Add GIPHY image search feature

backend/services/gemini_test.go

@@ -15,7 +15,7 @@ func TestTranslateQueryFallsBackToGoogleWithoutGeminiKey(t *testing.T) {
 	}))
 	defer server.Close()
 
-	service := NewGeminiService("")
+	service := NewGeminiService("", "")
 	service.Client = &http.Client{Timeout: 2 * time.Second}
 	service.TranslateEndpoint = server.URL
 
@@ -31,7 +31,7 @@ func TestTranslateQueryFallsBackToDictionaryWhenTranslateFails(t *testing.T) {
 	}))
 	defer server.Close()
 
-	service := NewGeminiService("")
+	service := NewGeminiService("", "")
 	service.Client = &http.Client{Timeout: 2 * time.Second}
 	service.TranslateEndpoint = server.URL
 
@@ -50,7 +50,7 @@ func TestTranslateSummaryToKoreanUsesGoogleAndCaches(t *testing.T) {
 	}))
 	defer server.Close()
 
-	service := NewGeminiService("")
+	service := NewGeminiService("", "")
 	service.Client = &http.Client{Timeout: 2 * time.Second}
 	service.TranslateEndpoint = server.URL
 
@@ -84,7 +84,7 @@ func TestBuildSupplementalQueriesReturnsGeneratedLines(t *testing.T) {
 	}))
 	defer server.Close()
 
-	service := NewGeminiService("dummy-key")
+	service := NewGeminiService("dummy-key", "")
 	service.Client = &http.Client{Timeout: 2 * time.Second}
 	service.GenerateEndpoint = server.URL
 
@@ -99,6 +99,52 @@ func TestBuildSupplementalQueriesReturnsGeneratedLines(t *testing.T) {
 	}
 }
 
+func TestExpandImageQueriesReturnsExactlyFiveEnglishQueries(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{"candidates":[{"content":{"parts":[{"text":"{\"queries\":[\"funny cat\",\"funny cat gif\",\"cute cat reaction\",\"cat meme gif\",\"animated cat sticker\"]}"}]}}]}`))
+	}))
+	defer server.Close()
+
+	service := NewGeminiService("dummy-key", "gemini-2.5-flash")
+	service.Client = &http.Client{Timeout: 2 * time.Second}
+	service.GenerateEndpoint = server.URL
+
+	queries, err := service.ExpandImageQueries("웃긴 고양이")
+	if err != nil {
+		t.Fatalf("expected image query expansion to succeed, got %v", err)
+	}
+	if len(queries) != 5 {
+		t.Fatalf("expected exactly 5 queries, got %#v", queries)
+	}
+	if queries[0] != "funny cat" || queries[4] != "animated cat sticker" {
+		t.Fatalf("unexpected image queries: %#v", queries)
+	}
+}
+
+func TestExpandImageQueriesFallsBackWhenGeminiFails(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		http.Error(w, "boom", http.StatusBadGateway)
+	}))
+	defer server.Close()
+
+	service := NewGeminiService("dummy-key", "gemini-2.5-flash")
+	service.Client = &http.Client{Timeout: 2 * time.Second}
+	service.GenerateEndpoint = server.URL
+	service.TranslateEndpoint = server.URL
+
+	queries, err := service.ExpandImageQueries("happy dog")
+	if err == nil {
+		t.Fatal("expected fallback warning error when gemini expansion fails")
+	}
+	if len(queries) != 5 {
+		t.Fatalf("expected fallback to still provide 5 queries, got %#v", queries)
+	}
+	if queries[0] != "happy dog" {
+		t.Fatalf("expected original query to be preserved in fallback, got %#v", queries)
+	}
+}
+
 func TestSelectUnevaluatedCandidatesSkipsReviewedLinks(t *testing.T) {
 	ranked := []SearchResult{
 		{Link: "https://a.example"},
@@ -129,7 +175,7 @@ func TestRemainingGeminiCapacityShrinksWithReviewedItems(t *testing.T) {
 }
 
 func TestGeminiVisualCacheRoundTrip(t *testing.T) {
-	service := NewGeminiService("")
+	service := NewGeminiService("", "")
 	service.setCachedVisual("image\nhttps://example.com/thumb.jpg", "abc", "image/jpeg", time.Minute)
 
 	data, mimeType, ok := service.getCachedVisual("image\nhttps://example.com/thumb.jpg")
@@ -142,7 +188,7 @@ func TestGeminiVisualCacheRoundTrip(t *testing.T) {
 }
 
 func TestGeminiTranslationCacheRoundTrip(t *testing.T) {
-	service := NewGeminiService("")
+	service := NewGeminiService("", "")
 	service.setCachedTranslation("비 오는 도시", "rainy city", time.Minute)
 
 	value, ok := service.getCachedTranslation("비 오는 도시")
@@ -155,7 +201,7 @@ func TestGeminiTranslationCacheRoundTrip(t *testing.T) {
 }
 
 func TestGeminiExpansionCacheRoundTrip(t *testing.T) {
-	service := NewGeminiService("")
+	service := NewGeminiService("", "")
 	service.setCachedExpansion("city rain", []string{"city rain", "city rain stock footage"}, time.Minute)
 
 	value, ok := service.getCachedExpansion("city rain")