# Help Text Pattern

## Objective

Put field guidance in one predictable place, phrased the same way every time.

A consistent treatment for the short explanatory text that sits with a field and its control.

## 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. Collect the guidance the app currently scatters across placeholders, tooltips, asterisked footnotes, and modal help, and move it into one slot beneath the field.
2. Keep guidance that is required to complete the field permanently visible. A format rule hidden behind a hover target is not available to a touch user or a keyboard user.
3. Write help as the rule the user needs before typing — the accepted format, the consequence of the choice — not as a restatement of the label.
4. Update conditional guidance when the thing it depends on changes, so a field whose rules differ by country or plan never shows the rule for a different one.
5. Do not repeat the validation message as help text. Help states the rule in advance; the error states what went wrong, and showing both leaves the user reading the same sentence twice.

## 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

- Help that only appears on hover or focus is unreachable on touch and easy to miss with a keyboard; anything essential must be visible at rest.
- Conditional guidance must re-render when its dependency changes and must be announced, or a user who switches country will act on a stale rule that no longer applies.
- When a field becomes invalid, the error takes over as the message the user acts on, but the help must remain associated with the control if it carries the format rule.
- Help text must be programmatically linked to the control, not merely placed near it, or a screen reader user reaches the input with no guidance at all.
- Placeholder text is not help text; it disappears the moment the user types and is invisible to anyone reviewing what they entered.
- Long guidance is a sign the field is wrong — link to documentation rather than growing a paragraph under an input.
- Where this text is rendered and how it is linked belongs to Form Field Shell; this entry owns the wording, the visibility rules, and the conditional behaviour.

## 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

- [ ] All field guidance appears in the same position relative to the control.
- [ ] Guidance needed to complete a field is visible without hover or focus.
- [ ] Help text is programmatically associated with its control.
- [ ] Conditional guidance updates and is announced when its dependency changes.
- [ ] No help text duplicates a validation message.
- [ ] No field relies on a placeholder to carry its guidance.
- [ ] 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.