# Domain Verification

## Objective

Prove an organization controls a domain before unlocking domain-wide powers.

A DNS or file-based challenge that verifies domain ownership and gates features like enforced SSO and domain-wide join.

## 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. Generate a unique, unguessable token per organization and domain, and verify it via a DNS TXT record or a file served over HTTPS at a fixed path.
2. Check the challenge server-side from the app's own infrastructure. A verification the browser performs can be faked.
3. Re-check verified domains on a schedule and mark a domain unverified when the evidence disappears, rather than trusting a one-time pass forever.
4. Make clear in the UI exactly what verification unlocks — enforced SSO, automatic joining, directory visibility — so the consequence of verifying is not a surprise.
5. Do NOT let a verified domain silently absorb existing accounts. Adding existing users to an organization is a separate, consented action.
6. Do NOT verify public email domains such as the large consumer mail providers; maintain a blocklist and refuse them outright.

## 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 same domain claimed by two organizations must resolve deterministically — first verified wins, later claimants are refused with a route to dispute.
- Apex domains and subdomains are distinct claims. Decide whether verifying an apex covers its subdomains and enforce that consistently.
- DNS propagation means the first check often fails legitimately — retry on a backoff and let the user re-check manually, rather than invalidating the token.
- Verification tokens must expire, and re-issuing a token must invalidate the previous one.
- Internationalised and punycode domains must normalise to one canonical form before comparison, or the same domain verifies twice.
- Losing verification must not instantly lock users out of an organization with enforced SSO — warn the admins first and define a grace period.

## 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

- [ ] Ownership is proven by a unique token via DNS TXT or an HTTPS-hosted file.
- [ ] Verification is performed server-side.
- [ ] Verified domains are re-checked periodically and revoked when evidence is gone.
- [ ] A domain can only be verified by one organization at a time, with a documented dispute path.
- [ ] Public consumer email domains are refused.
- [ ] The features a verified domain unlocks are stated before verification, and existing accounts are never absorbed without consent.
- [ ] 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.