Optimize backend search and evaluation pipeline

backend/handlers/api.go

@@ -444,9 +444,25 @@ func (a *App) searchMedia(c *gin.Context) {
 		if extraErr == nil && len(extraResults) > 0 {
 			results = mergeSearchResults(results, extraResults)
 			scored = services.RankSearchResults(strings.Join(explorationQueries[:min(len(explorationQueries), 3)], " "), results)
-			recommended, geminiStats, geminiErr = services.EvaluateAllCandidatesWithGeminiWithDeadline(a.GeminiService, req.Query, scored, deadline.Add(-3*time.Second))
 			a.debug("search supplemental query variants", gin.H{"variants": explorationQueries, "variantCount": len(explorationQueries)})
-			a.debug("search gemini evaluation after supplemental search", geminiStats)
+			reviewedLinks := services.ReviewedRecommendationLinks(recommended)
+			supplementalCandidates := services.SelectUnevaluatedCandidates(scored, reviewedLinks, services.RemainingGeminiCapacity(recommended))
+			if len(supplementalCandidates) > 0 {
+				extraRecommended, extraStats, extraGeminiErr := services.EvaluateAllCandidatesWithGeminiWithDeadline(
+					a.GeminiService,
+					req.Query,
+					supplementalCandidates,
+					deadline.Add(-3*time.Second),
+				)
+				recommended = services.MergeUniqueRecommendations(recommended, extraRecommended)
+				geminiStats = services.MergeGeminiBatchStats(geminiStats, extraStats)
+				geminiStats.RecommendedCount = len(services.ReviewedRecommendationLinks(recommended))
+				geminiErr = combineSearchWarnings(geminiErr, extraGeminiErr)
+				a.debug("search gemini evaluation after supplemental search", gin.H{
+					"stats":             geminiStats,
+					"supplementalCount": len(supplementalCandidates),
+				})
+			}
 		}
 	}
 	if geminiErr != nil && len(recommended) == 0 {
@@ -595,6 +611,19 @@ func mergeSearchResults(base, extra []services.SearchResult) []services.SearchRe
 	return merged
 }
 
+func combineSearchWarnings(base, extra error) error {
+	switch {
+	case base == nil:
+		return extra
+	case extra == nil:
+		return base
+	case base.Error() == extra.Error():
+		return base
+	default:
+		return fmt.Errorf("%s; %s", base.Error(), extra.Error())
+	}
+}
+
 func summarizeSearchResults(results []services.SearchResult, duration time.Duration, geminiCap int, warning string) searchDebugSummary {
 	bySource := map[string]int{}
 	withPreview := 0