# Booking Deposits

## Objective

Take a partial payment at booking so the slot is held against a real commitment.

A deposit charged during booking, tracked against the remaining balance and the cancellation policy.

## 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. Show the deposit amount, the remaining balance, and the refund terms on the booking screen before payment, not in the confirmation afterwards.
2. Hold the slot while payment is in progress, and confirm the booking only once the payment provider reports settlement. Treat an unsettled payment as no booking at all.
3. Reuse the app's existing hosted checkout and the callback handling that already confirms payments. Do not add a second payment integration for bookings, and do not confirm on the browser redirect alone, because a user who closes the tab never returns to it.
4. Record the deposit against the booking as a payment with its own state, so the remaining balance, later charges, and refunds all reconcile to one record rather than being recomputed from totals.
5. Do not charge the deposit again on a reschedule. Carry the existing payment across to the new time; recharging a customer for moving an appointment reads as a penalty and generates disputes.

## 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 booking must not be confirmed until the payment settles. Confirming on submit and reconciling later produces confirmed bookings that were never paid for.
- A failed or abandoned payment must release the held slot after a short window, and the hold must expire on its own rather than depending on the user returning to cancel it.
- The refund policy is tied to the cancellation window. Cancelling inside the window forfeits the deposit under stated terms; outside it, the refund is issued automatically rather than needing a support request.
- The deposit and the remaining balance must stay reconciled through partial refunds, price changes, and later top-up payments, so no booking ever shows a balance that disagrees with the payments recorded against it.
- A reschedule carries the existing deposit to the new booking without a second charge and without a refund-and-recharge cycle that leaves the customer out of pocket in between.
- A duplicate webhook or a retried callback must not record the deposit twice. Key payment handling on the provider's identifier so replays are ignored.
- If the app has Failed Payment Recovery, route a failed deposit into that flow instead of dropping the booking attempt silently.
- Currency, tax, and the amount displayed must match what the provider actually charges, including in the confirmation email.

## 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

- [ ] The deposit, remaining balance, and refund terms appear before payment is taken.
- [ ] A booking is confirmed only after the payment settles, verified server-side rather than on redirect.
- [ ] An abandoned or failed payment releases the held slot automatically.
- [ ] Cancellations apply the stated refund policy according to the cancellation window.
- [ ] Deposit, balance, and refunds reconcile to the booking record at all times.
- [ ] A reschedule preserves the deposit with no second charge.
- [ ] Repeated payment callbacks do not create duplicate charges or bookings.
- [ ] 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.