Fix 504 after restoring broader search baseline

backend/services/gemini.go

@@ -306,6 +306,7 @@ User query: ` + query,
 		},
 		"generationConfig": map[string]any{
 			"responseMimeType": "application/json",
+			"maxOutputTokens":  1400,
 		},
 	}
 

backend/services/ranker.go

@@ -105,7 +105,7 @@ func EvaluateAllCandidatesWithGemini(service *GeminiService, query string, ranke
 }
 
 func EvaluateAllCandidatesWithGeminiWithDeadline(service *GeminiService, query string, ranked []SearchResult, deadline time.Time) ([]AIRecommendation, GeminiBatchStats, error) {
-	const chunkSize = 8
+	const chunkSize = 6
 	const maxConcurrentBatches = 2
 	if service == nil {
 		return nil, GeminiBatchStats{}, fmt.Errorf("gemini service is not configured")
@@ -186,7 +186,7 @@ func EvaluateAllCandidatesWithGeminiWithDeadline(service *GeminiService, query s
 					"error":      batch.err.Error(),
 				})
 			}
-			recovered, recoveredErrs := recoverGeminiBatchSequentially(service, query, ranked, batch.index*chunkSize)
+			recovered, recoveredErrs := recoverGeminiBatchSequentially(service, query, ranked, batch.index*chunkSize, chunkSize, deadline)
 			if len(recovered) > 0 {
 				stats.SequentialRetried++
 				stats.Succeeded++
@@ -345,11 +345,17 @@ func MergeGeminiBatchStats(base, extra GeminiBatchStats) GeminiBatchStats {
 	return merged
 }
 
-func recoverGeminiBatchSequentially(service *GeminiService, query string, ranked []SearchResult, startIndex int) ([]AIRecommendation, []string) {
-	recovered := make([]AIRecommendation, 0, 8)
+func recoverGeminiBatchSequentially(service *GeminiService, query string, ranked []SearchResult, startIndex, chunkSize int, deadline time.Time) ([]AIRecommendation, []string) {
+	recovered := make([]AIRecommendation, 0, chunkSize)
 	errs := make([]string, 0, 4)
-	endIndex := min(startIndex+8, len(ranked))
+	endIndex := min(startIndex+chunkSize, len(ranked))
 	for idx := startIndex; idx < endIndex; idx++ {
+		if !deadline.IsZero() && time.Now().After(deadline) {
+			if len(errs) < 4 {
+				errs = append(errs, "sequential gemini recovery stopped at deadline")
+			}
+			break
+		}
 		recs, err := service.Recommend(query, []SearchResult{ranked[idx]})
 		if err != nil {
 			if len(errs) < 4 {