App Time Zone Launcher

Relaunch any macOS app with its own time zone, without changing the system time zone. For example, keep a chat app on Beijing time while your Mac stays on Los Angeles time.

Features

• Search installed apps and press Enter to open one with its remembered time zone. Apps you have not opened yet use the system time zone.
• Choose any standard IANA time zone with its UTC offset and current local time. The choice is remembered per app.
• Ask for confirmation before restarting an app that is already running. Closed apps open immediately.
• Sort apps by how often you open them with this extension, and pin apps to keep them on top.
• Check that the relaunched process actually received the time zone.

Usage

In the app list:

Shortcut	Action
↵	Open with the app's remembered time zone
⌘ ↵	Choose another time zone
⌘ ⇧ P	Pin or unpin the app
⌘ ⇧ F	Show the app in Finder

In the time zone list, ↵ opens the app with the selected time zone and remembers it. ⌘ S remembers it without opening the app.

How It Works

If the app is running, it is quit through AppleScript, falling back to SIGTERM. It is then relaunched with:

open -n --env TZ=<zone> --env __XPC_TZ=<zone> /path/to/App.app

TZ sets the time zone of the app process. __XPC_TZ passes it on to the app's XPC services, such as the WebKit processes behind web-based interfaces. Only that app instance is affected. The system time zone and all other apps stay unchanged.

Limitations

• The time zone lasts until the app quits. Opening the app from the Dock, Finder, or Spotlight afterwards uses the system time zone again.
• Apps that ignore the TZ environment variable, for example ones that take the time zone from an account setting, are not affected.
• macOS hides the process environment of Apple system apps, so the extension cannot check the result for them and reports it as not verifiable.
• If a running app does not quit within 30 seconds, for example because an unsaved-changes dialog is open, the relaunch is aborted.