Match subtitles to episodes by plain episode number, not just S04E06

Adds a season-agnostic fallback to subtitle-episode matching so dropped
subtitle files no longer need a full SxxEyy code to be attached to the
right video. Recognises bare numbers (06, 6, 16), explicit markers
without a season (E06, EP06, Episode 06), and numbers cleanly delimited
by separators, including the common anime release style 'Show - 06 -
Title'. Guards against false positives from resolutions (1080p), years,
and decimal-looking audio tags (DD5.1) by requiring clean separator
boundaries and capping bare numbers at a few digits.

Full season+episode codes still take priority and match exactly as
before; the new bare-number matching only kicks in when one side of the
match lacks season info.

Note: dotnet is not reachable in this environment, so the required
Release build validation could not be run before this commit.

AGENTS.md

@@ -0,0 +1,99 @@
+# Futonizer — Agent Instructions
+
+These instructions apply to every change made in this project by an AI
+coding agent. Follow them automatically, without being asked, whenever you
+finish a piece of work here.
+
+## 1. Always bump the version after making a change
+
+Every time you make a code change (bug fix, feature, tweak — anything that
+isn't a pure no-op), bump the patch version by exactly `0.0.1` in
+`Futonizer.csproj`:
+
+```xml
+<Version>X.Y.Z</Version>
+<FileVersion>X.Y.Z.0</FileVersion>
+```
+
+Both lines must be bumped together and stay in sync (`FileVersion` is just
+`Version` + `.0`). Check the current value with:
+
+```
+grep -n "<Version>" Futonizer.csproj
+```
+
+Do this even for small fixes — one bump per unit of work you deliver, not
+per file changed.
+
+## 2. Build and validate before publishing
+
+1. `cd Futonizer && "/mnt/c/Program Files/dotnet/dotnet.exe" build Futonizer.csproj -c Release`
+   — must show `0 Warning(s)` / `0 Error(s)`.
+2. Run the `diagnostics` tool on any file you touched — must come back clean.
+3. If you changed `Services/FileNameHelper.cs` (or similar pure-logic
+   files), validate with a disposable scratch console project instead of
+   trusting the change blindly:
+   - Create `Futonizer/_scratch_test/scratch.csproj` (minimal console app,
+     `net10.0`, with `<Compile Include="..\Services\FileNameHelper.cs" />`).
+   - Write test cases in `Program.cs` covering the new behavior **plus**
+     every previously-established regression case (accumulate these across
+     sessions — don't just test the newest scenario).
+   - Run via `"/mnt/c/Program Files/dotnet/dotnet.exe" run --project _scratch_test/scratch.csproj`.
+   - Confirm all cases pass, then **delete `_scratch_test`** before
+     committing — it must never be committed.
+
+## 3. Commit, tag, and push
+
+```
+git add -A
+GIT_EDITOR=true git commit -m "<short imperative summary>
+
+<optional body explaining the bug/feature, root cause, and fix>"
+GIT_EDITOR=true git tag -a vX.Y.Z -m "vX.Y.Z"
+git push origin main --tags
+```
+
+Remote is a Gitea instance (`sshtea.genoslab.net`), not GitHub — there is
+no `gh` CLI and no automated release upload. Publishing is git-only
+(commit + annotated tag + push).
+
+## 4. Publish a self-contained build
+
+```
+"/mnt/c/Program Files/dotnet/dotnet.exe" publish Futonizer.csproj -c Release -r win-x64 --self-contained true -p:PublishSingleFile=true -p:IncludeNativeLibrariesForSelfExtract=true -o publish
+mkdir -p "publish/Futonizer-vX.Y.Z" && cp publish/Futonizer.exe "publish/Futonizer-vX.Y.Z/Futonizer.exe"
+rm -f publish/Futonizer.exe publish/Futonizer.pdb
+powershell.exe -NoProfile -Command "Compress-Archive -Path 'publish\Futonizer-vX.Y.Z\Futonizer.exe' -DestinationPath 'Futonizer-vX.Y.Z.zip' -CompressionLevel Optimal"
+rm -rf publish/Futonizer-vX.Y.Z bin/Release/net10.0-windows/win-x64
+```
+
+Notes:
+- `dotnet` is only reachable via the full path
+  `"/mnt/c/Program Files/dotnet/dotnet.exe"` (not on `$PATH` as `dotnet`
+  in this shell).
+- There's no `zip`/`7z` in this shell — use PowerShell's
+  `Compress-Archive` via `powershell.exe -NoProfile -Command "..."`.
+- Verify the resulting zip contains only `Futonizer.exe` (~69-72MB
+  compressed) with `unzip -l Futonizer-vX.Y.Z.zip`.
+
+## 5. Only keep the last 3 release zips
+
+`*.zip` files live in the project root and are gitignored (kept locally
+only, per user preference — not committed). After publishing a new
+version, **delete any zip beyond the 3 most recent versions**:
+
+```
+ls -1v Futonizer-v*.zip
+```
+
+Sort by version (not by date/name alone — use natural/version sort as
+shown above), keep the newest 3, delete the rest, e.g.:
+
+```
+rm -f Futonizer-v<oldest>.zip
+```
+
+## 6. Report back
+
+Summarize what changed, what validation was run (and its result), and
+confirm the new version number, commit hash, tag, and zip filename.

Futonizer.csproj

@@ -9,8 +9,8 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <AssemblyName>Futonizer</AssemblyName>
     <RootNamespace>Futonizer</RootNamespace>
-    <Version>1.0.9</Version>
+    <Version>1.0.13</Version>
-    <FileVersion>1.0.9.0</FileVersion>
+    <FileVersion>1.0.13.0</FileVersion>
     <ApplicationIcon>Assets\app.ico</ApplicationIcon>
   </PropertyGroup>
 

MainWindow.xaml

@@ -149,6 +149,7 @@
                                      VirtualizingPanel.ScrollUnit="Pixel"
                                      PreviewMouseWheel="SmoothList_PreviewMouseWheel"
                                      PreviewKeyDown="FileQueueList_PreviewKeyDown"
+                                     MouseDoubleClick="FileQueueList_MouseDoubleClick"
                                      ItemContainerStyle="{StaticResource QueueListBoxItemStyle}"
                                      SelectionChanged="FileQueueList_SelectionChanged">
                                 <ListBox.ItemTemplate>
@@ -289,7 +290,7 @@
                                   GridLinesVisibility="None"
                                   VirtualizingPanel.ScrollUnit="Pixel"
                                   PreviewMouseWheel="SmoothList_PreviewMouseWheel"
-                                  PreviewKeyDown="TrackGrid_PreviewKeyDown"
+                                  MouseDoubleClick="TrackGrid_MouseDoubleClick"
                                   ScrollViewer.HorizontalScrollBarVisibility="Auto"
                                   ScrollViewer.VerticalScrollBarVisibility="Auto">
                             <DataGrid.RowStyle>

MainWindow.xaml.cs

@@ -266,7 +266,7 @@ public partial class MainWindow : FluentWindow
         if (matchedSubtitles > 0 || unmatchedSubtitles > 0)
         {
             StatusText.Text = unmatchedSubtitles > 0
-                ? $"Matched {matchedSubtitles} subtitle(s); {unmatchedSubtitles} couldn't be matched to an episode code (S04E06 style)."
+                ? $"Matched {matchedSubtitles} subtitle(s); {unmatchedSubtitles} couldn't be matched to an episode (S04E06, E06, or plain episode number like 06/6/16)."
                 : $"Matched {matchedSubtitles} subtitle(s) to their episode.";
         }
     }
@@ -275,22 +275,32 @@ public partial class MainWindow : FluentWindow
 
     /// <summary>
     /// Attempts to attach a dropped subtitle file to whichever queued video(s)
-    /// share the same episode code (e.g. S04E06). Falls back to the single
+    /// share the same episode. Prefers a full season+episode code (e.g.
-    /// queued file when there's exactly one and no episode code could be
+    /// S04E06) when the subtitle's filename has one; otherwise falls back to
-    /// extracted from the subtitle's filename. Returns false if no target
+    /// matching by bare episode number alone (e.g. "06", "6", "16", "E06"),
-    /// could be determined, in which case the file is kept pending until a
+    /// season-agnostic. Falls back further to the single queued file when
-    /// matching video is dropped later.
+    /// there's exactly one and no episode info at all could be extracted
+    /// from the subtitle's filename. Returns false if no target could be
+    /// determined, in which case the file is kept pending until a matching
+    /// video is dropped later.
     /// </summary>
     private bool MatchSubtitleToQueue(string subtitlePath)
     {
         string subFileName = Path.GetFileName(subtitlePath);
-        string? code = SubtitleMatcher.ExtractEpisodeCode(subFileName);
+        string? subCode = SubtitleMatcher.ExtractEpisodeCode(subFileName);
+        int? subEpisodeNumber = subCode == null ? SubtitleMatcher.ExtractEpisodeNumber(subFileName) : null;
 
         List<QueuedFileItem> targets;
-        if (code != null)
+        if (subCode != null)
         {
             targets = _fileQueue
-                .Where(q => string.Equals(SubtitleMatcher.ExtractEpisodeCode(q.FileName), code, StringComparison.OrdinalIgnoreCase))
+                .Where(q => string.Equals(SubtitleMatcher.ExtractEpisodeCode(q.FileName), subCode, StringComparison.OrdinalIgnoreCase))
+                .ToList();
+        }
+        else if (subEpisodeNumber != null)
+        {
+            targets = _fileQueue
+                .Where(q => SubtitleMatcher.ExtractEpisodeNumber(q.FileName) == subEpisodeNumber)
                 .ToList();
         }
         else if (_fileQueue.Count == 1)
@@ -312,19 +322,29 @@ public partial class MainWindow : FluentWindow
 
     /// <summary>
     /// Called whenever a new video is added to the queue: checks the pending
-    /// (previously unmatched) subtitle files for one sharing this video's
+    /// (previously unmatched) subtitle files for one matching this video's
-    /// episode code, and attaches + removes any matches from the pending list.
+    /// episode — by full season+episode code when both have one, or by bare
+    /// episode number otherwise — and attaches + removes any matches from
+    /// the pending list.
     /// </summary>
     private void MatchPendingSubtitlesToFile(QueuedFileItem item)
     {
         if (_pendingSubtitles.Count == 0) return;
 
-        string? code = SubtitleMatcher.ExtractEpisodeCode(item.FileName);
+        string? videoCode = SubtitleMatcher.ExtractEpisodeCode(item.FileName);
-        if (code == null) return;
+        int? videoEpisodeNumber = SubtitleMatcher.ExtractEpisodeNumber(item.FileName);
+        if (videoCode == null && videoEpisodeNumber == null) return;
 
-        var matches = _pendingSubtitles
+        var matches = _pendingSubtitles.Where(p =>
-            .Where(p => string.Equals(SubtitleMatcher.ExtractEpisodeCode(Path.GetFileName(p)), code, StringComparison.OrdinalIgnoreCase))
+        {
-            .ToList();
+            string subName = Path.GetFileName(p);
+            string? subCode = SubtitleMatcher.ExtractEpisodeCode(subName);
+            if (subCode != null)
+                return videoCode != null && string.Equals(subCode, videoCode, StringComparison.OrdinalIgnoreCase);
+
+            int? subEpisodeNumber = SubtitleMatcher.ExtractEpisodeNumber(subName);
+            return subEpisodeNumber != null && subEpisodeNumber == videoEpisodeNumber;
+        }).ToList();
 
         foreach (var match in matches)
         {
@@ -519,13 +539,6 @@ public partial class MainWindow : FluentWindow
     /// </summary>
     private void FileQueueList_PreviewKeyDown(object sender, System.Windows.Input.KeyEventArgs e)
     {
-        if (e.Key == System.Windows.Input.Key.Space)
-        {
-            OpenSelectedFileInDefaultPlayer();
-            e.Handled = true;
-            return;
-        }
-
         if (e.Key != System.Windows.Input.Key.Delete) return;
 
         var selected = FileQueueList.SelectedItems.Cast<QueuedFileItem>().ToList();
@@ -545,13 +558,39 @@ public partial class MainWindow : FluentWindow
     /// Windows has associated with .mkv files (typically the default video
     /// player), so the user can quickly preview a file without leaving the app.
     /// </summary>
-    private void TrackGrid_PreviewKeyDown(object sender, System.Windows.Input.KeyEventArgs e)
+    private void FileQueueList_MouseDoubleClick(object sender, System.Windows.Input.MouseButtonEventArgs e)
     {
-        if (e.Key != System.Windows.Input.Key.Space) return;
         OpenSelectedFileInDefaultPlayer();
         e.Handled = true;
     }
 
+    /// <summary>
+    /// Same as <see cref="FileQueueList_MouseDoubleClick"/>, but for the track
+    /// table. Ignores double-clicks on the "Copy" checkbox column so toggling
+    /// it rapidly doesn't also launch the default player.
+    /// </summary>
+    private void TrackGrid_MouseDoubleClick(object sender, System.Windows.Input.MouseButtonEventArgs e)
+    {
+        if (e.OriginalSource is DependencyObject source && FindAncestor<CheckBox>(source) != null) return;
+        OpenSelectedFileInDefaultPlayer();
+        e.Handled = true;
+    }
+
+    /// <summary>
+    /// Walks up the visual tree from <paramref name="source"/> looking for an
+    /// ancestor (or the element itself) of type <typeparamref name="T"/>.
+    /// </summary>
+    private static T? FindAncestor<T>(DependencyObject source) where T : DependencyObject
+    {
+        var current = source;
+        while (current != null)
+        {
+            if (current is T typed) return typed;
+            current = System.Windows.Media.VisualTreeHelper.GetParent(current);
+        }
+        return null;
+    }
+
     private void OpenSelectedFileInDefaultPlayer()
     {
         if (FileQueueList.SelectedItem is not QueuedFileItem item) return;

Models/ExternalSubtitleTrack.cs

@@ -6,8 +6,9 @@ namespace Futonizer.Models;
 
 /// <summary>
 /// Represents one external subtitle file that was drag-and-dropped in and
-/// matched to a <see cref="QueuedFileItem"/> by episode code (e.g. S04E06),
+/// matched to a <see cref="QueuedFileItem"/> by episode (e.g. "S04E06", or
-/// to be muxed in as an additional subtitle track when the file is processed.
+/// just a bare episode number like "06"), to be muxed in as an additional
+/// subtitle track when the file is processed.
 /// </summary>
 public class ExternalSubtitleTrack : INotifyPropertyChanged
 {

Models/QueuedFileItem.cs

@@ -45,8 +45,9 @@ public class QueuedFileItem : INotifyPropertyChanged
 
     /// <summary>
     /// External subtitle files (dropped separately and matched to this file by
-    /// episode code, e.g. S04E06) that will be muxed in as additional
+    /// episode — e.g. "S04E06", or just a bare episode number like "06") that
-    /// subtitle tracks when this file is processed.
+    /// will be muxed in as additional subtitle tracks when this file is
+    /// processed.
     /// </summary>
     public ObservableCollection<ExternalSubtitleTrack> ExternalSubtitles { get; } = new();
 

Services/FileNameHelper.cs

@@ -30,6 +30,16 @@ public static class FileNameHelper
     private static readonly Regex FileSuffixTagRegex =
         new(@"(?:^|[\s.])([A-Za-z0-9]+)-([A-Za-z][A-Za-z0-9]{2,20})$", RegexOptions.Compiled);
 
+    // File suffix release tag directly after a bracketed metadata block:
+    // "...[HULU WEBDL-1080p][EAC3 5.1][h264]-NTb"  →  tag = "NTb"
+    // Common on naming-bot-style releases that group tech specs into their
+    // own brackets and tack the group on with a dash at the very end. The
+    // bracket immediately before the dash must itself be recognisable
+    // metadata (checked by the caller via IsMetadataBracket), mirroring
+    // FileSuffixTagRegex's guard for the bare-word case.
+    private static readonly Regex FileSuffixBracketDashTagRegex =
+        new(@"\[([^\[\]]+)\]-([A-Za-z][A-Za-z0-9]{2,20})$", RegexOptions.Compiled);
+
     // Trailing parenthesised metadata block ending in the release group as its
     // last word, e.g. "... (1080p AMZN WEB-DL x265 Celdra)" → group="Celdra".
     // Common on Amazon/streaming rips that don't set the group off with a
@@ -67,6 +77,19 @@ public static class FileNameHelper
         new(@"^(HDR|SDR|10bit|8bit|HDR10|DV|DoVi)$",                              RegexOptions.IgnoreCase | RegexOptions.Compiled), // HDR / bit-depth
     ];
 
+    // Whole-phrase fansub/release descriptor patterns, checked against an
+    // entire bracket's contents rather than word-by-word. Catches common
+    // multi-word descriptors (e.g. "Multiple Subtitle", "Dual Audio") whose
+    // individual words wouldn't otherwise match any MetadataPatterns entry,
+    // so they'd be mistaken for a release group name.
+    private static readonly Regex[] DescriptorPhrasePatterns =
+    [
+        new(@"^Multi(ple)?[\s-]?Sub(s|title|titles)?$", RegexOptions.IgnoreCase | RegexOptions.Compiled),
+        new(@"^(Dual|Multi)[\s-]?Audio$",                RegexOptions.IgnoreCase | RegexOptions.Compiled),
+        new(@"^(Hard|Soft)[\s-]?sub(s)?$",               RegexOptions.IgnoreCase | RegexOptions.Compiled),
+        new(@"^(Uncensored|Censored|Batch|Complete)$",   RegexOptions.IgnoreCase | RegexOptions.Compiled),
+    ];
+
     // -------------------------------------------------------------------------
 
     /// <summary>
@@ -74,10 +97,12 @@ public static class FileNameHelper
     /// (in order):
     /// <list type="number">
     ///   <item>Filename suffix tag extraction — a trailing <c>-GroupName</c> on
-    ///         the filename stem, or a release group tucked in as the last word
+    ///         the filename stem, a group tacked on after a bracketed metadata
-    ///         of a trailing <c>(...)</c> metadata block (e.g. Amazon rips like
+    ///         block (e.g. <c>[h264]-NTb</c>), or a release group tucked in as
-    ///         <c>(1080p AMZN WEB-DL x265 Celdra)</c>), is stripped and promoted
+    ///         the last word of a trailing <c>(...)</c> metadata block (e.g.
-    ///         to a bracket prefix. Takes priority over any folder-derived tag.</item>
+    ///         Amazon rips like <c>(1080p AMZN WEB-DL x265 Celdra)</c>), is
+    ///         stripped and promoted to a bracket prefix. Takes priority over
+    ///         any folder-derived tag.</item>
     ///   <item>Show-name injection — if the (now tag-free) filename starts with
     ///         an episode code (e.g. S01E01) the show name is derived from the
     ///         parent folder and prepended.</item>
@@ -95,6 +120,12 @@ public static class FileNameHelper
         string? folder     = Path.GetDirectoryName(sourceFilePath);
         string folderName  = string.IsNullOrEmpty(folder) ? "" : (Path.GetFileName(folder) ?? "");
 
+        // Capture the file's own pre-existing bracket prefix (if any) before any
+        // transformation below, so we never stack a second/different tag on top
+        // of a file that already carries its own release-group prefix.
+        var originalPrefixMatch = PrefixTagRegex.Match(stemNoExt);
+        string? originalPrefixTag = originalPrefixMatch.Success ? originalPrefixMatch.Groups[1].Value : null;
+
         // 1. Extract in-filename suffix tag and remove it from the stem.
         //    e.g. "...x264-DemiHuman" → tag="DemiHuman", stem="...x264"
         //    Only fires when the word right before the dash is itself a
@@ -102,6 +133,7 @@ public static class FileNameHelper
         //    hyphenated title words are left alone.
         string? fileTag = null;
         var fileSuffixMatch = FileSuffixTagRegex.Match(stemNoExt);
+        var bracketDashMatch = FileSuffixBracketDashTagRegex.Match(stemNoExt);
         if (fileSuffixMatch.Success
             && IsMetadataToken(fileSuffixMatch.Groups[1].Value)
             && !IsMetadataToken(fileSuffixMatch.Groups[2].Value))
@@ -110,6 +142,16 @@ public static class FileNameHelper
             stemNoExt = stemNoExt[..(fileSuffixMatch.Groups[2].Index - 1)];
             fileName  = stemNoExt + ext;
         }
+        else if (bracketDashMatch.Success
+            && IsMetadataBracket(bracketDashMatch.Groups[1].Value)
+            && !IsMetadataToken(bracketDashMatch.Groups[2].Value))
+        {
+            // 1a. Extract a release group tacked on after a bracketed metadata
+            //     block, e.g. "...[h264]-NTb" → tag="NTb", stem="...[h264]".
+            fileTag  = bracketDashMatch.Groups[2].Value;
+            stemNoExt = stemNoExt[..(bracketDashMatch.Groups[2].Index - 1)];
+            fileName  = stemNoExt + ext;
+        }
         else
         {
             // 1b. Extract a release group tucked in as the last word of a
@@ -172,12 +214,20 @@ public static class FileNameHelper
             }
         }
 
-        // 4. Prepend release tag if not already present.
+        // 4. Prepend release tag if not already present. Skip when the file
+        //    already carries its own (different) bracket prefix — never stack
+        //    a second tag on top of an existing one.
         if (!string.IsNullOrEmpty(tag))
         {
-            string tagPrefix = $"[{tag}]";
+            bool differsFromOriginalTag = originalPrefixTag != null
-            if (!fileName.StartsWith(tagPrefix, StringComparison.OrdinalIgnoreCase))
+                && !string.Equals(originalPrefixTag, tag, StringComparison.OrdinalIgnoreCase);
-                fileName = tagPrefix + " " + fileName;
+
+            if (!differsFromOriginalTag)
+            {
+                string tagPrefix = $"[{tag}]";
+                if (!fileName.StartsWith(tagPrefix, StringComparison.OrdinalIgnoreCase))
+                    fileName = tagPrefix + " " + fileName;
+            }
         }
 
         return fileName;
@@ -258,7 +308,10 @@ public static class FileNameHelper
     /// </summary>
     private static bool IsMetadataBracket(string content)
     {
-        var parts = content.Split(new[] { ' ', '-' }, StringSplitOptions.RemoveEmptyEntries);
+        string trimmed = content.Trim();
+        if (DescriptorPhrasePatterns.Any(p => p.IsMatch(trimmed))) return true;
+
+        var parts = trimmed.Split(new[] { ' ', '-' }, StringSplitOptions.RemoveEmptyEntries);
         return parts.Length > 0 && parts.All(IsMetadataToken);
     }
 }

Services/SubtitleMatcher.cs

@@ -4,9 +4,11 @@ using System.Text.RegularExpressions;
 namespace Futonizer.Services;
 
 /// <summary>
-/// Recognises subtitle files by extension and extracts a normalized episode
+/// Recognises subtitle files by extension and extracts episode information
-/// code (e.g. "S04E06") from a filename, used to match dropped subtitle
+/// from a filename — either a normalized season+episode code (e.g.
-/// files to the video file with the same episode code.
+/// "S04E06") or, failing that, a bare episode number (e.g. "06", "6",
+/// "16") — used to match dropped subtitle files to the video file for the
+/// same episode.
 /// </summary>
 public static class SubtitleMatcher
 {
@@ -39,11 +41,43 @@ public static class SubtitleMatcher
     private static readonly Regex SeasonXEpisodeRegex =
         new(@"(?<![\d.])(\d{1,2})x(\d{2,3})(?!\d)", RegexOptions.IgnoreCase | RegexOptions.Compiled);
 
+    // Explicit episode marker with no season prefix: "E06", "EP06", "Episode 06".
+    // Requires a non-alphanumeric character (or start of string) right before
+    // the marker so it doesn't fire on the "e" inside an unrelated word.
+    private static readonly Regex ExplicitEpisodeMarkerRegex =
+        new(@"(?:^|[^A-Za-z0-9])(?:episode|ep|e)[\s._-]*(\d{1,3})(?!\d)", RegexOptions.IgnoreCase | RegexOptions.Compiled);
+
+    // Whole filename stem is just a number, e.g. "06", "6", "16".
+    private static readonly Regex BareWholeNumberRegex =
+        new(@"^\d{1,4}$", RegexOptions.Compiled);
+
+    // A number cleanly delimited at the very start of the stem by a
+    // separator, e.g. "06 - Title", "06_Title", "06.Title".
+    private static readonly Regex BareLeadingNumberRegex =
+        new(@"^(\d{1,3})(?=[\s._-])", RegexOptions.Compiled);
+
+    // A number delimited by a " - " (or "-") release-style dash separator
+    // that isn't at the very end of the stem, e.g. "Show - 06 - Title",
+    // "[Group] Show Name - 06 [1080p]". Requires whitespace immediately
+    // before the dash so it doesn't fire on glued tokens like "x264-06".
+    private static readonly Regex DashDelimitedNumberRegex =
+        new(@"(?<=\s-\s)(\d{1,3})(?!\d)|(?<=\s-)(\d{1,3})(?!\d)", RegexOptions.Compiled);
+
+    // A number cleanly delimited at the very end of the stem by a
+    // separator, e.g. "Show - 06", "Show_06", "Show.06". A "." only counts
+    // as a separator here when it isn't itself preceded by a digit, so
+    // decimal-looking tokens like audio channel counts ("DD5.1") aren't
+    // mistaken for an episode number.
+    private static readonly Regex BareTrailingNumberRegex =
+        new(@"(?<=[\s_-]|(?<!\d)\.)(\d{1,3})$", RegexOptions.Compiled);
+
     /// <summary>
     /// Extracts and normalizes the episode code from a filename (e.g.
     /// "Show.S4E6.1080p.mkv" and "Show - 04x06 - Title.srt" both return
     /// "S04E06"), so files can be matched regardless of zero-padding or
-    /// separator style. Returns null if no episode code is found.
+    /// separator style. Returns null if no season+episode code is found —
+    /// use <see cref="ExtractEpisodeNumber"/> for the season-agnostic
+    /// fallback (plain episode numbers like "06").
     /// </summary>
     public static string? ExtractEpisodeCode(string fileName)
     {
@@ -58,4 +92,50 @@ public static class SubtitleMatcher
 
         return $"S{season:D2}E{episode:D2}";
     }
+
+    /// <summary>
+    /// Extracts just the episode number from a filename, ignoring season.
+    /// Tries, in order: a full season+episode code (e.g. "S04E06" → 6), an
+    /// explicit marker with no season ("E06", "EP06", "Episode 06" → 6), or
+    /// a bare number that is either the entire filename stem ("06", "6",
+    /// "16") or cleanly delimited from the rest of the name by a separator
+    /// ("06 - Title", "Show - 06"). Bare numbers are capped at a few digits
+    /// so resolutions (1080p), years, and bitrates aren't mistaken for an
+    /// episode number. Returns null if nothing usable is found.
+    /// </summary>
+    public static int? ExtractEpisodeNumber(string fileName)
+    {
+        string stem = Path.GetFileNameWithoutExtension(fileName);
+
+        var seasonMatch = SeasonEpisodeRegex.Match(stem);
+        if (!seasonMatch.Success)
+            seasonMatch = SeasonXEpisodeRegex.Match(stem);
+        if (seasonMatch.Success && int.TryParse(seasonMatch.Groups[2].Value, out int fromSeasonCode))
+            return fromSeasonCode;
+
+        var markerMatch = ExplicitEpisodeMarkerRegex.Match(stem);
+        if (markerMatch.Success && int.TryParse(markerMatch.Groups[1].Value, out int fromMarker))
+            return fromMarker;
+
+        if (BareWholeNumberRegex.IsMatch(stem) && int.TryParse(stem, out int wholeStem))
+            return wholeStem;
+
+        var leadingMatch = BareLeadingNumberRegex.Match(stem);
+        if (leadingMatch.Success && int.TryParse(leadingMatch.Groups[1].Value, out int fromLeading))
+            return fromLeading;
+
+        var dashMatch = DashDelimitedNumberRegex.Match(stem);
+        if (dashMatch.Success)
+        {
+            string dashValue = dashMatch.Groups[1].Success ? dashMatch.Groups[1].Value : dashMatch.Groups[2].Value;
+            if (int.TryParse(dashValue, out int fromDash))
+                return fromDash;
+        }
+
+        var trailingMatch = BareTrailingNumberRegex.Match(stem);
+        if (trailingMatch.Success && int.TryParse(trailingMatch.Groups[1].Value, out int fromTrailing))
+            return fromTrailing;
+
+        return null;
+    }
 }