SEP-1705: Add BaseManager.exists() and convert existence checks

app/core/db/crud.py

@@ -1007,6 +1007,35 @@ async def count(
         result = await session.scalar(query)
         return result or 0
 
+    @classmethod
+    async def exists(
+        cls,
+        session: AsyncSession,
+        *whereclause: ColumnExpressionArgument[bool],
+        **equal_filters: Any,
+    ) -> bool:
+        """Return whether any record matches the query.
+
+        Emit a short-circuiting ``SELECT EXISTS (...)`` so the database can
+        stop at the first matching row. Filter arguments match :meth:`count`
+        and are applied through :meth:`_filter_query` (``None`` equal-filter
+        values are skipped — same behaviour as ``count``).
+
+        :param session: The SQLAlchemy asynchronous session to use for database
+            operations.
+        :type session: AsyncSession
+        :param whereclause: SQL expressions for the ``where`` clause of the query.
+        :type whereclause: ColumnExpressionArgument[bool]
+        :param equal_filters: Keyword arguments representing column names and their
+            respective filter values.
+        :type equal_filters: Any
+        :return: ``True`` when at least one matching row exists.
+        :rtype: bool
+        """
+        inner = cls._filter_query(select(cls.Model), *whereclause, **equal_filters)
+        result = await session.scalar(select(inner.exists()))
+        return bool(result)
+
 
 class BaseSQLModelManager(BaseManager):
     """Manage database operations for a BaseSQLModel-based model.

app/core/settings_override/api/routes.py

@@ -1088,11 +1088,8 @@ async def delete_setting(
         settings_cls, proxy = _resolve(setting_class)
         key = canonical_override_key(settings_cls, key)
         field_meta = _field_meta_or_404(settings_cls, key)
-        has_override_row = (
-            await SettingsOverrideManager.count(
-                session, setting_class=setting_class, key=key
-            )
-            > 0
+        has_override_row = await SettingsOverrideManager.exists(
+            session, setting_class=setting_class, key=key
         )
         _assert_key_deletable(
             settings_cls, field_meta, has_override_row=has_override_row

app/sep/app_drain.py

@@ -125,7 +125,7 @@ async def finalize_drain_if_complete(session: AsyncSession, app_key: str) -> boo
         != AppLifecycleEnum.DISABLING
     ):
         return False
-    if await AppRunningTaskManager.count(session, app_key=app_key):
+    if await AppRunningTaskManager.exists(session, app_key=app_key):
         return False
     result = await AppStateManager.update_where(
         session,

app/tasks/crud.py

@@ -19,7 +19,7 @@
 from collections.abc import AsyncGenerator, Mapping, Sequence
 from datetime import datetime
 
-from sqlalchemy import CursorResult, delete, func, literal, or_, update
+from sqlalchemy import CursorResult, delete, func, or_, update
 from sqlalchemy.orm import aliased
 from sqlalchemy.sql.elements import ColumnElement
 from sqlmodel import and_, col, select
@@ -802,30 +802,6 @@ async def delete_aged_batch(
         result = await cls.delete_where(session, col(TaskHistoryLog.id).in_(doomed))
         return result.rowcount
 
-    @classmethod
-    async def exists_for_task(cls, session: AsyncSession, task_history_id: int) -> bool:
-        """Return ``True`` when at least one chunk exists for the task history.
-
-        Uses a ``SELECT 1 ... LIMIT 1`` short-circuit query so the database
-        can stop scanning as soon as it finds the first matching row instead
-        of counting every chunk.
-
-        :param session: The SQLAlchemy asynchronous session to use for query
-            execution.
-        :type session: AsyncSession
-        :param task_history_id: The ``TaskHistory`` identifier.
-        :type task_history_id: int
-        :return: Whether any chunk rows exist for the task history.
-        :rtype: bool
-        """
-        query = (
-            select(literal(1))
-            .where(col(TaskHistoryLog.task_history_id) == task_history_id)
-            .limit(1)
-        )
-        result = await cls._exec(session, query)
-        return result.first() is not None
-
     @classmethod
     async def ids_with_chunks(
         cls,
@@ -836,7 +812,7 @@ async def ids_with_chunks(
 
         Emit a single ``SELECT DISTINCT task_history_id FROM taskhistory_log
         WHERE task_history_id IN (:ids)`` so list endpoints avoid an N+1
-        :meth:`exists_for_task` call per paginated row. Return an empty set
+        :meth:`exists` call per paginated row. Return an empty set
         for empty input without emitting any SQL -- an empty ``IN ()``
         predicate triggers a SQLAlchemy warning and is a no-op anyway.
 

app/tasks/logs/log_reader.py

@@ -415,7 +415,9 @@ async def iter_task_history_logs(
     offsets: defaultdict[str, dict[str | TaskLogType, int]] = defaultdict(
         dict, start_offsets or {}
     )
-    has_chunks = await TaskHistoryLogManager.exists_for_task(session, task_history.id)
+    has_chunks = await TaskHistoryLogManager.exists(
+        session, task_history_id=task_history.id
+    )
     if tail_lines is not None and tail_lines > 0:
         if has_chunks:
             tail_offsets = await compute_tail_offsets_from_chunks(

app/tasks/routes.py

@@ -360,7 +360,7 @@ async def _populate_has_logs(
     """Set ``has_logs`` on each history using chunk-store + legacy fallback.
 
     Read the chunk store in one batched query so list endpoints avoid an
-    N+1 :meth:`TaskHistoryLogManager.exists_for_task` call per row, then
+    N+1 :meth:`TaskHistoryLogManager.exists` call per row, then
     OR the result with :func:`has_legacy_logs` so legacy rows keep
     rendering the **View Logs** button until the backfill lands.
 
@@ -465,7 +465,9 @@ async def retrieve_task_history(
     logger.debug("Requesting task history %s", task_history.id)
     _set_has_logs(
         task_history,
-        value=await TaskHistoryLogManager.exists_for_task(session, task_history.id)
+        value=await TaskHistoryLogManager.exists(
+            session, task_history_id=task_history.id
+        )
         or has_legacy_logs(task_history),
     )
     return task_history
@@ -605,7 +607,7 @@ async def stop_task_history(
     stopped = await executor.stop_task(session, task_history)
     _set_has_logs(
         stopped,
-        value=await TaskHistoryLogManager.exists_for_task(session, stopped.id)
+        value=await TaskHistoryLogManager.exists(session, task_history_id=stopped.id)
         or has_legacy_logs(stopped),
     )
     return stopped
@@ -692,7 +694,7 @@ async def sync_task_history(
         await maybe_record_run(synced.id, executor)
     _set_has_logs(
         synced,
-        value=await TaskHistoryLogManager.exists_for_task(session, synced.id)
+        value=await TaskHistoryLogManager.exists(session, task_history_id=synced.id)
         or has_legacy_logs(synced),
     )
     return synced

tests/app/core/db/test_crud.py

@@ -1021,3 +1021,55 @@ async def _seed_nullable_parent_items(session: AsyncSession) -> None:
     )
     await _create_item(session, name="b1", created_at=base_time + timedelta(minutes=2))
     await _create_item(session, name="b2", created_at=base_time + timedelta(minutes=3))
+
+
+class TestExists:
+    """Cover ``BaseManager.exists`` short-circuit existence checks."""
+
+    @pytest.mark.asyncio
+    async def test_exists_false_on_empty_table(self, session: AsyncSession) -> None:
+        """Return ``False`` when the table has no rows."""
+        assert await UniqueKeyManager.exists(session) is False
+
+    @pytest.mark.asyncio
+    async def test_exists_true_with_no_filters(self, session: AsyncSession) -> None:
+        """Return ``True`` when any row exists and no filters are applied."""
+        await UniqueKeyManager.get_or_create(
+            session,
+            UniqueKeyModel(key="alpha", label="a"),
+            filter_include={"key"},
+        )
+        assert await UniqueKeyManager.exists(session) is True
+
+    @pytest.mark.asyncio
+    async def test_exists_with_equal_filters(self, session: AsyncSession) -> None:
+        """Apply keyword equal-filters the same way ``count`` does."""
+        await UniqueKeyManager.get_or_create(
+            session,
+            UniqueKeyModel(key="alpha", label="a"),
+            filter_include={"key"},
+        )
+        assert await UniqueKeyManager.exists(session, key="alpha") is True
+        assert await UniqueKeyManager.exists(session, key="missing") is False
+
+    @pytest.mark.asyncio
+    async def test_exists_with_whereclause(self, session: AsyncSession) -> None:
+        """Apply a positional ``whereclause`` expression."""
+        await UniqueKeyManager.get_or_create(
+            session,
+            UniqueKeyModel(key="alpha", label="keep"),
+            filter_include={"key"},
+        )
+        await UniqueKeyManager.get_or_create(
+            session,
+            UniqueKeyModel(key="beta", label="drop"),
+            filter_include={"key"},
+        )
+        assert (
+            await UniqueKeyManager.exists(session, col(UniqueKeyModel.label) == "keep")
+            is True
+        )
+        assert (
+            await UniqueKeyManager.exists(session, col(UniqueKeyModel.label) == "gone")
+            is False
+        )

tests/app/tasks/connectivity/test_routes.py

@@ -354,8 +354,8 @@ async def sync_task_history(
         assert data["success"] is True
         assert data["error"] is None
         assert call_count["n"] >= MIN_POLL_ITERATIONS
-        assert await TaskHistoryLogManager.exists_for_task(
-            session, data["task_history_id"]
+        assert await TaskHistoryLogManager.exists(
+            session, task_history_id=data["task_history_id"]
         )
 
     async def test_provisioning_latency_does_not_false_negative_over_http(
@@ -481,8 +481,8 @@ async def sync_task_history(
         # Provisioning spanned more polls than the connect budget alone permits,
         # yet the check still succeeded — the budgets are independent.
         assert call_count["n"] > connect_budget // POLL_INTERVAL
-        assert await TaskHistoryLogManager.exists_for_task(
-            session, data["task_history_id"]
+        assert await TaskHistoryLogManager.exists(
+            session, task_history_id=data["task_history_id"]
         )
 
     async def test_timeout_surfaces_partial_logs_and_id_over_http(
@@ -599,6 +599,6 @@ async def sync_task_history(
         assert "timed out" in data["error"]
         assert "installing deps..." in data["error"]
         assert data["task_history_id"] is not None
-        assert await TaskHistoryLogManager.exists_for_task(
-            session, data["task_history_id"]
+        assert await TaskHistoryLogManager.exists(
+            session, task_history_id=data["task_history_id"]
         )

tests/app/tasks/connectivity/test_service.py

@@ -323,8 +323,8 @@ async def sync_task_history(
 
         assert result.success is True
         assert result.error is None
-        assert await TaskHistoryLogManager.exists_for_task(
-            session, result.task_history_id
+        assert await TaskHistoryLogManager.exists(
+            session, task_history_id=result.task_history_id
         )
 
     async def test_terminal_run_records_nothing(
@@ -976,8 +976,8 @@ async def sync_task_history(
         )
         assert result.success is True
         assert result.error is None
-        assert await TaskHistoryLogManager.exists_for_task(
-            session, result.task_history_id
+        assert await TaskHistoryLogManager.exists(
+            session, task_history_id=result.task_history_id
         )
 
     async def test_provisioning_phase_does_not_consume_connect_budget(

tests/app/tasks/test_routes.py

@@ -2982,7 +2982,9 @@ async def fake_sync(
         call_kwargs = mock_executor.sync_task_history.await_args.kwargs
         assert "writer_session" in call_kwargs
         assert call_kwargs["writer_session"] is not None
-        assert await TaskHistoryLogManager.exists_for_task(session, saved_history.id)
+        assert await TaskHistoryLogManager.exists(
+            session, task_history_id=saved_history.id
+        )
 
     async def test_sync_hands_the_run_result_to_the_recorder(
         self,