# Reminder Scheduling

## Objective

Let users ask the app to bring something back to their attention later.

A reminder a user sets on a specific record, delivered at a chosen time through the notification channels the app already has.

## 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. Add a reminder action to the records users actually revisit, and store each reminder against both the user and the record.
2. Offer quick presets (tomorrow morning, next week) alongside an exact date and time.
3. Schedule against the user's time zone and show the resolved absolute time back to them before saving, so there is no ambiguity about what they picked.
4. Deliver through the existing notification center rather than adding a new inbox.
5. Do NOT fire a reminder without re-checking that the user can still see the record. Access changes between scheduling and delivery, and a reminder is a leak vector.

## 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

- Deleting, archiving, or completing the record must cancel its pending reminders.
- Saving the same reminder twice, or a retried job, must not produce two deliveries — key the schedule so it is idempotent.
- A reminder set for a time already in the past should be rejected at the form, not silently fired immediately.
- If the user changes time zone after scheduling, decide and document whether the reminder moves with them or stays at the original instant.
- A failed delivery (bounced email, revoked push permission) must be visible to the user, not silently discarded.
- Reminders on a record the user has lost access to are cancelled, not delivered with the title redacted.

## 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

- [ ] Users can set, edit, and cancel a reminder on a record.
- [ ] The resolved delivery time is shown before saving, in the user's time zone.
- [ ] Deleting or completing the record cancels its reminders.
- [ ] Duplicate saves and job retries produce exactly one delivery.
- [ ] Access is re-checked at delivery time.
- [ ] Delivery failures are surfaced to the user.
- [ ] 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.