# Safe Retry

## Objective

Let people retry failed work without doing it twice.

A retry control on failed operations that knows which failures are worth retrying and which are not.

## 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 every operation that can fail mid-flight and currently leaves the user guessing: payments, invitations, uploads, exports, webhooks.
2. Classify each failure as transient or permanent, and only offer retry on the transient ones. Invalid input, revoked permissions, and rejected cards will fail identically forever; explain the fix instead of offering a button that cannot work.
3. Preserve the original input and the original error so a retry does not mean re-entering the form.
4. Reuse the same idempotency key for every retry of one attempt so the second try cannot duplicate the first. The key mechanism itself belongs to Idempotent Form Submission — wire into it rather than building a second one.
5. Do not retry automatically without telling the user. A silent background retry that eventually fails leaves them believing the work is still in progress.

## 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 timeout is not a failure. The work may have succeeded, so the retry path must be idempotent or the user pays twice.
- The retry control must disable itself while an attempt is running, and stay disabled through the response.
- Automatic retries need exponential backoff with jitter, or a recovering server gets knocked over again.
- Cap the number of attempts and then say clearly that it has stopped trying.
- A retry after a partial success must resume, not restart from the beginning.
- A failure the user cannot act on still needs an exit: a way to abandon the operation and clear it out of their way.

## 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 retryable failure offers a retry, and every permanent one explains the fix instead.
- [ ] A retry reuses the original attempt's idempotency key rather than issuing a new one.
- [ ] Retry controls disable while an attempt is in flight.
- [ ] Permanent failures do not offer a retry.
- [ ] Original input and error context survive the retry.
- [ ] Automatic retries back off and stop at a defined limit.
- [ ] 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.