feat(admin): add Guard Events tab to AI Management page

Shows blocked AI chat messages from ai_guard_violations, paginated,
filterable by guard_type (keyword / moderation_api / length / flood).
Fetches from GET /api/admin/ai/guard-events.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/routes/admin/ai-management.tsx

@@ -28,7 +28,7 @@ async function fetchJson(path: string, opts?: RequestInit) {
 }
 
 export default function AiManagementPage() {
-  const [activeTab, setActiveTab] = createSignal<'plans' | 'features' | 'user' | 'usage'>('plans');
+  const [activeTab, setActiveTab] = createSignal<'plans' | 'features' | 'user' | 'usage' | 'guard'>('plans');
   const [userId, setUserId] = createSignal('');
   const [planCode, setPlanCode] = createSignal('');
   const [creditAmount, setCreditAmount] = createSignal(10);
@@ -75,11 +75,12 @@ export default function AiManagementPage() {
     }
   };
 
-  const tabs: { key: 'plans' | 'features' | 'user' | 'usage'; label: string }[] = [
+  const tabs: { key: 'plans' | 'features' | 'user' | 'usage' | 'guard'; label: string }[] = [
     { key: 'plans', label: 'Plans' },
     { key: 'features', label: 'Features' },
     { key: 'user', label: 'User Management' },
     { key: 'usage', label: 'Usage Lookup' },
+    { key: 'guard', label: '🛡 Guard Events' },
   ];
 
   return (
@@ -230,6 +231,160 @@ export default function AiManagementPage() {
           <UsageLookup />
         </section>
       </Show>
+
+      <Show when={activeTab() === 'guard'}>
+        <section class="rounded-xl border border-gray-200 bg-white shadow-sm p-6">
+          <h2 style="margin:0 0 16px;font-size:16px;font-weight:700;color:#1e293b">AI Guard Events</h2>
+          <p style="font-size:13px;color:#6b7280;margin-bottom:16px">
+            Messages blocked by the content guard (prompt injection keywords + OpenAI Moderation API).
+          </p>
+          <GuardEvents />
+        </section>
+      </Show>
+    </div>
+  );
+}
+
+// ── Guard Events panel ────────────────────────────────────────────────────────
+
+const GUARD_TYPE_LABELS: Record<string, { label: string; color: string }> = {
+  keyword:        { label: 'Keyword',        color: '#f59e0b' },
+  moderation_api: { label: 'Moderation API', color: '#ef4444' },
+  length:         { label: 'Length',         color: '#6b7280' },
+  flood:          { label: 'Flood',          color: '#8b5cf6' },
+};
+
+function GuardEvents() {
+  const [events, setEvents] = createSignal<any[]>([]);
+  const [total, setTotal] = createSignal(0);
+  const [filterType, setFilterType] = createSignal('');
+  const [offset, setOffset] = createSignal(0);
+  const [loading, setLoading] = createSignal(false);
+  const [err, setErr] = createSignal('');
+  const LIMIT = 50;
+
+  const load = async () => {
+    setLoading(true);
+    setErr('');
+    try {
+      const qs = new URLSearchParams({ limit: String(LIMIT), offset: String(offset()) });
+      if (filterType()) qs.set('guard_type', filterType());
+      const data = await fetchJson(`/guard-events?${qs.toString()}`);
+      setEvents(data.events || []);
+      setTotal(data.total ?? 0);
+    } catch (e: any) {
+      setErr(e.message);
+    } finally {
+      setLoading(false);
+    }
+  };
+
+  // Load on mount and whenever filter/offset changes
+  const handleFilter = () => { setOffset(0); load(); };
+  const handlePrev  = () => { setOffset(Math.max(0, offset() - LIMIT)); load(); };
+  const handleNext  = () => { setOffset(offset() + LIMIT); load(); };
+
+  // Initial load
+  load();
+
+  return (
+    <div style="display:flex;flex-direction:column;gap:16px">
+      {/* Filter bar */}
+      <div style="display:flex;gap:10px;align-items:center;flex-wrap:wrap">
+        <select
+          value={filterType()}
+          onChange={(e) => setFilterType(e.currentTarget.value)}
+          style="padding:7px 10px;border:1px solid #e2e8f0;border-radius:6px;font-size:13px"
+        >
+          <option value="">All types</option>
+          <option value="keyword">Keyword</option>
+          <option value="moderation_api">Moderation API</option>
+          <option value="length">Length</option>
+          <option value="flood">Flood</option>
+        </select>
+        <button
+          class="btn-primary"
+          onClick={handleFilter}
+          disabled={loading()}
+          style="padding:7px 16px;font-size:13px"
+        >
+          {loading() ? 'Loading…' : 'Refresh'}
+        </button>
+        <span style="font-size:13px;color:#6b7280;margin-left:auto">{total()} total events</span>
+      </div>
+
+      <Show when={err()}><p style="color:#b91c1c;font-size:13px">{err()}</p></Show>
+
+      {/* Table */}
+      <div class="overflow-x-auto">
+        <table class="data-table w-full text-sm" style="font-size:13px">
+          <thead>
+            <tr>
+              <th style="width:130px">Time</th>
+              <th style="width:110px">Type</th>
+              <th>Reason</th>
+              <th>Message excerpt</th>
+              <th style="width:130px">User ID</th>
+            </tr>
+          </thead>
+          <tbody>
+            <Show when={events().length === 0 && !loading()}>
+              <tr>
+                <td colspan="5" style="text-align:center;color:#9ca3af;padding:24px">No guard events found.</td>
+              </tr>
+            </Show>
+            <For each={events()}>
+              {(ev: any) => {
+                const typeInfo = GUARD_TYPE_LABELS[ev.guard_type] ?? { label: ev.guard_type, color: '#6b7280' };
+                return (
+                  <tr>
+                    <td style="white-space:nowrap;color:#6b7280">
+                      {new Date(ev.created_at).toLocaleString()}
+                    </td>
+                    <td>
+                      <span style={`display:inline-block;padding:2px 8px;border-radius:12px;font-size:11px;font-weight:600;background:${typeInfo.color}22;color:${typeInfo.color}`}>
+                        {typeInfo.label}
+                      </span>
+                    </td>
+                    <td style="color:#374151">{ev.reason}</td>
+                    <td style="font-family:monospace;font-size:12px;color:#4b5563;max-width:320px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap" title={ev.message_excerpt}>
+                      {ev.message_excerpt}
+                    </td>
+                    <td style="font-family:monospace;font-size:11px;color:#9ca3af">
+                      {ev.user_id ? ev.user_id.slice(0, 8) + '…' : '—'}
+                    </td>
+                  </tr>
+                );
+              }}
+            </For>
+          </tbody>
+        </table>
+      </div>
+
+      {/* Pagination */}
+      <Show when={total() > LIMIT}>
+        <div style="display:flex;gap:10px;align-items:center;justify-content:flex-end;font-size:13px">
+          <button
+            class="btn-secondary"
+            onClick={handlePrev}
+            disabled={offset() === 0 || loading()}
+            style="padding:5px 14px"
+          >
+            ← Prev
+          </button>
+          <span style="color:#6b7280">
+            {offset() + 1}–{Math.min(offset() + LIMIT, total())} of {total()}
+          </span>
+          <button
+            class="btn-secondary"
+            onClick={handleNext}
+            disabled={offset() + LIMIT >= total() || loading()}
+            style="padding:5px 14px"
+          >
+            Next →
+          </button>
+        </div>
+      </Show>
     </div>
   );
 }