feat(workbench): persist operational workflows and events

app/infra/db/postgresql/workbench_events.py

@@ -0,0 +1,37 @@
+"""Cursor reads for the durable project-scoped workbench event log."""
+from __future__ import annotations
+
+from psycopg import AsyncConnection
+
+
+class WorkbenchEventRepository:
+    def __init__(self, connection: AsyncConnection, project_id):
+        self.connection = connection
+        self.project_id = str(project_id)
+
+    async def current_cursor(self) -> int:
+        cursor = await self.connection.execute(
+            "SELECT COALESCE(max(event_seq),0) AS cursor FROM workbench.domain_event_log WHERE project_id=%s",
+            (self.project_id,),
+        )
+        row = await cursor.fetchone()
+        return int(row["cursor"])
+
+    async def oldest_cursor(self) -> int | None:
+        cursor = await self.connection.execute(
+            "SELECT min(event_seq) AS cursor FROM workbench.domain_event_log WHERE project_id=%s",
+            (self.project_id,),
+        )
+        row = await cursor.fetchone()
+        return int(row["cursor"]) if row and row["cursor"] is not None else None
+
+    async def read_after(self, after: int, limit: int = 200) -> list[dict]:
+        cursor = await self.connection.execute(
+            """SELECT event_seq,event_id,project_id,topic,aggregate_type,aggregate_id,
+                      aggregate_revision,occurred_at,metadata
+               FROM workbench.domain_event_log
+               WHERE project_id=%s AND event_seq>%s
+               ORDER BY event_seq LIMIT %s""",
+            (self.project_id, after, limit),
+        )
+        return [dict(row) for row in await cursor.fetchall()]