# Dropbox Sign Signature Request

## Objective

Create Dropbox Sign requests from app documents and keep signer status in sync.

A signature request flow that submits app documents to Dropbox Sign, mirrors per-signer progress, and stores the completed file.

## 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. Represent the request, each signer, and the signing order in the app's own data before any outbound call, so status can be rendered from local state instead of a live request on every page load.
2. Place signature fields through a configured template with named fields wherever one exists, and fall back to explicit coordinates only for documents the app itself generates at a fixed layout it controls.
3. Make submission idempotent against the app record, keyed on something generated before the call, so a request that timed out after the provider accepted it is resumed rather than sent again to the same signers.
4. Verify each callback before it is allowed to change local status, deduplicate repeated deliveries, and ignore events that would move a request backwards from a terminal state.
5. If DocuSign Signature Request is also being applied, do not build two signing stacks. The app's request, signer, and status model is shared and belongs to whichever brief is applied first; this brief owns only the Dropbox Sign transport, template mapping, and callback verification.

## 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

- Field placement by coordinate is fragile. A document whose layout, font, or page count shifts will put a signature block over body text or off the page entirely, and nothing about the request will look wrong until a human opens it.
- Multiple signers need an explicit order, and the app must distinguish sequential from parallel signing. Sending everything in parallel when the agreement requires a counter-signature produces a legally awkward document.
- Callbacks must be verified as genuine before local status changes. An unverified endpoint that marks a request complete lets anyone who finds the URL mark any agreement as signed.
- A timeout during submission does not mean the request was not created. Without an idempotency key generated before the call, the retry sends every signer a second copy of the same agreement.
- Completed documents must be stored under the app's own permissions, and any temporary download link the provider issues must be treated as short-lived and never persisted in the database or emailed as a permanent reference.
- Cancelled, declined, and expired requests need represented states and a defined effect on whatever the app was gating behind the signature.
- Rate limits and provider outages must queue and back off, with the user shown a pending state rather than a false confirmation that the request was sent.
- Lost callbacks leave requests stuck. Reconcile open requests on a schedule so status converges even when an event was never delivered.

## 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

- [ ] Requests, signers, and their statuses are stored locally and rendered without a live provider call.
- [ ] Field placement uses named template fields wherever a template exists.
- [ ] Submission is idempotent, so a timeout retry never sends signers a duplicate request.
- [ ] Callbacks are verified and deduplicated, and cannot move a request out of a terminal state.
- [ ] Cancelled, declined, expired, and completed requests each have a defined state and consequence.
- [ ] Completed documents are stored under app permissions, with provider links treated as expiring.
- [ ] Scheduled reconciliation resolves any request whose callback was lost.
- [ ] 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.