# Assign Ownership

## Objective

Make it obvious who is responsible for each record.

An assignee on records, with a picker, notifications on change, and a history of who owned what.

## 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 nullable assignee to the relevant records. Unassigned is a real, valid state — do not force a default owner just to avoid the null.
2. Restrict the picker to users who can actually access the item, and validate that server-side as well as filtering the list.
3. Notify the new assignee when they are assigned by someone else, and record every change with the actor and timestamp.
4. Show the assignee everywhere the record appears in a list, and let people filter by 'assigned to me'.
5. Do NOT notify on self-assignment, and do NOT re-notify when an unrelated field is saved. Those two mistakes are what make assignment features get muted.

## 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

- A suspended, removed, or deleted assignee must not silently vanish from the record — surface it as needing reassignment.
- Bulk reassignment across many records must report which ones failed rather than reporting success for a partial run.
- Assignment history must survive the assignee's account being deleted; keep the name, not just the foreign key.
- Reassigning away should notify the outgoing owner too, otherwise they keep working on something that is no longer theirs.
- Rapid back-and-forth reassignment should collapse into one notification rather than several.
- Filtering by assignee must handle the unassigned case explicitly, not treat it as a missing filter.

## 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

- [ ] Records can be assigned, reassigned, and unassigned.
- [ ] Only users with access to the item can be selected, enforced on the server.
- [ ] The assignee is visible in list views and filterable, including unassigned.
- [ ] Assignment changes notify the incoming and outgoing owners, but never on self-assignment.
- [ ] Every change is recorded with actor and timestamp and survives account deletion.
- [ ] Bulk reassignment reports per-record failures.
- [ ] 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.