Stabilize search pipeline and improve preview diagnostics

backend/services/gemini.go

@@ -27,6 +27,7 @@ type GeminiService struct {
 type AIRecommendation struct {
 	Title           string `json:"title"`
 	Link            string `json:"link"`
+	Snippet         string `json:"snippet"`
 	ThumbnailURL    string `json:"thumbnailUrl"`
 	PreviewVideoURL string `json:"previewVideoUrl"`
 	Source          string `json:"source"`
@@ -232,6 +233,7 @@ User query: ` + query,
 		recommendations = append(recommendations, AIRecommendation{
 			Title:           src.Title,
 			Link:            src.Link,
+			Snippet:         src.Snippet,
 			ThumbnailURL:    src.ThumbnailURL,
 			PreviewVideoURL: src.PreviewVideoURL,
 			Source:          src.Source,
@@ -245,6 +247,7 @@ User query: ` + query,
 			recommendations = append(recommendations, AIRecommendation{
 				Title:           candidate.Title,
 				Link:            candidate.Link,
+				Snippet:         candidate.Snippet,
 				ThumbnailURL:    candidate.ThumbnailURL,
 				PreviewVideoURL: candidate.PreviewVideoURL,
 				Source:          candidate.Source,
@@ -262,10 +265,26 @@ func fetchImageAsInlineData(client *http.Client, imageURL string) (string, strin
 		return "", "", fmt.Errorf("image url is empty")
 	}
 	resp, err := client.Get(imageURL)
-	if err != nil {
-		return "", "", err
+	if err == nil {
+		defer resp.Body.Close()
+	}
+	if err != nil || resp.StatusCode >= 300 {
+		req, reqErr := newBrowserStyleImageRequest(imageURL)
+		if reqErr != nil {
+			if err != nil {
+				return "", "", err
+			}
+			return "", "", reqErr
+		}
+		if resp != nil {
+			resp.Body.Close()
+		}
+		resp, err = client.Do(req)
+		if err != nil {
+			return "", "", err
+		}
+		defer resp.Body.Close()
 	}
-	defer resp.Body.Close()
 
 	if resp.StatusCode >= 300 {
 		return "", "", fmt.Errorf("thumbnail fetch failed with %d", resp.StatusCode)
@@ -284,6 +303,17 @@ func fetchImageAsInlineData(client *http.Client, imageURL string) (string, strin
 	return base64.StdEncoding.EncodeToString(data), mimeType, nil
 }
 
+func newBrowserStyleImageRequest(imageURL string) (*http.Request, error) {
+	req, err := http.NewRequest(http.MethodGet, imageURL, nil)
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("User-Agent", "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36")
+	req.Header.Set("Accept", "image/avif,image/webp,image/apng,image/svg+xml,image/*,*/*;q=0.8")
+	req.Header.Set("Accept-Language", "en-US,en;q=0.9")
+	return req, nil
+}
+
 func fetchCandidateVisualInlineData(client *http.Client, candidate SearchResult) (string, string, error) {
 	if candidate.ThumbnailURL != "" {
 		data, mimeType, err := fetchImageAsInlineData(client, candidate.ThumbnailURL)