# Accessible Chart Summary

## Objective

Say in words what each chart shows, and let people read the numbers behind it.

A short generated description and an equivalent data table attached to every chart the app renders.

## 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. For each chart type in the app, define a summary template stating what is measured, over what range, and the one or two facts that matter — the overall direction, the extremes, and anything conspicuous — filled from the same data the chart draws from.
2. Attach the summary as the chart's accessible description and render it visibly beneath or beside the chart, since a plain sentence saying what the picture shows helps every reader, not only screen reader users.
3. Offer the underlying data as a real table reachable from the chart, sorted and formatted as the chart presents it, with units and the same rounding.
4. Regenerate the summary and the table whenever the chart's inputs change — a filter, a date range, a comparison toggle — and make sure the visible chart and its description can never disagree.
5. Do not describe the encoding instead of the data. A summary that says a bar chart with five bars in blue is useless; visual encoding, colour, and pattern are owned by Chart Color Tokens, and this brief owns the meaning.

## 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

- The summary must describe the trend without asserting more than the data supports — no causation, no forecast, and no calling a two-point difference a trend. Where the movement is within noise, say the values are broadly flat.
- The data table is the real alternative and must be genuinely equivalent: proper header cells, the same units and precision as the chart, and a caption naming what it contains, not a visually hidden dump of numbers.
- Summaries computed once at render go stale the moment a filter is applied, leaving a description of data no longer on screen; tie regeneration to the same input the chart consumes.
- Reading every data point aloud by default is worse than saying nothing useful — a hundred-point series produces an unlistenable wall of numbers. Summarise by default and put the full detail in the table the user opts into.
- Empty, single-point, and all-zero series need their own phrasing rather than a summary that reads as though something were plotted.
- Missing or partial periods must be named in the summary, because an apparent decline that is really an incomplete final month is a misleading statement of fact.
- The summary is generated text and must be localised and formatted for the user's locale, including number, date, and currency conventions.

## 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 chart in the app has a text summary exposed as its accessible description and visible on the page.
- [ ] Every chart has an equivalent data table with proper headers, units, and a caption.
- [ ] Summaries state direction and extremes without claiming causation or forecasting.
- [ ] Changing a filter or range updates the summary and the table in the same pass as the chart.
- [ ] Empty, single-point, and incomplete series produce accurate, distinct wording.
- [ ] Full point-by-point detail is available on request and is not read by default.
- [ ] 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.