refactor(dry-F1): shared useAsyncAction lifecycle helper for stores

New composables/useAsyncAction.js owns the loading/error/try-finally
lifecycle. Migrated 11 stores: credentials, downloads, sources, posts
(error=raw) + ml, artistDirectory, tagDirectory, showcase, suggestions,
seriesReader, modal (error=message). The errorAs option preserves each
store's existing error shape so store.error keeps the same type for
components (~50 consumption sites unchanged). Stores whose catch also
reset data (suggestions/seriesReader/modal) clear it upfront instead.

Deliberately NOT migrated (special control flow, would change behavior):
artist (conditional 404 catch + dual loading states), migration (rethrows),
gallery (inflight-id stale-response guard), and the Shape-B no-catch /
loaded-guard / keyed-cache stores.

Net -77 lines.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/composables/useAsyncAction.js

@@ -0,0 +1,28 @@
+import { ref } from 'vue'
+
+// Owns the loading/error lifecycle shared by most Pinia stores. `run`
+// flips loading on, clears error, runs `fn`, captures any throw into error
+// (swallowed so callers can read `store.error`), and always resets loading.
+// Returns fn's resolved value on success, or undefined if it threw.
+//
+// `errorAs` matches each store's existing convention so migrations don't
+// change what `store.error` holds: 'raw' keeps the thrown object (the
+// ApiError, with .status/.body), 'message' keeps just the string.
+export function useAsyncAction({ errorAs = 'raw' } = {}) {
+  const loading = ref(false)
+  const error = ref(null)
+
+  async function run(fn) {
+    loading.value = true
+    error.value = null
+    try {
+      return await fn()
+    } catch (e) {
+      error.value = errorAs === 'message' ? (e?.message ?? String(e)) : e
+    } finally {
+      loading.value = false
+    }
+  }
+
+  return { loading, error, run }
+}

frontend/src/stores/artistDirectory.js

@@ -1,6 +1,7 @@
 import { defineStore } from 'pinia'
 import { ref, computed } from 'vue'
 import { useApi } from '../composables/useApi.js'
+import { useAsyncAction } from '../composables/useAsyncAction.js'
 
 const PAGE = 60
 
@@ -8,8 +9,7 @@ export const useArtistDirectoryStore = defineStore('artistDirectory', () => {
   const api = useApi()
   const cards = ref([])
   const nextCursor = ref(null)
-  const loading = ref(false)
-  const error = ref(null)
+  const { loading, error, run } = useAsyncAction({ errorAs: 'message' })
   const q = ref('')
   const platform = ref(null)
   let started = false
@@ -17,9 +17,7 @@ export const useArtistDirectoryStore = defineStore('artistDirectory', () => {
   async function loadMore() {
     if (loading.value) return
     if (started && nextCursor.value === null) return
-    loading.value = true
-    error.value = null
-    try {
+    await run(async () => {
       const params = { limit: PAGE }
       if (q.value) params.q = q.value
       if (platform.value) params.platform = platform.value
@@ -28,11 +26,7 @@ export const useArtistDirectoryStore = defineStore('artistDirectory', () => {
       cards.value.push(...body.cards)
       nextCursor.value = body.next_cursor
       started = true
-    } catch (e) {
-      error.value = e.message
-    } finally {
-      loading.value = false
-    }
+    })
   }
 
   async function reset() {

frontend/src/stores/credentials.js

@@ -1,28 +1,22 @@
 import { defineStore } from 'pinia'
 import { ref } from 'vue'
 import { useApi } from '../composables/useApi.js'
+import { useAsyncAction } from '../composables/useAsyncAction.js'
 
 export const useCredentialsStore = defineStore('credentials', () => {
   const api = useApi()
 
   const byPlatform = ref(new Map())
   const extensionKey = ref(null)
-  const loading = ref(false)
-  const error = ref(null)
+  const { loading, error, run } = useAsyncAction()
 
   async function loadAll() {
-    loading.value = true
-    error.value = null
-    try {
+    await run(async () => {
       const arr = await api.get('/api/credentials')
       const m = new Map()
       for (const c of arr) m.set(c.platform, c)
       byPlatform.value = m
-    } catch (e) {
-      error.value = e
-    } finally {
-      loading.value = false
-    }
+    })
   }
 
   async function upload(platform, credential_type, data) {

frontend/src/stores/downloads.js

@@ -1,6 +1,7 @@
 import { defineStore } from 'pinia'
 import { ref } from 'vue'
 import { useApi } from '../composables/useApi.js'
+import { useAsyncAction } from '../composables/useAsyncAction.js'
 
 export const useDownloadsStore = defineStore('downloads', () => {
   const api = useApi()
@@ -13,8 +14,7 @@ export const useDownloadsStore = defineStore('downloads', () => {
     from_date: null, to_date: null,
   })
   const selected = ref(null)
-  const loading = ref(false)
-  const error = ref(null)
+  const { loading, error, run } = useAsyncAction()
   const stats = ref({ pending: 0, running: 0, ok: 0, error: 0, skipped: 0 })
   const activity = ref({ hours: 24, buckets: [] })
   const failing = ref([])
@@ -28,33 +28,22 @@ export const useDownloadsStore = defineStore('downloads', () => {
   }
 
   async function loadFirst() {
-    loading.value = true
-    error.value = null
-    try {
+    await run(async () => {
       const body = await api.get('/api/downloads', { params: _params() })
       events.value = body
       cursor.value = body.length ? body[body.length - 1].id : null
       hasMore.value = body.length === 50
-    } catch (e) {
-      error.value = e
-    } finally {
-      loading.value = false
-    }
+    })
   }
 
   async function loadMore() {
     if (!hasMore.value || cursor.value == null) return
-    loading.value = true
-    try {
+    await run(async () => {
       const body = await api.get('/api/downloads', { params: _params({ before: cursor.value }) })
       events.value.push(...body)
       cursor.value = body.length ? body[body.length - 1].id : cursor.value
       hasMore.value = body.length === 50
-    } catch (e) {
-      error.value = e
-    } finally {
-      loading.value = false
-    }
+    })
   }
 
   async function loadOne(id) {

frontend/src/stores/ml.js

@@ -1,23 +1,17 @@
 import { defineStore } from 'pinia'
 import { ref } from 'vue'
 import { useApi } from '../composables/useApi.js'
+import { useAsyncAction } from '../composables/useAsyncAction.js'
 
 export const useMLStore = defineStore('ml', () => {
   const api = useApi()
   const settings = ref(null)
-  const loading = ref(false)
-  const error = ref(null)
+  const { loading, error, run } = useAsyncAction({ errorAs: 'message' })
 
   async function loadSettings() {
-    loading.value = true
-    error.value = null
-    try {
+    await run(async () => {
       settings.value = await api.get('/api/ml/settings')
-    } catch (e) {
-      error.value = e.message
-    } finally {
-      loading.value = false
-    }
+    })
   }
 
   async function patchSettings(patch) {

frontend/src/stores/modal.js

@@ -2,14 +2,14 @@ import { defineStore } from 'pinia'
 import { toast } from '../utils/toast.js'
 import { ref, computed } from 'vue'
 import { useApi } from '../composables/useApi.js'
+import { useAsyncAction } from '../composables/useAsyncAction.js'
 
 export const useModalStore = defineStore('modal', () => {
   const api = useApi()
 
   const currentImageId = ref(null)
   const current = ref(null)
-  const loading = ref(false)
-  const error = ref(null)
+  const { loading, error, run } = useAsyncAction({ errorAs: 'message' })
 
   // Post-scoped cycle. When set, prev/next cycles within this array
   // (used by PostCard's expanded-mosaic PostImageGrid clicks). When
@@ -20,8 +20,7 @@ export const useModalStore = defineStore('modal', () => {
 
   async function open (id, opts = {}) {
     currentImageId.value = id
-    loading.value = true
-    error.value = null
+    current.value = null  // cleared upfront so it stays null on error
     // Update post-scoped state if caller passed it; otherwise clear so
     // the next open() from gallery context uses neighbors mode.
     if (opts.postImageIds != null) {
@@ -32,14 +31,9 @@ export const useModalStore = defineStore('modal', () => {
       postImageIds.value = null
       postImageIndex.value = 0
     }
-    try {
+    await run(async () => {
       current.value = await api.get(`/api/gallery/image/${id}`)
-    } catch (e) {
-      error.value = e.message
-      current.value = null
-    } finally {
-      loading.value = false
-    }
+    })
   }
 
   async function close () {

frontend/src/stores/posts.js

@@ -1,15 +1,15 @@
 import { defineStore } from 'pinia'
 import { ref } from 'vue'
 import { useApi } from '../composables/useApi.js'
+import { useAsyncAction } from '../composables/useAsyncAction.js'
 
 export const usePostsStore = defineStore('posts', () => {
   const api = useApi()
 
   const items = ref([])
   const cursor = ref(null)
-  const loading = ref(false)
+  const { loading, error, run } = useAsyncAction()
   const done = ref(false)
-  const error = ref(null)
   const filters = ref({ artist_id: null, platform: null })
 
   function _qs() {
@@ -38,18 +38,12 @@ export const usePostsStore = defineStore('posts', () => {
 
   async function loadMore() {
     if (loading.value || done.value) return
-    loading.value = true
-    error.value = null
-    try {
+    await run(async () => {
       const body = await api.get('/api/posts', { params: _qs() })
       items.value.push(...body.items)
       cursor.value = body.next_cursor
       if (body.next_cursor == null) done.value = true
-    } catch (e) {
-      error.value = e
-    } finally {
-      loading.value = false
-    }
+    })
   }
 
   async function getPostFull(id) {

frontend/src/stores/seriesReader.js

@@ -1,6 +1,7 @@
 import { defineStore } from 'pinia'
 import { ref } from 'vue'
 import { useApi } from '../composables/useApi.js'
+import { useAsyncAction } from '../composables/useAsyncAction.js'
 
 // IR reader.js "viewport-center-in-third" rule, pure for unit tests.
 // metrics: [{page_number, top, height}] in page order.
@@ -33,23 +34,16 @@ export const useSeriesReaderStore = defineStore('seriesReader', () => {
 
   const series = ref(null)
   const pages = ref([])
-  const loading = ref(false)
-  const error = ref(null)
+  const { loading, error, run } = useAsyncAction({ errorAs: 'message' })
 
   async function load(tagId) {
-    loading.value = true
-    error.value = null
-    try {
+    series.value = null  // cleared upfront so they stay reset on error
+    pages.value = []
+    await run(async () => {
       const body = await api.get(`/api/series/${tagId}/pages`)
       series.value = body.series
       pages.value = body.pages
-    } catch (e) {
-      error.value = e.message
-      series.value = null
-      pages.value = []
-    } finally {
-      loading.value = false
-    }
+    })
   }
 
   return { series, pages, loading, error, load }

frontend/src/stores/showcase.js

@@ -1,32 +1,26 @@
 import { defineStore } from 'pinia'
 import { ref, computed } from 'vue'
 import { useApi } from '../composables/useApi.js'
+import { useAsyncAction } from '../composables/useAsyncAction.js'
 
 const PAGE = 60
 
 export const useShowcaseStore = defineStore('showcase', () => {
   const api = useApi()
   const images = ref([])
-  const loading = ref(false)
-  const error = ref(null)
+  const { loading, error, run } = useAsyncAction({ errorAs: 'message' })
   const exhausted = ref(false)
   const seen = new Set()
 
   async function fetchPage() {
     if (loading.value) return
-    loading.value = true
-    error.value = null
-    try {
+    await run(async () => {
       const body = await api.get('/api/showcase', { params: { limit: PAGE } })
       const fresh = body.images.filter(i => !seen.has(i.id))
       if (fresh.length === 0) { exhausted.value = true; return }
       for (const i of fresh) seen.add(i.id)
       images.value.push(...fresh)
-    } catch (e) {
-      error.value = e.message
-    } finally {
-      loading.value = false
-    }
+    })
   }
 
   async function shuffle() {

frontend/src/stores/sources.js

@@ -1,42 +1,30 @@
 import { defineStore } from 'pinia'
 import { ref, computed } from 'vue'
 import { useApi } from '../composables/useApi.js'
+import { useAsyncAction } from '../composables/useAsyncAction.js'
 
 export const useSourcesStore = defineStore('sources', () => {
   const api = useApi()
 
   // keyed cache: null => all sources, number => artist_id filtered
   const byArtist = ref(new Map())
-  const loading = ref(false)
-  const error = ref(null)
+  const { loading, error, run } = useAsyncAction()
   const scheduleStatus = ref(null)
 
   const allSources = computed(() => byArtist.value.get(null) ?? [])
 
   async function loadAll() {
-    loading.value = true
-    error.value = null
-    try {
+    await run(async () => {
       const body = await api.get('/api/sources')
       byArtist.value.set(null, body)
-    } catch (e) {
-      error.value = e
-    } finally {
-      loading.value = false
-    }
+    })
   }
 
   async function loadForArtist(artistId) {
-    loading.value = true
-    error.value = null
-    try {
+    await run(async () => {
       const body = await api.get('/api/sources', { params: { artist_id: artistId } })
       byArtist.value.set(artistId, body)
-    } catch (e) {
-      error.value = e
-    } finally {
-      loading.value = false
-    }
+    })
   }
 
   function _invalidate(artistId) {

frontend/src/stores/suggestions.js

@@ -2,6 +2,7 @@ import { defineStore } from 'pinia'
 import { toast } from '../utils/toast.js'
 import { ref } from 'vue'
 import { useApi } from '../composables/useApi.js'
+import { useAsyncAction } from '../composables/useAsyncAction.js'
 
 // Category display order: people/sources first, general last.
 export const CATEGORY_ORDER = ['artist', 'character', 'copyright', 'general']
@@ -15,23 +16,16 @@ export const CATEGORY_LABELS = {
 export const useSuggestionsStore = defineStore('suggestions', () => {
   const api = useApi()
   const byCategory = ref({})       // { category: [suggestion, ...] }
-  const loading = ref(false)
-  const error = ref(null)
+  const { loading, error, run } = useAsyncAction({ errorAs: 'message' })
   let currentImageId = null
 
   async function load(imageId) {
     currentImageId = imageId
-    loading.value = true
-    error.value = null
-    try {
+    byCategory.value = {}  // cleared upfront so it stays empty on error
+    await run(async () => {
       const body = await api.get(`/api/images/${imageId}/suggestions`)
       byCategory.value = body.by_category || {}
-    } catch (e) {
-      error.value = e.message
-      byCategory.value = {}
-    } finally {
-      loading.value = false
-    }
+    })
   }
 
   function _drop(category, predicate) {

frontend/src/stores/tagDirectory.js

@@ -1,6 +1,7 @@
 import { defineStore } from 'pinia'
 import { ref, computed } from 'vue'
 import { useApi } from '../composables/useApi.js'
+import { useAsyncAction } from '../composables/useAsyncAction.js'
 
 const PAGE = 60
 
@@ -8,8 +9,7 @@ export const useTagDirectoryStore = defineStore('tagDirectory', () => {
   const api = useApi()
   const cards = ref([])
   const nextCursor = ref(null)
-  const loading = ref(false)
-  const error = ref(null)
+  const { loading, error, run } = useAsyncAction({ errorAs: 'message' })
   const kind = ref(null)
   const q = ref('')
   let started = false
@@ -17,9 +17,7 @@ export const useTagDirectoryStore = defineStore('tagDirectory', () => {
   async function loadMore() {
     if (loading.value) return
     if (started && nextCursor.value === null) return
-    loading.value = true
-    error.value = null
-    try {
+    await run(async () => {
       const params = { limit: PAGE }
       if (kind.value) params.kind = kind.value
       if (q.value) params.q = q.value
@@ -28,11 +26,7 @@ export const useTagDirectoryStore = defineStore('tagDirectory', () => {
       cards.value.push(...body.cards)
       nextCursor.value = body.next_cursor
       started = true
-    } catch (e) {
-      error.value = e.message
-    } finally {
-      loading.value = false
-    }
+    })
   }
 
   async function reset() {