feat: add uuidv7 primary key mixin

src/brussels/__tests__/mixins/test_primary_key_mixin.py

@@ -9,7 +9,7 @@
 from sqlalchemy.orm import Mapped, Session, mapped_column
 
 from brussels.base import DataclassBase
-from brussels.mixins import PrimaryKeyMixin, TimestampMixin
+from brussels.mixins import PrimaryKeyMixin, TimestampMixin, UUIDv7PrimaryKeyMixin
 
 
 class Widget(DataclassBase, PrimaryKeyMixin, TimestampMixin):
@@ -18,6 +18,12 @@ class Widget(DataclassBase, PrimaryKeyMixin, TimestampMixin):
     name: Mapped[str] = mapped_column()
 
 
+class UUIDv7Widget(DataclassBase, UUIDv7PrimaryKeyMixin, TimestampMixin):
+    __tablename__ = "primary_key_v7_widgets"
+
+    name: Mapped[str] = mapped_column()
+
+
 @pytest.fixture
 def engine() -> Iterator[Engine]:
     engine = create_engine("sqlite:///:memory:")
@@ -57,3 +63,41 @@ def test_id_default_factory_generates_uuid_on_flush(engine: Engine) -> None:
         session.flush()
 
         assert isinstance(widget.id, UUID)
+
+
+def test_uuidv7_id_column_definition() -> None:
+    table = cast("Table", UUIDv7Widget.__table__)
+    column = table.c.id
+
+    assert column.primary_key is True
+
+    insert_default = column.default
+    assert insert_default is not None
+    compiled_insert_default = cast("Any", insert_default).arg.compile(dialect=postgresql.dialect())
+    assert "uuidv7" in str(compiled_insert_default)
+
+    server_default = column.server_default
+    assert server_default is not None
+    compiled_server_default = cast("Any", server_default).arg.compile(dialect=postgresql.dialect())
+    assert "uuidv7" in str(compiled_server_default)
+
+
+def test_uuidv7_id_not_in_init_signature() -> None:
+    signature = inspect.signature(UUIDv7Widget)
+    assert "id" not in signature.parameters
+
+    widget_cls = cast("Any", UUIDv7Widget)
+    with pytest.raises(TypeError):
+        widget_cls(id=uuid4(), name="widget")
+
+
+def test_uuidv7_id_is_not_populated_before_flush() -> None:
+    widget = UUIDv7Widget(name="widget")
+
+    assert widget.id is None
+
+
+def test_uuidv7_models_satisfy_primary_key_mixin_contract() -> None:
+    widget = UUIDv7Widget(name="widget")
+
+    assert isinstance(widget, PrimaryKeyMixin)

src/brussels/__tests__/types/file/test_file.py

@@ -2,13 +2,13 @@
 
 from datetime import UTC, datetime
 from typing import TYPE_CHECKING, cast
-from uuid import UUID
+from uuid import UUID, uuid4
 
 import pytest
 from sqlalchemy.orm import Mapped, Session, mapped_column
 
 from brussels.base import Base, DataclassBase
-from brussels.mixins import PrimaryKeyMixin
+from brussels.mixins import PrimaryKeyMixin, UUIDv7PrimaryKeyMixin
 
 try:
     from obstore.store import MemoryStore
@@ -20,6 +20,7 @@
 if TYPE_CHECKING:
     from obstore import GetOptions, PutMode
     from sqlalchemy import Engine
+    from sqlalchemy.ext.asyncio import AsyncSession
 
     from brussels.types.file._types import RemoteMetadataField
 
@@ -45,6 +46,12 @@ class OtherFileModel(DataclassBase, PrimaryKeyMixin):
     file: Mapped[RemoteMetadata | None] = mapped_column(RemoteStorage(store=MemoryStore()), nullable=True, default=None)
 
 
+class UUIDv7FileModel(DataclassBase, UUIDv7PrimaryKeyMixin):
+    __tablename__ = "uuidv7_file_model"
+
+    file: Mapped[RemoteMetadata | None] = mapped_column(RemoteStorage(store=MemoryStore()), nullable=True, default=None)
+
+
 class TablelessPrimaryKeyModel(PrimaryKeyMixin):
     pass
 
@@ -54,10 +61,29 @@ def _configure_store(store_ops: FakeStoreOps) -> None:
     remote_storage.store = store_ops
 
 
+def _configure_uuidv7_store(store_ops: FakeStoreOps) -> None:
+    remote_storage = cast("RemoteStorage", UUIDv7FileModel.__table__.c["file"].type)
+    remote_storage.store = store_ops
+
+
 def _file_handle(model: FileModel) -> RemoteFile:
     return RemoteFile.from_metadata(model, FileModel.file)
 
 
+def _uuidv7_file_handle(model: UUIDv7FileModel) -> RemoteFile:
+    return RemoteFile.from_metadata(model, UUIDv7FileModel.file)
+
+
+class AsyncSessionShim:
+    def __init__(self, sync_session: Session, *, on_flush=None) -> None:
+        self.sync_session = sync_session
+        self._on_flush = on_flush
+
+    async def flush(self) -> None:
+        if self._on_flush is not None:
+            self._on_flush()
+
+
 def test_from_metadata_rejects_models_without_primary_key_mixin() -> None:
     model = NoPrimaryKeyMixinModel(id=1)
 
@@ -105,6 +131,14 @@ def test_from_metadata_accepts_models_with_primary_key_mixin() -> None:
     assert remote_file.field_name == "file"
 
 
+def test_from_metadata_accepts_uuidv7_primary_key_models() -> None:
+    model = UUIDv7FileModel()
+
+    remote_file = RemoteFile.from_metadata(model, UUIDv7FileModel.file)
+
+    assert remote_file.field_name == "file"
+
+
 def test_put_sync_without_sqlalchemy_session_raises_and_does_not_call_store() -> None:
     store_ops = FakeStoreOps()
     _configure_store(store_ops)
@@ -120,6 +154,62 @@ def test_put_sync_without_sqlalchemy_session_raises_and_does_not_call_store() ->
     assert model.file is None
 
 
+def test_put_sync_flush_populates_uuidv7_id_before_key_generation(
+    engine: Engine,
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    store_ops = FakeStoreOps()
+    _configure_uuidv7_store(store_ops)
+
+    with Session(engine) as session:
+        model = UUIDv7FileModel()
+        session.add(model)
+        assigned_id = uuid4()
+        flush_calls = 0
+
+        def fake_flush() -> None:
+            nonlocal flush_calls
+            flush_calls += 1
+            if model.id is None:
+                model.id = assigned_id
+
+        monkeypatch.setattr(session, "flush", fake_flush)
+
+        put_result = _uuidv7_file_handle(model).put(
+            b"hello",
+            content_type="text/plain",
+            session=session,
+            flush=True,
+        )
+
+        assert put_result == {"e_tag": None, "version": None}
+        assert flush_calls == 2
+        assert model.id == assigned_id
+        assert model.file is not None
+        assert model.file.key == f"{assigned_id}/file"
+        assert model.file.status == "pending"
+        assert store_ops.calls == []
+
+
+def test_put_sync_rejects_uuidv7_model_without_flush(engine: Engine) -> None:
+    store_ops = FakeStoreOps()
+    _configure_uuidv7_store(store_ops)
+
+    with Session(engine) as session:
+        model = UUIDv7FileModel()
+        session.add(model)
+
+        with pytest.raises(ValueError, match=r"Pass flush=True or flush the model before calling put"):
+            _uuidv7_file_handle(model).put(
+                b"hello",
+                content_type="text/plain",
+                session=session,
+            )
+
+        assert model.file is None
+        assert store_ops.calls == []
+
+
 def test_put_sync_defers_and_commits_when_sqlalchemy_session_is_attached(engine: Engine) -> None:
     store_ops = FakeStoreOps()
     _configure_store(store_ops)
@@ -256,6 +346,58 @@ async def test_put_rejects_invalid_model_id_type(engine: Engine) -> None:
             await _file_handle(model).put_async(b"data")
 
 
+@pytest.mark.asyncio
+async def test_put_async_flush_populates_uuidv7_id_before_key_generation(engine: Engine) -> None:
+    store_ops = FakeStoreOps()
+    _configure_uuidv7_store(store_ops)
+
+    with Session(engine) as session:
+        model = UUIDv7FileModel()
+        session.add(model)
+        assigned_id = uuid4()
+        flush_calls = 0
+
+        def on_flush() -> None:
+            nonlocal flush_calls
+            flush_calls += 1
+            if model.id is None:
+                model.id = assigned_id
+
+        await _uuidv7_file_handle(model).put_async(
+            b"data",
+            content_type="text/plain",
+            session=cast("AsyncSession", AsyncSessionShim(session, on_flush=on_flush)),
+            flush=True,
+        )
+
+        assert flush_calls == 2
+        assert model.id == assigned_id
+        assert model.file is not None
+        assert model.file.key == f"{assigned_id}/file"
+        assert model.file.status == "pending"
+        assert store_ops.calls == []
+
+
+@pytest.mark.asyncio
+async def test_put_async_rejects_uuidv7_model_without_flush(engine: Engine) -> None:
+    store_ops = FakeStoreOps()
+    _configure_uuidv7_store(store_ops)
+
+    with Session(engine) as session:
+        model = UUIDv7FileModel()
+        session.add(model)
+
+        with pytest.raises(ValueError, match=r"Pass flush=True or flush the model before calling put_async"):
+            await _uuidv7_file_handle(model).put_async(
+                b"data",
+                content_type="text/plain",
+                session=session,
+            )
+
+        assert model.file is None
+        assert store_ops.calls == []
+
+
 @pytest.mark.asyncio
 async def test_put_allows_uuid_model_id(engine: Engine) -> None:
     store_ops = FakeStoreOps()

src/brussels/mixins/__init__.py

@@ -1,5 +1,5 @@
 from brussels.mixins.ordered import OrderedMixin
-from brussels.mixins.primary_key import PrimaryKeyMixin
+from brussels.mixins.primary_key import PrimaryKeyMixin, UUIDv7PrimaryKeyMixin
 from brussels.mixins.timestamp import TimestampMixin
 
-__all__ = ["OrderedMixin", "PrimaryKeyMixin", "TimestampMixin"]
+__all__ = ["OrderedMixin", "PrimaryKeyMixin", "TimestampMixin", "UUIDv7PrimaryKeyMixin"]

src/brussels/mixins/primary_key.py

@@ -32,3 +32,30 @@ class MyModel(DataclassBase, PrimaryKeyMixin, TimestampMixin):
         server_default=func.gen_random_uuid(),
         init=False,
     )
+
+
+@declarative_mixin
+class UUIDv7PrimaryKeyMixin(PrimaryKeyMixin):
+    """Mixin that adds a PostgreSQL 18+ UUIDv7 primary key column.
+
+    Extends PrimaryKeyMixin so models continue to satisfy APIs that require the
+    existing primary-key mixin contract. The id field is excluded from __init__
+    (init=False) and is generated during insert using PostgreSQL's uuidv7()
+    function. Because the UUID is database generated, ID-derived workflows
+    require the row to be flushed or already persisted.
+
+    Usage:
+        class MyModel(DataclassBase, UUIDv7PrimaryKeyMixin, TimestampMixin):
+            __tablename__ = "my_table"
+            name: Mapped[str]
+
+    This mixin is only supported on PostgreSQL 18+ because it relies on the
+    built-in uuidv7() database function.
+    """
+
+    id: Mapped[UUID] = mapped_column(
+        primary_key=True,
+        insert_default=func.uuidv7(),
+        server_default=func.uuidv7(),
+        init=False,
+    )

src/brussels/types/file/file.py

@@ -72,6 +72,13 @@ def _model_id(self) -> str:
             raise TypeError(msg)
         return str(model_id)
 
+    @staticmethod
+    def _missing_model_id_message(*, operation: str) -> str:
+        return (
+            f"RemoteStorage {operation} requires model.id to be set. "
+            f"Pass flush=True or flush the model before calling {operation}."
+        )
+
     @staticmethod
     def _flush_sync(*, session: Session | None, flush: bool) -> None:
         if not flush or session is None:
@@ -86,6 +93,44 @@ async def _flush_async(*, session: Session | AsyncSession | None, flush: bool) -
         if isawaitable(maybe_awaitable):
             await maybe_awaitable
 
+    def _ensure_model_id_ready_sync(
+        self,
+        *,
+        session: Session | None,
+        flush: bool,
+        operation: str,
+    ) -> None:
+        if getattr(self.model, "id", None) is not None:
+            return
+        if not flush:
+            raise ValueError(self._missing_model_id_message(operation=operation))
+
+        self._flush_sync(session=session, flush=True)
+        if getattr(self.model, "id", None) is not None:
+            return
+
+        msg = f"RemoteStorage {operation} requires model.id to be set after flush."
+        raise ValueError(msg)
+
+    async def _ensure_model_id_ready_async(
+        self,
+        *,
+        session: Session | AsyncSession | None,
+        flush: bool,
+        operation: str,
+    ) -> None:
+        if getattr(self.model, "id", None) is not None:
+            return
+        if not flush:
+            raise ValueError(self._missing_model_id_message(operation=operation))
+
+        await self._flush_async(session=session, flush=True)
+        if getattr(self.model, "id", None) is not None:
+            return
+
+        msg = f"RemoteStorage {operation} requires model.id to be set after flush."
+        raise ValueError(msg)
+
     @staticmethod
     def _resolve_sync_session(
         *,
@@ -168,6 +213,11 @@ def put(  # noqa: PLR0913
         flush: bool = False,
     ) -> PutResult:
         resolved_session = self._required_sync_session(session=session, operation="put")
+        self._ensure_model_id_ready_sync(
+            session=session or resolved_session,
+            flush=flush,
+            operation="put",
+        )
         metadata = self._prepare_pending_metadata(
             key=key,
             content_type=content_type,
@@ -207,6 +257,11 @@ async def put_async(  # noqa: PLR0913
         flush: bool = False,
     ) -> PutResult:
         resolved_session = self._required_sync_session(session=session, operation="put")
+        await self._ensure_model_id_ready_async(
+            session=session or resolved_session,
+            flush=flush,
+            operation="put_async",
+        )
         metadata = self._prepare_pending_metadata(
             key=key,
             content_type=content_type,