# Brand Palette Generator

## Objective

Turn one brand colour into a full ramp the app can use without breaking contrast.

A generator that expands a single seed colour into light and dark ramps with contrast held at every step.

## 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. Take a single seed colour and produce a ramp of named steps, each with a defined contrast target against the surfaces it is meant to sit on, rather than an evenly spaced set of tints that happens to look plausible.
2. Generate the light and dark ramps independently. Inverting the light ramp gives dark mode a palette that is too saturated at the top and indistinguishable at the bottom — dark surfaces need less chroma and different spacing.
3. Keep the status colours out of the brand ramp. Danger, warning, and success must remain legible as danger, warning, and success even when the brand colour is itself red or green, so derive them separately and only borrow the brand's chroma character.
4. Let a person lock individual steps — usually the exact brand colour itself — and regenerate everything else around the locked values rather than overwriting them.
5. Write the output into the existing semantic token map defined by Semantic Color Tokens. Do not emit a parallel palette file that components can reference directly; two sources of colour truth diverge within a release.

## 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

- Light and dark ramps must be generated separately rather than by inversion, because a ramp that reads correctly on white becomes either glaring or muddy when placed on a dark surface.
- Every step needs its contrast checked against the surfaces it will actually be used on, not just against pure white and pure black, or the mid-range steps pass in theory and fail on cards.
- The brand colour must not become the colour of every status. A brand-coloured success state and a brand-coloured error state leave users unable to tell an outcome apart from decoration.
- Locked values must survive regeneration exactly. A brand colour that shifts by a fraction on each regeneration will eventually no longer match the printed guidelines it came from.
- A very light or very dark seed leaves no room to extend the ramp in one direction — detect that case and say so rather than producing a ramp with five identical steps at one end.
- A near-grey seed with almost no chroma produces a ramp indistinguishable from the neutral scale; require a minimum chroma or warn explicitly.
- Regeneration must be previewable before it is applied, since it changes every screen at once.

## 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

- [ ] One seed colour produces a complete named ramp for both light and dark.
- [ ] The dark ramp is generated independently rather than derived by inverting the light ramp.
- [ ] Every step meets its contrast target against the surfaces it is used on.
- [ ] Status colours are derived separately and remain distinguishable from the brand colour.
- [ ] Locked steps are preserved byte for byte through a regeneration.
- [ ] Output populates the existing semantic token map, with no parallel palette file.
- [ ] Degenerate seeds produce an explicit warning rather than a silently unusable ramp.
- [ ] 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.