Preserve numeric title token order during matching

src/Chaptarr.Core.Test/MediaFiles/BookImport/LogicalWorkGroupingFixture.cs

@@ -200,6 +200,72 @@ private static FileMatchingService CreateSut(
                 logger: logger);
         }
 
+        [TestCase("The Primal Hunter 6", 6598)]
+        [TestCase("The Primal Hunter 6: A LitRPG Adventure", 6598)]
+        [TestCase("The Primal Hunter", 6589)]
+        public void should_keep_numbered_book_identity_when_file_title_has_a_subtitle(string fileTitle, int expectedBookId)
+        {
+            var books = new List<Book>
+            {
+                new Book
+                {
+                    Id = 6598,
+                    Title = "The Primal Hunter 6",
+                    BaseBookId = "hc:1093426",
+                    AuthorId = 25,
+                    MediaType = BookMediaType.Ebook
+                },
+                new Book
+                {
+                    Id = 6589,
+                    Title = "The Primal Hunter, Vol. 1",
+                    BaseBookId = "primal-hunter-1",
+                    AuthorId = 25,
+                    MediaType = BookMediaType.Ebook
+                }
+            };
+            var candidates = new List<EditionFtsMatch>
+            {
+                new EditionFtsMatch
+                {
+                    EditionId = 16318,
+                    BookId = 6598,
+                    EditionTitle = "The Primal Hunter 6",
+                    BookTitle = "The Primal Hunter 6",
+                    AuthorId = 25,
+                    AuthorName = "J.K. Rowling",
+                    ReadingFormatId = 3,
+                    MatchScore = 10.0
+                },
+                new EditionFtsMatch
+                {
+                    EditionId = 16309,
+                    BookId = 6589,
+                    EditionTitle = "The Primal Hunter",
+                    BookTitle = "The Primal Hunter, Vol. 1",
+                    AuthorId = 25,
+                    AuthorName = "J.K. Rowling",
+                    ReadingFormatId = 3,
+                    MatchScore = 9.0
+                }
+            };
+            var file = new DiscoveredFileWithMetadata
+            {
+                Path = "/ebooks/The Primal Hunter/book.epub",
+                AllTags = new Dictionary<string, List<string>>(StringComparer.OrdinalIgnoreCase)
+                {
+                    { "TITLE", new List<string> { fileTitle } },
+                    { "AUTHOR", new List<string> { "J.K. Rowling" } }
+                }
+            };
+
+            var match = CreateSut(candidates, books).HolyGrailMatchFile(file, BookMediaType.Ebook, restrictToAuthorId: 25);
+
+            Assert.That(match, Is.Not.Null);
+            Assert.That(match.BookId, Is.EqualTo(expectedBookId));
+            Assert.That(match.EditionId, Is.EqualTo(expectedBookId == 6598 ? 16318 : 16309));
+        }
+
         [Test]
         public void should_treat_same_provider_work_clones_as_one_title_candidate()
         {

src/Chaptarr.Core.Test/MediaFiles/BookImport/NearExactTitleEvidenceFixture.cs

@@ -195,6 +195,14 @@ public void should_accept_compact_and_split_litrpg_title_tokens(string editionTi
 
         private static IEnumerable<TestCaseData> TitleEvidenceRegressionCases()
         {
+            yield return new TestCaseData("numbered-title-with-subtitle", "The Primal Hunter 6", "The Primal Hunter 6: A LitRPG Adventure", false, true, false);
+            yield return new TestCaseData("numbered-title-without-subtitle", "The Primal Hunter 6", "The Primal Hunter 6", false, true, false);
+            yield return new TestCaseData("numbered-title-without-number", "The Primal Hunter 6", "The Primal Hunter", false, false, false);
+            yield return new TestCaseData("numbered-title-with-wrong-number", "The Primal Hunter 6", "The Primal Hunter 5: A LitRPG Adventure", false, false, false);
+            yield return new TestCaseData("number-after-subtitle", "The Primal Hunter 6", "The Primal Hunter: A LitRPG Adventure 6", false, false, false);
+            yield return new TestCaseData("number-before-title", "The Primal Hunter 6", "6 The Primal Hunter", false, false, false);
+            yield return new TestCaseData("conflicting-number-before-title-number", "The Primal Hunter 6", "The Primal Hunter 5 6", false, false, false);
+            yield return new TestCaseData("numeric-title-prefix", "1984 Volume 2", "1984 Volume 2: A Novel", false, true, false);
             yield return new TestCaseData("exact-title", "Fantastic Beasts and Where to Find Them", "Fantastic Beasts and Where to Find Them", false, true, false);
             yield return new TestCaseData("single-trailing-char", "Fantastic Beasts and Where to Find Them", "Fantastic Beast and Where to Find Them", false, true, false);
             yield return new TestCaseData("short-title-no-token-count-magic", "It Takes Two", "It Take Two", false, true, false);
@@ -231,5 +239,21 @@ public void should_preserve_title_evidence_regression_matrix(
                 Assert.That(evidence.Single().RequiresAudiobookDurationCorroboration, Is.EqualTo(shouldRequireDuration), name);
             }
         }
+
+        [TestCase("Harry Potter 5 - The Order of the Phoenix", false)]
+        [TestCase("Harry Potter 5 - The Order of the Phoeni", true)]
+        public void should_preserve_numeric_metadata_in_title_evidence(string tagTitle, bool isNearExact)
+        {
+            var evidence = CreateValidator().GetEditionTitleEvidence(
+                "Harry Potter and the Order of the Phoenix",
+                new Dictionary<string, List<string>>
+                {
+                    { "ALBUM", new List<string> { tagTitle } }
+                });
+
+            Assert.That(evidence, Has.Count.EqualTo(1));
+            Assert.That(evidence.Single().IsNearExact, Is.EqualTo(isNearExact));
+            Assert.That(evidence.Single().FieldValue, Is.EqualTo(tagTitle));
+        }
     }
 }

src/NzbDrone.Core/MediaFiles/BookImport/Services/ContainmentValidator.cs

@@ -70,8 +70,7 @@ public class ContainmentValidator : IContainmentValidator
 
 	        // Unicode-aware word boundary pattern
 	        private static readonly Regex WordPattern = new Regex(@"\p{L}+", RegexOptions.Compiled);
-        // Numeric tokens (e.g., 1984)
-        private static readonly Regex NumberPattern = new Regex(@"\b\d+\b", RegexOptions.Compiled);
+        private static readonly Regex TitleTokenPattern = new Regex(@"\p{L}+|\b\d+\b", RegexOptions.Compiled);
         // Roman numerals (conservative)
         private static readonly Regex RomanRegex = new Regex(@"^(M{0,4}(CM|CD|D?C{0,3})(XC|XL|L?X{0,3})(IX|IV|V?I{0,3}))$", RegexOptions.Compiled | RegexOptions.IgnoreCase);
 
@@ -487,7 +486,7 @@ private IReadOnlyList<EditionTitleEvidence> TryGetNearExactTitleEvidence(string
                         continue;
                     }
 
-                    if (TitleTokenAlignment.TryAlignStructural(editionTokens, fieldTokens, allowNearExact: true, allowTransposition: includeDurationGatedNearExact, out var alignment) &&
+                    if (TitleTokenAlignment.TryAlignStructural(editionTokens, GetFieldTokensForTitleAlignment(editionTokens, fieldTokens), allowNearExact: true, allowTransposition: includeDurationGatedNearExact, out var alignment) &&
                         alignment.UsedNearExact)
                     {
                         evidence.Add(new EditionTitleEvidence(
@@ -887,12 +886,7 @@ private static List<string> ExtractTokensAsList(string normalized)
             var list = new List<string>();
             if (string.IsNullOrWhiteSpace(normalized)) return list;
 
-            foreach (Match m in WordPattern.Matches(normalized))
-            {
-                var v = m.Value.ToLowerInvariant();
-                if (!string.IsNullOrEmpty(v)) list.Add(v);
-            }
-            foreach (Match m in NumberPattern.Matches(normalized))
+            foreach (Match m in TitleTokenPattern.Matches(normalized))
             {
                 var v = m.Value.ToLowerInvariant();
                 if (!string.IsNullOrEmpty(v)) list.Add(v);
@@ -908,12 +902,19 @@ private static bool CanConsumeAllTokens(List<string> editionTokens, List<string>
         {
             return TitleTokenAlignment.TryAlignStructural(
                 editionTokens,
-                fieldTokens,
+                GetFieldTokensForTitleAlignment(editionTokens, fieldTokens),
                 allowNearExact: false,
                 allowTransposition: false,
                 out _);
         }
 
+        private static List<string> GetFieldTokensForTitleAlignment(List<string> editionTokens, List<string> fieldTokens)
+        {
+            return editionTokens.Any(token => token.All(char.IsDigit))
+                ? fieldTokens
+                : fieldTokens.Where(token => !token.All(char.IsDigit)).ToList();
+        }
+
         private List<AuthorWord> ParseIntoWords(string authorName)
         {
             var normalized = NormalizeForWordExtraction(authorName);