# Goal Tracking

## Objective

Let people define an outcome and watch progress toward it.

User-defined goals built on tracked events or metrics, with a target, a period, and progress that stays truthful as definitions change.

## 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. Let a user define a goal as a metric or event, a target value, and a period, and show progress as both the raw figure and the fraction of target.
2. Scope goals explicitly to a user, a workspace, or the whole account, and make the scope visible on the goal. An ambiguous goal is argued about in meetings.
3. Version goal definitions. When someone edits a target or a metric, create a new version rather than mutating the old one, so past periods keep the numbers they were judged on.
4. Show pace against the period — whether the goal is on track for the time elapsed — not just the total so far.
5. Do NOT silently recalculate historical periods when a definition changes. Retroactively rewriting a hit goal into a miss destroys trust in the whole dashboard.
6. Attribute each event to a period by a defined timestamp — when it occurred, not when it was ingested.

## 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

- Events arriving late must land in the period they occurred in, and the affected figure must be marked as recently revised.
- Duplicate events must be deduplicated by a stable identifier before they count toward a goal.
- A goal whose underlying metric or event is deleted must show as broken rather than reading zero — zero looks like failure, not absence.
- Changing the period mid-flight changes the denominator; show the old period's result rather than reshaping it.
- A completed goal needs a terminal state, not a progress bar stuck at 100%.
- Timezone matters for daily and weekly goals — a goal that resets at the wrong midnight is wrong every day.
- Users must not be able to create a goal against data they cannot otherwise see; check permissions at definition time and again at read time.

## 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

- [ ] A goal has a metric, target, period, and explicit scope, all visible on the goal.
- [ ] Editing a goal creates a new version and leaves past periods unchanged.
- [ ] Progress shows both absolute value and pace against elapsed time.
- [ ] Late events land in the period they occurred in; duplicates are excluded.
- [ ] A goal with a missing or inaccessible metric reads as broken, not zero.
- [ ] Completed and failed goals have terminal states.
- [ ] 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.