feat: Display User's Local Time and Message Timestamp in Sender’s Timezone*

Problem Statement

Rocket.Chat is used by teams working across different time zones, making it difficult to coordinate effectively.

• Message Timestamp Issue: While hovering over a message timestamp shows a detailed time format, it only displays it in the viewer’s local time rather than the sender’s original timezone.

Proposed Solution

Show Message Timestamp in Sender’s Timezone on Hover:

• When hovering over a message timestamp, display both:
  • Viewer’s local time (current behavior).
  • Sender’s local time when the message was sent (new feature).
• Example format:

  Sent: Monday, 12 Feb 2025, 10:30 AM (Sender’s Timezone: PST)
  

Implementation Approach

• Use [Day.js](https://day.js.org/) with the timezone plugin, which is already widely used in JS/TS applications.
• Update message timestamps to store and retrieve the original sending time in the sender’s timezone.

Benefits

✅ Less confusion about when messages were actually sent.
✅ Uses a robust and lightweight library (Day.js), ensuring easy integration.

Would love feedback from the maintainers and community on this! 🚀

Start by locating the message timestamp hover UI and the existing Day.js usage, then review how message send times and sender timezone data are stored and retrieved. Confirm the expected display with maintainers before changing behavior. Done means the hover shows both viewer-local time and the sender’s local time with timezone information, with coverage for different timezones.