.flush()
+        await mixin_session.delete(transient)
+        await mixin_session.commit()
+        await asyncio.sleep(0)
+
+        creates = [e for e in _test_events if e["event"] == "create"]
+        deletes = [e for e in _test_events if e["event"] == "delete"]
+        assert len(creates) == 1
+        assert creates[0]["obj_id"] == survivor.id
+        assert deletes == []
+
+    @pytest.mark.anyio
+    async def test_distinct_create_and_delete_both_fire(self, mixin_session):
+        """on_create and on_delete both fire when different objects are created and deleted."""
+        existing = WatchedModel(status="old", other="x")
+        mixin_session.add(existing)
+        await mixin_session.commit()
+        await asyncio.sleep(0)
+        _test_events.clear()
+
+        new_obj = WatchedModel(status="new", other="y")
+        mixin_session.add(new_obj)
+        await mixin_session.delete(existing)
+        await mixin_session.commit()
+        await asyncio.sleep(0)
+
+        creates = [e for e in _test_events if e["event"] == "create"]
+        deletes = [e for e in _test_events if e["event"] == "delete"]
+        assert len(creates) == 1
+        assert len(deletes) == 1
+
+
+class TestPolymorphism:
+    """WatchedFieldsMixin with STI (Single Table Inheritance)."""
+
+    @pytest.fixture(autouse=True)
+    def clear_events(self):
+        _poly_events.clear()
+        yield
+        _poly_events.clear()
+
+    @pytest.mark.anyio
+    async def test_on_create_fires_once_for_subclass(self, mixin_session):
+        """on_create fires exactly once for a STI subclass instance."""
+        dog = PolyDog(name="Rex")
+        mixin_session.add(dog)
+        await mixin_session.commit()
+        await asyncio.sleep(0)
+
+        assert len(_poly_events) == 1
+        assert _poly_events[0]["event"] == "create"
+        assert _poly_events[0]["type"] == "PolyDog"
+
+    @pytest.mark.anyio
+    async def test_on_delete_fires_for_subclass(self, mixin_session):
+        """on_delete fires for a STI subclass instance."""
+        dog = PolyDog(name="Rex")
+        mixin_session.add(dog)
+        await mixin_session.commit()
+        await asyncio.sleep(0)
+        _poly_events.clear()
+
+        await mixin_session.delete(dog)
+        await mixin_session.commit()
+        await asyncio.sleep(0)
+
+        assert len(_poly_events) == 1
+        assert _poly_events[0]["event"] == "delete"
+        assert _poly_events[0]["type"] == "PolyDog"
+
+    @pytest.mark.anyio
+    async def test_transient_subclass_fires_no_events(self, mixin_session):
+        """Create + delete of a STI subclass in one transaction fires no events."""
+        dog = PolyDog(name="Rex")
+        mixin_session.add(dog)
+        await mixin_session.flush()
+        await mixin_session.delete(dog)
+        await mixin_session.commit()
+        await asyncio.sleep(0)
+
+        assert _poly_events == []
+
+
 class TestWatchAll:
     @pytest.fixture(autouse=True)
     def clear_events(self):
@@ -968,6 +1194,28 @@ class TestSyncCallbacks:
         assert updates[0]["changes"]["status"] == {"old": "initial", "new": "updated"}
 
 
+class TestFutureCallbacks:
+    """Callbacks returning a non-coroutine awaitable (asyncio.Task / Future)."""
+
+    @pytest.fixture(autouse=True)
+    def clear_events(self):
+        _future_events.clear()
+        yield
+        _future_events.clear()
+
+    @pytest.mark.anyio
+    async def test_task_callback_is_awaited(self, mixin_session):
+        """on_create returning an asyncio.Task is awaited and its work completes."""
+        obj = FutureCallbackModel(name="test")
+        mixin_session.add(obj)
+        await mixin_session.commit()
+        # Two turns: one for _run() to execute, one for the inner _work() task.
+        await asyncio.sleep(0)
+        await asyncio.sleep(0)
+
+        assert _future_events == ["created"]
+
+
 class TestAttributeAccessInCallbacks:
     """Verify that self attributes are accessible inside every callback type.
 

uv.lock

@@ -251,7 +251,7 @@ wheels = [
 
 [[package]]
 name = "fastapi-toolsets"
-version = "2.4.1"
+version = "2.4.2"
 source = { editable = "." }
 dependencies = [
     { name = "asyncpg" },
@@ -286,6 +286,7 @@ dev = [
     { name = "fastapi-toolsets", extra = ["all"] },
     { name = "httpx" },
     { name = "mkdocstrings-python" },
+    { name = "prek" },
     { name = "pytest" },
     { name = "pytest-anyio" },
     { name = "pytest-cov" },
@@ -328,6 +329,7 @@ dev = [
     { name = "fastapi-toolsets", extras = ["all"] },
     { name = "httpx", specifier = ">=0.25.0" },
     { name = "mkdocstrings-python", specifier = ">=2.0.2" },
+    { name = "prek", specifier = ">=0.3.8" },
     { name = "pytest", specifier = ">=8.0.0" },
     { name = "pytest-anyio", specifier = ">=0.0.0" },
     { name = "pytest-cov", specifier = ">=4.0.0" },
@@ -417,6 +419,7 @@ wheels = [
 name = "griffelib"
 version = "2.0.0"
 source = { registry = "https://pypi.org/simple" }
+sdist = { url = "https://files.pythonhosted.org/packages/ad/06/eccbd311c9e2b3ca45dbc063b93134c57a1ccc7607c5e545264ad092c4a9/griffelib-2.0.0.tar.gz", hash = "sha256:e504d637a089f5cab9b5daf18f7645970509bf4f53eda8d79ed71cce8bd97934", size = 166312, upload-time = "2026-03-23T21:06:55.954Z" }
 wheels = [
     { url = "https://files.pythonhosted.org/packages/4d/51/c936033e16d12b627ea334aaaaf42229c37620d0f15593456ab69ab48161/griffelib-2.0.0-py3-none-any.whl", hash = "sha256:01284878c966508b6d6f1dbff9b6fa607bc062d8261c5c7253cb285b06422a7f", size = 142004, upload-time = "2026-02-09T19:09:40.561Z" },
 ]
@@ -720,6 +723,30 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/54/20/4d324d65cc6d9205fabedc306948156824eb9f0ee1633355a8f7ec5c66bf/pluggy-1.6.0-py3-none-any.whl", hash = "sha256:e920276dd6813095e9377c0bc5566d94c932c33b27a3e3945d8389c374dd4746", size = 20538, upload-time = "2025-05-15T12:30:06.134Z" },
 ]
 
+[[package]]
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+version = "0.3.8"
+source = { registry = "https://pypi.org/simple" }
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+wheels = [
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