/vue-best-practices

name: vue-best-practices
description: MUST be used for Vue.js tasks. Strongly recommends Composition API with `<script setup>` and TypeScript as the standard approach. Covers Vue 3, SSR, Volar, vue-tsc. Load for any Vue, .vue files, Vue Router, Pinia, or Vite with Vue work. ALWAYS use Composition API unless the project explicitly requires Options API.
license: MIT
metadata:
  author: github.com/vuejs-ai
  version: "18.0.0"

Vue Best Practices Workflow

Use this skill as an instruction set. Follow the workflow in order unless the user explicitly asks for a different order.

Core Principles

• **Keep state predictable:** one source of truth, derive everything else.
• **Make data flow explicit:** Props down, Events up for most cases.
• **Favor small, focused components:** easier to test, reuse, and maintain.
• **Avoid unnecessary re-renders:** use computed properties and watchers wisely.
• **Readability counts:** write clear, self-documenting code.

1) Confirm architecture before coding (required)

• Default stack: Vue 3 + Composition API + `<script setup lang="ts">`.
• If the project explicitly uses Options API, load `vue-options-api-best-practices` skill if available.
• If the project explicitly uses JSX, load `vue-jsx-best-practices` skill if available.

1.1 Must-read core references (required)

• Before implementing any Vue task, make sure to read and apply these core references:
• `references/reactivity.md`
• `references/sfc.md`
• `references/component-data-flow.md`
• `references/composables.md`
• Keep these references in active working context for the entire task, not only when a specific issue appears.

1.2 Plan component boundaries before coding (required)

Create a brief component map before implementation for any non-trivial feature.

• Define each component's single responsibility in one sentence.
• Keep entry/root and route-level view components as composition surfaces by default.
• Move feature UI and feature logic out of entry/root/view components unless the task is intentionally a tiny single-file demo.
• Define props/emits contracts for each child component in the map.
• Prefer a feature folder layout (`components/<feature>/...`, `composables/use<Feature>.ts`) when adding more than one component.

2) Apply essential Vue foundations (required)

These are essential, must-know foundations. Apply all of them in every Vue task using the core references already loaded in section `1.1`.

Reactivity

• Must-read reference from `1.1`: [reactivity](references/reactivity.md)
• Keep source state minimal (`ref`/`reactive`), derive everything possible with `computed`.
• Use watchers for side effects if needed.
• Avoid recomputing expensive logic in templates.

SFC structure and template safety

• Must-read reference from `1.1`: [sfc](references/sfc.md)
• Keep SFC sections in this order: `<script>` → `<template>` → `<style>`.
• Keep SFC responsibilities focused; split large components.
• Keep templates declarative; move branching/derivation to script.
• Apply Vue template safety rules (`v-html`, list rendering, conditional rendering choices).

Keep components focused

Split a component when it has **more than one clear responsibility** (e.g. data orchestration + UI, or multiple independent UI sections).

• Prefer **smaller components + composables** over one “mega component”
• Move **UI sections** into child components (props in, events out).
• Move **state/side effects** into composables (`useXxx()`).

Apply objective split triggers. Split the component if **any** condition is true:

• It owns both orchestration/state and substantial presentational markup for multiple sections.
• It has 3+ distinct UI sections (for example: form, filters, list, footer/status).
• A template block is repeated or could become reusable (item rows, cards, list entries).

Entry/root and route view rule:

• Keep entry/root and route view components thin: app shell/layout, provider wiring, and feature composition.
• Do not place full feature implementations in entry/root/view components when those features contain independent parts.
• For CRUD/list features (todo, table, catalog, inbox), split at least into:
• feature container component
• input/form component
• list (and/or item) component
• footer/actions or filter/status component
• Allow a single-file implementation only for very small throwaway demos; if chosen, explicitly justify why splitting is unnecessary.

Component data flow

• Must-read reference from `1.1`: [component-data-flow](references/component-data-flow.md)
• Use props down, events up as the primary model.
• Use `v-model` only for true two-way component contracts.
• Use provide/inject only for deep-tree dependencies or shared context.
• Keep contracts explicit and typed with `defineProps`, `defineEmits`, and `InjectionKey` as needed.

Composables

• Must-read reference from `1.1`: [composables](references/composables.md)
• Extract logic into composables when it is reused, stateful, or side-effect heavy.
• Keep composable APIs small, typed, and predictable.
• Separate feature logic from presentational components.

3) Consider optional features only when requirements call for them

3.1 Standard optional features

Do not add these by default. Load the matching reference only when the requirement exists.

• Slots: parent needs to control child content/layout -> [component-slots](references/component-slots.md)
• Fallthrough attributes: wrapper/base components must forward attrs/events safely -> [component-fallthrough-attrs](references/component-fallthrough-attrs.md)
• Built-in component `<KeepAlive>` for stateful view caching -> [component-keep-alive](references/component-keep-alive.md)
• Built-in component `<Teleport>` for overlays/portals -> [component-teleport](references/component-teleport.md)
• Built-in component `<Suspense>` for async subtree fallback boundaries -> [component-suspense](references/component-suspense.md)
• Ani