# Responsive Grid Tokens

## Objective

Express columns, gaps, and spans as shared tokens rather than per-component guesses.

A token set describing column counts, gutters, and span behaviour at each breakpoint, used by every grid in the app.

## 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. Find the grids already in the app — card lists, dashboards, form layouts, media galleries — and record how many columns each uses at each size. The reconciled set is normally three or four column counts, not one per screen.
2. Define gutters from the spacing scale rather than inventing grid-specific values, so the gap between cards matches the rhythm of everything around them.
3. Express spans in tokens tied to the column count, so a component asking for half a row keeps working when the row drops from four columns to two instead of overflowing.
4. Let grids collapse on the content's minimum width rather than on a fixed column count, so a card that needs a certain width to be legible triggers the reflow itself.
5. Breakpoint names and values are owned by Breakpoint Token System and outer page widths by Container Width System. Consume both here and do not define a second set of thresholds inside the grid.

## 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 grid nested inside another grid inherits gutters it should not, producing a visibly wider gap in the inner layout. Nested grids need their own gutter step or an explicit reset.
- Collapsing purely on breakpoints ignores the container, so a four-column grid placed inside a narrow sidebar will squeeze its cards below legibility on a wide screen. The minimum content width, not the viewport, should drive the reflow.
- Reordering items visually with the grid leaves the source order untouched, so keyboard and screen reader users receive a sequence that contradicts what is on screen. Keep visual order and source order aligned.
- A grid must not assume how many children it will receive. Three cards in a four-column layout, or a single card, must both look deliberate rather than leaving a ragged hole.
- Items of unequal height will either stretch to the tallest in the row or leave gaps, and which of those is correct depends on the content, so it has to be a stated choice per grid.
- A grid rendered inside a resizable or split layout changes width without the viewport changing at all, so anything keyed to viewport width alone will be wrong there.
- Long unbroken strings and wide media inside a cell will push the column past its share unless the cell is allowed to shrink below its content.

## 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

- [ ] Every grid in the app draws its column count, gutters, and spans from shared tokens.
- [ ] Gutter values come from the app's spacing scale, not from grid-specific numbers.
- [ ] Nested grids do not inherit the outer gutter.
- [ ] Grids reflow on content minimum width, so they behave correctly inside narrow containers as well as narrow viewports.
- [ ] Visual order matches source order in every grid.
- [ ] Grids render sensibly with one item, with a partial final row, and with items of unequal height.
- [ ] No grid defines its own breakpoint values.
- [ ] 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.