feat(ask): Phase 3.5a guardrails (classifier + refusal gate + grounding + partial)

신규 파일:
- classifier_service.py: exaone binary classifier (sufficient/insufficient)
  parallel with evidence, circuit breaker, timeout 5s
- refusal_gate.py: multi-signal fusion (score + classifier)
  AND 조건, conservative fallback 3-tier (classifier 부재 시)
- grounding_check.py: strong/weak flag 분리
  strong: fabricated_number + intent_misalignment(important keywords)
  weak: uncited_claim + low_overlap + intent_misalignment(generic)
  re-gate: 2+ strong → refuse, 1 strong → partial
- sentence_splitter.py: regex 기반 (Phase 3.5b KSS 업그레이드)
- classifier.txt: exaone Y+ prompt (calibration examples 포함)
- search_synthesis_partial.txt: partial answer 전용 프롬프트
- 102_ask_events.sql: /ask 관측 테이블 (completeness 3-분리 지표)
- queries.yaml: Phase 3.5 smoke test 평가셋 10개

수정 파일:
- search.py /ask: classifier parallel + refusal gate + grounding re-gate
  + defense_layers 로깅 + AskResponse completeness/aspects/confirmed_items
- config.yaml: classifier model 섹션 (exaone3.5:7.8b GPU Ollama)
- config.py: classifier optional 파싱
- AskAnswer.svelte: 4분기 렌더 (full/partial/insufficient/loading)
- ask.ts: Completeness + ConfirmedItem 타입

P1 실측: exaone ternary 불안정 → binary gate 축소. partial은 grounding이 담당.
토론 9라운드 확정. plan: quiet-meandering-nova.md

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/lib/components/ask/AskAnswer.svelte

@@ -63,10 +63,14 @@
   };
 
   let tokens = $derived(data?.ai_answer ? splitAnswer(data.ai_answer) : []);
-  let showAnswer = $derived(
-    !!data && !!data.ai_answer && data.synthesis_status === 'completed' && !data.refused,
+  let showFullAnswer = $derived(
+    !!data && !!data.ai_answer && data.completeness === 'full'
+    && data.synthesis_status === 'completed' && !data.refused,
   );
-  let showWarning = $derived(!!data && !showAnswer);
+  let showPartial = $derived(
+    !!data && data.completeness === 'partial' && !data.refused,
+  );
+  let showWarning = $derived(!!data && !showFullAnswer && !showPartial);
 </script>
 
 <section class="bg-surface border border-default rounded-card p-5">
@@ -107,7 +111,7 @@
         근거 기반 답변 생성 중… 약 15초 소요
       </p>
     </div>
-  {:else if showAnswer && data}
+  {:else if showFullAnswer && data}
     <div class="text-sm leading-7 text-text">
       {#each tokens as tok}
         {#if tok.type === 'cite'}
@@ -124,6 +128,67 @@
         {/if}
       {/each}
     </div>
+  {:else if showPartial && data}
+    <!-- Phase 3.5a: question-aligned partial structure -->
+    <div>
+      <Badge tone="warning" size="sm">일부 답변</Badge>
+
+      {#if data.ai_answer}
+        <div class="mt-3 text-sm leading-7 text-text">
+          {#each tokens as tok}
+            {#if tok.type === 'cite'}
+              <button
+                type="button"
+                class="inline-block align-baseline text-accent font-semibold hover:underline rounded px-0.5"
+                onclick={() => onCitationClick(tok.n)}
+              >{tok.raw}</button>
+            {:else}
+              <span>{tok.value}</span>
+            {/if}
+          {/each}
+        </div>
+      {:else if data.confirmed_items?.length}
+        <div class="mt-3">
+          <h4 class="text-xs font-semibold text-dim uppercase tracking-wider">✓ 답변 가능</h4>
+          <ul class="mt-2 space-y-2">
+            {#each data.confirmed_items as item}
+              <li class="text-sm text-text">
+                <strong class="text-accent">{item.aspect}:</strong>
+                <span>{item.text}</span>
+                {#each item.citations as n}
+                  <button
+                    type="button"
+                    class="text-accent font-semibold hover:underline px-0.5"
+                    onclick={() => onCitationClick(n)}
+                  >[{n}]</button>
+                {/each}
+              </li>
+            {/each}
+          </ul>
+        </div>
+      {/if}
+
+      {#if data.missing_aspects?.length}
+        <div class="mt-4 border-t border-default pt-3">
+          <h4 class="text-xs font-semibold text-dim uppercase tracking-wider">✗ 답변 불가</h4>
+          <ul class="mt-2 space-y-1">
+            {#each data.missing_aspects as aspect}
+              <li class="text-sm text-dim">{aspect} <span class="text-[10px]">(근거 없음)</span></li>
+            {/each}
+          </ul>
+        </div>
+      {/if}
+
+      <div class="mt-4">
+        <Button
+          variant="secondary"
+          size="sm"
+          href={`/documents?q=${encodeURIComponent(data.query)}`}
+        >
+          검색 결과 확인하기
+        </Button>
+      </div>
+    </div>
   {:else if showWarning && data}
     <EmptyState
       icon={AlertTriangle}

frontend/src/lib/types/ask.ts

@@ -50,6 +50,14 @@ export interface SearchResult {
   rerank_score: number | null;
 }
 
+export type Completeness = 'full' | 'partial' | 'insufficient';
+
+export interface ConfirmedItem {
+  aspect: string;
+  text: string;
+  citations: number[];
+}
+
 export interface AskResponse {
   results: SearchResult[];
   ai_answer: string | null;
@@ -61,4 +69,9 @@ export interface AskResponse {
   no_results_reason: string | null;
   query: string;
   total: number;
+  /** Phase 3.5a */
+  completeness: Completeness;
+  covered_aspects: string[] | null;
+  missing_aspects: string[] | null;
+  confirmed_items: ConfirmedItem[] | null;
 }