Copilot instructions for Vue

# GitHub Copilot instructions

These instructions apply to the whole Vue repository. Copilot reads them from `.github/copilot-instructions.md`.
Prefer the commands and layout below over guesses.

## Stack

This repository is a Vue 3 app. New components use the Composition API and `<script setup>`. Single-file components stay the unit of UI.

## Layout

- Feature UI lives next to the route or view that uses it.
- Reusable components live in `components/`. Composables live in `composables/`.
- Keep SFCs focused. Move non-UI logic into a composable or a plain function.

## Commands

- Dev server: `npm run dev`
- Production build: `npm run build`
- Lint: `npm run lint`
- Tests: `npm test`

Use the script the repo already defines when it differs from the command above.

## Conventions

- Use `<script setup>` and the Composition API for new components.
- Type props and emits. Do not read a parent through a DOM query.
- Use `computed` for derived values. Do not mirror props into local state without a reason.
- Add Pinia or Vue Router only when the project already uses them.
- Template refs are for DOM access, not for stashing business data.
- Match the existing CSS approach, whether that is scoped CSS, Tailwind, or another system.

## Testing

Add or update tests when behavior changes.

Use the repo's runner. Mount the component and assert on rendered text and emitted events.

## Style

- Optimize for the next reader over the shortest diff.
- Comment only when the why is non-obvious.
- Name things the way neighboring files already do.
- Do not reformat code you did not change.

## Errors

- Fail at the boundary. Do not swallow errors.
- Fail in the composable or the submit handler with a message the component can render. Do not swallow rejected promises.

## Scope

- Do the requested task. Do not refactor unrelated code.
- Match the rigor already in the repo. Fix what you touch.
- Ask one clarifying question only when the task cannot be finished without it. Otherwise state the assumption and continue.

## Avoid

- Do not mix Options API and Composition API in the same new component.
- Do not mutate props.
- Do not lose reactivity by destructuring a reactive object without `toRefs`.
- Do not reach for `watch` when a computed value is enough.

## Done when

- The requested behavior works.
- `npm run build` still succeeds, and you ran the repo's lint or test script when one exists.
- The diff stays inside the task.
- You list anything you could not run.

## Review checklist

- The change matches the commands and layout in this file.
- No new dependency was added without a reason already present in the repo.
- Do not use v-html on untrusted strings.
- Keep tokens out of the bundle. Read them on the server.
- Validate form payloads before they reach an API.