# AI Text Rewriting

## Objective

Rewrite selected text for clarity, brevity, more detail, or a different audience.

A rewrite action on a text selection that returns a proposed replacement the user can compare, accept, or discard.

## 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. Operate on the user's current selection and nothing else. Send the surrounding text as read-only context if it improves the result, but return and replace only what was selected.
2. Present the result as a proposal the user accepts. Do not overwrite the editor content directly, and make the replacement a single undoable step in the editor's existing history stack.
3. Preserve every literal the author put there: names, figures, dates, links, code, and any terminology the workspace has marked as required. A rewrite that improves the sentence and changes the number is a failure.
4. Offer a small fixed set of rewrite goals such as clearer, shorter, more detailed, or for a non-expert reader. Do not expose a free-text instruction box, which turns a bounded feature into an unbounded one.
5. Changing register while holding meaning fixed belongs to AI Tone Adjustment, and flagging errors without rewriting belongs to AI Grammar and Clarity Review. This feature owns restructuring for a stated goal; share one selection and preview mechanism across all three.

## 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

- Names, numbers, links, and locked terminology must survive verbatim. Compare them between source and result and refuse the rewrite when any of them has changed rather than showing it and hoping the user notices.
- Unless the goal explicitly asks for expansion or reduction, the rewrite must not add a claim or drop a condition. A shortened paragraph that quietly loses a caveat has changed the meaning.
- Text outside the selection must be untouched, including trailing punctuation, list markers, and the paragraph the selection ends inside.
- The original must remain recoverable after the rewrite is applied, both through a visible comparison before accepting and through a single undo afterwards.
- Very short fragments, structured content such as tables and lists, and text that is already clean all need a defined behaviour. Return the text unchanged with a short explanation instead of manufacturing a difference.
- A selection larger than the token ceiling must be refused up front with the limit stated, not silently truncated into a rewrite that ends mid-sentence.
- A refusal, timeout, or truncated response must leave the document exactly as it was, with the selection intact.
- With the model unavailable the editor and its selection behave normally and the rewrite control is disabled with a reason.

## 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 rewrite applies only to the selection and leaves surrounding content untouched.
- [ ] The result is shown for comparison and requires an explicit accept.
- [ ] Names, numbers, links, and locked terms are verified identical before the rewrite is offered.
- [ ] Accepting a rewrite is a single undo step and the original remains recoverable.
- [ ] Short, structured, or already-clean text returns unchanged with an explanation.
- [ ] Selections over the token ceiling are refused with the limit stated rather than truncated.
- [ ] Model failure leaves the document unmodified.
- [ ] 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.