Audit of every rendered time found five families of ad-hoc formatting:
the shared Time component + copies of its today/yesterday branch
(forwarded header, thread summary, read receipts, device tile, moderation
alerts, edit history), locale-default toLocale*String calls that ignored
the user's 12/24 h and date-format settings (scheduled tray, reminders,
schedule preview, notification snooze, bookmarks, threads list, search
cache line, room insights, media gallery), a hard-coded en-US date in the
activity log, and three relative-age variants.
utils/formatTimestamp.ts now holds the rules — today → time; yesterday /
tomorrow → day word + time; last 6 days → weekday + time; older → date +
time in dateFormatString — plus autoDate / time / date / dateTime styles,
formatDayDivider (full weekday), formatShortAge (room list) and
formatRelativeAge (list rows). useTimestampFormatter binds them to the
settings. 11 unit tests with an injected 'now'.
Visible changes are limited to consistency: 12 h times keep the existing
zero-padded hh:mm A; the a11y label and Created-by line use the user's
date format instead of a fixed long month.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA
- Each message is role="article"; collapsed messages (consecutive from one
sender) now carry an aria-label with sender + time — previously a screen
reader heard only the body with no attribution (the biggest a11y gap).
Pure messageAriaLabel() reuses the existing time utils (+3 tests).
- Editing a message announces "Editing message from <sender>" (ariaLabel
threaded MessageEditor → CustomEditor; the main composer is unaffected).
- System emoji get role="img" + aria-label from the shortcode; custom
emoticons always have an accessible name.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>