# Notification Digests

## Objective

Bundle routine notifications into one scheduled summary instead of a stream.

Batched delivery of low-urgency notifications on a per-user schedule, grouped into a readable summary.

## 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. Extend the existing notification preference model with a per-category delivery cadence — instant, daily, weekly, off — rather than creating a separate digest settings table.
2. Mark each notification type as digestible or urgent. Security alerts, mentions, and direct assignments should keep going out immediately; routine activity is what batches.
3. Assemble a digest from the notifications accumulated since the last one, grouped by record and by actor so it reads as a summary rather than a log dump.
4. Schedule sends in the user's own time zone at a chosen local hour, and define a cutoff so events arriving mid-assembly land in the next digest instead of being dropped.
5. Do NOT send an empty digest. No activity means no email, and no 'nothing happened this week' message either.

## 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

- Anything already delivered instantly must be excluded, or users get told twice.
- Items the user can no longer access by send time must be filtered out at assembly, not just at enqueue.
- Ten changes to one record should collapse into one line with a count, not ten lines.
- A user changing time zone mid-window must not get a double digest or skip one entirely.
- Switching a category from instant to daily must not replay the backlog that was already sent.
- Digest assembly must be idempotent — a retried job cannot send the same summary twice.

## 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

- [ ] Cadence is set per category on the existing preference model.
- [ ] Urgent types bypass digesting and still send immediately.
- [ ] Digests group and deduplicate events by record and actor.
- [ ] Delivery lands at the chosen local hour in the user's time zone.
- [ ] No digest is sent for an empty window.
- [ ] Retried assembly jobs do not produce duplicate sends.
- [ ] 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.