# Inline Editing

## Objective

Let people change a single value in place instead of opening a whole edit screen.

Click-to-edit fields in lists, tables, and detail views, with keyboard commit, validation, and rollback.

## 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. Pick the fields worth editing inline: short, single-value, low-risk. Long text, relationships, and anything with side effects belong in a real form.
2. Make the editable region obviously interactive before it is clicked, and require a deliberate gesture to enter edit mode.
3. Support Enter to commit, Escape to cancel, and Tab to commit and move to the next field. Keyboard-only editing must be complete.
4. Keep the original value until the save succeeds, and restore it visibly with an explanation if it fails.
5. Do NOT enter edit mode on a stray click during text selection or row navigation. An accidental edit mode that eats a keystroke is worse than a slower flow.

## 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 failed save must restore the previous value and say why, not leave the invalid input sitting there looking saved.
- If another user changed the value while this one was editing, say so and let them choose. Do not silently overwrite.
- Losing permission mid-edit must exit edit mode with an explanation, not fail confusingly on submit.
- Screen readers need the mode change announced and the field labelled — an unlabelled input appearing in a table cell is invisible.
- The editor must not resize the row or shift the table layout when it opens.
- Clicking outside should commit or cancel, but pick one and be consistent across the app.
- Rapid edits to several fields must not race each other into an inconsistent record.

## 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

- [ ] Editable fields are visually identifiable before interaction.
- [ ] Enter commits, Escape cancels, and Tab commits and advances.
- [ ] A failed save restores the original value and explains the failure.
- [ ] Concurrent edits by another user are detected and surfaced rather than overwritten.
- [ ] Entering and leaving edit mode is announced to assistive technology.
- [ ] Edit mode is never triggered by text selection or row navigation.
- [ ] Row height and column widths do not shift when an editor opens.
- [ ] 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.