Update

Author: BenjaminMichaelis

EssentialCSharp.Web/Areas/Identity/Data/EssentialCSharpWebContext.cs

@@ -15,6 +15,8 @@ protected override void OnModelCreating(ModelBuilder builder)
     {
         base.OnModelCreating(builder);
 
+        // EF design-time model building does not infer Identity store options,
+        // so keep the persisted schema explicit for login/token key lengths.
         builder.Entity<IdentityUserLogin<string>>(login =>
         {
             login.Property(entry => entry.LoginProvider).HasMaxLength(EssentialCSharpWebIdentitySchema.KeyMaxLength);

EssentialCSharp.Web/Data/EssentialCSharpWebIdentitySchema.cs

@@ -1,6 +1,18 @@
 namespace EssentialCSharp.Web.Data;
 
+/// <summary>
+/// Mirrors the ASP.NET Core Identity <c>AddDefaultIdentity</c> default for
+/// <c>IdentityOptions.Stores.MaxLengthForKeys</c>.
+/// EF model building does not derive that runtime option automatically, so the
+/// schema contract keeps the explicit model configuration and runtime options aligned.
+/// </summary>
 public static class EssentialCSharpWebIdentitySchema
 {
+    /// <summary>
+     /// ASP.NET Core Identity defaults login/token key lengths to 128.
+    /// Source: https://github.com/dotnet/aspnetcore/blob/c4db2306aad327f8c45c546f82625082156f73bb/src/Identity/UI/src/IdentityServiceCollectionUIExtensions.cs#L48-L51
+    /// Keep this in sync with <c>options.Stores.MaxLengthForKeys</c> and the explicit
+    /// Identity model configuration so migrations continue to match the existing schema.
+    /// </summary>
     public const int KeyMaxLength = 128;
 }