fix(modal): keyboard focus flow for the Pick-a-fandom dialog

Operator-specified flow for character-tag creation: focus starts in the
fandom search dropdown; Tab moves to the new-fandom field where Enter
creates; creating fills the dropdown and returns focus there; Enter in the
dropdown accepts the selection.

- Drive focus from the dialog's @after-enter (autofocus is unreliable inside
  a v-dialog — the focus-trap steals it post-mount); FandomPicker exposes
  focusSearch.
- Drop the @update:model-value auto-confirm that closed the dialog the instant
  selectedId was set — that's what broke create-then-accept (creating set the
  value and immediately confirmed). Enter now accepts (menu-closed + value),
  while an open menu lets Vuetify pick the highlighted item first.
- Tab from search → new-fandom field; Enter there creates, then focus returns
  to the dropdown for a single Enter-to-accept.
- Restore focus to the tag input after the dialog confirms/cancels so the
  keyboard flow continues into the next tag.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/components/modal/FandomPicker.vue

@@ -2,22 +2,37 @@
   <v-card>
     <v-card-title>Pick a fandom</v-card-title>
     <v-card-text>
-      <!-- A2/A3 (2026-06-07): autofocus so the operator types immediately, and
-           picking a fandom (keyboard: type → arrow → Enter, or a click) confirms
-           in one step — selecting IS the decision in this dialog. -->
+      <!-- Keyboard flow (operator-specified 2026-06-07):
+           1. Focus lands here (driven by the dialog's @after-enter calling the
+              exposed focusSearch — `autofocus` is unreliable inside a v-dialog
+              because the focus-trap activates after mount and steals it).
+           2. Tab moves to the "new fandom" field below.
+           3. Selecting a fandom (click, or arrow+Enter to pick from the menu)
+              leaves it in the field; a SECOND Enter (menu closed) accepts it.
+           We bind v-model:menu so the Enter handler can tell "pick from the open
+           menu" (let Vuetify handle) apart from "accept the chosen value". -->
       <v-autocomplete
+        ref="fandomRef"
         v-model="selectedId"
+        v-model:menu="menuOpen"
         :items="store.fandomCache"
         :item-title="(f) => f.name"
         :item-value="(f) => f.id"
         label="Fandom" clearable density="compact"
-        autofocus
-        @update:model-value="onSelect"
+        @keydown.enter="onSearchEnter"
+        @keydown.tab="onSearchTab"
       />
       <v-divider class="my-3" />
       <p class="text-caption mb-2">Or create a new fandom:</p>
       <div class="d-flex" style="gap: 8px;">
-        <v-text-field v-model="newName" placeholder="New fandom name" density="compact" hide-details />
+        <!-- Enter creates; on success focus returns to the dropdown (onCreate),
+             so the operator can immediately Enter-to-accept the new fandom. -->
+        <v-text-field
+          ref="newNameRef"
+          v-model="newName" placeholder="New fandom name"
+          density="compact" hide-details
+          @keydown.enter.prevent="onCreate"
+        />
         <v-btn :disabled="!newName.trim()" rounded="pill" @click="onCreate">Create</v-btn>
       </div>
     </v-card-text>
@@ -34,7 +49,7 @@
 </template>
 
 <script setup>
-import { onMounted, ref } from 'vue'
+import { nextTick, onMounted, ref } from 'vue'
 import { useTagStore } from '../../stores/tags.js'
 
 const emit = defineEmits(['confirm', 'cancel'])
@@ -42,28 +57,61 @@ const store = useTagStore()
 
 const selectedId = ref(null)
 const newName = ref('')
+const menuOpen = ref(false)
+const fandomRef = ref(null)
+const newNameRef = ref(null)
 
 // Always refresh on open so the list reflects fandoms created elsewhere (#712).
 onMounted(() => store.loadFandoms())
 
-async function onCreate() {
-  const f = await store.createFandom(newName.value.trim())
+// Exposed so the parent dialog can focus the search field on @after-enter —
+// the reliable point to grab focus (the dialog transition + focus-trap are done).
+function focusSearch () {
+  nextTick(() => {
+    fandomRef.value?.focus?.()
+    // Keep the menu closed after a programmatic focus so the very next Enter
+    // accepts the value instead of being swallowed as a menu interaction.
+    menuOpen.value = false
+  })
+}
+defineExpose({ focusSearch })
+
+async function onCreate () {
+  const name = newName.value.trim()
+  if (!name) return
+  const f = await store.createFandom(name)
   selectedId.value = f.id
   newName.value = ''
+  // The created fandom is now the selection; hand focus back to the dropdown
+  // so a single Enter accepts it (operator-specified flow 2026-06-07).
+  focusSearch()
 }
-function onConfirm() {
+
+function onConfirm () {
   const f = store.fandomCache.find(x => x.id === selectedId.value)
   if (f) emit('confirm', f)
 }
-// Picking a fandom (keyboard Enter or click) confirms immediately. Ignore the
-// clear action (null) so clearing the field doesn't fire a confirm.
-function onSelect(id) {
-  if (id == null) return
-  onConfirm()
+
+// Enter on the search field. When the menu is open Vuetify is picking the
+// highlighted item (it sets selectedId + closes the menu) — don't also accept
+// on that keystroke. With the menu closed and a value chosen, Enter accepts.
+function onSearchEnter () {
+  if (menuOpen.value) return
+  if (selectedId.value != null) onConfirm()
 }
+
+// Tab from the search field goes to the "new fandom" text field (operator-
+// specified). Shift+Tab keeps normal reverse traversal.
+function onSearchTab (e) {
+  if (e.shiftKey) return
+  e.preventDefault()
+  menuOpen.value = false
+  nextTick(() => newNameRef.value?.focus?.())
+}
+
 // Create the character with no fandom. Emits null so the caller knows this
 // was a deliberate "unassigned", not a cancel.
-function onNoFandom() {
+function onNoFandom () {
   emit('confirm', null)
 }
 </script>

frontend/src/components/modal/TagAutocomplete.vue

@@ -48,8 +48,17 @@
       </v-list-item>
     </v-list>
 
-    <v-dialog v-model="fandomDialog" max-width="480">
-      <FandomPicker @confirm="onFandomChosen" @cancel="fandomDialog = false" />
+    <!-- @after-enter is the reliable moment to focus the picker: the dialog's
+         open transition + focus-trap have settled, so focusSearch lands in the
+         fandom field instead of fighting the trap (operator-flagged 2026-06-07). -->
+    <v-dialog
+      v-model="fandomDialog" max-width="480"
+      @after-enter="fandomPickerRef?.focusSearch?.()"
+    >
+      <FandomPicker
+        ref="fandomPickerRef"
+        @confirm="onFandomChosen" @cancel="onFandomCancel"
+      />
     </v-dialog>
   </div>
 </template>
@@ -74,10 +83,11 @@ const store = useTagStore()
 // the modal's stacked-layout breakpoint (ImageViewer.vue). matchMedia is
 // safe on plain HTTP (not a secure-context API).
 const inputRef = ref(null)
-onMounted(() => {
+function focusInput () {
   if (window.matchMedia?.('(max-width: 900px)')?.matches) return
   nextTick(() => inputRef.value?.focus?.())
-})
+}
+onMounted(focusInput)
 
 // Single text input; no kind dropdown. Client-side mirror of the
 // backend's parse_kind_prefix lives below — kept in sync with
@@ -89,6 +99,7 @@ const hits = ref([])
 const highlight = ref(0)
 const listRef = ref(null)
 const fandomDialog = ref(false)
+const fandomPickerRef = ref(null)
 let pendingNewName = null
 
 const KNOWN_KINDS = new Set([
@@ -178,6 +189,17 @@ function onFandomChosen (fandom) {
   })
   pendingNewName = null
   reset()
+  // Return focus to the tag input so the keyboard flow continues straight into
+  // the next tag instead of dropping to <body> (operator-flagged 2026-06-07).
+  focusInput()
+}
+
+// Cancelling the fandom dialog drops the pending character and hands focus back
+// to the tag input, same as a successful pick.
+function onFandomCancel () {
+  fandomDialog.value = false
+  pendingNewName = null
+  focusInput()
 }
 
 function onEnter () {