fuel-price/.agents/skills/pinia/references/features-composables.md

name, description

name	description
composables-in-stores	Using Vue composables within Pinia stores

Composables in Stores

Pinia stores can leverage Vue composables for reusable stateful logic.

Option Stores

Call composables inside the state property, but only those returning writable refs:

import { defineStore } from 'pinia'
import { useLocalStorage } from '@vueuse/core'

export const useAuthStore = defineStore('auth', {
  state: () => ({
    user: useLocalStorage('pinia/auth/login', 'bob'),
  }),
})

Works: Composables returning ref():

• useLocalStorage
• useAsyncState

Doesn't work in Option Stores:

• Composables exposing functions
• Composables exposing readonly data

Setup Stores

More flexible - can use almost any composable:

import { defineStore } from 'pinia'
import { useMediaControls } from '@vueuse/core'
import { ref } from 'vue'

export const useVideoPlayer = defineStore('video', () => {
  const videoElement = ref<HTMLVideoElement>()
  const src = ref('/data/video.mp4')
  const { playing, volume, currentTime, togglePictureInPicture } =
    useMediaControls(videoElement, { src })

  function loadVideo(element: HTMLVideoElement, newSrc: string) {
    videoElement.value = element
    src.value = newSrc
  }

  return {
    src,
    playing,
    volume,
    currentTime,
    loadVideo,
    togglePictureInPicture,
  }
})

Note: Don't return non-serializable DOM refs like videoElement - they're internal implementation details.

SSR Considerations

Option Stores with hydrate()

Define a hydrate() function to handle client-side hydration:

import { defineStore } from 'pinia'
import { useLocalStorage } from '@vueuse/core'

export const useAuthStore = defineStore('auth', {
  state: () => ({
    user: useLocalStorage('pinia/auth/login', 'bob'),
  }),

  hydrate(state, initialState) {
    // Ignore server state, read from browser
    state.user = useLocalStorage('pinia/auth/login', 'bob')
  },
})

Setup Stores with skipHydrate()

Mark state that shouldn't hydrate from server:

import { defineStore, skipHydrate } from 'pinia'
import { useEyeDropper, useLocalStorage } from '@vueuse/core'

export const useColorStore = defineStore('colors', () => {
  const { isSupported, open, sRGBHex } = useEyeDropper()
  const lastColor = useLocalStorage('lastColor', sRGBHex)

  return {
    // Skip hydration for client-only state
    lastColor: skipHydrate(lastColor),
    open,       // Function - no hydration needed
    isSupported, // Boolean - not reactive
  }
})

skipHydrate() only applies to state properties (refs), not functions or non-reactive values.