# Labels and Tags

## Objective

Organise records with reusable labels you can filter by.

A label catalog with a defined scope, normalised names, safe rename and delete, and label-based filtering on every list.

## 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. Decide the scope of the catalog before anything else — per user, per workspace, or global — and enforce it in every query. Mixing scopes later is a migration, not a setting.
2. Normalise names on the way in: trim whitespace, collapse internal spaces, and compare case-insensitively so 'Urgent', 'urgent' and ' urgent ' cannot coexist. Store the display form the user typed.
3. Make rename a true rename on the label record, so every record already carrying it updates at once. Never implement rename as delete-and-recreate.
4. Deleting a label must remove it from every record that has it in the same operation, and must warn with the affected count first. An assignment pointing at a deleted label is a bug that shows up as a blank chip months later.
5. Add label filtering to every list that shows these records, including combining multiple labels. Do not build a new chip-entry control for assigning labels — that input is owned by Tag Input; use it.

## 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

- Role-gated creation: some apps want anyone to apply labels but only admins to create new ones. Make that a setting, not a hardcoded rule.
- Colour is decoration, never the only signal — a label must be identifiable by its name for colour-blind users and in monochrome contexts.
- Cap the number of labels per record and the label name length, and say so before the user hits the limit.
- Merging two labels that mean the same thing must reassign records without creating duplicate assignments.
- A record whose labels the viewer cannot all see must not leak the hidden ones through filter counts or autocomplete.
- Filtering by several labels needs a defined meaning — all of them or any of them — shown in the UI rather than assumed.

## 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

- [ ] Label scope is enforced in every query, with no cross-scope leakage.
- [ ] Names are normalised so case and whitespace variants cannot create duplicates.
- [ ] Renaming updates every record instantly; deleting removes assignments and warns with a count first.
- [ ] Label creation can be restricted by role independently of label use.
- [ ] Every list showing these records can be filtered by one or more labels, with the combining rule stated.
- [ ] Assignment uses the existing tag input control rather than a new one.
- [ ] 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.