fix(v2): atomically record execution mutations

backend/src/backup_tool/worker.py

@@ -17,7 +17,14 @@ from sqlalchemy.ext.asyncio import async_sessionmaker
 from backup_tool.config import Settings
 from backup_tool.db.engine import create_engine
 from backup_tool.db.models import Execution
-from backup_tool.execution import claim, complete_cancellation, heartbeat, recover_stale, transition
+from backup_tool.execution import (
+    claim,
+    complete_cancellation,
+    heartbeat,
+    record_event,
+    recover_stale,
+    transition,
+)
 
 
 class Worker:
@@ -51,7 +58,7 @@ class Worker:
                 await complete_cancellation(db, execution.id, self.owner)
                 return True
             now = datetime.now(UTC)
-            await db.execute(
+            result = await db.execute(
                 update(Execution)
                 .where(
                     Execution.id == execution.id,
@@ -61,6 +68,9 @@ class Worker:
                 )
                 .values(state=transition("preparing", "running"), started_at=now)
             )
+            if getattr(result, "rowcount", 0) == 1:
+                await db.refresh(execution)
+                await record_event(db, execution)
             await db.commit()
             await heartbeat(db, execution.id, self.owner)
             return True