M0：灵台 Kernel 骨架（事件溯源/命台席位/瀑布总线/插件注册）与神识客户端边界，新增 POST /runs 占位闭环与测试，Alembic 基线合并为单一起点

backend/app/kernel/eventlog.py

@@ -0,0 +1,63 @@
+"""Kernel 事件日志：一炁（EventStore）之上的 Kernel 写入接口。
+
+- 落库走 ``DbEventStore``（run 内单调 sequence，DB 为事实源，SSE 断线重放依据）；
+- 双发进程内 ``bus``（RunEventBus）供既有 ``/runs/{id}/stream`` SSE 实时转发。
+  该双发是 M0 骨架的过渡接法，M2 重建 runs 路由时收敛为 EventStore 单通道。
+"""
+
+from __future__ import annotations
+
+from typing import Any
+
+from app.modules.runtime.events import Event, EventStore
+from app.schemas.runtime import EventResponse
+from app.services.event_bus import bus
+
+
+class KernelEventLog:
+    """Kernel 视角的事件写入与检索。"""
+
+    def __init__(self, store: EventStore) -> None:
+        self._store = store
+
+    async def emit(
+        self,
+        *,
+        type: str,  # noqa: A002 — 对齐事件字段名
+        run_id: str,
+        character_id: str,
+        source: str = "kernel",
+        payload: dict[str, Any] | None = None,
+        visibility: str = "public",
+        trace_id: str | None = None,
+    ) -> Event:
+        event = await self._store.append(
+            Event(
+                type=type,
+                source=source,
+                payload=payload or {},
+                visibility=visibility,  # type: ignore[arg-type]
+                run_id=run_id,
+                character_id=character_id,
+                trace_id=trace_id,
+            )
+        )
+        bus.publish(run_id, _to_response(event))
+        return event
+
+    async def list_by_run(self, run_id: str) -> list[Event]:
+        return await self._store.list_by_run(run_id)
+
+
+def _to_response(event: Event) -> EventResponse:
+    return EventResponse(
+        event_id=event.id,
+        run_id=event.run_id or "",
+        character_id=event.character_id or "",
+        type=event.type,
+        sequence=event.sequence if event.sequence is not None else 0,
+        visibility=event.visibility,
+        payload=event.payload,
+        created_at=event.created_at,
+        trace_id=event.trace_id,
+    )