refactor(runtime): add run DDD boundary skeleton

backend/packages/harness/deerflow/runtime/runs/streams/__init__.py

@@ -0,0 +1,8 @@
+"""Realtime stream contracts for run application use cases."""
+
+from .run_stream_broker import RunStreamBroker, RunStreamEvent
+
+__all__ = [
+    "RunStreamBroker",
+    "RunStreamEvent",
+]

backend/packages/harness/deerflow/runtime/runs/streams/run_stream_broker.py

@@ -0,0 +1,40 @@
+"""Realtime run stream broker contract."""
+
+from __future__ import annotations
+
+from collections.abc import AsyncIterator
+from dataclasses import dataclass
+from typing import Any, Protocol
+
+from ..domain import RunId
+
+
+@dataclass(frozen=True)
+class RunStreamEvent:
+    id: str
+    event: str
+    data: Any
+
+
+class RunStreamBroker(Protocol):
+    """Realtime publish/subscribe boundary for run streams."""
+
+    async def publish(self, run_id: RunId, event: str, data: Any) -> None: ...
+
+    async def publish_terminal(self, run_id: RunId, *, event: str = "end", data: Any = None) -> None: ...
+
+    def subscribe(
+        self,
+        run_id: RunId,
+        *,
+        last_event_id: str | None = None,
+        heartbeat_interval: float = 15.0,
+    ) -> AsyncIterator[RunStreamEvent]: ...
+
+    async def cleanup(self, run_id: RunId, *, delay: float = 0) -> None: ...
+
+
+__all__ = [
+    "RunStreamBroker",
+    "RunStreamEvent",
+]