fix: isolate invalid cron rules during scheduler recovery

back/shared/cronSchedule.ts

@@ -0,0 +1,27 @@
+import cronParser from 'cron-parser-v4';
+import { ScheduleType } from '../interface/schedule';
+
+// Keep validation aligned with node-schedule's locked cron-parser version.
+// cron-parser 5 accepts syntax (e.g. H) that the scheduler cannot execute.
+export function isValidCronSchedule(schedule: unknown): schedule is string {
+  if (typeof schedule !== 'string' || !schedule.trim()) return false;
+  try {
+    return cronParser.parseExpression(schedule).hasNext();
+  } catch {
+    return false;
+  }
+}
+
+export function getInvalidCronSchedules(cron: {
+  schedule?: string;
+  extra_schedules?: Array<{ schedule: string }>;
+}): unknown[] {
+  if (
+    cron.schedule?.startsWith(ScheduleType.ONCE) ||
+    cron.schedule?.startsWith(ScheduleType.BOOT)
+  ) {
+    return [];
+  }
+  return [cron.schedule, ...(cron.extra_schedules || []).map((x) => x.schedule)]
+    .filter((schedule) => !isValidCronSchedule(schedule));
+}