Return partial search results before proxy timeout

backend/services/ranker.go

@@ -91,6 +91,10 @@ func GeminiCandidateLimit(total int) int {
 }
 
 func EvaluateAllCandidatesWithGemini(service *GeminiService, query string, ranked []SearchResult) ([]AIRecommendation, GeminiBatchStats, error) {
+	return EvaluateAllCandidatesWithGeminiWithDeadline(service, query, ranked, time.Time{})
+}
+
+func EvaluateAllCandidatesWithGeminiWithDeadline(service *GeminiService, query string, ranked []SearchResult, deadline time.Time) ([]AIRecommendation, GeminiBatchStats, error) {
 	const chunkSize = 8
 	const maxConcurrentBatches = 2
 	if service == nil {
@@ -135,6 +139,13 @@ func EvaluateAllCandidatesWithGemini(service *GeminiService, query string, ranke
 		wg.Add(1)
 		go func(batchIndex int, candidates []SearchResult) {
 			defer wg.Done()
+			if !deadline.IsZero() && time.Now().After(deadline) {
+				results[batchIndex] = batchResult{
+					index: batchIndex,
+					err:   fmt.Errorf("skipped gemini batch due to deadline"),
+				}
+				return
+			}
 			sem <- struct{}{}
 			defer func() { <-sem }()
 			recommended, err := service.Recommend(query, candidates)