From cfb0b4c6caf04b9bc81e148e3c2eedfff43018c7 Mon Sep 17 00:00:00 2001
From: dny238 <rb7683@hotmail.com>
Date: Mon, 21 Sep 2026 15:34:51 -0600
Subject: [PATCH] Tolerate a differing leading article in book-boundary title
 matching
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Rebased onto canary 1.3.4 (the previous head was based on 1.3.2, before #717
rewrote the scanner, so CI failed testing the merge into current canary).

A folder whose title drops or adds a leading article ("The"/"A"/"An") — e.g.
"Language of Emotions" for "The Language of Emotions", or "The Myth of Normal"
for "Myth of Normal" — now matches the expected title. This stays full-title
equality modulo the article: it never widens into substring or author matching,
so the same-author / different-book boundary guards remain intact (covered by a
test that two "The …" siblings under one author are not cross-linked).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 .../Scanning/ScanFileDiscovery.Metadata.cs    | 30 ++++++++++
 .../Scanning/ScanFileDiscoveryTests.cs        | 55 +++++++++++++++++++
 2 files changed, 85 insertions(+)

diff --git a/listenarr.infrastructure/Library/Scanning/ScanFileDiscovery.Metadata.cs b/listenarr.infrastructure/Library/Scanning/ScanFileDiscovery.Metadata.cs
index 39d70adfa..d1380504a 100644
--- a/listenarr.infrastructure/Library/Scanning/ScanFileDiscovery.Metadata.cs
+++ b/listenarr.infrastructure/Library/Scanning/ScanFileDiscovery.Metadata.cs
@@ -145,6 +145,21 @@ private static bool SegmentMatchesExpectedTitle(
             return true;
         }
 
+        // Tolerate a differing leading article ("The"/"A"/"An") on either side, so a
+        // folder named "Language of Emotions" still matches the expected title
+        // "The Language of Emotions" (and vice versa). This stays a full-title equality
+        // modulo the article -- it never widens into substring or author matching, so
+        // the same-author / different-book boundary guards remain intact.
+        var articleFreeSegment = StripLeadingArticle(normalizedSegment);
+        if (titleTokens.Any(token =>
+                string.Equals(
+                    StripLeadingArticle(token),
+                    articleFreeSegment,
+                    StringComparison.Ordinal)))
+        {
+            return true;
+        }
+
         var components = segment
             .Split(
                 [" - ", " – ", " — "],
@@ -167,6 +182,21 @@ private static bool SegmentMatchesExpectedTitle(
         return false;
     }
 
+    private static readonly string[] LeadingArticlePrefixes = ["the ", "a ", "an "];
+
+    private static string StripLeadingArticle(string normalizedToken)
+    {
+        foreach (var prefix in LeadingArticlePrefixes)
+        {
+            if (normalizedToken.StartsWith(prefix, StringComparison.Ordinal))
+            {
+                return normalizedToken[prefix.Length..];
+            }
+        }
+
+        return normalizedToken;
+    }
+
     private static string? TryFindIdentifierBoundary(
         string candidate,
         string canonicalRoot,
diff --git a/tests/Features/Infrastructure/Library/Scanning/ScanFileDiscoveryTests.cs b/tests/Features/Infrastructure/Library/Scanning/ScanFileDiscoveryTests.cs
index 83b43ae27..313d94d24 100644
--- a/tests/Features/Infrastructure/Library/Scanning/ScanFileDiscoveryTests.cs
+++ b/tests/Features/Infrastructure/Library/Scanning/ScanFileDiscoveryTests.cs
@@ -314,6 +314,61 @@ public void Discover_LinkedDirectoryInsideIdentifierBoundary_IsNotTraversed()
             && issue.Path == link);
     }
 
+    [Fact]
+    public void FindMatchingAudioFiles_FolderDropsLeadingThe_StillMatches()
+    {
+        var requested = CreateAudioFile(
+            "Karla McLaren",
+            "Language of Emotions",
+            "Language of Emotions.m4b");
+        var audiobook = new AudiobookBuilder()
+            .WithTitle("The Language of Emotions")
+            .WithAuthor("Karla McLaren")
+            .Build();
+
+        var result = Discover(audiobook);
+
+        var found = Assert.Single(result);
+        Assert.Equal(requested, found);
+    }
+
+    [Fact]
+    public void FindMatchingAudioFiles_FolderAddsLeadingArticle_StillMatches()
+    {
+        var requested = CreateAudioFile(
+            "Gabor Mate",
+            "The Myth of Normal",
+            "The Myth of Normal.m4b");
+        var audiobook = new AudiobookBuilder()
+            .WithTitle("Myth of Normal")
+            .WithAuthor("Gabor Mate")
+            .Build();
+
+        var result = Discover(audiobook);
+
+        var found = Assert.Single(result);
+        Assert.Equal(requested, found);
+    }
+
+    [Fact]
+    public void FindMatchingAudioFiles_ArticleToleranceDoesNotCrossLinkSiblingBooks()
+    {
+        // Same author, two books that both start with "The". Article-insensitivity
+        // must still compare the full remaining title, so only the requested book
+        // is attributed -- it must not collapse "The Reckoning" onto "The Awakening".
+        var requested = CreateAudioFile("Shared Author", "The Reckoning", "The Reckoning.m4b");
+        _ = CreateAudioFile("Shared Author", "The Awakening", "The Awakening.m4b");
+        var audiobook = new AudiobookBuilder()
+            .WithTitle("The Reckoning")
+            .WithAuthor("Shared Author")
+            .Build();
+
+        var result = Discover(audiobook);
+
+        var found = Assert.Single(result);
+        Assert.Equal(requested, found);
+    }
+
     private List<string> Discover(Audiobook audiobook) =>
         DiscoverResult(audiobook).AttributedFiles.ToList();