# Relative Time Component

## Objective

Show times as ages people can read, without losing the exact moment underneath.

One shared timestamp element that renders an age in words and carries the precise local date with it.

## Before You Begin

This feature is being added to an application that already exists and already
works. Do not scaffold a new project, and do not assume a blank slate.

Inspect the codebase first and establish:

- The existing application structure and where code of this kind already lives.
- The framework and version in use.
- The existing design system — colours, spacing, typography, and component conventions.
- Existing UI components you can reuse instead of writing new ones.
- The existing database structure, if this feature needs to persist anything.
- The existing authentication and authorization system, if this feature is user-scoped.
- Dependencies already installed, so you don't add a library that duplicates one.
- The existing test setup and conventions.

Only start writing code once you understand the above. If the application
already implements part of this feature, extend it rather than replacing it.

## Implementation Instructions

1. Find every place the app prints a date or a time — activity feeds, comment headers, audit rows, table cells, tooltips — and route them all through one component so the wording is identical everywhere.
2. Render from a machine-readable instant supplied by the server in a single unambiguous format, and do the conversion to the viewer's zone at display time rather than storing a formatted string.
3. Refresh the visible text on a schedule that matches its own granularity: something a few seconds old updates often, something two days old does not need to update at all.
4. Cross over to an absolute date once relative wording stops helping. Anything older than about a week reads better as a real date than as a count of days.
5. Do not run one global timer that re-renders every timestamp on the page each second. On a long feed that is a repeated layout cost for text that has not changed.

## UI and UX Requirements

Match the application's existing design system exactly. Reuse its components,
spacing, and typography. This feature should look like it was always there.

## Responsive Requirements

Works on mobile, tablet, and desktop. Touch targets are large enough to hit on a
phone, and nothing overflows horizontally at 320px.

## Accessibility Requirements

- Fully keyboard navigable.
- Correct semantic elements and ARIA roles.
- Visible focus states.
- Meets WCAG AA contrast.
- Dynamic changes are announced to screen readers.
- Respects prefers-reduced-motion.

## Edge Cases

- Update intervals must follow the age of the value — a per-second tick on a timestamp measured in months is wasted work, and a per-minute tick on something seconds old reads as frozen.
- There has to be a defined threshold at which relative wording gives way to an absolute date, because 'in 428 days' tells a reader nothing they can act on.
- A device clock that is wrong, or a record written a moment ago on a server that is slightly ahead, will produce a timestamp in the future. Clamp small skew to 'just now' rather than printing a negative age.
- The exact local time must be reachable, not just visible on hover. Put it in the element's accessible text and its title so keyboard and screen reader users get the same detail as a mouse user.
- Time zone and locale come from the viewer, not the server, and a user who travels or changes their profile zone must see the new zone without a hard reload.
- Boundaries like 'yesterday' and 'today' shift at local midnight, so a page left open overnight must not still be claiming that a two-day-old event happened today.
- Durations and ranges are a different problem from ages — do not force a start-to-end span through the same wording.

## Testing

Exercise the feature end to end in the running application. Cover every edge case
above, then run the existing test suite and confirm nothing regressed.

## Acceptance Criteria

- [ ] Every rendered date and time in the app comes from the single shared component.
- [ ] Relative text updates at an interval proportional to the value's age, with no global per-second re-render.
- [ ] Values past the defined threshold render as absolute dates in the viewer's locale.
- [ ] Timestamps slightly in the future render as 'just now' rather than as a negative or nonsensical age.
- [ ] The precise local date and time are available to screen readers and keyboard users, not only on hover.
- [ ] Zone and locale follow the viewer's settings and update when those settings change.
- [ ] The feature matches the existing design system.
- [ ] No existing functionality is broken.

## Adaptation Rules

- Match the existing design system. Do not introduce a new colour palette,
  spacing scale, or component library.
- Reuse existing components and utilities wherever they fit.
- Follow the naming, file layout, and code style already present.
- Do not upgrade, replace, or remove existing dependencies to make this
  feature fit. Adapt the feature to the app, not the app to the feature.
- Do not break existing functionality. If a change is genuinely required in
  existing code, make the smallest one that works and say so.
- If something in these instructions conflicts with how the application is
  built, follow the application and explain the deviation.

## Final Verification

Before you report the work as done:

1. Re-read the acceptance criteria above and check each one against what you
   actually built.
2. Run the application and exercise the feature end to end.
3. Run the existing test suite and confirm you have broken nothing.
4. Check the feature on mobile, tablet, and desktop widths.
5. Check keyboard navigation and focus handling.
6. Summarize what changed: files added, files modified, and anything you
   deliberately did differently because of how this application is built.

If any acceptance criterion is unmet, fix it before reporting completion.