Adopt RFC 5322 or ISO 8601 for date/time formats to avoid ambiguity

Background / Problem

The proposal deadline for Kaigi on Rails was displayed as Jul 13, 2026 at 12:00am JST.

However, because the "12:00 AM/PM" format can be highly ambiguous and confusing, I noticed that several people misunderstood this as 12:00 PM (noon) on July 13th, and unfortunately missed the deadline.

To prevent such confusion in the future, I would like to propose changing the date/time display format to a standardized one, such as RFC 5322 or ISO 8601.

Proposal

I suggest adopting one of the following formats. Personally, I think RFC 5322 is a great candidate because it is highly readable for humans while eliminating any ambiguity.

Option A: RFC 5322 (Highly recommended for readability)

Mon, 13 Jul 2026 00:00:00 +0900

Option B: ISO 8601

2026-07-13T00:00:00+09:00

Contribution

If the maintainers are open to this change, I am more than happy to work on the implementation. Please let me know your thoughts, and feel free to assign this issue to me!

Thank you for maintaining this wonderful project.

Start by locating where the Rails app formats and displays proposal deadlines, then check whether existing tests cover date and time presentation. Confirm which standardized format maintainers choose, update the relevant display behavior, and verify that midnight and timezone offsets are unambiguous.