refactor(schedule): move orchestrator to application/ + review fixes (stage 8)

Follow-up to the layered refactor (review-driven):

- Move scheduling/orchestrator.py -> application/orchestrator.py
  (orchestrator is application-level coordination, not a cron-trigger
  primitive; matches the intended target tree)
- Migrate orchestrator re-exports from scheduling/__init__.py to
  application/__init__.py; scheduling/ now exposes only CronScheduler
- Rewrite imports + 5 mock.patch string targets in test_janitor.py and
  the orchestrator import in test_layering.py
- Update docstring refs in application/service.py + execution/worker.py
- Add 4 runner smoke tests (test_layering.py): _limited_log under-limit /
  empty-sentinel / above-MAX_LOG_BYTES truncation; execute_artifact
  rejects unsupported script_type with ValueError
- infrastructure/__init__.py re-exports SchedulerStorageClient so
  ``from schedule.infrastructure import SchedulerStorageClient`` is a
  stable top-level surface
- CLAUDE.md engineering note: extend the commit trail to 7476c27 and
  note the stage-8 orchestrator placement

Zero behavior change; schedule/pyproject.toml untouched. 29 tests green.

Co-Authored-By: Claude <noreply@anthropic.com>

CLAUDE.md

@@ -78,7 +78,7 @@ Hard-won lessons. Read the relevant bullet before touching the named area.
 
 ### Schedule service layering (domain / scheduling / application / execution / infrastructure)
 
-Lessons from the zero-behavior-change refactor that split the flat 11-file `schedule/src/schedule/` into five subpackages (commits 3118694 → c89132a). Public class names (`SchedulerService`, `CronScheduler`, `DispatchOrchestrator`, `NodeExecutor`, `SchedulerStorageClient`) and `schedule/pyproject.toml` are unchanged.
+Lessons from the zero-behavior-change refactor that split the flat 11-file `schedule/src/schedule/` into five subpackages (commits 3118694 → 7476c27, with a follow-up `git mv` in stage 8 placing the orchestrator under `application/`). Public class names (`SchedulerService`, `CronScheduler`, `DispatchOrchestrator`, `NodeExecutor`, `SchedulerStorageClient`) and `schedule/pyproject.toml` are unchanged.
 
 - **`python -m schedule.notebook_runner` is a stable external contract.** The worker launches the notebook subprocess with `sys.executable, "-m", "schedule.notebook_runner"`. That `-m` string must never change — so `schedule/notebook_runner.py` survives as a 6-line shim re-exporting `main` from `schedule.execution.runners.notebook`. Don't "clean up" the shim.
 - **Mock `patch()` string targets and in-function lazy imports are invisible to import-line greps.** `test_janitor.py` patched `"schedule.orchestrator.session_scope"` and `test_worker.py` patched `"schedule.service.build_object_store"`; `worker.py` also had a `from schedule.service import ...` *inside a function body*. When files move, these silently no-op against the old path — and hard-crash once the old file is deleted. After any move, grep the whole tree for the old module path (including tests) and rewrite every hit, not just top-level imports.

schedule/src/schedule/application/__init__.py

@@ -1,9 +1,20 @@
 """Application layer — service assembly for the scheduler.
 
-Home of the old flat ``schedule/service.py``: ``SchedulerService`` plus the
-``build_object_store`` / ``build_storage_http_client`` factories.
+Houses:
+
+- ``SchedulerService`` plus the ``build_object_store`` /
+  ``build_storage_http_client`` factories (the old flat ``schedule/service.py``).
+- ``DispatchOrchestrator`` and the cron / node event constants (the old
+  ``schedule/orchestrator.py`` — the outbox-polling / DAG coordinator is
+  application-level glue, not a cron-trigger primitive).
 """
 
+from schedule.application.orchestrator import (
+    NODE_EXECUTE_EVENT,
+    NODE_FINISHED_EVENT,
+    SCHEDULE_RUN_REQUESTED_EVENT,
+    DispatchOrchestrator,
+)
 from schedule.application.service import (
     SchedulerService,
     build_object_store,
@@ -14,4 +25,8 @@ __all__ = [
     "SchedulerService",
     "build_object_store",
     "build_storage_http_client",
+    "DispatchOrchestrator",
+    "SCHEDULE_RUN_REQUESTED_EVENT",
+    "NODE_EXECUTE_EVENT",
+    "NODE_FINISHED_EVENT",
 ]

schedule/src/schedule/application/service.py

@@ -3,7 +3,7 @@
 Composes three single-purpose components into one bootable service:
 
   - :class:`schedule.scheduling.scheduler.CronScheduler` — APScheduler + cron sync loop
-  - :class:`schedule.scheduling.orchestrator.DispatchOrchestrator` — Outbox polling + DAG
+  - :class:`schedule.application.orchestrator.DispatchOrchestrator` — Outbox polling + DAG
   - :class:`schedule.execution.worker.NodeExecutor` — node-level execution
 
 This module also exposes the factory function ``build_object_store``
@@ -36,7 +36,7 @@ from common.storage import create_storage
 from loguru import logger
 from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker
 
-from schedule.scheduling.orchestrator import DispatchOrchestrator
+from schedule.application.orchestrator import DispatchOrchestrator
 from schedule.scheduling.scheduler import CronScheduler
 from schedule.execution.worker import NodeExecutor
 

schedule/src/schedule/execution/worker.py

@@ -1,6 +1,6 @@
 """Node-level worker: executes one ``job.node.execute`` event.
 
-The orchestrator (see ``schedule.scheduling.orchestrator``) writes a ``job.node.execute``
+The orchestrator (see ``schedule.application.orchestrator``) writes a ``job.node.execute``
 Outbox row with all the metadata needed to run the node (script type,
 artifact location, timeout, arguments ...). The polling loop picks those up
 and calls :meth:`NodeExecutor.handle_node_execute`. This module owns the

schedule/src/schedule/infrastructure/__init__.py

@@ -1 +1,5 @@
 """Infrastructure layer — external I/O adapters (storage API)."""
+
+from schedule.infrastructure.storage import SchedulerStorageClient
+
+__all__ = ["SchedulerStorageClient"]

schedule/src/schedule/scheduling/__init__.py

@@ -1,22 +1,11 @@
-"""Scheduling layer — cron trigger + DAG orchestration.
+"""Scheduling layer — cron trigger.
 
-Home of the old flat ``schedule/scheduler.py`` (``CronScheduler``) and
-``schedule/orchestrator.py`` (``DispatchOrchestrator``). Classes moved
-byte-identical in the layered refactor; names unchanged.
+Home of the old flat ``schedule/scheduler.py`` (``CronScheduler``).
+The class moved byte-identical in the layered refactor; name unchanged.
+The outbox-polling orchestrator used to live here too, but it is an
+application-level coordinator — see ``schedule.application.orchestrator``.
 """
 
-from schedule.scheduling.orchestrator import (
-    NODE_EXECUTE_EVENT,
-    NODE_FINISHED_EVENT,
-    SCHEDULE_RUN_REQUESTED_EVENT,
-    DispatchOrchestrator,
-)
 from schedule.scheduling.scheduler import CronScheduler
 
-__all__ = [
-    "CronScheduler",
-    "DispatchOrchestrator",
-    "SCHEDULE_RUN_REQUESTED_EVENT",
-    "NODE_EXECUTE_EVENT",
-    "NODE_FINISHED_EVENT",
-]
+__all__ = ["CronScheduler"]

schedule/tests/test_janitor.py

@@ -23,7 +23,7 @@ import pytest
 
 from common.db.models import ScheduleNodeRuns
 from common.eventing import utcnow
-from schedule.scheduling.orchestrator import NODE_FINISHED_EVENT, DispatchOrchestrator
+from schedule.application.orchestrator import NODE_FINISHED_EVENT, DispatchOrchestrator
 
 
 def _make_orchestrator() -> DispatchOrchestrator:
@@ -195,7 +195,7 @@ async def test_reap_kills_running_row_past_deadline() -> None:
     fake_session.add = MagicMock()
 
     with patch(
-        "schedule.scheduling.orchestrator.session_scope",
+        "schedule.application.orchestrator.session_scope",
         return_value=_open_session_scope(fake_session),
     ):
         killed = await orch._reap_stuck_node_runs()
@@ -223,7 +223,7 @@ async def test_reap_skips_healthy_row() -> None:
     fake_session.add = MagicMock()
 
     with patch(
-        "schedule.scheduling.orchestrator.session_scope",
+        "schedule.application.orchestrator.session_scope",
         return_value=_open_session_scope(fake_session),
     ):
         killed = await orch._reap_stuck_node_runs()
@@ -266,7 +266,7 @@ async def test_reap_processes_multiple_rows_in_one_pass() -> None:
     fake_session.add = MagicMock()
 
     with patch(
-        "schedule.scheduling.orchestrator.session_scope",
+        "schedule.application.orchestrator.session_scope",
         return_value=_open_session_scope(fake_session),
     ):
         killed = await orch._reap_stuck_node_runs()
@@ -289,7 +289,7 @@ async def test_janitor_loop_propagates_cancellation() -> None:
         raise asyncio.CancelledError
 
     with patch(
-        "schedule.scheduling.orchestrator.asyncio.sleep",
+        "schedule.application.orchestrator.asyncio.sleep",
         side_effect=cancel_on_sleep,
     ):
         with pytest.raises(asyncio.CancelledError):
@@ -321,7 +321,7 @@ async def test_janitor_loop_continues_after_reap_exception() -> None:
             raise asyncio.CancelledError
 
     with patch(
-        "schedule.scheduling.orchestrator.asyncio.sleep",
+        "schedule.application.orchestrator.asyncio.sleep",
         side_effect=_count_sleeps,
     ):
         with pytest.raises(asyncio.CancelledError):

schedule/tests/test_layering.py

@@ -36,7 +36,7 @@ from schedule.domain.context import (
 from schedule.domain.execution import ExecutionResult
 from schedule.execution import NodeExecutor
 from schedule.infrastructure.storage import SchedulerStorageClient
-from schedule.scheduling.orchestrator import DispatchOrchestrator
+from schedule.application.orchestrator import DispatchOrchestrator
 from schedule.scheduling.scheduler import CronScheduler
 
 
@@ -175,3 +175,48 @@ def test_notebook_runner_shim_reexports_real_main() -> None:
     from schedule.notebook_runner import main as shim_main
 
     assert shim_main is real.main
+
+
+# ── execution/runners: stage-4 merge boundary smoke (F4) ──────────────────
+
+
+def test_limited_log_under_limit_returns_encoded_unchanged() -> None:
+    from schedule.execution.runners import notebook
+
+    assert notebook._limited_log("hello") == b"hello"
+
+
+def test_limited_log_empty_returns_sentinel() -> None:
+    from schedule.execution.runners import notebook
+
+    assert notebook._limited_log("") == b"execution produced no console output\n"
+
+
+def test_limited_log_above_max_bytes_truncates_with_suffix() -> None:
+    from schedule.execution.runners import notebook
+
+    sentinel = b"\n[log truncated by scheduler worker]\n"
+    overflowing = "x" * (notebook.MAX_LOG_BYTES + 1)
+    truncated = notebook._limited_log(overflowing)
+    assert len(truncated) == notebook.MAX_LOG_BYTES
+    assert truncated.endswith(sentinel)
+
+
+@pytest.mark.asyncio
+async def test_execute_artifact_unsupported_script_type_raises() -> None:
+    """``script_type`` outside ``{"notebook", "python"}`` must raise —
+    otherwise the worker would silently drop a malformed run into the
+    queue and the node would hang.
+    """
+    from schedule.execution.runners import notebook
+
+    with pytest.raises(ValueError, match="unsupported script_type"):
+        await notebook.execute_artifact(
+            source=b"print('hi')\n",
+            run_id="01RUN0000000000000000000A",
+            node_run_id="01NODE000000000000000000A",
+            script_type="bogus",
+            artifact_path="x.py",
+            arguments=[],
+            timeout_seconds=30,
+        )