[BUG] Routine scheduler skips Monday when timezone is UTC+8 (SGT/CST) — weekday check applied in UTC instead of local time

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Bug Description

A Claude Code routine configured to run "weekdays at 4:10 AM SGT"
(UTC+8) never fires on Monday.

Root Cause

4:10 AM SGT = 20:10 UTC the previous day.
Monday 4:10 AM SGT = Sunday 20:10 UTC.

If the scheduler applies the "weekdays only" filter in UTC, Sunday is
excluded, so the Monday run is silently skipped. Tuesday–Friday work
correctly (they map to Mon–Thu UTC).

Affected Timezones

Any UTC+ timezone where early-morning routines cross the UTC date
boundary back into the previous (weekend) day. SGT (UTC+8), CST
(UTC+8), JST (UTC+9), AEST (UTC+10), etc.

What Should Happen?

Expected Behavior

"Weekdays" should be evaluated in the routine's configured timezone,
not in UTC.

Error Messages/Logs

Steps to Reproduce

Workaround

Set routine time to 08:01 AM SGT or later (UTC equivalent is 00:01
the same day, safely within UTC weekdays). Earlier times cannot be
used without hitting this bug.

Environment

• Claude Code on the web (claude.ai/code)
• Routine schedule: "Runs weekdays at 4:10 AM SGT"
• Observed: routine did not fire on Monday 2026-06-02 at 04:10 SGT

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude 1.9659.2 (390d6c) 2026-05-28T21:50:01.000Z

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_