feat(suggestions): visible, reversible rejection in the modal rail

A red-✗ dismissal no longer makes the suggestion vanish. The rejected tag
stays in the rail — dimmed, struck-through, with a "rejected" pill and a
one-click undo (↶) in place of the ✗ — so a misclick is recoverable and the
operator can see what they've said no to (operator-asked 2026-06-27).

Backend: SuggestionService.for_image now KEEPS rejected tags, flagged
rejected=True, sorted to the bottom of their category, instead of dropping
them. New AllowlistService.undismiss + POST /suggestions/undismiss clears the
TagSuggestionRejection. Rejected items are still excluded from bulk consensus
(for_selection) and the type-to-add dropdown, whose jobs are unchanged.

Frontend: store.dismiss flags in place (canonical tags) rather than dropping;
new store.undismiss reverts. SuggestionItem renders the rejected state and
swaps ✗→↶; ✓ still accepts (which clears the rejection server-side).

Tests: rejected-surfaced-flagged-then-reversible (service) + undismiss
endpoint idempotency (API).

Completes #1134's reversible-rejection half. Heads-as-suggestion-source is
the remaining piece.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ttrj5P7upUTueSfoJcxEqa

frontend/src/components/modal/SuggestionItem.vue

@@ -3,10 +3,12 @@
        name, score, and action buttons as one "object" (operator-asked
        2026-06-01). The row itself is informational; the green ✓ / red ✗
        verdict pair + 3-dot alias menu are the action affordances. -->
-  <div class="fc-suggestion">
+  <div class="fc-suggestion" :class="{ 'fc-suggestion--rejected': suggestion.rejected }">
     <span class="fc-suggestion__name">
       {{ suggestion.display_name }}
-      <span v-if="suggestion.creates_new_tag" class="fc-suggestion__new"
+      <span v-if="suggestion.rejected" class="fc-suggestion__rejected-tag"
+        title="You rejected this for this image — un-reject to recover">rejected</span>
+      <span v-else-if="suggestion.creates_new_tag" class="fc-suggestion__new"
         title="No matching tag yet — accepting creates it">+ new</span>
       <span v-else-if="suggestion.via_alias" class="fc-suggestion__alias"
         :title="`Mapped from the tagger's “${suggestion.raw_name}” via an alias`">alias</span>
@@ -17,7 +19,8 @@
          for this image (records a TagSuggestionRejection — a hard negative the
          heads train on). Together they occupy ~the footprint of the old single
          Accept pill, so rejecting is now a one-click peer of accepting rather
-         than buried in the kebab. -->
+         than buried in the kebab. When the row is already rejected the ✗ swaps
+         to an undo (↶) so the rejection is reversible in place. -->
     <div class="fc-suggestion__acts">
       <button
         class="fc-act fc-act--yes" type="button"
@@ -26,6 +29,14 @@
         @click="$emit('accept', suggestion)"
       ><v-icon size="16">mdi-check</v-icon></button>
       <button
+        v-if="suggestion.rejected"
+        class="fc-act fc-act--undo" type="button"
+        :aria-label="`Un-reject ${suggestion.display_name}`"
+        :title="`Undo — restore ${suggestion.display_name} as a suggestion`"
+        @click="$emit('undismiss', suggestion)"
+      ><v-icon size="16">mdi-undo-variant</v-icon></button>
+      <button
+        v-else
         class="fc-act fc-act--no" type="button"
         :aria-label="`Reject ${suggestion.display_name}`"
         :title="`No — not ${suggestion.display_name}`"
@@ -65,7 +76,7 @@ import { computed } from 'vue'
 import KebabMenu from '../common/KebabMenu.vue'
 
 const props = defineProps({ suggestion: { type: Object, required: true } })
-defineEmits(['accept', 'alias', 'remove-alias', 'dismiss'])
+defineEmits(['accept', 'alias', 'remove-alias', 'dismiss', 'undismiss'])
 
 const scorePct = computed(() => `${Math.round(props.suggestion.score * 100)}%`)
 // Kebab now only carries alias actions: show it when this suggestion can be
@@ -137,7 +148,35 @@ const hasMenu = computed(() =>
 }
 .fc-act--yes { background: rgb(var(--v-theme-success)); }
 .fc-act--no { background: rgb(var(--v-theme-error)); }
+/* Undo reads as neutral-secondary, not a verdict: outlined, not filled. */
+.fc-act--undo {
+  background: transparent; color: rgb(var(--v-theme-on-surface-variant));
+  border: 1px solid rgb(var(--v-theme-on-surface-variant), 0.5);
+}
 .fc-suggestion__menu {
   flex: 0 0 auto;
 }
+
+/* Rejected state: the row stays put (recovery), dimmed + red-edged so it
+   reads as "handled, negative" without shouting over live suggestions. */
+.fc-suggestion--rejected {
+  border-color: rgb(var(--v-theme-error), 0.4);
+  background: rgb(var(--v-theme-error), 0.06);
+}
+.fc-suggestion--rejected .fc-suggestion__name {
+  color: rgb(var(--v-theme-on-surface-variant));
+  text-decoration: line-through;
+  text-decoration-color: rgb(var(--v-theme-error), 0.6);
+}
+.fc-suggestion__rejected-tag {
+  display: inline-block;
+  font-size: 10px; font-weight: 600;
+  color: rgb(var(--v-theme-error));
+  background: rgb(var(--v-theme-error), 0.12);
+  border: 1px solid rgb(var(--v-theme-error), 0.4);
+  padding: 1px 6px; border-radius: 999px;
+  margin-left: 6px;
+  text-transform: uppercase; letter-spacing: 0.04em;
+  text-decoration: none;
+}
 </style>

frontend/src/components/modal/SuggestionsCategoryGroup.vue

@@ -18,6 +18,7 @@
         @alias="$emit('alias', $event)"
         @remove-alias="$emit('remove-alias', $event)"
         @dismiss="$emit('dismiss', $event)"
+        @undismiss="$emit('undismiss', $event)"
       />
     </div>
   </div>
@@ -33,7 +34,7 @@ const props = defineProps({
   collapsible: { type: Boolean, default: false },
   defaultOpen: { type: Boolean, default: true }
 })
-defineEmits(['accept', 'alias', 'remove-alias', 'dismiss'])
+defineEmits(['accept', 'alias', 'remove-alias', 'dismiss', 'undismiss'])
 
 const open = ref(props.collapsible ? props.defaultOpen : true)
 </script>

frontend/src/components/modal/SuggestionsPanel.vue

@@ -21,14 +21,14 @@
         v-show="store.byCategory[cat] && store.byCategory[cat].length"
         :label="labelFor(cat)" :items="store.byCategory[cat] || []"
         @accept="onAccept" @alias="onAlias" @remove-alias="onRemoveAlias"
-        @dismiss="store.dismiss"
+        @dismiss="store.dismiss" @undismiss="store.undismiss"
       />
       <SuggestionsCategoryGroup
         v-if="store.byCategory.general && store.byCategory.general.length"
         label="General" :items="store.byCategory.general"
         collapsible :default-open="true"
         @accept="onAccept" @alias="onAlias" @remove-alias="onRemoveAlias"
-        @dismiss="store.dismiss"
+        @dismiss="store.dismiss" @undismiss="store.undismiss"
       />
     </div>
 

frontend/src/components/modal/TagAutocomplete.vue

@@ -202,6 +202,10 @@ const suggestionHits = computed(() => {
   const out = []
   for (const list of Object.values(suggestions.allByCategory)) {
     for (const s of list || []) {
+      // Rejected suggestions now stay in allByCategory (flagged) so the panel
+      // can show + un-reject them; keep them OUT of the type-to-add dropdown,
+      // whose job is finding a tag to ADD (un-reject lives in the panel).
+      if (s.rejected) continue
       const key = `${s.category}:${s.display_name.toLowerCase()}`
       if (!s.display_name.toLowerCase().includes(q)) continue
       if (seen.has(key)) continue