Add legacy update channel

Knossos.NET/Classes/KnUtils.cs

@@ -1391,5 +1391,28 @@ public static void CreateDesktopShortcut(string shortcutName, string destFileFul
                 Log.Add(Log.LogSeverity.Error, "KnUtils.CreateDesktopShortcut()", ex);
             }
         }
+
+        /// <summary>
+        /// Determines if the current OS meets the requirements for .NET 10 / "latest" channel updates.
+        /// Windows 10+ or macOS 12.0+ qualify.
+        /// </summary>
+        public static bool IsModernOS()
+        {
+            if (IsWindows)
+            {
+                // Windows build 10240 = Windows 10 RTM
+                return Environment.OSVersion.Version.Major >= 10;
+            }
+
+            if (IsMacOS)
+            {
+                var ver = Environment.OSVersion.Version;
+                // macOS 12.0
+                return ver.Major >= 12;
+            }
+
+            // Linux and anything else: treat as modern (no restriction planned)
+            return true;
+        }
     }
 }

Knossos.NET/Models/GitHubApi.cs

@@ -1,6 +1,10 @@
-using System;
+using Knossos.NET.Classes;
+using System;
+using System.Collections.Generic;
+using System.Linq;
 using System.Net.Http;
 using System.Net.Http.Headers;
+using System.Runtime.InteropServices;
 using System.Text.Json;
 using System.Threading.Tasks;
 
@@ -9,28 +13,127 @@ namespace Knossos.NET.Models
     public static class GitHubApi
     {
         /// <summary>
-        /// Get the last release on Knet github repo
-        /// URL of this repo is set on the Knossos class
+        /// Gets the latest applicable release from GitHub.
+        /// - Modern platforms (Win10+ / macOS 12.0+): uses /releases/latest (current behaviour).
+        /// - Legacy platforms: scans /releases, keeps only v1.3.x tags, returns the newest one.
         /// </summary>
-        /// <returns>GitHubRelease or null if the api call failed</returns>
+        /// <returns>GitHubRelease or null if the API call failed.</returns>
         public static async Task<GitHubRelease?> GetLastRelease()
+        {
+            if (KnUtils.IsModernOS())
+            {
+                return await GetLatestRelease();
+            }
+            else
+            {
+                return await GetLatestLegacyRelease();
+            }
+        }
+
+        /// <summary>
+        /// Calls /releases/latest — for modern platforms.
+        /// </summary>
+        private static async Task<GitHubRelease?> GetLatestRelease()
         {
             try
             {
                 var client = KnUtils.GetHttpClient();
                 client.DefaultRequestHeaders.UserAgent.Add(new ProductInfoHeaderValue("product", "1"));
                 using var response = await client.GetAsync(Knossos.GitHubUpdateRepoURL + "/releases/latest");
                 var json = await response.Content.ReadAsStringAsync();
-                return JsonSerializer.Deserialize<GitHubRelease>(json)!;
+                return JsonSerializer.Deserialize<GitHubRelease>(json);
             }
             catch (Exception ex)
             {
-                Log.Add(Log.LogSeverity.Error, "GitHubApi.GetLastRelease()", ex);
+                Log.Add(Log.LogSeverity.Error, "GitHubApi.GetLatestRelease()", ex);
                 return null;
             }
         }
+
+        /// <summary>
+        /// Scans /releases pages looking for v1.3.x tags and returns the newest one.
+        /// Stops paginating early once tags leave the 1.3.x range (assumes releases
+        /// are returned newest-first by the API).
+        /// </summary>
+        private static async Task<GitHubRelease?> GetLatestLegacyRelease()
+        {
+            try
+            {
+                var client = KnUtils.GetHttpClient();
+                client.DefaultRequestHeaders.UserAgent.Add(new ProductInfoHeaderValue("product", "1"));
+
+                var candidates = new List<GitHubRelease>();
+                int page = 1;
+                const int perPage = 30; // GitHub default; max is 100
+
+                while (true)
+                {
+                    var url = $"{Knossos.GitHubUpdateRepoURL}/releases?per_page={perPage}&page={page}";
+                    using var response = await client.GetAsync(url);
+                    var json = await response.Content.ReadAsStringAsync();
+                    var releases = JsonSerializer.Deserialize<List<GitHubRelease>>(json);
+
+                    if (releases == null || releases.Count == 0)
+                        break;
+
+                    foreach (var release in releases)
+                    {
+                        if (IsLegacyTag(release.tag_name))
+                        {
+                            candidates.Add(release);
+                        }
+                    }
+
+                    // If the oldest release on this page is already below 1.3.7, no need to go further
+                    var lastTag = releases.Last().tag_name;
+                    if (lastTag != null && IsBelowLegacyMinor(lastTag))
+                        break;
+
+                    if (releases.Count < perPage)
+                        break; // last page
+
+                    page++;
+                }
+
+                // Return the candidate with the highest semantic version
+                return candidates
+                    .Where(r => r.tag_name != null)
+                    .MaxBy(r => new SemanticVersion(NormalizeTag(r.tag_name!)));
+            }
+            catch (Exception ex)
+            {
+                Log.Add(Log.LogSeverity.Error, "GitHubApi.GetLatestLegacyRelease()", ex);
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// Returns true if the tag is a v1.3.x release (e.g. "v1.3.7", "v1.3.10-rc1").
+        /// </summary>
+        private static bool IsLegacyTag(string? tag)
+        {
+            if (string.IsNullOrWhiteSpace(tag)) return false;
+            var version = new SemanticVersion(NormalizeTag(tag));
+            // Check major == 1 and minor == 3 by comparing against sentinels
+            return SemanticVersion.Compare(NormalizeTag(tag), "1.3.0") >= 0 &&
+                   SemanticVersion.Compare(NormalizeTag(tag), "1.4.0") < 0;
+        }
+
+        /// <summary>
+        /// Returns true if the tag is strictly older than 1.3.7 — used as an early-exit
+        /// hint while paginating (GitHub returns releases newest-first).
+        /// </summary>
+        private static bool IsBelowLegacyMinor(string tag)
+        {
+            return SemanticVersion.Compare(NormalizeTag(tag), "1.3.7") < 0;
+        }
+
+        /// <summary>Strips the leading "v" that GitHub tags typically have.</summary>
+        private static string NormalizeTag(string tag) =>
+            tag.ToLower().Replace("v", "").Trim();
     }
 
+
     public class GitHubRelease
     {
         public string? url { get; set; }

Knossos.NET/ViewModels/GlobalSettingsViewModel.cs

@@ -36,7 +36,9 @@ public partial class GlobalSettingsViewModel : ViewModelBase
         private const long speed10MB = 170000000;
 
         /* For display only */
-		[ObservableProperty]
+        [ObservableProperty]
+        internal string knossosUpdateChannelInfo = "";
+        [ObservableProperty]
         internal bool isPortableMode = false;
         [ObservableProperty]
         internal bool flagDataLoaded = false;
@@ -552,6 +554,14 @@ public string GlobalCmd
         public GlobalSettingsViewModel()
         {
             isPortableMode = Knossos.inPortableMode;
+            if (KnUtils.IsModernOS())
+            {
+                knossosUpdateChannelInfo = "(Main Update Channel)";
+            }
+            else
+            {
+                knossosUpdateChannelInfo = "(Legacy Update Channel)";
+            }
         }
 
         public void CheckDisplaySettingsWarning()

Knossos.NET/Views/GlobalSettingsView.axaml

@@ -73,6 +73,7 @@
 						<WrapPanel Margin="5,10,0,0">
 							<Label Margin="0,5,0,0" Width="205">Auto Update KnosssosNET</Label>
 							<ToggleSwitch IsVisible="{Binding CheckUpdates}" Margin="5,0,0,0" IsChecked="{Binding AutoUpdate}" ToolTip.Tip="The update will be automatically downloaded and installed. KnossosNET will be restarted without any user input."></ToggleSwitch>
+							<Label Margin="10,1,0,0" Content="{Binding KnossosUpdateChannelInfo}" VerticalAlignment="Center"/>
 						</WrapPanel>
 						<WrapPanel Margin="5,10,0,0">
 							<Label Margin="0,5,0,0" Width="205">Auto Update FSO Builds</Label>