Bug Report

Description

When a cron job's schedule expression is updated mid-day via cron action=update, the scheduler miscalculates nextRunAtMs, skipping the next expected run entirely.

Steps to Reproduce

1. Have a daily cron job running on schedule (e.g., 30 3 * * * — 3:30 AM daily)
2. Job runs successfully at 3:30 AM on Day 1
3. Mid-day on Day 1 (~9:20 AM), update the job's schedule to 30 4 * * * (4:30 AM)
4. Observe nextRunAtMs — it should be set to Day 2 at 4:30 AM

Expected Behavior

After updating the schedule from 30 3 * * * to 30 4 * * * on Day 1, the next run should be Day 2 at 4:30 AM (the very next occurrence of the new schedule).

Actual Behavior

nextRunAtMs was set to Day 3 at 4:30 AM, completely skipping Day 2. The job did not fire on Day 2.

Timeline:

• Jan 29, 3:30 AM: Job fires successfully (old schedule 30 3 * * *)
• Jan 29, ~9:20 AM: Schedule updated to 30 4 * * *
• Jan 30, 4:30 AM: Job does NOT fire (skipped)
• Jan 31, 4:30 AM: nextRunAtMs is set here

Observed State

{
  "schedule": { "kind": "cron", "expr": "30 4 * * *" },
  "state": {
    "lastRunAtMs": 1769675400014,
    "nextRunAtMs": 1769851800000,
    "lastStatus": "ok"
  }
}

The gap between lastRunAtMs and nextRunAtMs is ~49 hours instead of the expected ~24 hours for a daily cron.

Impact

Any cron schedule update can silently skip the next occurrence, causing scheduled tasks to miss a day. In our case, this caused a critical daily inventory import to not run.

Environment

• Clawdbot version: 2026.1.24-3
• OS: Windows 10 (x64)
• Node: v24.13.0

Workaround

After updating a cron schedule, manually verify nextRunAtMs is correct. If it skipped a day, force-run the job or delete and recreate it.