Vue Reactive Composition and Dependency Flow Lab

• Composition-oriented Vue apps

  Component trees with typed props/emits, focused composables, and deliberate Options API coexistence where teams need it.

• State ownership maps

  Clear boundaries among local UI state, Pinia session state, server caches, and shareable router state.

• Vue and Nuxt delivery plans

  Honest choices between plain Vue hosts and Nuxt when SSR, routing conventions, or server endpoints matter.

• Setup-oriented composition

  Composition API organizes stateful logic in setup (or <script setup>) with explicit returns. Options API remains valid for existing codebases and teams that prefer its structure—it is not universally obsolete.

• Refs and reactive objects

  ref wraps primitives and objects with .value access in script; reactive deep-proxies objects. Prefer clear ownership over reflexively nesting everything in one reactive blob.

• Computed values

  Use computed for derived state. Do not perform side effects inside computed getters.

• watch / watchEffect boundaries

  Watchers sync external systems (storage, analytics, imperative APIs). Prefer computed for pure derivation. Always clean up effects.

• Reusable composables

  Extract shared reactive logic into useX functions with narrow inputs/outputs. Avoid oversized composables that hide mutation and networking together.

• Lifecycle hooks

  onMounted/onBeforeUnmount pair with subscriptions. Prefer composables that register and dispose their own listeners.

• Testability

  Composables that accept dependencies are easier to unit test than ones that reach into globals.

• Component-local state

  When: Ephemeral UI: open/closed, hover, local field drafts.

  Caution: Do not trap shareable business truth only inside a leaf component.

• Lifted / shared parent state

  When: Siblings need the same draft or selection without app-wide scope.

  Caution: Prop drilling becomes painful—consider provide/inject or a store when depth grows.

• provide / inject

  When: Tree-scoped services (theme, form context) without global coupling.

  Caution: Implicit dependencies can hide contracts—document injected keys.

• Pinia

  When: Cross-route session concerns: auth, cart, entitlements.

  Caution: Not every ref belongs in Pinia; overuse recreates a global mutable dump.

• Server-state cache / query layer

  When: Remote resources with loading, error, and invalidation.

  Caution: Do not duplicate server entities as the long-term source of truth in Pinia without a sync strategy.

• Router / query state

  When: Shareable filters, tabs, and resource ids.

  Caution: Keep secrets and oversized payloads out of the URL.

• Persistent browser state

  When: Preferences and drafts with explicit versioning.

  Caution: Treat persistence as untrusted input on read; never casual token storage.

• Vue as UI framework

  Vue provides components, reactivity, and rendering. Routing, SSR, and deployment conventions are application concerns you add yourself or via a framework.

• Nuxt as application framework

  Nuxt layers routing, server rendering/static generation options, server endpoints, metadata conventions, and deployment integrations on top of Vue.

• Routing

  Vue apps may use Vue Router directly. Nuxt file-based routing is a Nuxt responsibility, not automatic in plain Vue.

• SSR, SSG, and server endpoints

  Nuxt provides structured SSR/SSG and server routes. Plain Vue needs a custom server or host integration for equivalent capabilities.

• Metadata and deployment

  Document head and deployment presets are easier with Nuxt conventions; Vue SPAs still need explicit SEO and hosting choices.

• When plain Vue may be enough

  Embedded widgets, admin screens behind auth, or apps with a simple client-only host may not need Nuxt.

• When Nuxt may be appropriate

  Content sites, SEO-sensitive marketing, and full-stack Vue apps that benefit from SSR/SSG and server routes.

• Typed props

  Declare prop types and defaults so parent contracts stay explicit.

  defineProps<{ open: boolean; title: string }>()

• Emitted events

  Emit intent upward instead of mutating parent state directly.

  defineEmits<{ close: []; save: [payload: Draft] }>()

• Slots

  Slots compose structure without hard-coding every child layout.

  <slot name="actions" :disabled="!valid" />

• Controlled data flow

  Prefer clear ownership: parent passes modelValue or explicit props; child emits updates.

  modelValue + update:modelValue for reversible bindings

• Form binding

  v-model is convenience over prop + emit—keep validation near the owner of truth.

  <input v-model="email" aria-invalid="..." />

• Variants and async UI states

  Components should expose loading, empty, and error presentations—not only the happy path.

  status: 'idle' | 'loading' | 'error' | 'ready'

• Accessibility ownership

  Labeled controls, focus order, and keyboard operation are part of the component contract.

  aria-labelledby on dialogs; never icon-only without accessible names

1. 1

   Product interaction and route discovery

   Map user journeys, shareable URLs, and which screens need SSR or client-only behavior.

2. 2

   Component and ownership model

   Define presentational versus container components and who owns each piece of state.

3. 3

   Reactive dependency design

   Separate source state, computed derivation, and intentional side effects.

4. 4

   Server / store / router boundaries

   Place remote data, Pinia session state, and URL state deliberately—avoid duplication.

5. 5

   Accessibility and state feedback

   Plan focus, errors, empty states, and announcements with the same rigor as reactivity.

6. 6

   Testing and delivery architecture

   Test composables and contracts; choose Vue SPA versus Nuxt delivery intentionally.

7. 7

   Production monitoring and maintenance

   Watch client errors, slow queries, and hydration issues; keep composables maintainable as the product grows.

• Watcher overuse

  Watchers that reimplement computed logic or create write loops.

• Hidden mutation

  Composables that mutate injected objects without an obvious API.

• Giant reactive objects

  One reactive graph for the whole app that is hard to reason about and costly to track.

• Derived values stored redundantly

  Caching computed results in writable state that drifts from sources.

• Global store overuse

  Pinia for every local toggle creates coupling and noisy updates.

• Composable with too many responsibilities

  Networking, routing, and UI flags packed into a single useX.

• Unstable list keys

  Index keys on reorderable lists causing incorrect DOM reuse.

• Side effects inside computed

  Fetches or analytics inside computed getters.

• Deep-watch performance assumptions

  Assuming deep watch is free on large structures.

• Inaccessible custom controls

  Div-based widgets without keyboard or accessible names.

• Client-only meaningful content

  SEO- or task-critical copy that only appears after client hydration when SSR was required.

• Vue / Nuxt responsibility confusion

  Expecting plain Vue to provide Nuxt SSR, file routing, and server endpoints automatically.

Place state where it is owned, derive deliberately, test contracts, and choose Vue versus Nuxt based on delivery needs—not slogans.

• React
• Next.js
• TypeScript
• Framer Motion
• Tailwind CSS

Place state where it is owned, derive with computed, isolate side effects, and choose Vue versus Nuxt deliberately. Reactivity is a tool for dependency flow—not a substitute for architecture.