Fix canonical archive writes and retain scoped lifecycle evidence

internal/platform/canvas_model_http.go

@@ -415,6 +415,18 @@ func (s *service) submitCanvasModelOperations(w http.ResponseWriter, r *http.Req
 			}
 		}
 	}
+	for id := range after.DeadRecords {
+		if before.Elements[id] != nil || before.Tombstones[id] > 0 {
+			continue
+		}
+		var foreign bool
+		if err = tx.QueryRowContext(r.Context(), `SELECT EXISTS(SELECT 1 FROM canvas_model_elements WHERE project=$1 AND element_id=$2 AND (workspace_id<>$3 OR root_id<>$4))`, project, id, workspace, root).Scan(&foreign); err != nil {
+			return err
+		}
+		if foreign {
+			return rejectBatch(409, "element_identity_conflict")
+		}
+	}
 	if err = s.saveCanvasModel(r, tx, project, workspace, account, before, after, touched); err != nil {
 		return err
 	}