refactor(schedule): promote the domain errors to exceptions.py

Move model/errors.py up one level to domain/schedule/exceptions.py, a
sibling of the model, matching the AWS domain layout the spec mandates
(exceptions/ is its own member of the domain folder, not part of the
model) and the feedback reference implementation. Class names keep the
PEP 8 Error suffix. Pure move -- the nine classes are AST-identical to
the originals; imports across the domain, adapters, router, and tests
now take errors from deerflow.domain.schedule.exceptions.

backend/app/adapters/schedule/run_launcher.py

@@ -25,7 +25,7 @@ from typing import Any
 
 from fastapi import HTTPException
 
-from deerflow.domain.schedule.model import LaunchFailedError, ThreadBusyError
+from deerflow.domain.schedule.exceptions import LaunchFailedError, ThreadBusyError
 from deerflow.domain.schedule.ports import LaunchedRun, RunLauncher
 from deerflow.runtime import ConflictError
 

backend/app/adapters/schedule/scheduled_run_repository.py

@@ -19,14 +19,8 @@ from sqlalchemy import func, select
 from sqlalchemy.exc import IntegrityError
 from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker
 
-from deerflow.domain.schedule.model import (
+from deerflow.domain.schedule.exceptions import ActiveRunConflictError
-    ACTIVE_RUN_STATUSES,
+from deerflow.domain.schedule.model import ACTIVE_RUN_STATUSES, TERMINAL_RUN_STATUSES, RunStatus, ScheduledRun, TriggerKind
-    TERMINAL_RUN_STATUSES,
-    ActiveRunConflictError,
-    RunStatus,
-    ScheduledRun,
-    TriggerKind,
-)
 from deerflow.domain.schedule.ports import ScheduledRunRepository
 
 # Transitional: the ORM row stays in the harness until engine, models, and

backend/app/adapters/schedule/scheduled_task_repository.py

@@ -26,15 +26,8 @@ from datetime import UTC, datetime, timedelta
 from sqlalchemy import and_, or_, select
 from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker
 
-from deerflow.domain.schedule.model import (
+from deerflow.domain.schedule.exceptions import InvalidScheduleError
-    TERMINAL_TASK_STATUSES,
+from deerflow.domain.schedule.model import TERMINAL_TASK_STATUSES, ContextMode, ScheduledTask, ScheduleSpec, ScheduleType, TaskStatus
-    ContextMode,
-    InvalidScheduleError,
-    ScheduledTask,
-    ScheduleSpec,
-    ScheduleType,
-    TaskStatus,
-)
 from deerflow.domain.schedule.ports import ScheduledTaskRepository
 
 # Transitional: the ORM row stays in the harness until engine, models, and

backend/app/gateway/routers/schedule/router.py

@@ -30,8 +30,7 @@ from app.gateway.routers.schedule.models import (
     ScheduledTaskUpdateRequest,
     TriggerResponse,
 )
-from deerflow.domain.schedule.model import (
+from deerflow.domain.schedule.exceptions import (
-    DispatchOutcome,
     InvalidContextModeError,
     InvalidScheduleError,
     ScheduleError,
@@ -39,6 +38,7 @@ from deerflow.domain.schedule.model import (
     TaskNotMutableError,
     ThreadNotFoundError,
 )
+from deerflow.domain.schedule.model import DispatchOutcome
 from deerflow.domain.schedule.service import ContextChange
 
 router = APIRouter(prefix="/api", tags=["scheduled-tasks"])

backend/packages/harness/deerflow/domain/schedule/__init__.py

@@ -7,28 +7,30 @@ tests, not everyday call-site symbols.
 `ScheduleService` is not exported yet: the application service has not landed.
 """
 
+from deerflow.domain.schedule.exceptions import (
+    ActiveRunConflictError,
+    InvalidContextModeError,
+    InvalidScheduleError,
+    LaunchFailedError,
+    ScheduleError,
+    TaskNotFoundError,
+    TaskNotMutableError,
+    ThreadBusyError,
+    ThreadNotFoundError,
+)
 from deerflow.domain.schedule.model import (
     ACTIVE_RUN_STATUSES,
     TERMINAL_RUN_STATUSES,
     TERMINAL_TASK_STATUSES,
-    ActiveRunConflictError,
     ContextMode,
     DispatchOutcome,
-    InvalidContextModeError,
-    InvalidScheduleError,
-    LaunchFailedError,
     RunStatus,
     ScheduledRun,
     ScheduledTask,
-    ScheduleError,
     SchedulePolicy,
     ScheduleSpec,
     ScheduleType,
-    TaskNotFoundError,
-    TaskNotMutableError,
     TaskStatus,
-    ThreadBusyError,
-    ThreadNotFoundError,
     TriggerKind,
 )
 

backend/packages/harness/deerflow/domain/schedule/exceptions.py

@@ -1,3 +1,11 @@
+"""The known errors of the schedule context.
+
+One family under one base class, so the primary adapter can map the whole
+family onto protocol codes in a single table. Class names keep the PEP 8
+``Error`` suffix; the module is named ``exceptions`` after the AWS
+hexagonal guidance's domain folder of the same name.
+"""
+
 from __future__ import annotations
 
 

backend/packages/harness/deerflow/domain/schedule/model/__init__.py

@@ -8,8 +8,11 @@ what a single `model.py` would have.
 
 The re-exports below are ordered alphabetically because ruff's isort rule
 owns that block; alphabetical happens to satisfy the real dependency order
-too (enums and errors depend on nothing, run depends on enums, spec depends
+too (enums depend on nothing, run depends on enums, spec depends on enums,
-on enums and errors, task depends on all three), so it needs no override.
+task depends on both), so it needs no override. The domain errors are not
+re-exported here: they live one level up in
+`deerflow.domain.schedule.exceptions`, a sibling of the model per the AWS
+domain layout, and are imported from there.
 
 What actually keeps the package acyclic is a rule isort cannot express:
 **a submodule imports its siblings directly, never this package.** Reaching
@@ -27,17 +30,6 @@ from deerflow.domain.schedule.model.enums import (
     TaskStatus,
     TriggerKind,
 )
-from deerflow.domain.schedule.model.errors import (
-    ActiveRunConflictError,
-    InvalidContextModeError,
-    InvalidScheduleError,
-    LaunchFailedError,
-    ScheduleError,
-    TaskNotFoundError,
-    TaskNotMutableError,
-    ThreadBusyError,
-    ThreadNotFoundError,
-)
 from deerflow.domain.schedule.model.run import ACTIVE_RUN_STATUSES, TERMINAL_RUN_STATUSES, ScheduledRun
 from deerflow.domain.schedule.model.spec import SchedulePolicy, ScheduleSpec
 from deerflow.domain.schedule.model.task import TERMINAL_TASK_STATUSES, ScheduledTask
@@ -46,23 +38,14 @@ __all__ = [
     "ACTIVE_RUN_STATUSES",
     "TERMINAL_RUN_STATUSES",
     "TERMINAL_TASK_STATUSES",
-    "ActiveRunConflictError",
     "ContextMode",
     "DispatchOutcome",
-    "InvalidContextModeError",
-    "InvalidScheduleError",
-    "LaunchFailedError",
     "RunStatus",
-    "ScheduleError",
     "SchedulePolicy",
     "ScheduleSpec",
     "ScheduleType",
     "ScheduledRun",
     "ScheduledTask",
-    "TaskNotFoundError",
-    "TaskNotMutableError",
     "TaskStatus",
-    "ThreadBusyError",
-    "ThreadNotFoundError",
     "TriggerKind",
 ]

backend/packages/harness/deerflow/domain/schedule/model/spec.py

@@ -6,8 +6,8 @@ from zoneinfo import ZoneInfo, ZoneInfoNotFoundError
 
 from croniter import croniter
 
+from deerflow.domain.schedule.exceptions import InvalidScheduleError
 from deerflow.domain.schedule.model.enums import ScheduleType
-from deerflow.domain.schedule.model.errors import InvalidScheduleError
 
 CRON_FIELD_COUNT = 5
 

backend/packages/harness/deerflow/domain/schedule/model/task.py

@@ -4,8 +4,8 @@ import uuid
 from dataclasses import dataclass, field, replace
 from datetime import UTC, datetime
 
+from deerflow.domain.schedule.exceptions import InvalidContextModeError, TaskNotMutableError
 from deerflow.domain.schedule.model.enums import ContextMode, RunStatus, ScheduleType, TaskStatus, TriggerKind
-from deerflow.domain.schedule.model.errors import InvalidContextModeError, TaskNotMutableError
 from deerflow.domain.schedule.model.spec import SchedulePolicy, ScheduleSpec
 
 TERMINAL_TASK_STATUSES = frozenset({TaskStatus.COMPLETED, TaskStatus.FAILED, TaskStatus.CANCELLED})

backend/packages/harness/deerflow/domain/schedule/service.py

@@ -17,20 +17,22 @@ from __future__ import annotations
 from dataclasses import dataclass, replace
 from datetime import datetime
 
-from deerflow.domain.schedule.model import (
+from deerflow.domain.schedule.exceptions import (
     ActiveRunConflictError,
+    LaunchFailedError,
+    TaskNotFoundError,
+    ThreadBusyError,
+    ThreadNotFoundError,
+)
+from deerflow.domain.schedule.model import (
     ContextMode,
     DispatchOutcome,
-    LaunchFailedError,
     RunStatus,
     ScheduledRun,
     ScheduledTask,
     SchedulePolicy,
     ScheduleSpec,
     ScheduleType,
-    TaskNotFoundError,
-    ThreadBusyError,
-    ThreadNotFoundError,
     TriggerKind,
 )
 from deerflow.domain.schedule.ports import (

backend/tests/schedule_fakes.py

@@ -17,11 +17,11 @@ from __future__ import annotations
 from dataclasses import dataclass, field, replace
 from datetime import datetime, timedelta
 
+from deerflow.domain.schedule.exceptions import ActiveRunConflictError
 from deerflow.domain.schedule.model import (
     ACTIVE_RUN_STATUSES,
     TERMINAL_RUN_STATUSES,
     TERMINAL_TASK_STATUSES,
-    ActiveRunConflictError,
     RunStatus,
     ScheduledRun,
     ScheduledTask,

backend/tests/test_schedule_domain.py

@@ -19,17 +19,15 @@ from datetime import UTC, datetime, timedelta
 
 import pytest
 
+from deerflow.domain.schedule.exceptions import InvalidContextModeError, InvalidScheduleError, TaskNotMutableError
 from deerflow.domain.schedule.model import (
     ContextMode,
-    InvalidContextModeError,
-    InvalidScheduleError,
     RunStatus,
     ScheduledRun,
     ScheduledTask,
     SchedulePolicy,
     ScheduleSpec,
     ScheduleType,
-    TaskNotMutableError,
     TaskStatus,
     TriggerKind,
 )

backend/tests/test_schedule_fakes.py

@@ -31,16 +31,8 @@ from schedule_fakes import (
 from app.adapters.schedule.scheduled_run_repository import SqlScheduledRunRepository
 from app.adapters.schedule.scheduled_task_repository import SqlScheduledTaskRepository
 from deerflow.config.database_config import DatabaseConfig
-from deerflow.domain.schedule.model import (
+from deerflow.domain.schedule.exceptions import ActiveRunConflictError
-    ActiveRunConflictError,
+from deerflow.domain.schedule.model import ContextMode, RunStatus, ScheduledRun, ScheduledTask, ScheduleSpec, TaskStatus, TriggerKind
-    ContextMode,
-    RunStatus,
-    ScheduledRun,
-    ScheduledTask,
-    ScheduleSpec,
-    TaskStatus,
-    TriggerKind,
-)
 from deerflow.domain.schedule.ports import ScheduledRunRepository, ScheduledTaskRepository
 from deerflow.persistence.engine import close_engine, get_session_factory, init_engine_from_config
 

backend/tests/test_schedule_response_models.py

@@ -17,15 +17,7 @@ from datetime import UTC, datetime, timedelta, timezone
 import pytest
 
 from app.gateway.routers.schedule.models import ScheduledRunResponse, ScheduledTaskResponse
-from deerflow.domain.schedule.model import (
+from deerflow.domain.schedule.model import ContextMode, RunStatus, ScheduledRun, ScheduledTask, ScheduleSpec, TaskStatus, TriggerKind
-    ContextMode,
-    RunStatus,
-    ScheduledRun,
-    ScheduledTask,
-    ScheduleSpec,
-    TaskStatus,
-    TriggerKind,
-)
 
 # Exactly the frontend's `ScheduledTask` type (frontend/src/core/scheduled-tasks/types.ts).
 FRONTEND_TASK_FIELDS = {

backend/tests/test_schedule_router.py

@@ -30,15 +30,8 @@ from schedule_fakes import (
 )
 
 from app.gateway.routers.schedule import router as router_module
-from deerflow.domain.schedule.model import (
+from deerflow.domain.schedule.exceptions import LaunchFailedError, ThreadBusyError
-    LaunchFailedError,
+from deerflow.domain.schedule.model import RunStatus, ScheduledRun, SchedulePolicy, TaskStatus, TriggerKind
-    RunStatus,
-    ScheduledRun,
-    SchedulePolicy,
-    TaskStatus,
-    ThreadBusyError,
-    TriggerKind,
-)
 from deerflow.domain.schedule.service import ScheduleService
 
 USER = "user-1"
@@ -528,7 +521,7 @@ class TestRunHistory:
 
 class TestErrorMapping:
     def test_every_mapped_error_is_a_schedule_error(self):
-        from deerflow.domain.schedule.model import ScheduleError
+        from deerflow.domain.schedule.exceptions import ScheduleError
 
         assert all(issubclass(error, ScheduleError) for error in router_module._STATUS_BY_ERROR)
 
@@ -537,7 +530,7 @@ class TestErrorMapping:
         """A new domain error is a new protocol decision. Letting it through
         surfaces as a 500 that has to be classified, rather than shipping as
         whatever 4xx happened to be nearest."""
-        from deerflow.domain.schedule.model import ScheduleError
+        from deerflow.domain.schedule.exceptions import ScheduleError
 
         class NewDomainError(ScheduleError):
             pass
@@ -551,7 +544,7 @@ class TestErrorMapping:
 
     @pytest.mark.asyncio
     async def test_a_mapped_error_keeps_its_message_as_the_detail(self):
-        from deerflow.domain.schedule.model import TaskNotFoundError
+        from deerflow.domain.schedule.exceptions import TaskNotFoundError
 
         @router_module._map_domain_errors
         async def handler():

backend/tests/test_schedule_run_launcher.py

@@ -26,7 +26,7 @@ import pytest
 from fastapi import HTTPException
 
 from app.adapters.schedule.run_launcher import GatewayRunLauncher
-from deerflow.domain.schedule.model import LaunchFailedError, ThreadBusyError
+from deerflow.domain.schedule.exceptions import LaunchFailedError, ThreadBusyError
 from deerflow.domain.schedule.ports import LaunchedRun
 from deerflow.runtime import ConflictError
 

backend/tests/test_schedule_service.py

@@ -23,19 +23,21 @@ from schedule_fakes import (
     InMemoryScheduledTaskRepository,
 )
 
+from deerflow.domain.schedule.exceptions import (
+    InvalidScheduleError,
+    LaunchFailedError,
+    TaskNotFoundError,
+    TaskNotMutableError,
+    ThreadBusyError,
+    ThreadNotFoundError,
+)
 from deerflow.domain.schedule.model import (
     ContextMode,
     DispatchOutcome,
-    InvalidScheduleError,
-    LaunchFailedError,
     RunStatus,
     SchedulePolicy,
     ScheduleSpec,
-    TaskNotFoundError,
-    TaskNotMutableError,
     TaskStatus,
-    ThreadBusyError,
-    ThreadNotFoundError,
     TriggerKind,
 )
 from deerflow.domain.schedule.ports import RunOutcome