fix(search): apply RelevanceFilter in DownloadService and LibraryController auto-pick flows too

The previous commit wired the context-aware RelevanceFilter into
AutomaticSearchService only. The two other auto-pick callers
(DownloadService.SearchAndDownloadAsync via the manual "search and
download" endpoint, and LibraryController.ProcessAudiobookForSearchAsync
via the bulk-search-all endpoint) bypassed the filter and went straight
from search to scoring — so they could still pick an irrelevant result
when the indexer returned only weak matches.

DownloadService injects SearchResultFilterPipeline via its primary
constructor; LibraryController resolves it from the existing scope
factory to avoid widening its constructor. Both call
pipeline.ApplyFilters(searchResults, audiobook: audiobook) before
ScoreSearchResults, matching the AutomaticSearchService pattern.

Manual search (no audiobook context) keeps the old behavior — the
filter fails open without context.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: 2 people

listenarr.api/Controllers/LibraryController.cs

@@ -3195,6 +3195,30 @@ private async Task<int> ProcessAudiobookForSearchAsync(
                 return 0;
             }
 
+            // Context-aware filter pass — reject results whose title isn't relevant to
+            // this specific audiobook before scoring picks one to download. This is the
+            // bulk-search-all endpoint, an auto-pick flow like AutomaticSearchService.
+            try
+            {
+                using var filterScope = _scopeFactory.CreateScope();
+                var filterPipeline = filterScope.ServiceProvider.GetRequiredService<Listenarr.Application.Search.Filters.SearchResultFilterPipeline>();
+                var preFilterCount = searchResults.Count;
+                searchResults = filterPipeline.ApplyFilters(searchResults, logFilteredResults: true, audiobook: audiobook);
+                if (searchResults.Count < preFilterCount)
+                {
+                    _logger.LogInformation("Filtered {Removed} of {Total} raw results for audiobook '{Title}' via context-aware pipeline", preFilterCount - searchResults.Count, preFilterCount, LogRedaction.SanitizeText(audiobook.Title));
+                }
+                if (!searchResults.Any())
+                {
+                    _logger.LogInformation("All search results filtered for audiobook '{Title}'", LogRedaction.SanitizeText(audiobook.Title));
+                    return 0;
+                }
+            }
+            catch (Exception ex) when (ex is not OperationCanceledException && ex is not OutOfMemoryException && ex is not StackOverflowException)
+            {
+                _logger.LogDebug(ex, "SearchResultFilterPipeline unavailable; skipping context-aware filtering for audiobook {Id}", audiobook.Id);
+            }
+
             // Score results against quality profile
             var scoredResults = await qualityProfileService.ScoreSearchResults(searchResults, audiobook.QualityProfile!);
 

listenarr.application/Downloads/DownloadService.cs

@@ -25,6 +25,7 @@
 using Listenarr.Application.Interfaces;
 using Listenarr.Domain.Models;
 using Listenarr.Application.Interfaces.Repositories;
+using Listenarr.Application.Search.Filters;
 using Microsoft.Extensions.Logging;
 using Listenarr.Application.Security;
 
@@ -44,7 +45,8 @@ public class DownloadService(
         IDownloadQueueService downloadQueueService,
         INotificationService notificationService,
         IHubBroadcaster hubBroadcaster,
-        IDownloadHistoryService downloadHistoryService) : IDownloadService
+        IDownloadHistoryService downloadHistoryService,
+        SearchResultFilterPipeline filterPipeline) : IDownloadService
     {
         // Cache expiration constants
         private const int QueueCacheExpirationSeconds = 10;
@@ -206,6 +208,23 @@ public async Task<SearchAndDownloadResult> SearchAndDownloadAsync(int audiobookI
                 };
             }
 
+            // Context-aware filter pass — reject results whose title isn't relevant to
+            // this specific audiobook before scoring picks one to download.
+            var preFilterCount = searchResults.Count;
+            searchResults = filterPipeline.ApplyFilters(searchResults, logFilteredResults: true, audiobook: audiobook);
+            if (searchResults.Count < preFilterCount)
+            {
+                logger.LogInformation("Filtered {Removed} of {Total} raw results for audiobook '{Title}' via context-aware pipeline", preFilterCount - searchResults.Count, preFilterCount, LogRedaction.SanitizeText(audiobook.Title));
+            }
+            if (!searchResults.Any())
+            {
+                return new SearchAndDownloadResult
+                {
+                    Success = false,
+                    Message = "All results filtered as irrelevant"
+                };
+            }
+
             // Score results against quality profile
             var scoredResults = await qualityProfileService.ScoreSearchResults(searchResults, audiobook.QualityProfile);