# Webhook Delivery Log and Retry

## Objective

Show exactly what you sent, what came back, and how to send it again safely.

An outbound webhook pipeline with signed payloads, automatic retries with backoff, a per-attempt log, and manual replay.

## 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. Record every delivery attempt: event ID, endpoint, request body, response status, response body excerpt, duration, and attempt number.
2. Sign each payload with a per-endpoint secret and include a timestamp in the signed material so receivers can reject replays.
3. Retry failed deliveries with exponential backoff and jitter, cap the attempts, then move the delivery to a dead-letter state the user can see and act on.
4. Include a stable event ID on every attempt so receivers can deduplicate, and let users replay any past event on demand.
5. Do NOT retry on a 4xx that indicates the receiver rejected the payload outright — retrying a 400 forever just burns the endpoint. Retry timeouts, connection failures, 429, and 5xx.

## 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

- Support two active signing secrets during rotation so receivers can cut over without dropped deliveries.
- Redact tokens, keys, and personal fields from the stored request and response bodies; the log is a support tool, not a secret store.
- Retries arrive out of order by definition — the payload must carry enough state, or a sequence number, for the receiver to resolve that.
- A consistently failing endpoint should be auto-disabled after a threshold, with the owner notified, rather than retried indefinitely.
- Cap and time out the response body you store; a receiver returning a 10MB HTML error page must not fill the log table.
- A manual replay of a very old event must be marked as a replay, not presented as a fresh delivery.

## 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 attempt is logged with status, timing, and attempt number.
- [ ] Payloads are signed with a timestamped signature and rotation is supported.
- [ ] Failures retry with exponential backoff and land in a dead-letter state after a cap.
- [ ] The same event ID is preserved across all attempts of a delivery.
- [ ] Users can replay any logged event, and replays are marked as such.
- [ ] Stored request and response bodies are redacted and size-capped.
- [ ] 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.