Harden single-candidate gemini recovery

backend/services/gemini_test.go

@@ -265,3 +265,17 @@ func TestGeminiVisionMaxOutputTokensShrinksForSingleCandidate(t *testing.T) {
 		t.Fatalf("expected 420 tokens for four candidates, got %d", got)
 	}
 }
+
+func TestParseSingleCandidateVisionTextParsesKeyValueResponse(t *testing.T) {
+	raw := "verdict: Yes\nassessment: positive\nrecommended: true\nreason_ko: 적합한 도시 야경\nsearch_hint: "
+	parsed, err := parseSingleCandidateVisionText(raw)
+	if err != nil {
+		t.Fatalf("expected parse success, got %v", err)
+	}
+	if parsed.Verdict != "Yes" || parsed.Assessment != "positive" || !parsed.Recommended {
+		t.Fatalf("unexpected parsed result: %#v", parsed)
+	}
+	if parsed.Reason != "적합한 도시 야경" {
+		t.Fatalf("unexpected reason: %#v", parsed)
+	}
+}