fix: plex other video tags (#3015)

CHANGELOG.md

@@ -30,6 +30,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Fix `/api/sessions` response when channels use Next streaming engine
 - Save and restore sequential schedule mid-roll, post-roll, and graphics state between builds
 - Fix subtitle playback with Plex other video libraries
+- Fix Plex other video tag generation when Plex server and ETV server use different path separators (i.e. Windows and Linux)
 
 ## [26.9.0] - 2026-09-06
 ### Fixed

ErsatzTV.Infrastructure.MySql/Migrations/20260911153628_Reset_PlexOtherVideoFolderTags.cs

@@ -0,0 +1,24 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace ErsatzTV.Infrastructure.MySql.Migrations
+{
+    /// <inheritdoc />
+    public partial class Reset_PlexOtherVideoFolderTags : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.Sql("UPDATE PlexOtherVideo SET Etag = NULL;");
+            migrationBuilder.Sql(
+                @"UPDATE Library SET LastScan = '1970-01-01 00:00:00'
+                  WHERE MediaKind = 4 AND Id IN (SELECT Id FROM PlexLibrary);");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+        }
+    }
+}

ErsatzTV.Infrastructure.Sqlite/Migrations/20260911153541_Reset_PlexOtherVideoFolderTags.cs

@@ -0,0 +1,24 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace ErsatzTV.Infrastructure.Sqlite.Migrations
+{
+    /// <inheritdoc />
+    public partial class Reset_PlexOtherVideoFolderTags : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.Sql("UPDATE PlexOtherVideo SET Etag = NULL;");
+            migrationBuilder.Sql(
+                @"UPDATE Library SET LastScan = '1970-01-01 00:00:00'
+                  WHERE MediaKind = 4 AND Id IN (SELECT Id FROM PlexLibrary);");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+        }
+    }
+}

ErsatzTV.Infrastructure.Tests/Plex/PlexServerApiClientTests.cs

@@ -0,0 +1,49 @@
+using ErsatzTV.Infrastructure.Plex;
+using NUnit.Framework;
+using Shouldly;
+
+namespace ErsatzTV.Infrastructure.Tests.Plex;
+
+[TestFixture]
+public class PlexServerApiClientTests
+{
+    [TestCase(@"C:\media\other\Travel\Summer\clip.mkv", @"C:\media\other")]
+    [TestCase("/media/other/Travel/Summer/clip.mkv", "/media/other")]
+    [TestCase(@"\\server\media\other\Travel\Summer\clip.mkv", @"\\server\media\other")]
+    [TestCase(@"C:\media\other/Travel\Summer/clip.mkv", "C:/media/other/")]
+    [TestCase("/media/other/Travel/Summer/clip.mkv", "/media/other/")]
+    [TestCase(@"C:\media\other\Travel\Summer\clip.mkv", @"c:\MEDIA\OTHER\")]
+    public void FolderTags_Should_Include_Library_And_Each_Subfolder(string file, string libraryPath)
+    {
+        PlexServerApiClient.GetFolderTags(file, [libraryPath])
+            .ShouldBe(["other", "Travel", "Summer"]);
+    }
+
+    [TestCase("/media/other/clip.mkv", "/media/other", new[] { "other" })]
+    [TestCase(@"C:\media\other\clip.mkv", @"C:\media\other", new[] { "other" })]
+    [TestCase("/Travel/clip.mkv", "/", new[] { "Travel" })]
+    [TestCase(@"C:\Travel\clip.mkv", @"C:\", new[] { "Travel" })]
+    [TestCase("/clip.mkv", "/", new string[0])]
+    [TestCase(@"C:\clip.mkv", @"C:\", new string[0])]
+    [TestCase("/media/other-extra/clip.mkv", "/media/other", new string[0])]
+    [TestCase(@"C:\media\other-extra\clip.mkv", @"C:\media\other", new string[0])]
+    [TestCase("clip.mkv", "/media/other", new string[0])]
+    [TestCase("", "/media/other", new string[0])]
+    [TestCase(null, "/media/other", new string[0])]
+    public void FolderTags_Should_Handle_Roots_And_Require_Folder_Boundaries(
+        string? file,
+        string libraryPath,
+        string[] expected)
+    {
+        PlexServerApiClient.GetFolderTags(file!, [libraryPath]).ShouldBe(expected);
+    }
+
+    [Test]
+    public void FolderTags_Should_Use_First_Matching_Library_Path()
+    {
+        PlexServerApiClient.GetFolderTags(
+                "/media/other-extra/Travel/clip.mkv",
+                ["", "/media/other", "/media/other-extra", "/media/other-extra/Travel"])
+            .ShouldBe(["other-extra", "Travel"]);
+    }
+}

ErsatzTV.Infrastructure/Plex/PlexServerApiClient.cs

@@ -1311,40 +1311,14 @@ public class PlexServerApiClient(PlexEtag plexEtag, ILogger<PlexServerApiClient>
                 .MaxBy(media => media.Id);
 
             PlexXmlPartResponse part = media.Part.Head();
-            string folder = Path.GetDirectoryName(part.File);
+            IEnumerable<string> libraryPaths = library.Paths
+                .HeadOrNone()
+                .Map(p => p.Path)
+                .Map(JsonConvert.DeserializeObject<LibraryPaths>)
+                .Map(lp => lp.Paths)
+                .Flatten();
 
-            if (!string.IsNullOrWhiteSpace(folder))
-            {
-                IEnumerable<string> libraryPaths = library.Paths
-                    .HeadOrNone()
-                    .Map(p => p.Path)
-                    .Map(JsonConvert.DeserializeObject<LibraryPaths>)
-                    .Map(lp => lp.Paths)
-                    .Flatten();
-
-                // check each library path from plex
-                foreach (string libraryPath in libraryPaths)
-                {
-                    // if the media file belongs to this library path
-                    if (folder.StartsWith(libraryPath, StringComparison.OrdinalIgnoreCase))
-                    {
-                        // try to get a parent directory of the library path
-                        string parent = Optional(Directory.GetParent(libraryPath)).Match(
-                            di => di.FullName,
-                            () => libraryPath);
-
-                        // get all folders between parent and media file
-                        string diff = Path.GetRelativePath(parent, folder);
-
-                        // each folder becomes a tag
-                        IEnumerable<Tag> tags = diff.Split(Path.DirectorySeparatorChar)
-                            .Map(t => new Tag { Name = t });
-
-                        metadata.Tags.AddRange(tags);
-                        break;
-                    }
-                }
-            }
+            metadata.Tags.AddRange(GetFolderTags(part.File, libraryPaths).Map(t => new Tag { Name = t }));
         }
         else
         {
@@ -1405,6 +1379,44 @@ public class PlexServerApiClient(PlexEtag plexEtag, ILogger<PlexServerApiClient>
         return metadata;
     }
 
+    internal static IEnumerable<string> GetFolderTags(string file, IEnumerable<string> libraryPaths)
+    {
+        if (string.IsNullOrWhiteSpace(file))
+        {
+            return [];
+        }
+
+        // plex paths belong to the server, so do not interpret them with host path apis
+        string normalizedFile = file.Replace('\\', '/');
+        int separator = normalizedFile.LastIndexOf('/');
+        if (separator < 0)
+        {
+            return [];
+        }
+
+        string folder = normalizedFile[..separator];
+        foreach (string libraryPath in libraryPaths)
+        {
+            if (string.IsNullOrWhiteSpace(libraryPath))
+            {
+                continue;
+            }
+
+            string root = libraryPath.Replace('\\', '/').TrimEnd('/');
+            if (!folder.Equals(root, StringComparison.OrdinalIgnoreCase) &&
+                !folder.StartsWith(root + "/", StringComparison.OrdinalIgnoreCase))
+            {
+                continue;
+            }
+
+            // include the library folder itself; never a filesystem root or drive name
+            int start = root.Length == 2 && root[1] == ':' ? root.Length : root.LastIndexOf('/') + 1;
+            return folder[start..].Split('/', StringSplitOptions.RemoveEmptyEntries);
+        }
+
+        return [];
+    }
+
     private Option<string> NormalizeGuid(string guid)
     {
         if (guid.StartsWith("plex://show", StringComparison.OrdinalIgnoreCase) ||