fix(host-sdk): remove legacy module directory fallback

Author: Hongwei-MB

src/Modulus.HostSdk.Runtime/ModulusHostSdkBuilder.cs

@@ -49,16 +49,6 @@ public ModulusHostSdkBuilder AddDefaultModuleDirectories()
         var userModules = Path.Combine(LocalStorage.GetUserRoot(), "Modules");
         _moduleDirectories.Add(new HostModuleDirectory(userModules, IsSystem: false));
 
-        // Backward compatibility: some hosts may have used ApplicationData directly on non-Windows before LocalStorage aligned paths.
-        var legacyUserModules = Path.Combine(
-            Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
-            "Modulus",
-            "Modules");
-        if (!IsSameDirectory(userModules, legacyUserModules))
-        {
-            _moduleDirectories.Add(new HostModuleDirectory(legacyUserModules, IsSystem: false));
-        }
-
         return this;
     }
 
@@ -122,12 +112,6 @@ private static string NormalizeDirectoryPath(string path)
         var full = Path.GetFullPath(path);
         return full.TrimEnd(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar);
     }
-
-    private static bool IsSameDirectory(string a, string b)
-    {
-        var comparer = OperatingSystem.IsWindows() ? StringComparer.OrdinalIgnoreCase : StringComparer.Ordinal;
-        return comparer.Equals(NormalizeDirectoryPath(a), NormalizeDirectoryPath(b));
-    }
 }
 
 

tests/Modulus.HostSdk.Tests/HostSdkBuilderTests.cs

@@ -40,19 +40,9 @@ public void AddDefaultModuleDirectories_AddsExpectedDefaultDirectories()
 
         var systemDir = Path.Combine(AppContext.BaseDirectory, "Modules");
         var userDir = Path.Combine(LocalStorage.GetUserRoot(), "Modules");
-        var legacyUserDir = Path.Combine(
-            Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
-            "Modulus",
-            "Modules");
 
         Assert.Contains(list, d => d.IsSystem && PathEquals(d.Path, systemDir));
         Assert.Contains(list, d => !d.IsSystem && PathEquals(d.Path, userDir));
-
-        // Only included when distinct from the canonical user directory.
-        if (!PathEquals(userDir, legacyUserDir))
-        {
-            Assert.Contains(list, d => !d.IsSystem && PathEquals(d.Path, legacyUserDir));
-        }
     }
 
     [Fact]