fix(audit-g2): async race / state-leak across eight stores

Extracts gallery.js's hand-rolled inflightId pattern into a new
useInflightToken composable; adopts in every store that previously
had no guard against late-response overwrites or wrong-image URL
interpolation.

Two operator-impacting bugs the audit (workflow wf_bbe3fdb1-e62)
flagged:

- modal.removeTag rolled back the chip rail unconditionally even
  when only the secondary dismiss POST had failed — UI lied until
  refresh. And all tag-mutation URLs interpolated currentImageId
  AFTER an await, so a fast prev/next could route DELETE/POST to
  the wrong image. Both fixed: split try/catch (dismiss failure
  surfaces a warning, doesn't roll back the delete); imageId
  captured at call-time and used in URLs throughout.

- suggestions.accept dereferenced currentImageId after the awaited
  POST /api/tags, so the subsequent /suggestions/accept could
  apply A's chosen tag to image B AND push it to B's allowlist.
  Fixed by capturing imageId at click-time + inflight guard on
  load().

Same shape across artist / downloads / artistDirectory /
tagDirectory / posts stores: rapid filter/nav changes used to
interleave responses (last-writer-wins). Now the late response is
discarded and the most-recent request wins. Filter-change-during-
search no longer drops the second fetch because the loading flag
was still true from the first.

gallery.js's inflightId removed in favor of the shared composable
so the pattern stays consistent.

frontend/src/stores/posts.js

@@ -2,6 +2,7 @@ import { defineStore } from 'pinia'
 import { ref } from 'vue'
 import { useApi } from '../composables/useApi.js'
 import { useAsyncAction } from '../composables/useAsyncAction.js'
+import { useInflightToken } from '../composables/useInflightToken.js'
 
 export const usePostsStore = defineStore('posts', () => {
   const api = useApi()
@@ -19,6 +20,12 @@ export const usePostsStore = defineStore('posts', () => {
   const doneOlder = ref(false)
   const doneNewer = ref(false)
   const anchorId = ref(null)
+  // loadInitial, loadMore, loadAround, loadOlder, loadNewer all share
+  // one `loading` flag and previously had no inflight guard. A filter
+  // change (loadInitial) racing a still-in-flight loadMore would
+  // append the prior filter's items into the new filter's feed.
+  // Audit 2026-06-02.
+  const inflight = useInflightToken()
 
   function _qs() {
     const q = {}
@@ -36,6 +43,7 @@ export const usePostsStore = defineStore('posts', () => {
   }
 
   async function loadInitial(newFilters) {
+    inflight.cancel()
     filters.value = {
       artist_id: newFilters?.artist_id ?? null,
       platform: newFilters?.platform ?? null,
@@ -46,8 +54,10 @@ export const usePostsStore = defineStore('posts', () => {
 
   async function loadMore() {
     if (loading.value || done.value) return
+    const t = inflight.claim()
     await run(async () => {
       const body = await api.get('/api/posts', { params: _qs() })
+      if (!t.isCurrent()) return
       items.value.push(...body.items)
       cursor.value = body.next_cursor
       if (body.next_cursor == null) done.value = true
@@ -79,6 +89,7 @@ export const usePostsStore = defineStore('posts', () => {
   // posts feed; without this the older/newer scroll loaded unfiltered
   // global posts instead of staying in the artist's stream).
   async function loadAround(postId, newFilters) {
+    inflight.cancel()
     filters.value = {
       artist_id: newFilters?.artist_id ?? null,
       platform: newFilters?.platform ?? null,
@@ -86,10 +97,12 @@ export const usePostsStore = defineStore('posts', () => {
     loading.value = true
     error.value = null
     anchorId.value = null
+    const t = inflight.claim()
     try {
       const body = await api.get('/api/posts', {
         params: _aroundParams({ around: postId }),
       })
+      if (!t.isCurrent()) return
       items.value = body.items
       cursorOlder.value = body.cursor_older
       cursorNewer.value = body.cursor_newer
@@ -97,47 +110,54 @@ export const usePostsStore = defineStore('posts', () => {
       doneNewer.value = body.cursor_newer == null
       anchorId.value = body.anchor_id
     } catch (e) {
+      if (!t.isCurrent()) return
       error.value = e
     } finally {
-      loading.value = false
+      if (t.isCurrent()) loading.value = false
     }
   }
 
   async function loadOlder() {
     if (loading.value || doneOlder.value || cursorOlder.value == null) return
     loading.value = true
+    const t = inflight.claim()
     try {
       const body = await api.get('/api/posts', {
         params: _aroundParams({
           cursor: cursorOlder.value, direction: 'older',
         }),
       })
+      if (!t.isCurrent()) return
       items.value.push(...body.items)
       cursorOlder.value = body.next_cursor
       if (body.next_cursor == null) doneOlder.value = true
     } catch (e) {
+      if (!t.isCurrent()) return
       error.value = e
     } finally {
-      loading.value = false
+      if (t.isCurrent()) loading.value = false
     }
   }
 
   async function loadNewer() {
     if (loading.value || doneNewer.value || cursorNewer.value == null) return
     loading.value = true
+    const t = inflight.claim()
     try {
       const body = await api.get('/api/posts', {
         params: _aroundParams({
           cursor: cursorNewer.value, direction: 'newer',
         }),
       })
+      if (!t.isCurrent()) return
       items.value.unshift(...body.items)
       cursorNewer.value = body.next_cursor
       if (body.next_cursor == null) doneNewer.value = true
     } catch (e) {
+      if (!t.isCurrent()) return
       error.value = e
     } finally {
-      loading.value = false
+      if (t.isCurrent()) loading.value = false
     }
   }