feat(ai-sdk): authority-aware re-ranking for legal RAG (Phase 1) (#31)

ai-compliance-sdk/internal/ucca/legal_rag_test.go

@@ -399,8 +399,9 @@ func TestHybridSearch_UsesQueryAPI(t *testing.T) {
 			return
 		}
 
-		// Fallback: should not reach dense search
-		t.Error("Unexpected dense search call when hybrid succeeded")
+		// /points/search is now the stratified binding-law augmentation query (it AUGMENTS
+		// the hybrid pool, it is not a dense fallback). Return empty so the hybrid hit
+		// remains the sole result for this test.
 		json.NewEncoder(w).Encode(qdrantSearchResponse{Result: []qdrantSearchHit{}})
 	}))
 	defer qdrantMock.Close()
@@ -446,6 +447,59 @@ func TestHybridSearch_UsesQueryAPI(t *testing.T) {
 	}
 }
 
+// TestSearch_StratifiedBindingRerank verifies that the binding-law pool augments the
+// semantic pool and that authority re-ranking lifts binding law above higher-semantic guidance.
+func TestSearch_StratifiedBindingRerank(t *testing.T) {
+	ollamaMock := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		json.NewEncoder(w).Encode(ollamaEmbeddingResponse{Embedding: make([]float64, 1024)})
+	}))
+	defer ollamaMock.Close()
+
+	qdrantMock := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if strings.Contains(r.URL.Path, "/index") {
+			w.WriteHeader(http.StatusOK)
+			w.Write([]byte(`{"result":{"status":"completed"}}`))
+			return
+		}
+		if strings.Contains(r.URL.Path, "/points/query") {
+			json.NewEncoder(w).Encode(qdrantQueryResponse{Result: []qdrantSearchHit{
+				{ID: "g1", Score: 0.72, Payload: map[string]interface{}{
+					"chunk_text": "ENISA guidance", "regulation_short": "ENISA",
+					"article_label": "ENISA CRA Mapping", "source_class": "supervisory_guidance",
+					"authority_weight": float64(70), "jurisdiction": "EU",
+				}},
+			}})
+			return
+		}
+		// /points/search = stratified binding-law pool (source_class=binding_law)
+		json.NewEncoder(w).Encode(qdrantSearchResponse{Result: []qdrantSearchHit{
+			{ID: "b1", Score: 0.66, Payload: map[string]interface{}{
+				"chunk_text": "CRA Anhang I requirement", "regulation_short": "CRA",
+				"article_label": "CRA Anhang I", "source_class": "binding_law",
+				"authority_weight": float64(100), "jurisdiction": "EU",
+			}},
+		}})
+	}))
+	defer qdrantMock.Close()
+
+	client := &LegalRAGClient{
+		qdrantURL: qdrantMock.URL, ollamaURL: ollamaMock.URL, embeddingModel: "bge-m3",
+		collection: "bp_compliance_ce", textIndexEnsured: make(map[string]bool),
+		hybridEnabled: true, httpClient: http.DefaultClient,
+	}
+
+	results, err := client.Search(context.Background(), "Was gilt hier?", nil, 5)
+	if err != nil {
+		t.Fatalf("search failed: %v", err)
+	}
+	if len(results) != 2 {
+		t.Fatalf("expected 2 merged results (guidance + binding), got %d", len(results))
+	}
+	if results[0].RegulationShort != "CRA" {
+		t.Errorf("binding CRA must rank first over higher-semantic guidance, got %q", results[0].RegulationShort)
+	}
+}
+
 func TestHybridSearch_FallbackToDense(t *testing.T) {
 	var requestedPaths []string