From 239b61b6eb13aa078705965085333640722ac6cb Mon Sep 17 00:00:00 2001
From: Daria Tiurina <dariatiurina@microsoft.com>
Date: Wed, 21 Jan 2026 11:56:53 +0100
Subject: [PATCH 01/11] Create SupplyParameterFromSessionAttribute and
 connected infrastructure

---
 .../Components/src/PublicAPI.Unshipped.txt    |  4 ++
 .../SupplyParameterFromSessionAttribute.cs    | 20 ++++++++++
 ...orComponentsServiceCollectionExtensions.cs |  2 +
 .../src/Rendering/EndpointHtmlRenderer.cs     |  5 +++
 .../Endpoints/src/SessionValueMapper.cs       | 26 ++++++++++++
 .../Web/src/PublicAPI.Unshipped.txt           |  4 ++
 .../Web/src/Session/ISessionValueMapper.cs    | 15 +++++++
 ...rFromSessionServiceCollectionExtensions.cs | 25 ++++++++++++
 ...SupplyParameterFromSessionValueProvider.cs | 40 +++++++++++++++++++
 .../Components.TestServer.csproj              |  1 +
 .../Components.TestServer/Program.cs          |  1 +
 ...omponentEndpointsNoInteractivityStartup.cs |  9 +++++
 .../SupplyParameterFromSessionComponent.razor | 27 +++++++++++++
 13 files changed, 179 insertions(+)
 create mode 100644 src/Components/Components/src/SupplyParameterFromSessionAttribute.cs
 create mode 100644 src/Components/Endpoints/src/SessionValueMapper.cs
 create mode 100644 src/Components/Web/src/Session/ISessionValueMapper.cs
 create mode 100644 src/Components/Web/src/Session/SupplyParameterFromSessionServiceCollectionExtensions.cs
 create mode 100644 src/Components/Web/src/Session/SupplyParameterFromSessionValueProvider.cs
 create mode 100644 src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor

diff --git a/src/Components/Components/src/PublicAPI.Unshipped.txt b/src/Components/Components/src/PublicAPI.Unshipped.txt
index 8bba68ef9bd1..2eddec351c76 100644
--- a/src/Components/Components/src/PublicAPI.Unshipped.txt
+++ b/src/Components/Components/src/PublicAPI.Unshipped.txt
@@ -6,3 +6,7 @@ Microsoft.AspNetCore.Components.IComponentPropertyActivator.GetActivator(System.
 *REMOVED*Microsoft.AspNetCore.Components.ResourceAsset.ResourceAsset(string! url, System.Collections.Generic.IReadOnlyList<Microsoft.AspNetCore.Components.ResourceAssetProperty!>? properties) -> void
 *REMOVED*Microsoft.AspNetCore.Components.Routing.Router.PreferExactMatches.get -> bool
 *REMOVED*Microsoft.AspNetCore.Components.Routing.Router.PreferExactMatches.set -> void
+Microsoft.AspNetCore.Components.SupplyParameterFromSessionAttribute
+Microsoft.AspNetCore.Components.SupplyParameterFromSessionAttribute.Name.get -> string?
+Microsoft.AspNetCore.Components.SupplyParameterFromSessionAttribute.Name.set -> void
+Microsoft.AspNetCore.Components.SupplyParameterFromSessionAttribute.SupplyParameterFromSessionAttribute() -> void
diff --git a/src/Components/Components/src/SupplyParameterFromSessionAttribute.cs b/src/Components/Components/src/SupplyParameterFromSessionAttribute.cs
new file mode 100644
index 000000000000..d61238a00279
--- /dev/null
+++ b/src/Components/Components/src/SupplyParameterFromSessionAttribute.cs
@@ -0,0 +1,20 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.AspNetCore.Components;
+
+/// <summary>
+/// Indicates that the value of the associated property should be supplied from
+/// the session attribute with the specified name.
+/// </summary>
+[AttributeUsage(AttributeTargets.Property, AllowMultiple = false, Inherited = true)]
+public sealed class SupplyParameterFromSessionAttribute : CascadingParameterAttributeBase
+{
+    /// <summary>
+    /// Gets or sets the name of the session attribute. If not specified, the property name will be used.
+    /// </summary>
+    public string? Name { get; set; }
+
+    /// <inheritdoc />
+    internal override bool SingleDelivery => true;
+}
diff --git a/src/Components/Endpoints/src/DependencyInjection/RazorComponentsServiceCollectionExtensions.cs b/src/Components/Endpoints/src/DependencyInjection/RazorComponentsServiceCollectionExtensions.cs
index dc365194fcbe..166104f9f0f0 100644
--- a/src/Components/Endpoints/src/DependencyInjection/RazorComponentsServiceCollectionExtensions.cs
+++ b/src/Components/Endpoints/src/DependencyInjection/RazorComponentsServiceCollectionExtensions.cs
@@ -69,7 +69,9 @@ public static IRazorComponentsBuilder AddRazorComponents(this IServiceCollection
         services.TryAddScoped<EndpointRoutingStateProvider>();
         services.TryAddScoped<IRoutingStateProvider>(sp => sp.GetRequiredService<EndpointRoutingStateProvider>());
         services.TryAddScoped<AuthenticationStateProvider, ServerAuthenticationStateProvider>();
+        services.TryAddScoped<ISessionValueMapper, SessionValueMapper>();
         services.AddSupplyValueFromQueryProvider();
+        services.AddSupplyValueFromSessionProvider();
         services.AddSupplyValueFromPersistentComponentStateProvider();
         services.TryAddCascadingValue(sp => sp.GetRequiredService<EndpointHtmlRenderer>().HttpContext);
         services.TryAddScoped<WebAssemblySettingsEmitter>();
diff --git a/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.cs b/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.cs
index ac24baa2f7d5..b8fc15aacf16 100644
--- a/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.cs
+++ b/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.cs
@@ -122,6 +122,11 @@ internal async Task InitializeStandardComponentServicesAsync(
             antiforgery.SetRequestContext(httpContext);
         }
 
+        if (httpContext.RequestServices.GetService<ISessionValueMapper>() is SessionValueMapper sessionValueMapper)
+        {
+            sessionValueMapper.SetRequestContext(httpContext);
+        }
+
         // It's important that this is initialized since a component might try to restore state during prerendering
         // (which will obviously not work, but should not fail)
         var componentApplicationLifetime = httpContext.RequestServices.GetRequiredService<ComponentStatePersistenceManager>();
diff --git a/src/Components/Endpoints/src/SessionValueMapper.cs b/src/Components/Endpoints/src/SessionValueMapper.cs
new file mode 100644
index 000000000000..33345e9c345d
--- /dev/null
+++ b/src/Components/Endpoints/src/SessionValueMapper.cs
@@ -0,0 +1,26 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Components.Endpoints;
+
+internal class SessionValueMapper : ISessionValueMapper
+{
+    private HttpContext? _httpContext;
+
+    internal void SetRequestContext(HttpContext httpContext)
+    {
+        _httpContext = httpContext;
+    }
+
+    public object? GetValue(string sessionKey)
+    {
+        var session = _httpContext?.Session;
+        if (session is null)
+        {
+            return null;
+        }
+        return session.GetString(sessionKey);
+    }
+}
diff --git a/src/Components/Web/src/PublicAPI.Unshipped.txt b/src/Components/Web/src/PublicAPI.Unshipped.txt
index 92f616da9831..9928f0fab63a 100644
--- a/src/Components/Web/src/PublicAPI.Unshipped.txt
+++ b/src/Components/Web/src/PublicAPI.Unshipped.txt
@@ -1,6 +1,10 @@
 #nullable enable
+Microsoft.AspNetCore.Components.ISessionValueMapper
+Microsoft.AspNetCore.Components.ISessionValueMapper.GetValue(string! sessionKey) -> object?
 Microsoft.AspNetCore.Components.Routing.NavLink.RelativeToCurrentUri.get -> bool
 Microsoft.AspNetCore.Components.Routing.NavLink.RelativeToCurrentUri.set -> void
+Microsoft.Extensions.DependencyInjection.SupplyParameterFromSessionServiceCollectionExtensions
+static Microsoft.Extensions.DependencyInjection.SupplyParameterFromSessionServiceCollectionExtensions.AddSupplyValueFromSessionProvider(this Microsoft.Extensions.DependencyInjection.IServiceCollection! services) -> Microsoft.Extensions.DependencyInjection.IServiceCollection!
 *REMOVED*Microsoft.AspNetCore.Components.Forms.RemoteBrowserFileStreamOptions
 *REMOVED*Microsoft.AspNetCore.Components.Forms.RemoteBrowserFileStreamOptions.MaxBufferSize.get -> int
 *REMOVED*Microsoft.AspNetCore.Components.Forms.RemoteBrowserFileStreamOptions.MaxBufferSize.set -> void
diff --git a/src/Components/Web/src/Session/ISessionValueMapper.cs b/src/Components/Web/src/Session/ISessionValueMapper.cs
new file mode 100644
index 000000000000..b57049b4d58b
--- /dev/null
+++ b/src/Components/Web/src/Session/ISessionValueMapper.cs
@@ -0,0 +1,15 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.AspNetCore.Components;
+
+/// <summary>
+/// Maps session data values to a model.
+/// </summary>
+public interface ISessionValueMapper
+{
+    /// <summary>
+    /// Returns the session value with the specified name.
+    /// </summary>
+    object? GetValue(string sessionKey);
+}
diff --git a/src/Components/Web/src/Session/SupplyParameterFromSessionServiceCollectionExtensions.cs b/src/Components/Web/src/Session/SupplyParameterFromSessionServiceCollectionExtensions.cs
new file mode 100644
index 000000000000..a6dd64a9794b
--- /dev/null
+++ b/src/Components/Web/src/Session/SupplyParameterFromSessionServiceCollectionExtensions.cs
@@ -0,0 +1,25 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.AspNetCore.Components;
+using Microsoft.AspNetCore.Components.Web;
+using Microsoft.Extensions.DependencyInjection.Extensions;
+
+namespace Microsoft.Extensions.DependencyInjection;
+
+/// <summary>
+/// Enables component parameters to be supplied from the session with <see cref="SupplyParameterFromSessionAttribute"/>.
+/// </summary>
+public static class SupplyParameterFromSessionServiceCollectionExtensions
+{
+    /// <summary>
+    /// Enables component parameters to be supplied from the session with <see cref="SupplyParameterFromSessionAttribute"/>.
+    /// </summary>
+    /// <param name="services">The <see cref="IServiceCollection"/>.</param>
+    /// <returns>The <see cref="IServiceCollection"/>.</returns>
+    public static IServiceCollection AddSupplyValueFromSessionProvider(this IServiceCollection services)
+    {
+        services.TryAddEnumerable(ServiceDescriptor.Scoped<ICascadingValueSupplier, SupplyParameterFromSessionValueProvider>());
+        return services;
+    }
+}
diff --git a/src/Components/Web/src/Session/SupplyParameterFromSessionValueProvider.cs b/src/Components/Web/src/Session/SupplyParameterFromSessionValueProvider.cs
new file mode 100644
index 000000000000..9326f5cb47e5
--- /dev/null
+++ b/src/Components/Web/src/Session/SupplyParameterFromSessionValueProvider.cs
@@ -0,0 +1,40 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.AspNetCore.Components.Rendering;
+
+namespace Microsoft.AspNetCore.Components.Web;
+
+internal class SupplyParameterFromSessionValueProvider : ICascadingValueSupplier
+{
+    private readonly ISessionValueMapper _sessionValueMapper;
+
+    public SupplyParameterFromSessionValueProvider(ISessionValueMapper sessionValueMapper)
+    {
+        _sessionValueMapper = sessionValueMapper;
+    }
+
+    public bool IsFixed => true;
+
+    public bool CanSupplyValue(in CascadingParameterInfo parameterInfo)
+        => parameterInfo.Attribute is SupplyParameterFromSessionAttribute;
+
+    public object? GetCurrentValue(object? key, in CascadingParameterInfo parameterInfo)
+    {
+        if (_sessionValueMapper is null)
+        {
+            return null;
+        }
+
+        var attribute = (SupplyParameterFromSessionAttribute)parameterInfo.Attribute;
+        var sessionKey = attribute.Name ?? parameterInfo.PropertyName;
+
+        return _sessionValueMapper.GetValue(sessionKey);
+    }
+
+    public void Subscribe(ComponentState subscriber, in CascadingParameterInfo parameterInfo)
+        => throw new NotSupportedException(); // IsFixed = true, so the framework won't call this
+
+    public void Unsubscribe(ComponentState subscriber, in CascadingParameterInfo parameterInfo)
+        => throw new NotSupportedException(); // IsFixed = true, so the framework won't call this
+}
diff --git a/src/Components/test/testassets/Components.TestServer/Components.TestServer.csproj b/src/Components/test/testassets/Components.TestServer/Components.TestServer.csproj
index 44f1fcb9fc7f..61f6efd9d77d 100644
--- a/src/Components/test/testassets/Components.TestServer/Components.TestServer.csproj
+++ b/src/Components/test/testassets/Components.TestServer/Components.TestServer.csproj
@@ -78,6 +78,7 @@
     <Reference Include="Microsoft.AspNetCore.Razor.Runtime" />
     <Reference Include="Microsoft.AspNetCore.Routing" />
     <Reference Include="Microsoft.AspNetCore.Routing.Abstractions" />
+    <Reference Include="Microsoft.AspNetCore.Session" />
     <Reference Include="Microsoft.AspNetCore.StaticAssets" />
     <Reference Include="Microsoft.AspNetCore.StaticFiles" />
     <Reference Include="Microsoft.AspNetCore.WebSockets" />
diff --git a/src/Components/test/testassets/Components.TestServer/Program.cs b/src/Components/test/testassets/Components.TestServer/Program.cs
index 2f06b00b72ac..f42fbdc26f2e 100644
--- a/src/Components/test/testassets/Components.TestServer/Program.cs
+++ b/src/Components/test/testassets/Components.TestServer/Program.cs
@@ -38,6 +38,7 @@ public static async Task Main(string[] args)
             ["Hot Reload"] = (BuildWebHost<HotReloadStartup>(CreateAdditionalArgs(args)), "/subdir"),
             ["Dev server client-side blazor"] = CreateDevServerHost(CreateAdditionalArgs(args)),
             ["Global Interactivity"] = (BuildWebHost<RazorComponentEndpointsStartup<GlobalInteractivityApp>>(CreateAdditionalArgs(args)), "/subdir"),
+            ["SSR (No Interactivity)"] = (BuildWebHost<RazorComponentEndpointsNoInteractivityStartup<App>>(CreateAdditionalArgs(args)), "/subdir"),
         };
 
         var mainHost = BuildWebHost(args);
diff --git a/src/Components/test/testassets/Components.TestServer/RazorComponentEndpointsNoInteractivityStartup.cs b/src/Components/test/testassets/Components.TestServer/RazorComponentEndpointsNoInteractivityStartup.cs
index bed15d4a46d0..841fc524748d 100644
--- a/src/Components/test/testassets/Components.TestServer/RazorComponentEndpointsNoInteractivityStartup.cs
+++ b/src/Components/test/testassets/Components.TestServer/RazorComponentEndpointsNoInteractivityStartup.cs
@@ -5,6 +5,7 @@
 using System.Reflection;
 using System.Security.Claims;
 using System.Web;
+
 using Components.TestServer.RazorComponents;
 using Components.TestServer.RazorComponents.Pages.Forms;
 using Components.TestServer.Services;
@@ -33,6 +34,12 @@ public void ConfigureServices(IServiceCollection services)
         });
         services.AddHttpContextAccessor();
         services.AddCascadingAuthenticationState();
+        services.AddDistributedMemoryCache();
+        services.AddSession(options =>
+        {
+            options.Cookie.HttpOnly = true;
+            options.Cookie.IsEssential = true;
+        });
     }
 
     // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
@@ -88,6 +95,8 @@ public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
                 });
             });
 
+            app.UseSession();
+
             ConfigureSubdirPipeline(app, env);
         });
     }
diff --git a/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor b/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor
new file mode 100644
index 000000000000..9e249e632faf
--- /dev/null
+++ b/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor
@@ -0,0 +1,27 @@
+@page "/supply-parameter-from-session"
+@using Microsoft.AspNetCore.Components.Forms
+@inject IHttpContextAccessor HttpContextAccessor
+
+<h3>SupplyParameterFromSessionComponent</h3>
+
+<p id="text-email">@Email</p>
+
+<form @onsubmit="SetEmail" @formname="set-email" method="post">
+    <AntiforgeryToken />
+    <input id="input-email" @bind="EmailInput" name="EmailInput"/>
+    <button type="submit">Set Email</button>
+</form>
+
+@code {
+    [SupplyParameterFromSession]
+    public string? Email { get; set; }
+
+    [SupplyParameterFromForm]
+    public string? EmailInput { get; set; }
+
+    void SetEmail()
+    {
+        HttpContextAccessor.HttpContext?.Session.SetString(nameof(Email), EmailInput);
+        Email = EmailInput;
+    }
+}

From 596df7fbebccc3bee6a4df40e2b5bdd3d2c8bb80 Mon Sep 17 00:00:00 2001
From: Daria Tiurina <dariatiurina@microsoft.com>
Date: Thu, 22 Jan 2026 13:46:44 +0100
Subject: [PATCH 02/11] E2E Tests

---
 ...SupplyParameterFromSessionAttributeTest.cs | 31 +++++++++++++++++++
 .../SupplyParameterFromSessionComponent.razor |  2 +-
 2 files changed, 32 insertions(+), 1 deletion(-)
 create mode 100644 src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs

diff --git a/src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs b/src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs
new file mode 100644
index 000000000000..464126001a0d
--- /dev/null
+++ b/src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs
@@ -0,0 +1,31 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Components.TestServer.RazorComponents;
+using Microsoft.AspNetCore.Components.E2ETest.Infrastructure;
+using Microsoft.AspNetCore.Components.E2ETest.Infrastructure.ServerFixtures;
+using Microsoft.AspNetCore.E2ETesting;
+using OpenQA.Selenium;
+using TestServer;
+using Xunit.Abstractions;
+
+namespace Microsoft.AspNetCore.Components.E2ETests.Tests;
+
+public class SupplyParameterFromSessionAttributeTest : ServerTestBase<BasicTestAppServerSiteFixture<RazorComponentEndpointsNoInteractivityStartup<App>>>
+{
+    public SupplyParameterFromSessionAttributeTest(BrowserFixture browserFixture, BasicTestAppServerSiteFixture<RazorComponentEndpointsNoInteractivityStartup<App>> serverFixture, ITestOutputHelper output) : base(browserFixture, serverFixture, output)
+    {
+    }
+
+    [Fact]
+    public void SupplyParameterCanReadFromSession()
+    {
+        Navigate($"{ServerPathBase}/supply-parameter-from-session");
+        Browser.Exists(By.Id("input-email")).SendKeys("email");
+        Browser.Exists(By.Id("set-email")).Click();
+        Browser.Equal("email", () => Browser.Exists(By.Id("text-email")).Text);
+    }
+}
diff --git a/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor b/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor
index 9e249e632faf..e0421c62372e 100644
--- a/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor
+++ b/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor
@@ -9,7 +9,7 @@
 <form @onsubmit="SetEmail" @formname="set-email" method="post">
     <AntiforgeryToken />
     <input id="input-email" @bind="EmailInput" name="EmailInput"/>
-    <button type="submit">Set Email</button>
+    <button type="submit" id="set-email">Set Email</button>
 </form>
 
 @code {

From 215c5a7b88fe4e00124938280f72945113a94ed4 Mon Sep 17 00:00:00 2001
From: Daria Tiurina <dariatiurina@microsoft.com>
Date: Thu, 22 Jan 2026 16:01:22 +0100
Subject: [PATCH 03/11] Added serialization, deserialization to the
 SessionValueMapper

---
 .../SupplyParameterFromSessionAttribute.cs    |  2 +-
 .../Endpoints/src/SessionValueMapper.cs       | 29 +++++++++++++++++--
 .../Web/src/PublicAPI.Unshipped.txt           |  3 +-
 .../Web/src/Session/ISessionValueMapper.cs    |  7 ++++-
 ...SupplyParameterFromSessionValueProvider.cs | 27 ++++++++++++++---
 5 files changed, 59 insertions(+), 9 deletions(-)

diff --git a/src/Components/Components/src/SupplyParameterFromSessionAttribute.cs b/src/Components/Components/src/SupplyParameterFromSessionAttribute.cs
index d61238a00279..6e20887f0837 100644
--- a/src/Components/Components/src/SupplyParameterFromSessionAttribute.cs
+++ b/src/Components/Components/src/SupplyParameterFromSessionAttribute.cs
@@ -16,5 +16,5 @@ public sealed class SupplyParameterFromSessionAttribute : CascadingParameterAttr
     public string? Name { get; set; }
 
     /// <inheritdoc />
-    internal override bool SingleDelivery => true;
+    internal override bool SingleDelivery => false;
 }
diff --git a/src/Components/Endpoints/src/SessionValueMapper.cs b/src/Components/Endpoints/src/SessionValueMapper.cs
index 33345e9c345d..3a3d9eb3eebf 100644
--- a/src/Components/Endpoints/src/SessionValueMapper.cs
+++ b/src/Components/Endpoints/src/SessionValueMapper.cs
@@ -1,12 +1,14 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Text.Json;
 using Microsoft.AspNetCore.Http;
 
 namespace Microsoft.AspNetCore.Components.Endpoints;
 
 internal class SessionValueMapper : ISessionValueMapper
 {
+    private static readonly JsonSerializerOptions _jsonOptions = new(JsonSerializerDefaults.Web);
     private HttpContext? _httpContext;
 
     internal void SetRequestContext(HttpContext httpContext)
@@ -14,13 +16,36 @@ internal void SetRequestContext(HttpContext httpContext)
         _httpContext = httpContext;
     }
 
-    public object? GetValue(string sessionKey)
+    public object? GetValue(string sessionKey, Type type)
     {
         var session = _httpContext?.Session;
         if (session is null)
         {
             return null;
         }
-        return session.GetString(sessionKey);
+        var json = session.GetString(sessionKey);
+        if (String.IsNullOrEmpty(json))
+        {
+            return null;
+        }
+        return JsonSerializer.Deserialize(json, type, _jsonOptions);
+    }
+
+    public void SetValue(string sessionKey, object? value)
+    {
+        var session = _httpContext?.Session;
+        if (session is null)
+        {
+            return;
+        }
+        if (value is null)
+        {
+            session.Remove(sessionKey);
+        }
+        else
+        {
+            var json = JsonSerializer.Serialize(value, value.GetType(), _jsonOptions);
+            session.SetString(sessionKey, json);
+        }
     }
 }
diff --git a/src/Components/Web/src/PublicAPI.Unshipped.txt b/src/Components/Web/src/PublicAPI.Unshipped.txt
index 3e9781951806..afbe29e73019 100644
--- a/src/Components/Web/src/PublicAPI.Unshipped.txt
+++ b/src/Components/Web/src/PublicAPI.Unshipped.txt
@@ -1,6 +1,7 @@
 #nullable enable
 Microsoft.AspNetCore.Components.ISessionValueMapper
-Microsoft.AspNetCore.Components.ISessionValueMapper.GetValue(string! sessionKey) -> object?
+Microsoft.AspNetCore.Components.ISessionValueMapper.GetValue(string! sessionKey, System.Type! type) -> object?
+Microsoft.AspNetCore.Components.ISessionValueMapper.SetValue(string! sessionKey, object? value) -> void
 Microsoft.AspNetCore.Components.Web.EnvironmentBoundary
 Microsoft.AspNetCore.Components.Web.EnvironmentBoundary.ChildContent.get -> Microsoft.AspNetCore.Components.RenderFragment?
 Microsoft.AspNetCore.Components.Web.EnvironmentBoundary.ChildContent.set -> void
diff --git a/src/Components/Web/src/Session/ISessionValueMapper.cs b/src/Components/Web/src/Session/ISessionValueMapper.cs
index b57049b4d58b..ab39a40cc1fe 100644
--- a/src/Components/Web/src/Session/ISessionValueMapper.cs
+++ b/src/Components/Web/src/Session/ISessionValueMapper.cs
@@ -11,5 +11,10 @@ public interface ISessionValueMapper
     /// <summary>
     /// Returns the session value with the specified name.
     /// </summary>
-    object? GetValue(string sessionKey);
+    object? GetValue(string sessionKey, Type type);
+
+    ///<summary>
+    /// Sets the session value with the specified name.
+    ///</summary>
+    void SetValue(string sessionKey, object? value);
 }
diff --git a/src/Components/Web/src/Session/SupplyParameterFromSessionValueProvider.cs b/src/Components/Web/src/Session/SupplyParameterFromSessionValueProvider.cs
index 9326f5cb47e5..cbee51dcdd9a 100644
--- a/src/Components/Web/src/Session/SupplyParameterFromSessionValueProvider.cs
+++ b/src/Components/Web/src/Session/SupplyParameterFromSessionValueProvider.cs
@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Diagnostics.CodeAnalysis;
 using Microsoft.AspNetCore.Components.Rendering;
 
 namespace Microsoft.AspNetCore.Components.Web;
@@ -14,7 +15,7 @@ public SupplyParameterFromSessionValueProvider(ISessionValueMapper sessionValueM
         _sessionValueMapper = sessionValueMapper;
     }
 
-    public bool IsFixed => true;
+    public bool IsFixed => false;
 
     public bool CanSupplyValue(in CascadingParameterInfo parameterInfo)
         => parameterInfo.Attribute is SupplyParameterFromSessionAttribute;
@@ -29,12 +30,30 @@ public bool CanSupplyValue(in CascadingParameterInfo parameterInfo)
         var attribute = (SupplyParameterFromSessionAttribute)parameterInfo.Attribute;
         var sessionKey = attribute.Name ?? parameterInfo.PropertyName;
 
-        return _sessionValueMapper.GetValue(sessionKey);
+        return _sessionValueMapper.GetValue(sessionKey, parameterInfo.GetType());
     }
 
     public void Subscribe(ComponentState subscriber, in CascadingParameterInfo parameterInfo)
-        => throw new NotSupportedException(); // IsFixed = true, so the framework won't call this
+    {
+
+    }
 
+    [UnconditionalSuppressMessage(
+        "Trimming",
+        "IL2075:Target parameter argument does not satisfy 'DynamicallyAccessedMembersAttribute'",
+        Justification = "Component properties are preserved through other means.")]
     public void Unsubscribe(ComponentState subscriber, in CascadingParameterInfo parameterInfo)
-        => throw new NotSupportedException(); // IsFixed = true, so the framework won't call this
+    {
+        var attribute = (SupplyParameterFromSessionAttribute)parameterInfo.Attribute;
+        var sessionKey = attribute.Name ?? parameterInfo.PropertyName;
+
+        var componentType = subscriber.Component.GetType();
+        var propertyInfo = componentType.GetProperty(parameterInfo.PropertyName);
+        if (propertyInfo is null)
+        {
+            return;
+        }
+        var value = propertyInfo.GetValue(subscriber.Component);
+        _sessionValueMapper.SetValue(sessionKey, value);
+    }
 }

From 89422d9c4fdd19d19ba39eb9ed02052ea415caae Mon Sep 17 00:00:00 2001
From: Daria Tiurina <dariatiurina@microsoft.com>
Date: Thu, 22 Jan 2026 18:53:30 +0100
Subject: [PATCH 04/11] Check for callback

---
 .../SupplyParameterFromSessionAttribute.cs    |  2 +-
 .../Endpoints/src/SessionValueMapper.cs       | 36 ++++++++++++++++++-
 .../Web/src/PublicAPI.Unshipped.txt           |  3 +-
 .../Web/src/Session/ISessionValueMapper.cs    | 23 +++++++++---
 ...SupplyParameterFromSessionValueProvider.cs | 25 ++++++-------
 ...SupplyParameterFromSessionAttributeTest.cs | 30 ++++++++++++++++
 .../SupplyParameterFromSessionComponent.razor | 36 ++++++++++++++++++-
 ...ameterFromSessionNavigationComponent.razor | 10 ++++++
 8 files changed, 144 insertions(+), 21 deletions(-)
 create mode 100644 src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionNavigationComponent.razor

diff --git a/src/Components/Components/src/SupplyParameterFromSessionAttribute.cs b/src/Components/Components/src/SupplyParameterFromSessionAttribute.cs
index 6e20887f0837..8e1f7820c3fb 100644
--- a/src/Components/Components/src/SupplyParameterFromSessionAttribute.cs
+++ b/src/Components/Components/src/SupplyParameterFromSessionAttribute.cs
@@ -5,7 +5,7 @@ namespace Microsoft.AspNetCore.Components;
 
 /// <summary>
 /// Indicates that the value of the associated property should be supplied from
-/// the session attribute with the specified name.
+/// the session with the specified name.
 /// </summary>
 [AttributeUsage(AttributeTargets.Property, AllowMultiple = false, Inherited = true)]
 public sealed class SupplyParameterFromSessionAttribute : CascadingParameterAttributeBase
diff --git a/src/Components/Endpoints/src/SessionValueMapper.cs b/src/Components/Endpoints/src/SessionValueMapper.cs
index 3a3d9eb3eebf..2fd88d8513a4 100644
--- a/src/Components/Endpoints/src/SessionValueMapper.cs
+++ b/src/Components/Endpoints/src/SessionValueMapper.cs
@@ -10,10 +10,14 @@ internal class SessionValueMapper : ISessionValueMapper
 {
     private static readonly JsonSerializerOptions _jsonOptions = new(JsonSerializerDefaults.Web);
     private HttpContext? _httpContext;
+    private readonly Dictionary<string, Func<object?>> _valueCallbacks = new();
 
     internal void SetRequestContext(HttpContext httpContext)
     {
         _httpContext = httpContext;
+
+        // Register Response.OnStarting once to persist all values before response starts
+        _httpContext.Response.OnStarting(PersistAllValues);
     }
 
     public object? GetValue(string sessionKey, Type type)
@@ -24,13 +28,18 @@ internal void SetRequestContext(HttpContext httpContext)
             return null;
         }
         var json = session.GetString(sessionKey);
-        if (String.IsNullOrEmpty(json))
+        if (string.IsNullOrEmpty(json))
         {
             return null;
         }
         return JsonSerializer.Deserialize(json, type, _jsonOptions);
     }
 
+    public void RegisterValueCallback(string sessionKey, Func<object?> valueGetter)
+    {
+        _valueCallbacks[sessionKey] = valueGetter;
+    }
+
     public void SetValue(string sessionKey, object? value)
     {
         var session = _httpContext?.Session;
@@ -48,4 +57,29 @@ public void SetValue(string sessionKey, object? value)
             session.SetString(sessionKey, json);
         }
     }
+
+    private Task PersistAllValues()
+    {
+        var session = _httpContext?.Session;
+        if (session is null)
+        {
+            return Task.CompletedTask;
+        }
+
+        foreach (var (key, valueGetter) in _valueCallbacks)
+        {
+            var value = valueGetter();
+            if (value is not null)
+            {
+                var json = JsonSerializer.Serialize(value, value.GetType(), _jsonOptions);
+                session.SetString(key, json);
+            }
+            else
+            {
+                session.Remove(key);
+            }
+        }
+
+        return Task.CompletedTask;
+    }
 }
diff --git a/src/Components/Web/src/PublicAPI.Unshipped.txt b/src/Components/Web/src/PublicAPI.Unshipped.txt
index afbe29e73019..2c192e70f361 100644
--- a/src/Components/Web/src/PublicAPI.Unshipped.txt
+++ b/src/Components/Web/src/PublicAPI.Unshipped.txt
@@ -1,6 +1,7 @@
 #nullable enable
 Microsoft.AspNetCore.Components.ISessionValueMapper
-Microsoft.AspNetCore.Components.ISessionValueMapper.GetValue(string! sessionKey, System.Type! type) -> object?
+Microsoft.AspNetCore.Components.ISessionValueMapper.GetValue(string! sessionKey, System.Type! targetType) -> object?
+Microsoft.AspNetCore.Components.ISessionValueMapper.RegisterValueCallback(string! sessionKey, System.Func<object?>! valueGetter) -> void
 Microsoft.AspNetCore.Components.ISessionValueMapper.SetValue(string! sessionKey, object? value) -> void
 Microsoft.AspNetCore.Components.Web.EnvironmentBoundary
 Microsoft.AspNetCore.Components.Web.EnvironmentBoundary.ChildContent.get -> Microsoft.AspNetCore.Components.RenderFragment?
diff --git a/src/Components/Web/src/Session/ISessionValueMapper.cs b/src/Components/Web/src/Session/ISessionValueMapper.cs
index ab39a40cc1fe..c4db9a2973dd 100644
--- a/src/Components/Web/src/Session/ISessionValueMapper.cs
+++ b/src/Components/Web/src/Session/ISessionValueMapper.cs
@@ -9,12 +9,25 @@ namespace Microsoft.AspNetCore.Components;
 public interface ISessionValueMapper
 {
     /// <summary>
-    /// Returns the session value with the specified name.
+    /// Returns the session value with the specified name, deserialized to the specified type.
     /// </summary>
-    object? GetValue(string sessionKey, Type type);
+    /// <param name="sessionKey">The session key.</param>
+    /// <param name="targetType">The type to deserialize to.</param>
+    /// <returns>The deserialized value, or null if not found.</returns>
+    object? GetValue(string sessionKey, Type targetType);
 
-    ///<summary>
-    /// Sets the session value with the specified name.
-    ///</summary>
+    /// <summary>
+    /// Stores the value in the session with the specified key.
+    /// </summary>
+    /// <param name="sessionKey">The session key.</param>
+    /// <param name="value">The value to store.</param>
     void SetValue(string sessionKey, object? value);
+
+    /// <summary>
+    /// Registers a callback to retrieve the current value of a session property.
+    /// The callback will be invoked when the response starts to persist the value.
+    /// </summary>
+    /// <param name="sessionKey">The session key.</param>
+    /// <param name="valueGetter">A function that returns the current value.</param>
+    void RegisterValueCallback(string sessionKey, Func<object?> valueGetter);
 }
diff --git a/src/Components/Web/src/Session/SupplyParameterFromSessionValueProvider.cs b/src/Components/Web/src/Session/SupplyParameterFromSessionValueProvider.cs
index cbee51dcdd9a..4a893a43dfc9 100644
--- a/src/Components/Web/src/Session/SupplyParameterFromSessionValueProvider.cs
+++ b/src/Components/Web/src/Session/SupplyParameterFromSessionValueProvider.cs
@@ -29,31 +29,32 @@ public bool CanSupplyValue(in CascadingParameterInfo parameterInfo)
 
         var attribute = (SupplyParameterFromSessionAttribute)parameterInfo.Attribute;
         var sessionKey = attribute.Name ?? parameterInfo.PropertyName;
-
-        return _sessionValueMapper.GetValue(sessionKey, parameterInfo.GetType());
-    }
-
-    public void Subscribe(ComponentState subscriber, in CascadingParameterInfo parameterInfo)
-    {
-
+        return _sessionValueMapper.GetValue(sessionKey, parameterInfo.PropertyType);
     }
 
     [UnconditionalSuppressMessage(
         "Trimming",
         "IL2075:Target parameter argument does not satisfy 'DynamicallyAccessedMembersAttribute'",
         Justification = "Component properties are preserved through other means.")]
-    public void Unsubscribe(ComponentState subscriber, in CascadingParameterInfo parameterInfo)
+    public void Subscribe(ComponentState subscriber, in CascadingParameterInfo parameterInfo)
     {
         var attribute = (SupplyParameterFromSessionAttribute)parameterInfo.Attribute;
         var sessionKey = attribute.Name ?? parameterInfo.PropertyName;
 
-        var componentType = subscriber.Component.GetType();
-        var propertyInfo = componentType.GetProperty(parameterInfo.PropertyName);
+        // Capture these in the closure
+        var component = subscriber.Component;
+        var propertyName = parameterInfo.PropertyName;
+        var componentType = component.GetType();
+        var propertyInfo = componentType.GetProperty(propertyName);
+
         if (propertyInfo is null)
         {
             return;
         }
-        var value = propertyInfo.GetValue(subscriber.Component);
-        _sessionValueMapper.SetValue(sessionKey, value);
+        _sessionValueMapper.RegisterValueCallback(sessionKey, () => propertyInfo.GetValue(component));
+    }
+
+    public void Unsubscribe(ComponentState subscriber, in CascadingParameterInfo parameterInfo)
+    {
     }
 }
diff --git a/src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs b/src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs
index 464126001a0d..8e7b7ba64ed1 100644
--- a/src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs
+++ b/src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs
@@ -28,4 +28,34 @@ public void SupplyParameterCanReadFromSession()
         Browser.Exists(By.Id("set-email")).Click();
         Browser.Equal("email", () => Browser.Exists(By.Id("text-email")).Text);
     }
+
+    [Fact]
+    public void SupplyParameterNullWhenNoKeyInSession()
+    {
+        Navigate($"{ServerPathBase}/supply-parameter-from-session");
+        Browser.Exists(By.Id("input-email")).SendKeys("email");
+        Browser.Exists(By.Id("set-email")).Click();
+        Browser.Equal("email", () => Browser.Exists(By.Id("text-email")).Text);
+        Browser.Equal("", () => Browser.Exists(By.Id("text-null")).Text);
+    }
+
+    [Fact]
+    public void SupplyParameterWorksWhenDifferentName()
+    {
+        Navigate($"{ServerPathBase}/supply-parameter-from-session");
+        Browser.Exists(By.Id("input-another-email")).SendKeys("email");
+        Browser.Exists(By.Id("set-another-email")).Click();
+        Browser.Equal("email", () => Browser.Exists(By.Id("text-another-email")).Text);
+        Browser.Equal("email", () => Browser.Exists(By.Id("text-email")).Text);
+        Browser.Equal("", () => Browser.Exists(By.Id("text-null")).Text);
+    }
+
+    [Fact]
+    public void SupplyParameterWorksWithRedirect()
+    {
+        Navigate($"{ServerPathBase}/supply-parameter-from-session");
+        Browser.Exists(By.Id("input-email-redirect")).SendKeys("email");
+        Browser.Exists(By.Id("set-email-redirect")).Click();
+        Browser.Equal("email", () => Browser.Exists(By.Id("text-email")).Text);
+    }
 }
diff --git a/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor b/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor
index e0421c62372e..db46c864c88f 100644
--- a/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor
+++ b/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor
@@ -1,10 +1,13 @@
 @page "/supply-parameter-from-session"
 @using Microsoft.AspNetCore.Components.Forms
 @inject IHttpContextAccessor HttpContextAccessor
+@inject NavigationManager NavigationManager
 
 <h3>SupplyParameterFromSessionComponent</h3>
 
 <p id="text-email">@Email</p>
+<p id="text-another-email">@AnotherEmail</p>
+<p id="text-null">@NoElement</p>
 
 <form @onsubmit="SetEmail" @formname="set-email" method="post">
     <AntiforgeryToken />
@@ -12,16 +15,47 @@
     <button type="submit" id="set-email">Set Email</button>
 </form>
 
+<form @onsubmit="SetAnotherEmail" @formname="set-another-email" method="post">
+    <AntiforgeryToken />
+    <input id="input-another-email" @bind="EmailInput" name="EmailInput" />
+    <button type="submit" id="set-another-email">Set Email</button>
+</form>
+
+<form @onsubmit="SetEmailWithRedirect" @formname="set-email-redirect" method="post">
+    <AntiforgeryToken />
+    <input id="input-email-redirect" @bind="EmailInput" name="EmailInput" />
+    <button type="submit" id="set-email-redirect">Set Email</button>
+</form>
+
 @code {
     [SupplyParameterFromSession]
     public string? Email { get; set; }
 
+    [SupplyParameterFromSession(Name = "Email")]
+    public string? AnotherEmail { get; set; }
+
+    [SupplyParameterFromSession]
+    public string? NoElement { get; set; }
+
     [SupplyParameterFromForm]
     public string? EmailInput { get; set; }
 
     void SetEmail()
     {
-        HttpContextAccessor.HttpContext?.Session.SetString(nameof(Email), EmailInput);
         Email = EmailInput;
+        EmailInput = string.Empty;
+    }
+
+    void SetAnotherEmail()
+    {
+        AnotherEmail = EmailInput;
+        EmailInput = string.Empty;
+    }
+
+    void SetEmailWithRedirect()
+    {
+        Email = EmailInput;
+        EmailInput = string.Empty;
+        NavigationManager.NavigateTo("/subdir/supply-parameter-from-session/navigation", forceLoad: true);
     }
 }
diff --git a/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionNavigationComponent.razor b/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionNavigationComponent.razor
new file mode 100644
index 000000000000..4918d4c3901c
--- /dev/null
+++ b/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionNavigationComponent.razor
@@ -0,0 +1,10 @@
+@page "/supply-parameter-from-session/navigation"
+
+<h3>SupplyParameterFromSessionNavigationComponent</h3>
+
+<p id="text-email">@Email</p>
+
+@code {
+    [SupplyParameterFromSession]
+    public string? Email { get; set; }
+}

From b47e153c1043518c037224f978bee8ee4b0a70e6 Mon Sep 17 00:00:00 2001
From: Daria Tiurina <dariatiurina@microsoft.com>
Date: Fri, 23 Jan 2026 17:03:30 +0100
Subject: [PATCH 05/11] Fixes callbacks and added new tests

---
 .../Endpoints/src/SessionValueMapper.cs       |  83 +++--
 .../Endpoints/test/SessionValueMapperTest.cs  | 293 ++++++++++++++++++
 .../Web/src/PublicAPI.Unshipped.txt           |   1 -
 .../Web/src/Session/ISessionValueMapper.cs    |   7 -
 ...SupplyParameterFromSessionValueProvider.cs |  18 +-
 ...SupplyParameterFromSessionAttributeTest.cs |  27 ++
 ...omponentEndpointsNoInteractivityStartup.cs |  17 +-
 .../SupplyParameterFromSessionComponent.razor |  59 +++-
 ...ameterFromSessionNavigationComponent.razor |  13 +
 9 files changed, 467 insertions(+), 51 deletions(-)
 create mode 100644 src/Components/Endpoints/test/SessionValueMapperTest.cs

diff --git a/src/Components/Endpoints/src/SessionValueMapper.cs b/src/Components/Endpoints/src/SessionValueMapper.cs
index 2fd88d8513a4..ff80d8556793 100644
--- a/src/Components/Endpoints/src/SessionValueMapper.cs
+++ b/src/Components/Endpoints/src/SessionValueMapper.cs
@@ -3,72 +3,89 @@
 
 using System.Text.Json;
 using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Http.Features;
+using Microsoft.Extensions.Logging;
 
 namespace Microsoft.AspNetCore.Components.Endpoints;
 
-internal class SessionValueMapper : ISessionValueMapper
+internal partial class SessionValueMapper : ISessionValueMapper
 {
     private static readonly JsonSerializerOptions _jsonOptions = new(JsonSerializerDefaults.Web);
     private HttpContext? _httpContext;
-    private readonly Dictionary<string, Func<object?>> _valueCallbacks = new();
+    private readonly Dictionary<string, List<Func<object?>>> _valueCallbacks = new();
+    private readonly ILogger<SessionValueMapper> _logger;
+
+    public SessionValueMapper(ILogger<SessionValueMapper> logger)
+    {
+        _logger = logger;
+    }
 
     internal void SetRequestContext(HttpContext httpContext)
     {
         _httpContext = httpContext;
-
-        // Register Response.OnStarting once to persist all values before response starts
         _httpContext.Response.OnStarting(PersistAllValues);
     }
 
     public object? GetValue(string sessionKey, Type type)
     {
-        var session = _httpContext?.Session;
+        var session = _httpContext?.Features.Get<ISessionFeature>()?.Session;
         if (session is null)
         {
             return null;
         }
-        var json = session.GetString(sessionKey);
-        if (string.IsNullOrEmpty(json))
+        try
+        {
+            var json = session.GetString(sessionKey);
+            if (string.IsNullOrEmpty(json))
+            {
+                return null;
+            }
+            return JsonSerializer.Deserialize(json, type, _jsonOptions);
+        }
+        catch (JsonException ex)
         {
+            Log.SessionDeserializeFail(_logger, ex);
             return null;
         }
-        return JsonSerializer.Deserialize(json, type, _jsonOptions);
     }
 
     public void RegisterValueCallback(string sessionKey, Func<object?> valueGetter)
     {
-        _valueCallbacks[sessionKey] = valueGetter;
-    }
-
-    public void SetValue(string sessionKey, object? value)
-    {
-        var session = _httpContext?.Session;
-        if (session is null)
+        if (!_valueCallbacks.TryGetValue(sessionKey, out var callbacks))
         {
-            return;
-        }
-        if (value is null)
-        {
-            session.Remove(sessionKey);
-        }
-        else
-        {
-            var json = JsonSerializer.Serialize(value, value.GetType(), _jsonOptions);
-            session.SetString(sessionKey, json);
+            callbacks = new List<Func<object?>>();
+            _valueCallbacks[sessionKey] = callbacks;
         }
+        callbacks.Add(valueGetter);
     }
 
     private Task PersistAllValues()
     {
-        var session = _httpContext?.Session;
+        var session = _httpContext?.Features.Get<ISessionFeature>()?.Session;
         if (session is null)
         {
             return Task.CompletedTask;
         }
 
-        foreach (var (key, valueGetter) in _valueCallbacks)
+        foreach (var (key, callbacks) in _valueCallbacks)
         {
-            var value = valueGetter();
+            object? value = null;
+            foreach (var valueGetter in callbacks)
+            {
+                try
+                {
+                    var candidateValue = valueGetter();
+                    if (candidateValue is not null)
+                    {
+                        value = candidateValue;
+                        break;
+                    }
+                }
+                catch (Exception ex)
+                {
+                    Log.SessionPersistFail(_logger, ex);
+                }
+            }
             if (value is not null)
             {
                 var json = JsonSerializer.Serialize(value, value.GetType(), _jsonOptions);
@@ -79,7 +96,15 @@ private Task PersistAllValues()
                 session.Remove(key);
             }
         }
-
         return Task.CompletedTask;
     }
+
+    private static partial class Log
+    {
+        [LoggerMessage(1, LogLevel.Warning, "Persisting of the element failed.", EventName = "SessionPersistFail")]
+        public static partial void SessionPersistFail(ILogger logger, Exception exception);
+
+        [LoggerMessage(2, LogLevel.Warning, "Deserialization of the element from Session failed.", EventName = "SessionDeserializeFail")]
+        public static partial void SessionDeserializeFail(ILogger logger, JsonException exception);
+    }
 }
diff --git a/src/Components/Endpoints/test/SessionValueMapperTest.cs b/src/Components/Endpoints/test/SessionValueMapperTest.cs
new file mode 100644
index 000000000000..68f6e7f36f99
--- /dev/null
+++ b/src/Components/Endpoints/test/SessionValueMapperTest.cs
@@ -0,0 +1,293 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#nullable enable
+
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Http.Features;
+
+namespace Microsoft.AspNetCore.Components.Endpoints;
+
+public class SessionValueMapperTest
+{
+    private SessionValueMapper GetSessionValueMapper()
+    {
+        return new SessionValueMapper(new Microsoft.Extensions.Logging.Abstractions.NullLogger<SessionValueMapper>());
+    }
+
+    [Fact]
+    public void GetValue_ReturnsNull_WhenKeyNotFound()
+    {
+        // Arrange
+        var mapper = GetSessionValueMapper();
+        var httpContext = CreateHttpContextWithSession();
+        mapper.SetRequestContext(httpContext);
+
+        // Act
+        var result = mapper.GetValue("nonexistent", typeof(string));
+
+        // Assert
+        Assert.Null(result);
+    }
+
+    [Fact]
+    public void GetValue_ReturnsDeserializedValue_WhenKeyExists()
+    {
+        // Arrange
+        var mapper = GetSessionValueMapper();
+        var httpContext = CreateHttpContextWithSession();
+        httpContext.Session.SetString("email", "\"test@example.com\"");
+        mapper.SetRequestContext(httpContext);
+
+        // Act
+        var result = mapper.GetValue("email", typeof(string));
+
+        // Assert
+        Assert.Equal("test@example.com", result);
+    }
+
+    [Fact]
+    public void GetValue_DeserializesComplexType()
+    {
+        // Arrange
+        var mapper = GetSessionValueMapper();
+        var httpContext = CreateHttpContextWithSession();
+        httpContext.Session.SetString("user", "{\"name\":\"John\",\"age\":30}");
+        mapper.SetRequestContext(httpContext);
+
+        // Act
+        var result = mapper.GetValue("user", typeof(TestUser));
+
+        // Assert
+        var user = Assert.IsType<TestUser>(result);
+        Assert.Equal("John", user.Name);
+        Assert.Equal(30, user.Age);
+    }
+
+    [Fact]
+    public void RegisterValueCallback_AddsCallbackToList()
+    {
+        // Arrange
+        var mapper = GetSessionValueMapper();
+        var callCount = 0;
+
+        // Act
+        mapper.RegisterValueCallback("key", () => { callCount++; return "value"; });
+
+        // Assert
+        Assert.Equal(0, callCount);
+    }
+
+    [Fact]
+    public async Task RegisterValueCallback_AllowsMultipleCallbacksForSameKey()
+    {
+        // Arrange
+        var mapper = GetSessionValueMapper();
+        var httpContext = CreateHttpContextWithSession(out var responseFeature);
+        mapper.SetRequestContext(httpContext);
+
+        var callOrder = new List<int>();
+        mapper.RegisterValueCallback("key", () => { callOrder.Add(1); return null; });
+        mapper.RegisterValueCallback("key", () => { callOrder.Add(2); return "value2"; });
+        mapper.RegisterValueCallback("key", () => { callOrder.Add(3); return "value3"; });
+
+        // Act
+        await responseFeature.FireOnStartingAsync();
+
+        // Assert
+        Assert.Equal(new[] { 1, 2 }, callOrder);
+        Assert.Equal("\"value2\"", httpContext.Session.GetString("key"));
+    }
+
+    [Fact]
+    public async Task PersistAllValues_PersistsFirstNonNullValue()
+    {
+        // Arrange
+        var mapper = GetSessionValueMapper();
+        var httpContext = CreateHttpContextWithSession(out var responseFeature);
+        mapper.SetRequestContext(httpContext);
+
+        mapper.RegisterValueCallback("email", () => null);
+        mapper.RegisterValueCallback("email", () => "test@example.com");
+        mapper.RegisterValueCallback("email", () => "other@example.com");
+
+        // Act
+        await responseFeature.FireOnStartingAsync();
+
+        // Assert
+        Assert.Equal("\"test@example.com\"", httpContext.Session.GetString("email"));
+    }
+
+    [Fact]
+    public async Task PersistAllValues_RemovesKey_WhenAllCallbacksReturnNull()
+    {
+        // Arrange
+        var mapper = GetSessionValueMapper();
+        var httpContext = CreateHttpContextWithSession(out var responseFeature);
+        httpContext.Session.SetString("email", "\"existing@example.com\"");
+        mapper.SetRequestContext(httpContext);
+
+        mapper.RegisterValueCallback("email", () => null);
+        mapper.RegisterValueCallback("email", () => null);
+
+        // Act
+        await responseFeature.FireOnStartingAsync();
+
+        // Assert
+        Assert.Null(httpContext.Session.GetString("email"));
+    }
+
+    [Fact]
+    public async Task PersistAllValues_HandlesMultipleKeys()
+    {
+        // Arrange
+        var mapper = GetSessionValueMapper();
+        var httpContext = CreateHttpContextWithSession(out var responseFeature);
+        mapper.SetRequestContext(httpContext);
+
+        mapper.RegisterValueCallback("key1", () => "value1");
+        mapper.RegisterValueCallback("key2", () => "value2");
+
+        // Act
+        await responseFeature.FireOnStartingAsync();
+
+        // Assert
+        Assert.Equal("\"value1\"", httpContext.Session.GetString("key1"));
+        Assert.Equal("\"value2\"", httpContext.Session.GetString("key2"));
+    }
+
+    [Fact]
+    public async Task PersistAllValues_SerializesComplexTypes()
+    {
+        // Arrange
+        var mapper = GetSessionValueMapper();
+        var httpContext = CreateHttpContextWithSession(out var responseFeature);
+        mapper.SetRequestContext(httpContext);
+
+        mapper.RegisterValueCallback("user", () => new TestUser { Name = "Jane", Age = 25 });
+
+        // Act
+        await responseFeature.FireOnStartingAsync();
+
+        // Assert
+        var json = httpContext.Session.GetString("user");
+        Assert.NotNull(json);
+        Assert.Contains("\"name\":\"Jane\"", json);
+        Assert.Contains("\"age\":25", json);
+    }
+
+    [Fact]
+    public async Task HandlesIncorrectValuesInSession()
+    {
+        // Arrange
+        var mapper = GetSessionValueMapper();
+        var httpContext = CreateHttpContextWithSession(out var responseFeature);
+        mapper.SetRequestContext(httpContext);
+
+        mapper.RegisterValueCallback("number", () => "not-a-number");
+
+        // Act
+        await responseFeature.FireOnStartingAsync();
+        var result = mapper.GetValue("number", typeof(int));
+
+        // Assert
+        Assert.Null(result);
+    }
+
+    [Fact]
+    public async Task HandlesCallbackThrowing()
+    {
+        // Arrange
+        var mapper = GetSessionValueMapper();
+        var httpContext = CreateHttpContextWithSession(out var responseFeature);
+        mapper.SetRequestContext(httpContext);
+
+        mapper.RegisterValueCallback("number", () => throw new Exception("Callback exception"));
+
+        // Act
+        await responseFeature.FireOnStartingAsync();
+        var result = mapper.GetValue("number", typeof(int));
+
+        // Assert
+        Assert.Null(result);
+    }
+
+    private static DefaultHttpContext CreateHttpContextWithSession()
+    {
+        return CreateHttpContextWithSession(out _);
+    }
+
+    private static DefaultHttpContext CreateHttpContextWithSession(out TestHttpResponseFeature responseFeature)
+    {
+        var httpContext = new DefaultHttpContext();
+        var session = new TestSession();
+        httpContext.Features.Set<ISessionFeature>(new TestSessionFeature(session));
+
+        responseFeature = new TestHttpResponseFeature();
+        httpContext.Features.Set<IHttpResponseFeature>(responseFeature);
+
+        return httpContext;
+    }
+
+    private class TestUser
+    {
+        public string? Name { get; set; }
+        public int Age { get; set; }
+    }
+
+    private class TestSession : ISession
+    {
+        private readonly Dictionary<string, byte[]> _store = new();
+
+        public bool IsAvailable => true;
+        public string Id => "test-session";
+        public IEnumerable<string> Keys => _store.Keys;
+
+        public void Clear() => _store.Clear();
+        public Task CommitAsync(CancellationToken cancellationToken = default) => Task.CompletedTask;
+        public Task LoadAsync(CancellationToken cancellationToken = default) => Task.CompletedTask;
+        public void Remove(string key) => _store.Remove(key);
+        public void Set(string key, byte[] value) => _store[key] = value;
+        public bool TryGetValue(string key, [System.Diagnostics.CodeAnalysis.NotNullWhen(true)] out byte[]? value) => _store.TryGetValue(key, out value);
+    }
+
+    private class TestSessionFeature : ISessionFeature
+    {
+        public TestSessionFeature(ISession session)
+        {
+            Session = session;
+        }
+
+        public ISession Session { get; set; }
+    }
+
+    private class TestHttpResponseFeature : IHttpResponseFeature
+    {
+        private readonly Stack<(Func<object, Task> Callback, object State)> _onStarting = new();
+
+        public int StatusCode { get; set; } = 200;
+        public string? ReasonPhrase { get; set; }
+        public IHeaderDictionary Headers { get; set; } = new HeaderDictionary();
+        public Stream Body { get; set; } = new MemoryStream();
+        public bool HasStarted { get; private set; }
+
+        public void OnCompleted(Func<object, Task> callback, object state)
+        {
+        }
+
+        public void OnStarting(Func<object, Task> callback, object state)
+        {
+            _onStarting.Push((callback, state));
+        }
+
+        public async Task FireOnStartingAsync()
+        {
+            foreach (var (callback, state) in _onStarting)
+            {
+                await callback(state);
+            }
+            HasStarted = true;
+        }
+    }
+}
+
diff --git a/src/Components/Web/src/PublicAPI.Unshipped.txt b/src/Components/Web/src/PublicAPI.Unshipped.txt
index 2c192e70f361..e654d3486939 100644
--- a/src/Components/Web/src/PublicAPI.Unshipped.txt
+++ b/src/Components/Web/src/PublicAPI.Unshipped.txt
@@ -2,7 +2,6 @@
 Microsoft.AspNetCore.Components.ISessionValueMapper
 Microsoft.AspNetCore.Components.ISessionValueMapper.GetValue(string! sessionKey, System.Type! targetType) -> object?
 Microsoft.AspNetCore.Components.ISessionValueMapper.RegisterValueCallback(string! sessionKey, System.Func<object?>! valueGetter) -> void
-Microsoft.AspNetCore.Components.ISessionValueMapper.SetValue(string! sessionKey, object? value) -> void
 Microsoft.AspNetCore.Components.Web.EnvironmentBoundary
 Microsoft.AspNetCore.Components.Web.EnvironmentBoundary.ChildContent.get -> Microsoft.AspNetCore.Components.RenderFragment?
 Microsoft.AspNetCore.Components.Web.EnvironmentBoundary.ChildContent.set -> void
diff --git a/src/Components/Web/src/Session/ISessionValueMapper.cs b/src/Components/Web/src/Session/ISessionValueMapper.cs
index c4db9a2973dd..3ceade341174 100644
--- a/src/Components/Web/src/Session/ISessionValueMapper.cs
+++ b/src/Components/Web/src/Session/ISessionValueMapper.cs
@@ -16,13 +16,6 @@ public interface ISessionValueMapper
     /// <returns>The deserialized value, or null if not found.</returns>
     object? GetValue(string sessionKey, Type targetType);
 
-    /// <summary>
-    /// Stores the value in the session with the specified key.
-    /// </summary>
-    /// <param name="sessionKey">The session key.</param>
-    /// <param name="value">The value to store.</param>
-    void SetValue(string sessionKey, object? value);
-
     /// <summary>
     /// Registers a callback to retrieve the current value of a session property.
     /// The callback will be invoked when the response starts to persist the value.
diff --git a/src/Components/Web/src/Session/SupplyParameterFromSessionValueProvider.cs b/src/Components/Web/src/Session/SupplyParameterFromSessionValueProvider.cs
index 4a893a43dfc9..4242f459fb95 100644
--- a/src/Components/Web/src/Session/SupplyParameterFromSessionValueProvider.cs
+++ b/src/Components/Web/src/Session/SupplyParameterFromSessionValueProvider.cs
@@ -28,7 +28,7 @@ public bool CanSupplyValue(in CascadingParameterInfo parameterInfo)
         }
 
         var attribute = (SupplyParameterFromSessionAttribute)parameterInfo.Attribute;
-        var sessionKey = attribute.Name ?? parameterInfo.PropertyName;
+        var sessionKey = (attribute.Name ?? parameterInfo.PropertyName).ToLowerInvariant();
         return _sessionValueMapper.GetValue(sessionKey, parameterInfo.PropertyType);
     }
 
@@ -39,19 +39,21 @@ public bool CanSupplyValue(in CascadingParameterInfo parameterInfo)
     public void Subscribe(ComponentState subscriber, in CascadingParameterInfo parameterInfo)
     {
         var attribute = (SupplyParameterFromSessionAttribute)parameterInfo.Attribute;
-        var sessionKey = attribute.Name ?? parameterInfo.PropertyName;
-
-        // Capture these in the closure
-        var component = subscriber.Component;
+        var sessionKey = (attribute.Name ?? parameterInfo.PropertyName).ToLowerInvariant();
         var propertyName = parameterInfo.PropertyName;
-        var componentType = component.GetType();
-        var propertyInfo = componentType.GetProperty(propertyName);
+        var propertyInfo = subscriber.Component.GetType().GetProperty(propertyName);
 
         if (propertyInfo is null)
         {
             return;
         }
-        _sessionValueMapper.RegisterValueCallback(sessionKey, () => propertyInfo.GetValue(component));
+
+        var component = subscriber.Component;
+        _sessionValueMapper.RegisterValueCallback(sessionKey, () =>
+        {
+            var value = propertyInfo.GetValue(component);
+            return value;
+        });
     }
 
     public void Unsubscribe(ComponentState subscriber, in CascadingParameterInfo parameterInfo)
diff --git a/src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs b/src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs
index 8e7b7ba64ed1..d7fa5e740c9b 100644
--- a/src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs
+++ b/src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs
@@ -20,6 +20,12 @@ public SupplyParameterFromSessionAttributeTest(BrowserFixture browserFixture, Ba
     {
     }
 
+    protected override void InitializeAsyncCore()
+    {
+        _serverFixture.AdditionalArguments.Add("--UseSession=true");
+        base.InitializeAsyncCore();
+    }
+
     [Fact]
     public void SupplyParameterCanReadFromSession()
     {
@@ -58,4 +64,25 @@ public void SupplyParameterWorksWithRedirect()
         Browser.Exists(By.Id("set-email-redirect")).Click();
         Browser.Equal("email", () => Browser.Exists(By.Id("text-email")).Text);
     }
+
+    [Fact]
+    public void SupplyParameterWorksWithComplexTypes()
+    {
+        Navigate($"{ServerPathBase}/supply-parameter-from-session");
+        Browser.Exists(By.Id("input-testclass-email")).SendKeys("email");
+        Browser.Exists(By.Id("input-testclass-age")).SendKeys("30");
+        Browser.Exists(By.Id("set-testclass-object")).Click();
+        Browser.Equal("email", () => Browser.Exists(By.Id("text-testclass-email")).Text);
+        Browser.Equal("30", () => Browser.Exists(By.Id("text-testclass-age")).Text);
+    }
+
+    [Fact]
+    public void SupplyParameterPersistThroughNavigationAndBack()
+    {
+        Navigate($"{ServerPathBase}/supply-parameter-from-session");
+        Browser.Exists(By.Id("input-number")).SendKeys("12345");
+        Browser.Exists(By.Id("set-number")).Click();
+        Browser.Exists(By.Id("redirect")).Click();
+        Browser.Equal("12345", () => Browser.Exists(By.Id("text-number")).Text);
+    }
 }
diff --git a/src/Components/test/testassets/Components.TestServer/RazorComponentEndpointsNoInteractivityStartup.cs b/src/Components/test/testassets/Components.TestServer/RazorComponentEndpointsNoInteractivityStartup.cs
index 841fc524748d..84df9c7cb20b 100644
--- a/src/Components/test/testassets/Components.TestServer/RazorComponentEndpointsNoInteractivityStartup.cs
+++ b/src/Components/test/testassets/Components.TestServer/RazorComponentEndpointsNoInteractivityStartup.cs
@@ -35,11 +35,15 @@ public void ConfigureServices(IServiceCollection services)
         services.AddHttpContextAccessor();
         services.AddCascadingAuthenticationState();
         services.AddDistributedMemoryCache();
-        services.AddSession(options =>
+
+        if (Configuration.GetValue<bool>("UseSession"))
         {
-            options.Cookie.HttpOnly = true;
-            options.Cookie.IsEssential = true;
-        });
+            services.AddSession(options =>
+            {
+                options.Cookie.HttpOnly = true;
+                options.Cookie.IsEssential = true;
+            });
+        }
     }
 
     // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
@@ -95,7 +99,10 @@ public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
                 });
             });
 
-            app.UseSession();
+            if (Configuration.GetValue<bool>("UseSession"))
+            {
+                app.UseSession();
+            }
 
             ConfigureSubdirPipeline(app, env);
         });
diff --git a/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor b/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor
index db46c864c88f..69dc4a85c1a7 100644
--- a/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor
+++ b/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor
@@ -8,6 +8,10 @@
 <p id="text-email">@Email</p>
 <p id="text-another-email">@AnotherEmail</p>
 <p id="text-null">@NoElement</p>
+<p id="text-number">@Number</p>
+
+<p id="text-testclass-email">@TestClassObject?.Email</p>
+<p id="text-testclass-age">@TestClassObject?.Age</p>
 
 <form @onsubmit="SetEmail" @formname="set-email" method="post">
     <AntiforgeryToken />
@@ -21,35 +25,69 @@
     <button type="submit" id="set-another-email">Set Email</button>
 </form>
 
+<form @onsubmit="SetNumber" @formname="set-number" method="post">
+    <AntiforgeryToken />
+    <input id="input-number" @bind="NumberInput" name="NumberInput" />
+    <button type="submit" id="set-number">Set Number</button>
+</form>
+
 <form @onsubmit="SetEmailWithRedirect" @formname="set-email-redirect" method="post">
     <AntiforgeryToken />
     <input id="input-email-redirect" @bind="EmailInput" name="EmailInput" />
     <button type="submit" id="set-email-redirect">Set Email</button>
 </form>
 
+<form @onsubmit="SetTestClassObject" @formname="set-testclass-object" method="post">
+    <AntiforgeryToken />
+    <input id="input-testclass-email" @bind="EmailInput" name="EmailInput" />
+    <input id="input-testclass-age" @bind="AgeInput" name="AgeInput" />
+    <button type="submit" id="set-testclass-object">Set TestClass Object</button>
+</form>
+
 @code {
     [SupplyParameterFromSession]
     public string? Email { get; set; }
 
-    [SupplyParameterFromSession(Name = "Email")]
+    [SupplyParameterFromSession(Name = "email")]
     public string? AnotherEmail { get; set; }
 
     [SupplyParameterFromSession]
     public string? NoElement { get; set; }
 
+    [SupplyParameterFromSession]
+    public int? Number { get; set; }
+
     [SupplyParameterFromForm]
     public string? EmailInput { get; set; }
 
+    [SupplyParameterFromForm]
+    public int? NumberInput { get; set; }
+
+    [SupplyParameterFromForm]
+    public int? AgeInput { get; set; }
+
+    [SupplyParameterFromSession]
+    public TestClass? TestClassObject { get; set; }
+
     void SetEmail()
     {
         Email = EmailInput;
         EmailInput = string.Empty;
+        NavigationManager.NavigateTo("/subdir/supply-parameter-from-session", forceLoad: true);
     }
 
     void SetAnotherEmail()
     {
         AnotherEmail = EmailInput;
         EmailInput = string.Empty;
+        NavigationManager.NavigateTo("/subdir/supply-parameter-from-session", forceLoad: true);
+    }
+
+    void SetNumber()
+    {
+        Number = NumberInput;
+        NumberInput = null;
+        NavigationManager.NavigateTo("/subdir/supply-parameter-from-session/navigation", forceLoad: true);
     }
 
     void SetEmailWithRedirect()
@@ -58,4 +96,23 @@
         EmailInput = string.Empty;
         NavigationManager.NavigateTo("/subdir/supply-parameter-from-session/navigation", forceLoad: true);
     }
+
+    void SetTestClassObject()
+    {
+        if (TestClassObject == null)
+        {
+            TestClassObject = new TestClass();
+        }
+        TestClassObject.Email = EmailInput;
+        TestClassObject.Age = AgeInput;
+        EmailInput = string.Empty;
+        AgeInput = null;
+        NavigationManager.NavigateTo("/subdir/supply-parameter-from-session", forceLoad: true);
+    }
+
+    public class TestClass
+    {
+        public string? Email { get; set; }
+        public int? Age { get; set; }
+    }
 }
diff --git a/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionNavigationComponent.razor b/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionNavigationComponent.razor
index 4918d4c3901c..4bdd6697b8be 100644
--- a/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionNavigationComponent.razor
+++ b/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionNavigationComponent.razor
@@ -1,10 +1,23 @@
 @page "/supply-parameter-from-session/navigation"
+@using Microsoft.AspNetCore.Components.Forms
+@inject NavigationManager NavigationManager
 
 <h3>SupplyParameterFromSessionNavigationComponent</h3>
 
 <p id="text-email">@Email</p>
 
+<form @onsubmit="Redirect" @formname="redirect" method="post">
+    <AntiforgeryToken />
+    <button type="submit" id="redirect">Set Email</button>
+</form>
+
 @code {
     [SupplyParameterFromSession]
     public string? Email { get; set; }
+
+
+    void Redirect()
+    {
+        NavigationManager.NavigateTo("/subdir/supply-parameter-from-session");
+    }
 }

From 3ee272da2ac746b20421bb1536554e9960126903 Mon Sep 17 00:00:00 2001
From: Daria Tiurina <dariatiurina@microsoft.com>
Date: Mon, 9 Feb 2026 17:57:49 +0100
Subject: [PATCH 06/11] Small fixes

---
 .../Microsoft.AspNetCore.Components.csproj    |  1 +
 .../Endpoints/src/PublicAPI.Unshipped.txt     |  6 ++++++
 .../src/Rendering/EndpointComponentState.cs   |  2 +-
 .../EndpointHtmlRenderer.Prerendering.cs      |  4 ++--
 .../src/Rendering/EndpointHtmlRenderer.cs     |  2 +-
 .../src/Session/ISessionValueMapper.cs        | 12 +++++------
 .../src/{ => Session}/SessionValueMapper.cs   |  5 +++++
 ...rFromSessionServiceCollectionExtensions.cs |  6 ++----
 ...SupplyParameterFromSessionValueProvider.cs | 20 ++++++++++---------
 .../Web/src/PublicAPI.Unshipped.txt           |  5 -----
 10 files changed, 35 insertions(+), 28 deletions(-)
 rename src/Components/{Web => Endpoints}/src/Session/ISessionValueMapper.cs (65%)
 rename src/Components/Endpoints/src/{ => Session}/SessionValueMapper.cs (96%)
 rename src/Components/{Web => Endpoints}/src/Session/SupplyParameterFromSessionServiceCollectionExtensions.cs (88%)
 rename src/Components/{Web => Endpoints}/src/Session/SupplyParameterFromSessionValueProvider.cs (77%)

diff --git a/src/Components/Components/src/Microsoft.AspNetCore.Components.csproj b/src/Components/Components/src/Microsoft.AspNetCore.Components.csproj
index ba3ae6420645..58010a3bef6c 100644
--- a/src/Components/Components/src/Microsoft.AspNetCore.Components.csproj
+++ b/src/Components/Components/src/Microsoft.AspNetCore.Components.csproj
@@ -68,6 +68,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <InternalsVisibleTo Include="Microsoft.AspNetCore.Components.Endpoints" />
     <InternalsVisibleTo Include="Microsoft.AspNetCore.Components.Web" />
     <InternalsVisibleTo Include="Microsoft.AspNetCore.Blazor.Build.Tests" />
     <InternalsVisibleTo Include="Microsoft.AspNetCore.Components.Authorization.Tests" />
diff --git a/src/Components/Endpoints/src/PublicAPI.Unshipped.txt b/src/Components/Endpoints/src/PublicAPI.Unshipped.txt
index 2ebef8b69595..d6fa4f7da8b5 100644
--- a/src/Components/Endpoints/src/PublicAPI.Unshipped.txt
+++ b/src/Components/Endpoints/src/PublicAPI.Unshipped.txt
@@ -1,10 +1,15 @@
 #nullable enable
 Microsoft.AspNetCore.Components.Endpoints.BasePath
 Microsoft.AspNetCore.Components.Endpoints.BasePath.BasePath() -> void
+Microsoft.AspNetCore.Components.Endpoints.ISessionValueMapper
+Microsoft.AspNetCore.Components.Endpoints.ISessionValueMapper.DeleteValueCallback(string! sessionKey) -> void
+Microsoft.AspNetCore.Components.Endpoints.ISessionValueMapper.GetValue(string! sessionKey, System.Type! targetType) -> object?
+Microsoft.AspNetCore.Components.Endpoints.ISessionValueMapper.RegisterValueCallback(string! sessionKey, System.Func<object?>! valueGetter) -> void
 Microsoft.AspNetCore.Components.Endpoints.RazorComponentsServiceOptions.TempDataCookie.get -> Microsoft.AspNetCore.Http.CookieBuilder!
 Microsoft.AspNetCore.Components.Endpoints.RazorComponentsServiceOptions.TempDataCookie.set -> void
 Microsoft.AspNetCore.Components.Endpoints.RazorComponentsServiceOptions.TempDataProviderType.get -> Microsoft.AspNetCore.Components.Endpoints.TempDataProviderType
 Microsoft.AspNetCore.Components.Endpoints.RazorComponentsServiceOptions.TempDataProviderType.set -> void
+Microsoft.AspNetCore.Components.Endpoints.SupplyParameterFromSessionServiceCollectionExtensions
 Microsoft.AspNetCore.Components.Endpoints.TempDataProviderType
 Microsoft.AspNetCore.Components.Endpoints.TempDataProviderType.Cookie = 0 -> Microsoft.AspNetCore.Components.Endpoints.TempDataProviderType
 Microsoft.AspNetCore.Components.Endpoints.TempDataProviderType.SessionStorage = 1 -> Microsoft.AspNetCore.Components.Endpoints.TempDataProviderType
@@ -13,3 +18,4 @@ Microsoft.AspNetCore.Components.ITempData.Get(string! key) -> object?
 Microsoft.AspNetCore.Components.ITempData.Keep() -> void
 Microsoft.AspNetCore.Components.ITempData.Keep(string! key) -> void
 Microsoft.AspNetCore.Components.ITempData.Peek(string! key) -> object?
+static Microsoft.AspNetCore.Components.Endpoints.SupplyParameterFromSessionServiceCollectionExtensions.AddSupplyValueFromSessionProvider(this Microsoft.Extensions.DependencyInjection.IServiceCollection! services) -> Microsoft.Extensions.DependencyInjection.IServiceCollection!
diff --git a/src/Components/Endpoints/src/Rendering/EndpointComponentState.cs b/src/Components/Endpoints/src/Rendering/EndpointComponentState.cs
index 6c03d0585f2f..d85f67c4400d 100644
--- a/src/Components/Endpoints/src/Rendering/EndpointComponentState.cs
+++ b/src/Components/Endpoints/src/Rendering/EndpointComponentState.cs
@@ -47,7 +47,7 @@ public EndpointComponentState(Renderer renderer, int componentId, IComponent com
 
     public bool StreamRendering { get; }
 
-    protected override object? GetComponentKey()
+    protected internal override object? GetComponentKey()
     {
         if (ParentComponentState != null && ParentComponentState.Component is SSRRenderModeBoundary boundary)
         {
diff --git a/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.Prerendering.cs b/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.Prerendering.cs
index 0276cdfd1515..1fc08b49d889 100644
--- a/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.Prerendering.cs
+++ b/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.Prerendering.cs
@@ -18,7 +18,7 @@ internal partial class EndpointHtmlRenderer
 {
     private static readonly object ComponentSequenceKey = new object();
 
-    protected override IComponent ResolveComponentForRenderMode([DynamicallyAccessedMembers(Component)] Type componentType, int? parentComponentId, IComponentActivator componentActivator, IComponentRenderMode renderMode)
+    protected internal override IComponent ResolveComponentForRenderMode([DynamicallyAccessedMembers(Component)] Type componentType, int? parentComponentId, IComponentActivator componentActivator, IComponentRenderMode renderMode)
     {
         if (_isHandlingErrors)
         {
@@ -42,7 +42,7 @@ protected override IComponent ResolveComponentForRenderMode([DynamicallyAccessed
         }
     }
 
-    protected override IComponentRenderMode? GetComponentRenderMode(IComponent component)
+    protected internal override IComponentRenderMode? GetComponentRenderMode(IComponent component)
     {
         var componentState = GetComponentState(component);
         var ssrRenderBoundary = GetClosestRenderModeBoundary(componentState);
diff --git a/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.cs b/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.cs
index b8fc15aacf16..8a6eb4dc5b26 100644
--- a/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.cs
+++ b/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.cs
@@ -166,7 +166,7 @@ protected override ComponentState CreateComponentState(int componentId, ICompone
         => new EndpointComponentState(this, componentId, component, parentComponentState);
 
     /// <inheritdoc/>
-    protected override ResourceAssetCollection Assets =>
+    protected internal override ResourceAssetCollection Assets =>
         _resourceCollection ??= GetResourceCollection(_httpContext) ?? base.Assets;
 
     private static ResourceAssetCollection? GetResourceCollection(HttpContext httpContext) => httpContext.GetEndpoint()?.Metadata.GetMetadata<ResourceAssetCollection>();
diff --git a/src/Components/Web/src/Session/ISessionValueMapper.cs b/src/Components/Endpoints/src/Session/ISessionValueMapper.cs
similarity index 65%
rename from src/Components/Web/src/Session/ISessionValueMapper.cs
rename to src/Components/Endpoints/src/Session/ISessionValueMapper.cs
index 3ceade341174..956ecbc40b5e 100644
--- a/src/Components/Web/src/Session/ISessionValueMapper.cs
+++ b/src/Components/Endpoints/src/Session/ISessionValueMapper.cs
@@ -1,7 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-namespace Microsoft.AspNetCore.Components;
+namespace Microsoft.AspNetCore.Components.Endpoints;
 
 /// <summary>
 /// Maps session data values to a model.
@@ -11,16 +11,16 @@ public interface ISessionValueMapper
     /// <summary>
     /// Returns the session value with the specified name, deserialized to the specified type.
     /// </summary>
-    /// <param name="sessionKey">The session key.</param>
-    /// <param name="targetType">The type to deserialize to.</param>
-    /// <returns>The deserialized value, or null if not found.</returns>
     object? GetValue(string sessionKey, Type targetType);
 
     /// <summary>
     /// Registers a callback to retrieve the current value of a session property.
     /// The callback will be invoked when the response starts to persist the value.
     /// </summary>
-    /// <param name="sessionKey">The session key.</param>
-    /// <param name="valueGetter">A function that returns the current value.</param>
     void RegisterValueCallback(string sessionKey, Func<object?> valueGetter);
+
+    /// <summary>
+    /// Unregisters a previously registered callback for the specified session key.
+    /// </summary>
+    void DeleteValueCallback(string sessionKey);
 }
diff --git a/src/Components/Endpoints/src/SessionValueMapper.cs b/src/Components/Endpoints/src/Session/SessionValueMapper.cs
similarity index 96%
rename from src/Components/Endpoints/src/SessionValueMapper.cs
rename to src/Components/Endpoints/src/Session/SessionValueMapper.cs
index ff80d8556793..4dbeaabb2362 100644
--- a/src/Components/Endpoints/src/SessionValueMapper.cs
+++ b/src/Components/Endpoints/src/Session/SessionValueMapper.cs
@@ -59,6 +59,11 @@ public void RegisterValueCallback(string sessionKey, Func<object?> valueGetter)
         callbacks.Add(valueGetter);
     }
 
+    public void DeleteValueCallback(string sessionKey)
+    {
+        _valueCallbacks.Remove(sessionKey);
+    }
+
     private Task PersistAllValues()
     {
         var session = _httpContext?.Features.Get<ISessionFeature>()?.Session;
diff --git a/src/Components/Web/src/Session/SupplyParameterFromSessionServiceCollectionExtensions.cs b/src/Components/Endpoints/src/Session/SupplyParameterFromSessionServiceCollectionExtensions.cs
similarity index 88%
rename from src/Components/Web/src/Session/SupplyParameterFromSessionServiceCollectionExtensions.cs
rename to src/Components/Endpoints/src/Session/SupplyParameterFromSessionServiceCollectionExtensions.cs
index a6dd64a9794b..10fb4f99fb20 100644
--- a/src/Components/Web/src/Session/SupplyParameterFromSessionServiceCollectionExtensions.cs
+++ b/src/Components/Endpoints/src/Session/SupplyParameterFromSessionServiceCollectionExtensions.cs
@@ -1,11 +1,9 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-using Microsoft.AspNetCore.Components;
-using Microsoft.AspNetCore.Components.Web;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.DependencyInjection.Extensions;
-
-namespace Microsoft.Extensions.DependencyInjection;
+namespace Microsoft.AspNetCore.Components.Endpoints;
 
 /// <summary>
 /// Enables component parameters to be supplied from the session with <see cref="SupplyParameterFromSessionAttribute"/>.
diff --git a/src/Components/Web/src/Session/SupplyParameterFromSessionValueProvider.cs b/src/Components/Endpoints/src/Session/SupplyParameterFromSessionValueProvider.cs
similarity index 77%
rename from src/Components/Web/src/Session/SupplyParameterFromSessionValueProvider.cs
rename to src/Components/Endpoints/src/Session/SupplyParameterFromSessionValueProvider.cs
index 4242f459fb95..4004331fd944 100644
--- a/src/Components/Web/src/Session/SupplyParameterFromSessionValueProvider.cs
+++ b/src/Components/Endpoints/src/Session/SupplyParameterFromSessionValueProvider.cs
@@ -2,9 +2,10 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Diagnostics.CodeAnalysis;
+using Microsoft.AspNetCore.Components.Reflection;
 using Microsoft.AspNetCore.Components.Rendering;
 
-namespace Microsoft.AspNetCore.Components.Web;
+namespace Microsoft.AspNetCore.Components.Endpoints;
 
 internal class SupplyParameterFromSessionValueProvider : ICascadingValueSupplier
 {
@@ -28,7 +29,7 @@ public bool CanSupplyValue(in CascadingParameterInfo parameterInfo)
         }
 
         var attribute = (SupplyParameterFromSessionAttribute)parameterInfo.Attribute;
-        var sessionKey = (attribute.Name ?? parameterInfo.PropertyName).ToLowerInvariant();
+        var sessionKey = (attribute.Name ?? parameterInfo.PropertyName) ?? "";
         return _sessionValueMapper.GetValue(sessionKey, parameterInfo.PropertyType);
     }
 
@@ -39,9 +40,10 @@ public bool CanSupplyValue(in CascadingParameterInfo parameterInfo)
     public void Subscribe(ComponentState subscriber, in CascadingParameterInfo parameterInfo)
     {
         var attribute = (SupplyParameterFromSessionAttribute)parameterInfo.Attribute;
-        var sessionKey = (attribute.Name ?? parameterInfo.PropertyName).ToLowerInvariant();
+        var sessionKey = (attribute.Name ?? parameterInfo.PropertyName) ?? "";
         var propertyName = parameterInfo.PropertyName;
-        var propertyInfo = subscriber.Component.GetType().GetProperty(propertyName);
+        var componentType = subscriber.Component.GetType();
+        var propertyInfo = componentType.GetProperty(propertyName);
 
         if (propertyInfo is null)
         {
@@ -49,14 +51,14 @@ public void Subscribe(ComponentState subscriber, in CascadingParameterInfo param
         }
 
         var component = subscriber.Component;
-        _sessionValueMapper.RegisterValueCallback(sessionKey, () =>
-        {
-            var value = propertyInfo.GetValue(component);
-            return value;
-        });
+        var getter = new PropertyGetter(componentType, propertyInfo);
+        _sessionValueMapper.RegisterValueCallback(sessionKey, () => getter.GetValue(component));
     }
 
     public void Unsubscribe(ComponentState subscriber, in CascadingParameterInfo parameterInfo)
     {
+        var attribute = (SupplyParameterFromSessionAttribute)parameterInfo.Attribute;
+        var sessionKey = (attribute.Name ?? parameterInfo.PropertyName) ?? "";
+        _sessionValueMapper.DeleteValueCallback(sessionKey);
     }
 }
diff --git a/src/Components/Web/src/PublicAPI.Unshipped.txt b/src/Components/Web/src/PublicAPI.Unshipped.txt
index 1f1c48a41bca..b4c6d1f43c3a 100644
--- a/src/Components/Web/src/PublicAPI.Unshipped.txt
+++ b/src/Components/Web/src/PublicAPI.Unshipped.txt
@@ -1,7 +1,4 @@
 #nullable enable
-Microsoft.AspNetCore.Components.ISessionValueMapper
-Microsoft.AspNetCore.Components.ISessionValueMapper.GetValue(string! sessionKey, System.Type! targetType) -> object?
-Microsoft.AspNetCore.Components.ISessionValueMapper.RegisterValueCallback(string! sessionKey, System.Func<object?>! valueGetter) -> void
 Microsoft.AspNetCore.Components.Web.EnvironmentBoundary
 Microsoft.AspNetCore.Components.Web.EnvironmentBoundary.ChildContent.get -> Microsoft.AspNetCore.Components.RenderFragment?
 Microsoft.AspNetCore.Components.Web.EnvironmentBoundary.ChildContent.set -> void
@@ -12,8 +9,6 @@ Microsoft.AspNetCore.Components.Web.EnvironmentBoundary.Include.get -> string?
 Microsoft.AspNetCore.Components.Web.EnvironmentBoundary.Include.set -> void
 Microsoft.AspNetCore.Components.Routing.NavLink.RelativeToCurrentUri.get -> bool
 Microsoft.AspNetCore.Components.Routing.NavLink.RelativeToCurrentUri.set -> void
-Microsoft.Extensions.DependencyInjection.SupplyParameterFromSessionServiceCollectionExtensions
-static Microsoft.Extensions.DependencyInjection.SupplyParameterFromSessionServiceCollectionExtensions.AddSupplyValueFromSessionProvider(this Microsoft.Extensions.DependencyInjection.IServiceCollection! services) -> Microsoft.Extensions.DependencyInjection.IServiceCollection!
 *REMOVED*Microsoft.AspNetCore.Components.Forms.RemoteBrowserFileStreamOptions
 *REMOVED*Microsoft.AspNetCore.Components.Forms.RemoteBrowserFileStreamOptions.MaxBufferSize.get -> int
 *REMOVED*Microsoft.AspNetCore.Components.Forms.RemoteBrowserFileStreamOptions.MaxBufferSize.set -> void

From 5f9ca6007c4a3b6217eaaa6b6896300b18847bbd Mon Sep 17 00:00:00 2001
From: Daria Tiurina <dariatiurina@microsoft.com>
Date: Wed, 11 Feb 2026 20:25:18 +0100
Subject: [PATCH 07/11] Fixes

---
 .../SupplyParameterFromSessionAttribute.cs    |  2 +-
 .../src/Session/SessionValueMapper.cs         | 36 +++++++------------
 ...SupplyParameterFromSessionValueProvider.cs |  5 ---
 ...SupplyParameterFromSessionAttributeTest.cs | 11 ------
 .../Tests/TempDataSessionStorageTest.cs       |  1 +
 ...omponentEndpointsNoInteractivityStartup.cs |  4 +--
 .../SupplyParameterFromSessionComponent.razor | 18 ----------
 ...ameterFromSessionNavigationComponent.razor |  2 +-
 8 files changed, 18 insertions(+), 61 deletions(-)

diff --git a/src/Components/Components/src/SupplyParameterFromSessionAttribute.cs b/src/Components/Components/src/SupplyParameterFromSessionAttribute.cs
index 8e1f7820c3fb..50faa0b4dd4d 100644
--- a/src/Components/Components/src/SupplyParameterFromSessionAttribute.cs
+++ b/src/Components/Components/src/SupplyParameterFromSessionAttribute.cs
@@ -11,7 +11,7 @@ namespace Microsoft.AspNetCore.Components;
 public sealed class SupplyParameterFromSessionAttribute : CascadingParameterAttributeBase
 {
     /// <summary>
-    /// Gets or sets the name of the session attribute. If not specified, the property name will be used.
+    /// Gets or sets the name of the session key. If not specified, the property name will be used.
     /// </summary>
     public string? Name { get; set; }
 
diff --git a/src/Components/Endpoints/src/Session/SessionValueMapper.cs b/src/Components/Endpoints/src/Session/SessionValueMapper.cs
index 4dbeaabb2362..368ae831328a 100644
--- a/src/Components/Endpoints/src/Session/SessionValueMapper.cs
+++ b/src/Components/Endpoints/src/Session/SessionValueMapper.cs
@@ -12,7 +12,7 @@ internal partial class SessionValueMapper : ISessionValueMapper
 {
     private static readonly JsonSerializerOptions _jsonOptions = new(JsonSerializerDefaults.Web);
     private HttpContext? _httpContext;
-    private readonly Dictionary<string, List<Func<object?>>> _valueCallbacks = new();
+    private readonly Dictionary<string, Func<object?>> _valueCallbacks = new(StringComparer.OrdinalIgnoreCase);
     private readonly ILogger<SessionValueMapper> _logger;
 
     public SessionValueMapper(ILogger<SessionValueMapper> logger)
@@ -35,7 +35,7 @@ internal void SetRequestContext(HttpContext httpContext)
         }
         try
         {
-            var json = session.GetString(sessionKey);
+            var json = session.GetString(sessionKey.ToLowerInvariant());
             if (string.IsNullOrEmpty(json))
             {
                 return null;
@@ -51,12 +51,10 @@ internal void SetRequestContext(HttpContext httpContext)
 
     public void RegisterValueCallback(string sessionKey, Func<object?> valueGetter)
     {
-        if (!_valueCallbacks.TryGetValue(sessionKey, out var callbacks))
+        if (!_valueCallbacks.TryAdd(sessionKey, valueGetter))
         {
-            callbacks = new List<Func<object?>>();
-            _valueCallbacks[sessionKey] = callbacks;
+            throw new InvalidOperationException($"A callback is already registered for the session key '{sessionKey}'. Multiple components cannot use the same session key.");
         }
-        callbacks.Add(valueGetter);
     }
 
     public void DeleteValueCallback(string sessionKey)
@@ -72,33 +70,25 @@ private Task PersistAllValues()
             return Task.CompletedTask;
         }
 
-        foreach (var (key, callbacks) in _valueCallbacks)
+        foreach (var (key, valueGetter) in _valueCallbacks)
         {
             object? value = null;
-            foreach (var valueGetter in callbacks)
+            try
             {
-                try
-                {
-                    var candidateValue = valueGetter();
-                    if (candidateValue is not null)
-                    {
-                        value = candidateValue;
-                        break;
-                    }
-                }
-                catch (Exception ex)
-                {
-                    Log.SessionPersistFail(_logger, ex);
-                }
+                value = valueGetter();
+            }
+            catch (Exception ex)
+            {
+                Log.SessionPersistFail(_logger, ex);
             }
             if (value is not null)
             {
                 var json = JsonSerializer.Serialize(value, value.GetType(), _jsonOptions);
-                session.SetString(key, json);
+                session.SetString(key.ToLowerInvariant(), json);
             }
             else
             {
-                session.Remove(key);
+                session.Remove(key.ToLowerInvariant());
             }
         }
         return Task.CompletedTask;
diff --git a/src/Components/Endpoints/src/Session/SupplyParameterFromSessionValueProvider.cs b/src/Components/Endpoints/src/Session/SupplyParameterFromSessionValueProvider.cs
index 4004331fd944..180d25dc58c4 100644
--- a/src/Components/Endpoints/src/Session/SupplyParameterFromSessionValueProvider.cs
+++ b/src/Components/Endpoints/src/Session/SupplyParameterFromSessionValueProvider.cs
@@ -23,11 +23,6 @@ public bool CanSupplyValue(in CascadingParameterInfo parameterInfo)
 
     public object? GetCurrentValue(object? key, in CascadingParameterInfo parameterInfo)
     {
-        if (_sessionValueMapper is null)
-        {
-            return null;
-        }
-
         var attribute = (SupplyParameterFromSessionAttribute)parameterInfo.Attribute;
         var sessionKey = (attribute.Name ?? parameterInfo.PropertyName) ?? "";
         return _sessionValueMapper.GetValue(sessionKey, parameterInfo.PropertyType);
diff --git a/src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs b/src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs
index d7fa5e740c9b..f8537fd2ba23 100644
--- a/src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs
+++ b/src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs
@@ -45,17 +45,6 @@ public void SupplyParameterNullWhenNoKeyInSession()
         Browser.Equal("", () => Browser.Exists(By.Id("text-null")).Text);
     }
 
-    [Fact]
-    public void SupplyParameterWorksWhenDifferentName()
-    {
-        Navigate($"{ServerPathBase}/supply-parameter-from-session");
-        Browser.Exists(By.Id("input-another-email")).SendKeys("email");
-        Browser.Exists(By.Id("set-another-email")).Click();
-        Browser.Equal("email", () => Browser.Exists(By.Id("text-another-email")).Text);
-        Browser.Equal("email", () => Browser.Exists(By.Id("text-email")).Text);
-        Browser.Equal("", () => Browser.Exists(By.Id("text-null")).Text);
-    }
-
     [Fact]
     public void SupplyParameterWorksWithRedirect()
     {
diff --git a/src/Components/test/E2ETest/Tests/TempDataSessionStorageTest.cs b/src/Components/test/E2ETest/Tests/TempDataSessionStorageTest.cs
index f1836c8db8c4..42437ff68208 100644
--- a/src/Components/test/E2ETest/Tests/TempDataSessionStorageTest.cs
+++ b/src/Components/test/E2ETest/Tests/TempDataSessionStorageTest.cs
@@ -27,6 +27,7 @@ public TempDataSessionStorageTest(
     protected override void InitializeAsyncCore()
     {
         _serverFixture.AdditionalArguments.Add("--UseSessionStorageTempDataProvider=true");
+        _serverFixture.AdditionalArguments.Add("--UseSession=true");
         Browser.Manage().Cookies.DeleteCookieNamed(SessionCookieName);
         base.InitializeAsyncCore();
     }
diff --git a/src/Components/test/testassets/Components.TestServer/RazorComponentEndpointsNoInteractivityStartup.cs b/src/Components/test/testassets/Components.TestServer/RazorComponentEndpointsNoInteractivityStartup.cs
index ba0d5ac06bc9..de43c510a42a 100644
--- a/src/Components/test/testassets/Components.TestServer/RazorComponentEndpointsNoInteractivityStartup.cs
+++ b/src/Components/test/testassets/Components.TestServer/RazorComponentEndpointsNoInteractivityStartup.cs
@@ -36,7 +36,7 @@ public void ConfigureServices(IServiceCollection services)
         services.AddHttpContextAccessor();
         services.AddCascadingAuthenticationState();
 
-        if (Configuration.GetValue<bool>("UseSession") || Configuration.GetValue<bool>("UseSessionStorageTempDataProvider"))
+        if (Configuration.GetValue<bool>("UseSession"))
         {
             services.AddDistributedMemoryCache();
             services.AddSession(options =>
@@ -44,7 +44,7 @@ public void ConfigureServices(IServiceCollection services)
                 options.Cookie.HttpOnly = true;
                 options.Cookie.IsEssential = true;
             });
-            
+
             if (Configuration.GetValue<bool>("UseSessionStorageTempDataProvider"))
             {
                 services.Configure<RazorComponentsServiceOptions>(options =>
diff --git a/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor b/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor
index 69dc4a85c1a7..688553aa6e47 100644
--- a/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor
+++ b/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionComponent.razor
@@ -1,12 +1,10 @@
 @page "/supply-parameter-from-session"
 @using Microsoft.AspNetCore.Components.Forms
-@inject IHttpContextAccessor HttpContextAccessor
 @inject NavigationManager NavigationManager
 
 <h3>SupplyParameterFromSessionComponent</h3>
 
 <p id="text-email">@Email</p>
-<p id="text-another-email">@AnotherEmail</p>
 <p id="text-null">@NoElement</p>
 <p id="text-number">@Number</p>
 
@@ -19,12 +17,6 @@
     <button type="submit" id="set-email">Set Email</button>
 </form>
 
-<form @onsubmit="SetAnotherEmail" @formname="set-another-email" method="post">
-    <AntiforgeryToken />
-    <input id="input-another-email" @bind="EmailInput" name="EmailInput" />
-    <button type="submit" id="set-another-email">Set Email</button>
-</form>
-
 <form @onsubmit="SetNumber" @formname="set-number" method="post">
     <AntiforgeryToken />
     <input id="input-number" @bind="NumberInput" name="NumberInput" />
@@ -48,9 +40,6 @@
     [SupplyParameterFromSession]
     public string? Email { get; set; }
 
-    [SupplyParameterFromSession(Name = "email")]
-    public string? AnotherEmail { get; set; }
-
     [SupplyParameterFromSession]
     public string? NoElement { get; set; }
 
@@ -76,13 +65,6 @@
         NavigationManager.NavigateTo("/subdir/supply-parameter-from-session", forceLoad: true);
     }
 
-    void SetAnotherEmail()
-    {
-        AnotherEmail = EmailInput;
-        EmailInput = string.Empty;
-        NavigationManager.NavigateTo("/subdir/supply-parameter-from-session", forceLoad: true);
-    }
-
     void SetNumber()
     {
         Number = NumberInput;
diff --git a/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionNavigationComponent.razor b/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionNavigationComponent.razor
index 4bdd6697b8be..dfd2323010e8 100644
--- a/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionNavigationComponent.razor
+++ b/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/SupplyParameterFromSessionNavigationComponent.razor
@@ -8,7 +8,7 @@
 
 <form @onsubmit="Redirect" @formname="redirect" method="post">
     <AntiforgeryToken />
-    <button type="submit" id="redirect">Set Email</button>
+    <button type="submit" id="redirect">Redirect</button>
 </form>
 
 @code {

From 725040ad9b468f1a24448febb5c6cd6597b55343 Mon Sep 17 00:00:00 2001
From: Daria Tiurina <dariatiurina@microsoft.com>
Date: Wed, 11 Feb 2026 20:40:53 +0100
Subject: [PATCH 08/11] Fix

---
 .../Endpoints/test/SessionValueMapperTest.cs  | 27 ++++++-------------
 1 file changed, 8 insertions(+), 19 deletions(-)

diff --git a/src/Components/Endpoints/test/SessionValueMapperTest.cs b/src/Components/Endpoints/test/SessionValueMapperTest.cs
index 68f6e7f36f99..94a6c2d091e9 100644
--- a/src/Components/Endpoints/test/SessionValueMapperTest.cs
+++ b/src/Components/Endpoints/test/SessionValueMapperTest.cs
@@ -79,37 +79,27 @@ public void RegisterValueCallback_AddsCallbackToList()
     }
 
     [Fact]
-    public async Task RegisterValueCallback_AllowsMultipleCallbacksForSameKey()
+    public void RegisterValueCallback_ThrowsForDuplicateKey()
     {
         // Arrange
         var mapper = GetSessionValueMapper();
-        var httpContext = CreateHttpContextWithSession(out var responseFeature);
-        mapper.SetRequestContext(httpContext);
-
-        var callOrder = new List<int>();
-        mapper.RegisterValueCallback("key", () => { callOrder.Add(1); return null; });
-        mapper.RegisterValueCallback("key", () => { callOrder.Add(2); return "value2"; });
-        mapper.RegisterValueCallback("key", () => { callOrder.Add(3); return "value3"; });
+        mapper.RegisterValueCallback("key", () => "value1");
 
-        // Act
-        await responseFeature.FireOnStartingAsync();
-
-        // Assert
-        Assert.Equal(new[] { 1, 2 }, callOrder);
-        Assert.Equal("\"value2\"", httpContext.Session.GetString("key"));
+        // Act & Assert
+        var ex = Assert.Throws<InvalidOperationException>(() =>
+            mapper.RegisterValueCallback("key", () => "value2"));
+        Assert.Contains("key", ex.Message);
     }
 
     [Fact]
-    public async Task PersistAllValues_PersistsFirstNonNullValue()
+    public async Task PersistAllValues_PersistsValue()
     {
         // Arrange
         var mapper = GetSessionValueMapper();
         var httpContext = CreateHttpContextWithSession(out var responseFeature);
         mapper.SetRequestContext(httpContext);
 
-        mapper.RegisterValueCallback("email", () => null);
         mapper.RegisterValueCallback("email", () => "test@example.com");
-        mapper.RegisterValueCallback("email", () => "other@example.com");
 
         // Act
         await responseFeature.FireOnStartingAsync();
@@ -119,7 +109,7 @@ public async Task PersistAllValues_PersistsFirstNonNullValue()
     }
 
     [Fact]
-    public async Task PersistAllValues_RemovesKey_WhenAllCallbacksReturnNull()
+    public async Task PersistAllValues_RemovesKey_WhenCallbackReturnsNull()
     {
         // Arrange
         var mapper = GetSessionValueMapper();
@@ -127,7 +117,6 @@ public async Task PersistAllValues_RemovesKey_WhenAllCallbacksReturnNull()
         httpContext.Session.SetString("email", "\"existing@example.com\"");
         mapper.SetRequestContext(httpContext);
 
-        mapper.RegisterValueCallback("email", () => null);
         mapper.RegisterValueCallback("email", () => null);
 
         // Act

From ed0b04d3c5864bcbf11aa0c579461d4c91909da0 Mon Sep 17 00:00:00 2001
From: Daria Tiurina <dariatiurina@microsoft.com>
Date: Mon, 16 Feb 2026 09:17:12 +0100
Subject: [PATCH 09/11] Fix namespaces

---
 .../src/Session => Components/src}/ISessionValueMapper.cs   | 2 +-
 .../Components/src/Microsoft.AspNetCore.Components.csproj   | 1 -
 src/Components/Components/src/PublicAPI.Unshipped.txt       | 6 ++++++
 ...SupplyParameterFromSessionServiceCollectionExtensions.cs | 2 +-
 .../src}/SupplyParameterFromSessionValueProvider.cs         | 2 +-
 src/Components/Endpoints/src/PublicAPI.Unshipped.txt        | 6 ------
 .../Endpoints/src/Rendering/EndpointComponentState.cs       | 2 +-
 .../src/Rendering/EndpointHtmlRenderer.Prerendering.cs      | 4 ++--
 .../Endpoints/src/Rendering/EndpointHtmlRenderer.cs         | 2 +-
 src/Components/Endpoints/src/Session/SessionValueMapper.cs  | 4 ++--
 10 files changed, 15 insertions(+), 16 deletions(-)
 rename src/Components/{Endpoints/src/Session => Components/src}/ISessionValueMapper.cs (94%)
 rename src/Components/{Endpoints/src/Session => Components/src}/SupplyParameterFromSessionServiceCollectionExtensions.cs (95%)
 rename src/Components/{Endpoints/src/Session => Components/src}/SupplyParameterFromSessionValueProvider.cs (97%)

diff --git a/src/Components/Endpoints/src/Session/ISessionValueMapper.cs b/src/Components/Components/src/ISessionValueMapper.cs
similarity index 94%
rename from src/Components/Endpoints/src/Session/ISessionValueMapper.cs
rename to src/Components/Components/src/ISessionValueMapper.cs
index 956ecbc40b5e..4d8f2e2c1a57 100644
--- a/src/Components/Endpoints/src/Session/ISessionValueMapper.cs
+++ b/src/Components/Components/src/ISessionValueMapper.cs
@@ -1,7 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-namespace Microsoft.AspNetCore.Components.Endpoints;
+namespace Microsoft.AspNetCore.Components;
 
 /// <summary>
 /// Maps session data values to a model.
diff --git a/src/Components/Components/src/Microsoft.AspNetCore.Components.csproj b/src/Components/Components/src/Microsoft.AspNetCore.Components.csproj
index 58010a3bef6c..ba3ae6420645 100644
--- a/src/Components/Components/src/Microsoft.AspNetCore.Components.csproj
+++ b/src/Components/Components/src/Microsoft.AspNetCore.Components.csproj
@@ -68,7 +68,6 @@
   </ItemGroup>
 
   <ItemGroup>
-    <InternalsVisibleTo Include="Microsoft.AspNetCore.Components.Endpoints" />
     <InternalsVisibleTo Include="Microsoft.AspNetCore.Components.Web" />
     <InternalsVisibleTo Include="Microsoft.AspNetCore.Blazor.Build.Tests" />
     <InternalsVisibleTo Include="Microsoft.AspNetCore.Components.Authorization.Tests" />
diff --git a/src/Components/Components/src/PublicAPI.Unshipped.txt b/src/Components/Components/src/PublicAPI.Unshipped.txt
index 489644de389a..ead81dfb5570 100644
--- a/src/Components/Components/src/PublicAPI.Unshipped.txt
+++ b/src/Components/Components/src/PublicAPI.Unshipped.txt
@@ -7,7 +7,13 @@ Microsoft.AspNetCore.Components.IComponentPropertyActivator.GetActivator(System.
 *REMOVED*Microsoft.AspNetCore.Components.ResourceAsset.ResourceAsset(string! url, System.Collections.Generic.IReadOnlyList<Microsoft.AspNetCore.Components.ResourceAssetProperty!>? properties) -> void
 *REMOVED*Microsoft.AspNetCore.Components.Routing.Router.PreferExactMatches.get -> bool
 *REMOVED*Microsoft.AspNetCore.Components.Routing.Router.PreferExactMatches.set -> void
+Microsoft.AspNetCore.Components.ISessionValueMapper
+Microsoft.AspNetCore.Components.ISessionValueMapper.DeleteValueCallback(string! sessionKey) -> void
+Microsoft.AspNetCore.Components.ISessionValueMapper.GetValue(string! sessionKey, System.Type! targetType) -> object?
+Microsoft.AspNetCore.Components.ISessionValueMapper.RegisterValueCallback(string! sessionKey, System.Func<object?>! valueGetter) -> void
 Microsoft.AspNetCore.Components.SupplyParameterFromSessionAttribute
 Microsoft.AspNetCore.Components.SupplyParameterFromSessionAttribute.Name.get -> string?
 Microsoft.AspNetCore.Components.SupplyParameterFromSessionAttribute.Name.set -> void
 Microsoft.AspNetCore.Components.SupplyParameterFromSessionAttribute.SupplyParameterFromSessionAttribute() -> void
+Microsoft.AspNetCore.Components.SupplyParameterFromSessionServiceCollectionExtensions
+static Microsoft.AspNetCore.Components.SupplyParameterFromSessionServiceCollectionExtensions.AddSupplyValueFromSessionProvider(this Microsoft.Extensions.DependencyInjection.IServiceCollection! services) -> Microsoft.Extensions.DependencyInjection.IServiceCollection!
diff --git a/src/Components/Endpoints/src/Session/SupplyParameterFromSessionServiceCollectionExtensions.cs b/src/Components/Components/src/SupplyParameterFromSessionServiceCollectionExtensions.cs
similarity index 95%
rename from src/Components/Endpoints/src/Session/SupplyParameterFromSessionServiceCollectionExtensions.cs
rename to src/Components/Components/src/SupplyParameterFromSessionServiceCollectionExtensions.cs
index 10fb4f99fb20..bc90655e4275 100644
--- a/src/Components/Endpoints/src/Session/SupplyParameterFromSessionServiceCollectionExtensions.cs
+++ b/src/Components/Components/src/SupplyParameterFromSessionServiceCollectionExtensions.cs
@@ -3,7 +3,7 @@
 
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.DependencyInjection.Extensions;
-namespace Microsoft.AspNetCore.Components.Endpoints;
+namespace Microsoft.AspNetCore.Components;
 
 /// <summary>
 /// Enables component parameters to be supplied from the session with <see cref="SupplyParameterFromSessionAttribute"/>.
diff --git a/src/Components/Endpoints/src/Session/SupplyParameterFromSessionValueProvider.cs b/src/Components/Components/src/SupplyParameterFromSessionValueProvider.cs
similarity index 97%
rename from src/Components/Endpoints/src/Session/SupplyParameterFromSessionValueProvider.cs
rename to src/Components/Components/src/SupplyParameterFromSessionValueProvider.cs
index 180d25dc58c4..2b033b8d1fd6 100644
--- a/src/Components/Endpoints/src/Session/SupplyParameterFromSessionValueProvider.cs
+++ b/src/Components/Components/src/SupplyParameterFromSessionValueProvider.cs
@@ -5,7 +5,7 @@
 using Microsoft.AspNetCore.Components.Reflection;
 using Microsoft.AspNetCore.Components.Rendering;
 
-namespace Microsoft.AspNetCore.Components.Endpoints;
+namespace Microsoft.AspNetCore.Components;
 
 internal class SupplyParameterFromSessionValueProvider : ICascadingValueSupplier
 {
diff --git a/src/Components/Endpoints/src/PublicAPI.Unshipped.txt b/src/Components/Endpoints/src/PublicAPI.Unshipped.txt
index d6fa4f7da8b5..2ebef8b69595 100644
--- a/src/Components/Endpoints/src/PublicAPI.Unshipped.txt
+++ b/src/Components/Endpoints/src/PublicAPI.Unshipped.txt
@@ -1,15 +1,10 @@
 #nullable enable
 Microsoft.AspNetCore.Components.Endpoints.BasePath
 Microsoft.AspNetCore.Components.Endpoints.BasePath.BasePath() -> void
-Microsoft.AspNetCore.Components.Endpoints.ISessionValueMapper
-Microsoft.AspNetCore.Components.Endpoints.ISessionValueMapper.DeleteValueCallback(string! sessionKey) -> void
-Microsoft.AspNetCore.Components.Endpoints.ISessionValueMapper.GetValue(string! sessionKey, System.Type! targetType) -> object?
-Microsoft.AspNetCore.Components.Endpoints.ISessionValueMapper.RegisterValueCallback(string! sessionKey, System.Func<object?>! valueGetter) -> void
 Microsoft.AspNetCore.Components.Endpoints.RazorComponentsServiceOptions.TempDataCookie.get -> Microsoft.AspNetCore.Http.CookieBuilder!
 Microsoft.AspNetCore.Components.Endpoints.RazorComponentsServiceOptions.TempDataCookie.set -> void
 Microsoft.AspNetCore.Components.Endpoints.RazorComponentsServiceOptions.TempDataProviderType.get -> Microsoft.AspNetCore.Components.Endpoints.TempDataProviderType
 Microsoft.AspNetCore.Components.Endpoints.RazorComponentsServiceOptions.TempDataProviderType.set -> void
-Microsoft.AspNetCore.Components.Endpoints.SupplyParameterFromSessionServiceCollectionExtensions
 Microsoft.AspNetCore.Components.Endpoints.TempDataProviderType
 Microsoft.AspNetCore.Components.Endpoints.TempDataProviderType.Cookie = 0 -> Microsoft.AspNetCore.Components.Endpoints.TempDataProviderType
 Microsoft.AspNetCore.Components.Endpoints.TempDataProviderType.SessionStorage = 1 -> Microsoft.AspNetCore.Components.Endpoints.TempDataProviderType
@@ -18,4 +13,3 @@ Microsoft.AspNetCore.Components.ITempData.Get(string! key) -> object?
 Microsoft.AspNetCore.Components.ITempData.Keep() -> void
 Microsoft.AspNetCore.Components.ITempData.Keep(string! key) -> void
 Microsoft.AspNetCore.Components.ITempData.Peek(string! key) -> object?
-static Microsoft.AspNetCore.Components.Endpoints.SupplyParameterFromSessionServiceCollectionExtensions.AddSupplyValueFromSessionProvider(this Microsoft.Extensions.DependencyInjection.IServiceCollection! services) -> Microsoft.Extensions.DependencyInjection.IServiceCollection!
diff --git a/src/Components/Endpoints/src/Rendering/EndpointComponentState.cs b/src/Components/Endpoints/src/Rendering/EndpointComponentState.cs
index d85f67c4400d..6c03d0585f2f 100644
--- a/src/Components/Endpoints/src/Rendering/EndpointComponentState.cs
+++ b/src/Components/Endpoints/src/Rendering/EndpointComponentState.cs
@@ -47,7 +47,7 @@ public EndpointComponentState(Renderer renderer, int componentId, IComponent com
 
     public bool StreamRendering { get; }
 
-    protected internal override object? GetComponentKey()
+    protected override object? GetComponentKey()
     {
         if (ParentComponentState != null && ParentComponentState.Component is SSRRenderModeBoundary boundary)
         {
diff --git a/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.Prerendering.cs b/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.Prerendering.cs
index 1fc08b49d889..0276cdfd1515 100644
--- a/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.Prerendering.cs
+++ b/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.Prerendering.cs
@@ -18,7 +18,7 @@ internal partial class EndpointHtmlRenderer
 {
     private static readonly object ComponentSequenceKey = new object();
 
-    protected internal override IComponent ResolveComponentForRenderMode([DynamicallyAccessedMembers(Component)] Type componentType, int? parentComponentId, IComponentActivator componentActivator, IComponentRenderMode renderMode)
+    protected override IComponent ResolveComponentForRenderMode([DynamicallyAccessedMembers(Component)] Type componentType, int? parentComponentId, IComponentActivator componentActivator, IComponentRenderMode renderMode)
     {
         if (_isHandlingErrors)
         {
@@ -42,7 +42,7 @@ protected internal override IComponent ResolveComponentForRenderMode([Dynamicall
         }
     }
 
-    protected internal override IComponentRenderMode? GetComponentRenderMode(IComponent component)
+    protected override IComponentRenderMode? GetComponentRenderMode(IComponent component)
     {
         var componentState = GetComponentState(component);
         var ssrRenderBoundary = GetClosestRenderModeBoundary(componentState);
diff --git a/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.cs b/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.cs
index 8a6eb4dc5b26..b8fc15aacf16 100644
--- a/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.cs
+++ b/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.cs
@@ -166,7 +166,7 @@ protected override ComponentState CreateComponentState(int componentId, ICompone
         => new EndpointComponentState(this, componentId, component, parentComponentState);
 
     /// <inheritdoc/>
-    protected internal override ResourceAssetCollection Assets =>
+    protected override ResourceAssetCollection Assets =>
         _resourceCollection ??= GetResourceCollection(_httpContext) ?? base.Assets;
 
     private static ResourceAssetCollection? GetResourceCollection(HttpContext httpContext) => httpContext.GetEndpoint()?.Metadata.GetMetadata<ResourceAssetCollection>();
diff --git a/src/Components/Endpoints/src/Session/SessionValueMapper.cs b/src/Components/Endpoints/src/Session/SessionValueMapper.cs
index 368ae831328a..8a5c740870f5 100644
--- a/src/Components/Endpoints/src/Session/SessionValueMapper.cs
+++ b/src/Components/Endpoints/src/Session/SessionValueMapper.cs
@@ -26,7 +26,7 @@ internal void SetRequestContext(HttpContext httpContext)
         _httpContext.Response.OnStarting(PersistAllValues);
     }
 
-    public object? GetValue(string sessionKey, Type type)
+    public object? GetValue(string sessionKey, Type targetType)
     {
         var session = _httpContext?.Features.Get<ISessionFeature>()?.Session;
         if (session is null)
@@ -40,7 +40,7 @@ internal void SetRequestContext(HttpContext httpContext)
             {
                 return null;
             }
-            return JsonSerializer.Deserialize(json, type, _jsonOptions);
+            return JsonSerializer.Deserialize(json, targetType, _jsonOptions);
         }
         catch (JsonException ex)
         {

From 420c545079034645be3eecefb0bfd5432c0968f4 Mon Sep 17 00:00:00 2001
From: Daria Tiurina <dariatiurina@microsoft.com>
Date: Mon, 20 Apr 2026 15:05:05 +0200
Subject: [PATCH 10/11] Refactor SupplyParameterFromSession to use
 CascadingParameterSubscription pattern

---
 .../Components/src/ISessionValueMapper.cs     |  26 --
 .../Components/src/PublicAPI.Unshipped.txt    |  10 -
 ...rFromSessionServiceCollectionExtensions.cs |  23 --
 ...SupplyParameterFromSessionValueProvider.cs |  59 ----
 ...orComponentsServiceCollectionExtensions.cs |   5 +-
 .../src/Rendering/EndpointHtmlRenderer.cs     |  10 +-
 .../Session/SessionCascadingValueSupplier.cs  | 192 ++++++++++++
 .../src/Session/SessionValueMapper.cs         | 105 -------
 .../SessionCascadingValueSupplierTest.cs      | 250 ++++++++++++++++
 .../test/Session/SessionSubscriptionTest.cs   | 190 ++++++++++++
 .../Endpoints/test/SessionValueMapperTest.cs  | 282 ------------------
 .../Web/src/PublicAPI.Unshipped.txt           |   4 +
 .../SupplyParameterFromSessionAttribute.cs    |   2 +-
 13 files changed, 645 insertions(+), 513 deletions(-)
 delete mode 100644 src/Components/Components/src/ISessionValueMapper.cs
 delete mode 100644 src/Components/Components/src/SupplyParameterFromSessionServiceCollectionExtensions.cs
 delete mode 100644 src/Components/Components/src/SupplyParameterFromSessionValueProvider.cs
 create mode 100644 src/Components/Endpoints/src/Session/SessionCascadingValueSupplier.cs
 delete mode 100644 src/Components/Endpoints/src/Session/SessionValueMapper.cs
 create mode 100644 src/Components/Endpoints/test/Session/SessionCascadingValueSupplierTest.cs
 create mode 100644 src/Components/Endpoints/test/Session/SessionSubscriptionTest.cs
 delete mode 100644 src/Components/Endpoints/test/SessionValueMapperTest.cs
 rename src/Components/{Components => Web}/src/SupplyParameterFromSessionAttribute.cs (93%)

diff --git a/src/Components/Components/src/ISessionValueMapper.cs b/src/Components/Components/src/ISessionValueMapper.cs
deleted file mode 100644
index 4d8f2e2c1a57..000000000000
--- a/src/Components/Components/src/ISessionValueMapper.cs
+++ /dev/null
@@ -1,26 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-
-namespace Microsoft.AspNetCore.Components;
-
-/// <summary>
-/// Maps session data values to a model.
-/// </summary>
-public interface ISessionValueMapper
-{
-    /// <summary>
-    /// Returns the session value with the specified name, deserialized to the specified type.
-    /// </summary>
-    object? GetValue(string sessionKey, Type targetType);
-
-    /// <summary>
-    /// Registers a callback to retrieve the current value of a session property.
-    /// The callback will be invoked when the response starts to persist the value.
-    /// </summary>
-    void RegisterValueCallback(string sessionKey, Func<object?> valueGetter);
-
-    /// <summary>
-    /// Unregisters a previously registered callback for the specified session key.
-    /// </summary>
-    void DeleteValueCallback(string sessionKey);
-}
diff --git a/src/Components/Components/src/PublicAPI.Unshipped.txt b/src/Components/Components/src/PublicAPI.Unshipped.txt
index aa36b78a9d9e..c243d71cf252 100644
--- a/src/Components/Components/src/PublicAPI.Unshipped.txt
+++ b/src/Components/Components/src/PublicAPI.Unshipped.txt
@@ -11,16 +11,6 @@ Microsoft.AspNetCore.Components.IComponentPropertyActivator.GetActivator(System.
 *REMOVED*Microsoft.AspNetCore.Components.ResourceAsset.ResourceAsset(string! url, System.Collections.Generic.IReadOnlyList<Microsoft.AspNetCore.Components.ResourceAssetProperty!>? properties) -> void
 *REMOVED*Microsoft.AspNetCore.Components.Routing.Router.PreferExactMatches.get -> bool
 *REMOVED*Microsoft.AspNetCore.Components.Routing.Router.PreferExactMatches.set -> void
-Microsoft.AspNetCore.Components.ISessionValueMapper
-Microsoft.AspNetCore.Components.ISessionValueMapper.DeleteValueCallback(string! sessionKey) -> void
-Microsoft.AspNetCore.Components.ISessionValueMapper.GetValue(string! sessionKey, System.Type! targetType) -> object?
-Microsoft.AspNetCore.Components.ISessionValueMapper.RegisterValueCallback(string! sessionKey, System.Func<object?>! valueGetter) -> void
-Microsoft.AspNetCore.Components.SupplyParameterFromSessionAttribute
-Microsoft.AspNetCore.Components.SupplyParameterFromSessionAttribute.Name.get -> string?
-Microsoft.AspNetCore.Components.SupplyParameterFromSessionAttribute.Name.set -> void
-Microsoft.AspNetCore.Components.SupplyParameterFromSessionAttribute.SupplyParameterFromSessionAttribute() -> void
-Microsoft.AspNetCore.Components.SupplyParameterFromSessionServiceCollectionExtensions
-static Microsoft.AspNetCore.Components.SupplyParameterFromSessionServiceCollectionExtensions.AddSupplyValueFromSessionProvider(this Microsoft.Extensions.DependencyInjection.IServiceCollection! services) -> Microsoft.Extensions.DependencyInjection.IServiceCollection!
 static Microsoft.Extensions.DependencyInjection.CascadingValueServiceCollectionExtensions.TryAddCascadingValueSupplier<TAttribute>(this Microsoft.Extensions.DependencyInjection.IServiceCollection! serviceCollection, System.Func<System.IServiceProvider!, System.Func<Microsoft.AspNetCore.Components.Rendering.ComponentState!, TAttribute!, Microsoft.AspNetCore.Components.CascadingParameterInfo, Microsoft.AspNetCore.Components.CascadingParameterSubscription!>!>! subscribeFactory) -> Microsoft.Extensions.DependencyInjection.IServiceCollection!
 Microsoft.AspNetCore.Components.BrowserConfiguration
 Microsoft.AspNetCore.Components.BrowserConfiguration.BrowserConfiguration() -> void
diff --git a/src/Components/Components/src/SupplyParameterFromSessionServiceCollectionExtensions.cs b/src/Components/Components/src/SupplyParameterFromSessionServiceCollectionExtensions.cs
deleted file mode 100644
index bc90655e4275..000000000000
--- a/src/Components/Components/src/SupplyParameterFromSessionServiceCollectionExtensions.cs
+++ /dev/null
@@ -1,23 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-
-using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Extensions.DependencyInjection.Extensions;
-namespace Microsoft.AspNetCore.Components;
-
-/// <summary>
-/// Enables component parameters to be supplied from the session with <see cref="SupplyParameterFromSessionAttribute"/>.
-/// </summary>
-public static class SupplyParameterFromSessionServiceCollectionExtensions
-{
-    /// <summary>
-    /// Enables component parameters to be supplied from the session with <see cref="SupplyParameterFromSessionAttribute"/>.
-    /// </summary>
-    /// <param name="services">The <see cref="IServiceCollection"/>.</param>
-    /// <returns>The <see cref="IServiceCollection"/>.</returns>
-    public static IServiceCollection AddSupplyValueFromSessionProvider(this IServiceCollection services)
-    {
-        services.TryAddEnumerable(ServiceDescriptor.Scoped<ICascadingValueSupplier, SupplyParameterFromSessionValueProvider>());
-        return services;
-    }
-}
diff --git a/src/Components/Components/src/SupplyParameterFromSessionValueProvider.cs b/src/Components/Components/src/SupplyParameterFromSessionValueProvider.cs
deleted file mode 100644
index 2b033b8d1fd6..000000000000
--- a/src/Components/Components/src/SupplyParameterFromSessionValueProvider.cs
+++ /dev/null
@@ -1,59 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-
-using System.Diagnostics.CodeAnalysis;
-using Microsoft.AspNetCore.Components.Reflection;
-using Microsoft.AspNetCore.Components.Rendering;
-
-namespace Microsoft.AspNetCore.Components;
-
-internal class SupplyParameterFromSessionValueProvider : ICascadingValueSupplier
-{
-    private readonly ISessionValueMapper _sessionValueMapper;
-
-    public SupplyParameterFromSessionValueProvider(ISessionValueMapper sessionValueMapper)
-    {
-        _sessionValueMapper = sessionValueMapper;
-    }
-
-    public bool IsFixed => false;
-
-    public bool CanSupplyValue(in CascadingParameterInfo parameterInfo)
-        => parameterInfo.Attribute is SupplyParameterFromSessionAttribute;
-
-    public object? GetCurrentValue(object? key, in CascadingParameterInfo parameterInfo)
-    {
-        var attribute = (SupplyParameterFromSessionAttribute)parameterInfo.Attribute;
-        var sessionKey = (attribute.Name ?? parameterInfo.PropertyName) ?? "";
-        return _sessionValueMapper.GetValue(sessionKey, parameterInfo.PropertyType);
-    }
-
-    [UnconditionalSuppressMessage(
-        "Trimming",
-        "IL2075:Target parameter argument does not satisfy 'DynamicallyAccessedMembersAttribute'",
-        Justification = "Component properties are preserved through other means.")]
-    public void Subscribe(ComponentState subscriber, in CascadingParameterInfo parameterInfo)
-    {
-        var attribute = (SupplyParameterFromSessionAttribute)parameterInfo.Attribute;
-        var sessionKey = (attribute.Name ?? parameterInfo.PropertyName) ?? "";
-        var propertyName = parameterInfo.PropertyName;
-        var componentType = subscriber.Component.GetType();
-        var propertyInfo = componentType.GetProperty(propertyName);
-
-        if (propertyInfo is null)
-        {
-            return;
-        }
-
-        var component = subscriber.Component;
-        var getter = new PropertyGetter(componentType, propertyInfo);
-        _sessionValueMapper.RegisterValueCallback(sessionKey, () => getter.GetValue(component));
-    }
-
-    public void Unsubscribe(ComponentState subscriber, in CascadingParameterInfo parameterInfo)
-    {
-        var attribute = (SupplyParameterFromSessionAttribute)parameterInfo.Attribute;
-        var sessionKey = (attribute.Name ?? parameterInfo.PropertyName) ?? "";
-        _sessionValueMapper.DeleteValueCallback(sessionKey);
-    }
-}
diff --git a/src/Components/Endpoints/src/DependencyInjection/RazorComponentsServiceCollectionExtensions.cs b/src/Components/Endpoints/src/DependencyInjection/RazorComponentsServiceCollectionExtensions.cs
index a1f7c408cc76..298801a82a8a 100644
--- a/src/Components/Endpoints/src/DependencyInjection/RazorComponentsServiceCollectionExtensions.cs
+++ b/src/Components/Endpoints/src/DependencyInjection/RazorComponentsServiceCollectionExtensions.cs
@@ -69,9 +69,7 @@ public static IRazorComponentsBuilder AddRazorComponents(this IServiceCollection
         services.TryAddScoped<EndpointRoutingStateProvider>();
         services.TryAddScoped<IRoutingStateProvider>(sp => sp.GetRequiredService<EndpointRoutingStateProvider>());
         services.TryAddScoped<AuthenticationStateProvider, ServerAuthenticationStateProvider>();
-        services.TryAddScoped<ISessionValueMapper, SessionValueMapper>();
         services.AddSupplyValueFromQueryProvider();
-        services.AddSupplyValueFromSessionProvider();
         services.AddSupplyValueFromPersistentComponentStateProvider();
         services.TryAddCascadingValue(sp => sp.GetRequiredService<EndpointHtmlRenderer>().HttpContext);
         services.TryAddScoped<ResourcePreloadService>();
@@ -79,6 +77,9 @@ public static IRazorComponentsBuilder AddRazorComponents(this IServiceCollection
         services.TryAddScoped<TempDataCascadingValueSupplier>();
         services.TryAddCascadingValueSupplier<SupplyParameterFromTempDataAttribute>(
             sp => sp.GetRequiredService<TempDataCascadingValueSupplier>().CreateSubscription);
+        services.TryAddScoped<SessionCascadingValueSupplier>();
+        services.TryAddCascadingValueSupplier<SupplyParameterFromSessionAttribute>(
+            sp => sp.GetRequiredService<SessionCascadingValueSupplier>().CreateSubscription);
 
         services.TryAddScoped<ResourceCollectionProvider>();
         RegisterPersistentComponentStateServiceCollectionExtensions.AddPersistentServiceRegistration<ResourceCollectionProvider>(services, RenderMode.InteractiveWebAssembly);
diff --git a/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.cs b/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.cs
index 3f1bc4b9270b..62797ee22b23 100644
--- a/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.cs
+++ b/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.cs
@@ -122,14 +122,14 @@ internal async Task InitializeStandardComponentServicesAsync(
             antiforgery.SetRequestContext(httpContext);
         }
 
-        if (httpContext.RequestServices.GetService<ISessionValueMapper>() is SessionValueMapper sessionValueMapper)
+        if (httpContext.RequestServices.GetService<TempDataCascadingValueSupplier>() is { } tempDataSupplier)
         {
-            sessionValueMapper.SetRequestContext(httpContext);
+            tempDataSupplier.SetRequestContext(httpContext);
         }
-        
-        if (httpContext.RequestServices.GetService<TempDataCascadingValueSupplier>() is {} tempDataSupplier)
+
+        if (httpContext.RequestServices.GetService<SessionCascadingValueSupplier>() is { } sessionSupplier)
         {
-            tempDataSupplier.SetRequestContext(httpContext);
+            sessionSupplier.SetRequestContext(httpContext);
         }
 
         // It's important that this is initialized since a component might try to restore state during prerendering
diff --git a/src/Components/Endpoints/src/Session/SessionCascadingValueSupplier.cs b/src/Components/Endpoints/src/Session/SessionCascadingValueSupplier.cs
new file mode 100644
index 000000000000..877d65c45773
--- /dev/null
+++ b/src/Components/Endpoints/src/Session/SessionCascadingValueSupplier.cs
@@ -0,0 +1,192 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections.Concurrent;
+using System.Reflection;
+using System.Text.Json;
+using Microsoft.AspNetCore.Components.Reflection;
+using Microsoft.AspNetCore.Components.Rendering;
+using Microsoft.AspNetCore.Components.Web;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Http.Features;
+using Microsoft.Extensions.Logging;
+
+namespace Microsoft.AspNetCore.Components.Endpoints;
+
+internal partial class SessionCascadingValueSupplier
+{
+    private static readonly ConcurrentDictionary<(Type, string), PropertyGetter> _propertyGetterCache = new();
+    private static readonly JsonSerializerOptions _jsonOptions = new(JsonSerializerDefaults.Web);
+    private HttpContext? _httpContext;
+    private readonly Dictionary<string, Func<object?>> _valueCallbacks = new(StringComparer.OrdinalIgnoreCase);
+    private readonly ILogger<SessionCascadingValueSupplier> _logger;
+
+    public SessionCascadingValueSupplier(ILogger<SessionCascadingValueSupplier> logger)
+    {
+        _logger = logger;
+    }
+
+    internal void SetRequestContext(HttpContext httpContext)
+    {
+        if (ReferenceEquals(_httpContext, httpContext))
+        {
+            return;
+        }
+
+        if (_httpContext is not null)
+        {
+            throw new InvalidOperationException($"{nameof(SessionCascadingValueSupplier)} is already associated with a different {nameof(HttpContext)}.");
+        }
+
+        _httpContext = httpContext;
+        _httpContext.Response.OnStarting(PersistAllValues);
+    }
+
+    internal CascadingParameterSubscription CreateSubscription(
+        ComponentState componentState,
+        SupplyParameterFromSessionAttribute attribute,
+        CascadingParameterInfo parameterInfo)
+    {
+        var sessionKey = attribute.Name ?? parameterInfo.PropertyName;
+        var componentType = componentState.Component.GetType();
+        var getter = _propertyGetterCache.GetOrAdd((componentType, parameterInfo.PropertyName), PropertyGetterFactory);
+        Func<object?> valueGetter = () => getter.GetValue(componentState.Component);
+        RegisterValueCallback(sessionKey, valueGetter);
+        return new SessionSubscription(this, sessionKey, parameterInfo.PropertyType, valueGetter);
+    }
+
+    private static PropertyGetter PropertyGetterFactory((Type type, string propertyName) key)
+    {
+        var (type, propertyName) = key;
+        var propertyInfo = type.GetProperty(propertyName, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
+        if (propertyInfo is null)
+        {
+            throw new InvalidOperationException($"A property '{propertyName}' on component type '{type.FullName}' wasn't found.");
+        }
+        return new PropertyGetter(type, propertyInfo);
+    }
+
+    internal ISession? GetSession() => _httpContext?.Features.Get<ISessionFeature>()?.Session;
+
+    internal void RegisterValueCallback(string sessionKey, Func<object?> valueGetter)
+    {
+        if (!_valueCallbacks.TryAdd(sessionKey, valueGetter))
+        {
+            throw new InvalidOperationException($"A callback is already registered for the session key '{sessionKey}'. Multiple components cannot use the same session key for multiple [SupplyParameterFromSession] attributes.");
+        }
+    }
+
+    internal Task PersistAllValues()
+    {
+        if (_valueCallbacks.Count == 0)
+        {
+            return Task.CompletedTask;
+        }
+
+        var session = GetSession();
+        if (session is null)
+        {
+            return Task.CompletedTask;
+        }
+
+        foreach (var (key, valueGetter) in _valueCallbacks)
+        {
+            object? value = null;
+            try
+            {
+                value = valueGetter();
+            }
+            catch (Exception ex)
+            {
+                Log.SessionPersistFail(_logger, ex);
+                continue;
+            }
+
+            var sessionKey = key.ToLowerInvariant();
+            if (value is not null)
+            {
+                var json = JsonSerializer.Serialize(value, value.GetType(), _jsonOptions);
+                session.SetString(sessionKey, json);
+            }
+            else
+            {
+                session.Remove(sessionKey);
+            }
+        }
+        return Task.CompletedTask;
+    }
+
+    internal void DeleteValueCallback(string sessionKey)
+    {
+        _valueCallbacks.Remove(sessionKey);
+    }
+
+    private static partial class Log
+    {
+        [LoggerMessage(1, LogLevel.Warning, "Persisting of the session element failed.", EventName = "SessionPersistFail")]
+        public static partial void SessionPersistFail(ILogger logger, Exception exception);
+
+        [LoggerMessage(2, LogLevel.Warning, "Deserialization of the element from session failed.", EventName = "SessionDeserializeFail")]
+        public static partial void SessionDeserializeFail(ILogger logger, Exception exception);
+    }
+
+    internal partial class SessionSubscription : CascadingParameterSubscription
+    {
+        private readonly SessionCascadingValueSupplier _owner;
+        private readonly string _sessionKey;
+        private readonly Type _propertyType;
+        private readonly Func<object?> _currentValueGetter;
+        private bool _delivered;
+
+        public SessionSubscription(
+            SessionCascadingValueSupplier owner,
+            string sessionKey,
+            Type propertyType,
+            Func<object?> currentValueGetter)
+        {
+            _owner = owner;
+            _sessionKey = sessionKey;
+            _propertyType = propertyType;
+            _currentValueGetter = currentValueGetter;
+        }
+
+        public override object? GetCurrentValue()
+        {
+            if (_delivered)
+            {
+                // After the first delivery, return the component's current property value
+                // to avoid overriding modifications the component made during rendering.
+                return _currentValueGetter();
+            }
+
+            _delivered = true;
+
+            var session = _owner.GetSession();
+            if (session is null)
+            {
+                return null;
+            }
+
+            try
+            {
+                var json = session.GetString(_sessionKey.ToLowerInvariant());
+                if (string.IsNullOrEmpty(json))
+                {
+                    return null;
+                }
+
+                return JsonSerializer.Deserialize(json, _propertyType, _jsonOptions);
+            }
+            catch (Exception ex)
+            {
+                Log.SessionDeserializeFail(_owner._logger, ex);
+                return null;
+            }
+        }
+
+        public override void Dispose()
+        {
+            _owner.DeleteValueCallback(_sessionKey);
+        }
+    }
+}
diff --git a/src/Components/Endpoints/src/Session/SessionValueMapper.cs b/src/Components/Endpoints/src/Session/SessionValueMapper.cs
deleted file mode 100644
index 8a5c740870f5..000000000000
--- a/src/Components/Endpoints/src/Session/SessionValueMapper.cs
+++ /dev/null
@@ -1,105 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-
-using System.Text.Json;
-using Microsoft.AspNetCore.Http;
-using Microsoft.AspNetCore.Http.Features;
-using Microsoft.Extensions.Logging;
-
-namespace Microsoft.AspNetCore.Components.Endpoints;
-
-internal partial class SessionValueMapper : ISessionValueMapper
-{
-    private static readonly JsonSerializerOptions _jsonOptions = new(JsonSerializerDefaults.Web);
-    private HttpContext? _httpContext;
-    private readonly Dictionary<string, Func<object?>> _valueCallbacks = new(StringComparer.OrdinalIgnoreCase);
-    private readonly ILogger<SessionValueMapper> _logger;
-
-    public SessionValueMapper(ILogger<SessionValueMapper> logger)
-    {
-        _logger = logger;
-    }
-
-    internal void SetRequestContext(HttpContext httpContext)
-    {
-        _httpContext = httpContext;
-        _httpContext.Response.OnStarting(PersistAllValues);
-    }
-
-    public object? GetValue(string sessionKey, Type targetType)
-    {
-        var session = _httpContext?.Features.Get<ISessionFeature>()?.Session;
-        if (session is null)
-        {
-            return null;
-        }
-        try
-        {
-            var json = session.GetString(sessionKey.ToLowerInvariant());
-            if (string.IsNullOrEmpty(json))
-            {
-                return null;
-            }
-            return JsonSerializer.Deserialize(json, targetType, _jsonOptions);
-        }
-        catch (JsonException ex)
-        {
-            Log.SessionDeserializeFail(_logger, ex);
-            return null;
-        }
-    }
-
-    public void RegisterValueCallback(string sessionKey, Func<object?> valueGetter)
-    {
-        if (!_valueCallbacks.TryAdd(sessionKey, valueGetter))
-        {
-            throw new InvalidOperationException($"A callback is already registered for the session key '{sessionKey}'. Multiple components cannot use the same session key.");
-        }
-    }
-
-    public void DeleteValueCallback(string sessionKey)
-    {
-        _valueCallbacks.Remove(sessionKey);
-    }
-
-    private Task PersistAllValues()
-    {
-        var session = _httpContext?.Features.Get<ISessionFeature>()?.Session;
-        if (session is null)
-        {
-            return Task.CompletedTask;
-        }
-
-        foreach (var (key, valueGetter) in _valueCallbacks)
-        {
-            object? value = null;
-            try
-            {
-                value = valueGetter();
-            }
-            catch (Exception ex)
-            {
-                Log.SessionPersistFail(_logger, ex);
-            }
-            if (value is not null)
-            {
-                var json = JsonSerializer.Serialize(value, value.GetType(), _jsonOptions);
-                session.SetString(key.ToLowerInvariant(), json);
-            }
-            else
-            {
-                session.Remove(key.ToLowerInvariant());
-            }
-        }
-        return Task.CompletedTask;
-    }
-
-    private static partial class Log
-    {
-        [LoggerMessage(1, LogLevel.Warning, "Persisting of the element failed.", EventName = "SessionPersistFail")]
-        public static partial void SessionPersistFail(ILogger logger, Exception exception);
-
-        [LoggerMessage(2, LogLevel.Warning, "Deserialization of the element from Session failed.", EventName = "SessionDeserializeFail")]
-        public static partial void SessionDeserializeFail(ILogger logger, JsonException exception);
-    }
-}
diff --git a/src/Components/Endpoints/test/Session/SessionCascadingValueSupplierTest.cs b/src/Components/Endpoints/test/Session/SessionCascadingValueSupplierTest.cs
new file mode 100644
index 000000000000..cbe73efb0581
--- /dev/null
+++ b/src/Components/Endpoints/test/Session/SessionCascadingValueSupplierTest.cs
@@ -0,0 +1,250 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#nullable enable
+
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Http.Features;
+using Microsoft.Extensions.Logging.Abstractions;
+
+namespace Microsoft.AspNetCore.Components.Endpoints;
+
+public class SessionCascadingValueSupplierTest
+{
+    private readonly SessionCascadingValueSupplier _supplier;
+
+    public SessionCascadingValueSupplierTest()
+    {
+        _supplier = new SessionCascadingValueSupplier(NullLogger<SessionCascadingValueSupplier>.Instance);
+    }
+
+    [Fact]
+    public async Task RegisterValueCallback_AddsCallback()
+    {
+        var callbackInvoked = false;
+        _supplier.RegisterValueCallback("key", () =>
+        {
+            callbackInvoked = true;
+            return "value";
+        });
+
+        var httpContext = CreateHttpContextWithSession();
+        _supplier.SetRequestContext(httpContext);
+        await _supplier.PersistAllValues();
+
+        Assert.True(callbackInvoked);
+    }
+
+    [Fact]
+    public void RegisterValueCallback_ThrowsForDuplicateKey()
+    {
+        _supplier.RegisterValueCallback("key", () => "value1");
+
+        var ex = Assert.Throws<InvalidOperationException>(() =>
+            _supplier.RegisterValueCallback("key", () => "value2"));
+
+        Assert.Contains("key", ex.Message);
+    }
+
+    [Fact]
+    public async Task PersistAllValues_SetsValueInSession()
+    {
+        _supplier.RegisterValueCallback("key", () => "persisted value");
+
+        var httpContext = CreateHttpContextWithSession();
+        _supplier.SetRequestContext(httpContext);
+        await _supplier.PersistAllValues();
+
+        Assert.Equal("\"persisted value\"", httpContext.Session.GetString("key"));
+    }
+
+    [Fact]
+    public async Task PersistAllValues_RemovesKey_WhenCallbackReturnsNull()
+    {
+        var httpContext = CreateHttpContextWithSession();
+        httpContext.Session.SetString("key", "\"existing\"");
+
+        _supplier.RegisterValueCallback("key", () => null);
+        _supplier.SetRequestContext(httpContext);
+        await _supplier.PersistAllValues();
+
+        Assert.Null(httpContext.Session.GetString("key"));
+    }
+
+    [Fact]
+    public async Task PersistAllValues_HandlesMultipleKeys()
+    {
+        _supplier.RegisterValueCallback("key1", () => "value1");
+        _supplier.RegisterValueCallback("key2", () => "value2");
+        _supplier.RegisterValueCallback("key3", () => "value3");
+
+        var httpContext = CreateHttpContextWithSession();
+        _supplier.SetRequestContext(httpContext);
+        await _supplier.PersistAllValues();
+
+        Assert.Equal("\"value1\"", httpContext.Session.GetString("key1"));
+        Assert.Equal("\"value2\"", httpContext.Session.GetString("key2"));
+        Assert.Equal("\"value3\"", httpContext.Session.GetString("key3"));
+    }
+
+    [Fact]
+    public async Task PersistAllValues_ContinuesOnCallbackException()
+    {
+        _supplier.RegisterValueCallback("key1", () => throw new InvalidOperationException("Test exception"));
+        _supplier.RegisterValueCallback("key2", () => "value2");
+
+        var httpContext = CreateHttpContextWithSession();
+        _supplier.SetRequestContext(httpContext);
+        await _supplier.PersistAllValues();
+
+        Assert.Null(httpContext.Session.GetString("key1"));
+        Assert.Equal("\"value2\"", httpContext.Session.GetString("key2"));
+    }
+
+    [Fact]
+    public async Task PersistAllValues_LowercasesSessionKey()
+    {
+        _supplier.RegisterValueCallback("MyKey", () => "value");
+
+        var httpContext = CreateHttpContextWithSession();
+        _supplier.SetRequestContext(httpContext);
+        await _supplier.PersistAllValues();
+
+        Assert.Equal("\"value\"", httpContext.Session.GetString("mykey"));
+    }
+
+    [Fact]
+    public async Task PersistAllValues_NoOp_WhenSessionUnavailable()
+    {
+        _supplier.RegisterValueCallback("key", () => "value");
+
+        var httpContext = new DefaultHttpContext();
+        httpContext.Features.Set<IHttpResponseFeature>(new TestHttpResponseFeature());
+        _supplier.SetRequestContext(httpContext);
+
+        await _supplier.PersistAllValues();
+    }
+
+    [Fact]
+    public async Task DeleteCallbacks_RemovesCallbacksForKey()
+    {
+        var callbackInvoked = false;
+        _supplier.RegisterValueCallback("key", () =>
+        {
+            callbackInvoked = true;
+            return "value";
+        });
+
+        _supplier.DeleteValueCallback("key");
+
+        var httpContext = CreateHttpContextWithSession();
+        _supplier.SetRequestContext(httpContext);
+        await _supplier.PersistAllValues();
+
+        Assert.False(callbackInvoked);
+        Assert.Null(httpContext.Session.GetString("key"));
+    }
+
+    [Fact]
+    public async Task SetRequestContext_RegistersOnStartingCallback()
+    {
+        _supplier.RegisterValueCallback("key", () => "value");
+
+        var httpContext = CreateHttpContextWithSession(out var responseFeature);
+        _supplier.SetRequestContext(httpContext);
+
+        await responseFeature.FireOnStartingAsync();
+
+        Assert.Equal("\"value\"", httpContext.Session.GetString("key"));
+    }
+
+    [Fact]
+    public void SetRequestContext_IsIdempotent_ForSameHttpContext()
+    {
+        var httpContext = CreateHttpContextWithSession();
+        _supplier.SetRequestContext(httpContext);
+        _supplier.SetRequestContext(httpContext);
+    }
+
+    [Fact]
+    public void SetRequestContext_Throws_ForDifferentHttpContext()
+    {
+        var first = CreateHttpContextWithSession();
+        var second = CreateHttpContextWithSession();
+        _supplier.SetRequestContext(first);
+
+        Assert.Throws<InvalidOperationException>(() => _supplier.SetRequestContext(second));
+    }
+
+    internal static DefaultHttpContext CreateHttpContextWithSession()
+    {
+        return CreateHttpContextWithSession(out _);
+    }
+
+    internal static DefaultHttpContext CreateHttpContextWithSession(out TestHttpResponseFeature responseFeature)
+    {
+        var httpContext = new DefaultHttpContext();
+        var session = new TestSession();
+        httpContext.Features.Set<ISessionFeature>(new TestSessionFeature(session));
+
+        responseFeature = new TestHttpResponseFeature();
+        httpContext.Features.Set<IHttpResponseFeature>(responseFeature);
+
+        return httpContext;
+    }
+
+    internal class TestSession : ISession
+    {
+        private readonly Dictionary<string, byte[]> _store = new();
+
+        public bool IsAvailable => true;
+        public string Id => "test-session";
+        public IEnumerable<string> Keys => _store.Keys;
+
+        public void Clear() => _store.Clear();
+        public Task CommitAsync(CancellationToken cancellationToken = default) => Task.CompletedTask;
+        public Task LoadAsync(CancellationToken cancellationToken = default) => Task.CompletedTask;
+        public void Remove(string key) => _store.Remove(key);
+        public void Set(string key, byte[] value) => _store[key] = value;
+        public bool TryGetValue(string key, [System.Diagnostics.CodeAnalysis.NotNullWhen(true)] out byte[]? value) => _store.TryGetValue(key, out value);
+    }
+
+    internal class TestSessionFeature : ISessionFeature
+    {
+        public TestSessionFeature(ISession session)
+        {
+            Session = session;
+        }
+
+        public ISession Session { get; set; }
+    }
+
+    internal class TestHttpResponseFeature : IHttpResponseFeature
+    {
+        private readonly Stack<(Func<object, Task> Callback, object State)> _onStarting = new();
+
+        public int StatusCode { get; set; } = 200;
+        public string? ReasonPhrase { get; set; }
+        public IHeaderDictionary Headers { get; set; } = new HeaderDictionary();
+        public Stream Body { get; set; } = new MemoryStream();
+        public bool HasStarted { get; private set; }
+
+        public void OnCompleted(Func<object, Task> callback, object state)
+        {
+        }
+
+        public void OnStarting(Func<object, Task> callback, object state)
+        {
+            _onStarting.Push((callback, state));
+        }
+
+        public async Task FireOnStartingAsync()
+        {
+            foreach (var (callback, state) in _onStarting)
+            {
+                await callback(state);
+            }
+            HasStarted = true;
+        }
+    }
+}
diff --git a/src/Components/Endpoints/test/Session/SessionSubscriptionTest.cs b/src/Components/Endpoints/test/Session/SessionSubscriptionTest.cs
new file mode 100644
index 000000000000..e2b5e56a28e5
--- /dev/null
+++ b/src/Components/Endpoints/test/Session/SessionSubscriptionTest.cs
@@ -0,0 +1,190 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#nullable enable
+
+using Microsoft.AspNetCore.Components.Rendering;
+using Microsoft.AspNetCore.Components.Test.Helpers;
+using Microsoft.AspNetCore.Components.Web;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Logging.Abstractions;
+using static Microsoft.AspNetCore.Components.Endpoints.SessionCascadingValueSupplierTest;
+
+namespace Microsoft.AspNetCore.Components.Endpoints;
+
+public class SessionSubscriptionTest
+{
+    private readonly SessionCascadingValueSupplier _supplier;
+    private readonly TestComponent _component;
+
+    public SessionSubscriptionTest()
+    {
+        _supplier = new SessionCascadingValueSupplier(NullLogger<SessionCascadingValueSupplier>.Instance);
+        _component = new TestComponent();
+    }
+
+    private SessionCascadingValueSupplier.SessionSubscription CreateSubscription(string key, Type propertyType)
+    {
+        return new SessionCascadingValueSupplier.SessionSubscription(
+            _supplier,
+            key,
+            propertyType,
+            () => _component.Value);
+    }
+
+    [Fact]
+    public void GetValue_ReturnsNull_WhenHttpContextNotSet()
+    {
+        var subscription = CreateSubscription("key", typeof(string));
+
+        var result = subscription.GetCurrentValue();
+
+        Assert.Null(result);
+    }
+
+    [Fact]
+    public void GetValue_ReturnsNull_WhenKeyNotFound()
+    {
+        var httpContext = CreateHttpContextWithSession();
+        _supplier.SetRequestContext(httpContext);
+
+        var subscription = CreateSubscription("nonexistent", typeof(string));
+        var result = subscription.GetCurrentValue();
+
+        Assert.Null(result);
+    }
+
+    [Fact]
+    public void GetValue_ReturnsValue_WhenKeyExists()
+    {
+        var httpContext = CreateHttpContextWithSession();
+        httpContext.Session.SetString("mykey", "\"myvalue\"");
+        _supplier.SetRequestContext(httpContext);
+
+        var subscription = CreateSubscription("mykey", typeof(string));
+        var result = subscription.GetCurrentValue();
+
+        Assert.Equal("myvalue", result);
+    }
+
+    [Fact]
+    public void GetValue_LowercasesSessionKey()
+    {
+        var httpContext = CreateHttpContextWithSession();
+        httpContext.Session.SetString("mykey", "\"myvalue\"");
+        _supplier.SetRequestContext(httpContext);
+
+        var subscription = CreateSubscription("MyKey", typeof(string));
+        var result = subscription.GetCurrentValue();
+
+        Assert.Equal("myvalue", result);
+    }
+
+    [Fact]
+    public void GetValue_DeserializesEnum()
+    {
+        var httpContext = CreateHttpContextWithSession();
+        httpContext.Session.SetString("status", "1");
+        _supplier.SetRequestContext(httpContext);
+
+        var subscription = CreateSubscription("status", typeof(TestEnum));
+        var result = subscription.GetCurrentValue();
+
+        Assert.IsType<TestEnum>(result);
+        Assert.Equal(TestEnum.Active, result);
+    }
+
+    [Fact]
+    public void GetValue_DeserializesNullableEnum()
+    {
+        var httpContext = CreateHttpContextWithSession();
+        httpContext.Session.SetString("status", "2");
+        _supplier.SetRequestContext(httpContext);
+
+        var subscription = CreateSubscription("status", typeof(TestEnum?));
+        var result = subscription.GetCurrentValue();
+
+        Assert.IsType<TestEnum>(result);
+        Assert.Equal(TestEnum.Inactive, result);
+    }
+
+    [Fact]
+    public void GetValue_ReturnsNull_WhenKeyNotFound_ForEnumType()
+    {
+        var httpContext = CreateHttpContextWithSession();
+        _supplier.SetRequestContext(httpContext);
+
+        var subscription = CreateSubscription("missing", typeof(TestEnum));
+        var result = subscription.GetCurrentValue();
+
+        Assert.Null(result);
+    }
+
+    [Fact]
+    public void GetValue_ReturnsNull_WhenDeserializationFails()
+    {
+        var httpContext = CreateHttpContextWithSession();
+        httpContext.Session.SetString("key", "not-valid-json-for-int");
+        _supplier.SetRequestContext(httpContext);
+
+        var subscription = CreateSubscription("key", typeof(int));
+        var result = subscription.GetCurrentValue();
+
+        Assert.Null(result);
+    }
+
+    [Fact]
+    public void GetCurrentValue_ReturnsComponentValue_OnSubsequentCalls()
+    {
+        var httpContext = CreateHttpContextWithSession();
+        httpContext.Session.SetString("key", "\"original\"");
+        _supplier.SetRequestContext(httpContext);
+
+        var subscription = CreateSubscription("key", typeof(string));
+        var firstResult = subscription.GetCurrentValue();
+
+        _component.Value = "modified";
+        var secondResult = subscription.GetCurrentValue();
+
+        Assert.Equal("original", firstResult);
+        Assert.Equal("modified", secondResult);
+    }
+
+    [Fact]
+    public async Task CreateSubscription_RegistersValueCallbackAndReturnsSubscription()
+    {
+        var httpContext = CreateHttpContextWithSession(out var responseFeature);
+        httpContext.Session.SetString(nameof(TestComponent.Value).ToLowerInvariant(), "\"from-session\"");
+        _supplier.SetRequestContext(httpContext);
+
+        var renderer = new TestRenderer();
+        var componentState = new ComponentState(renderer, 0, _component, null);
+        var attribute = new SupplyParameterFromSessionAttribute();
+        var parameterInfo = new CascadingParameterInfo(attribute, nameof(TestComponent.Value), typeof(string));
+
+        var subscription = _supplier.CreateSubscription(componentState, attribute, parameterInfo);
+
+        Assert.NotNull(subscription);
+        Assert.Equal("from-session", subscription.GetCurrentValue());
+
+        _component.Value = "updated";
+        await responseFeature.FireOnStartingAsync();
+        Assert.Equal("\"updated\"", httpContext.Session.GetString(nameof(TestComponent.Value).ToLowerInvariant()));
+    }
+
+    private class TestComponent : IComponent
+    {
+        public object? Value { get; set; }
+
+        public void Attach(RenderHandle renderHandle) { }
+
+        public Task SetParametersAsync(ParameterView parameters) => Task.CompletedTask;
+    }
+
+    public enum TestEnum
+    {
+        None = 0,
+        Active = 1,
+        Inactive = 2,
+    }
+}
diff --git a/src/Components/Endpoints/test/SessionValueMapperTest.cs b/src/Components/Endpoints/test/SessionValueMapperTest.cs
deleted file mode 100644
index 94a6c2d091e9..000000000000
--- a/src/Components/Endpoints/test/SessionValueMapperTest.cs
+++ /dev/null
@@ -1,282 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-
-#nullable enable
-
-using Microsoft.AspNetCore.Http;
-using Microsoft.AspNetCore.Http.Features;
-
-namespace Microsoft.AspNetCore.Components.Endpoints;
-
-public class SessionValueMapperTest
-{
-    private SessionValueMapper GetSessionValueMapper()
-    {
-        return new SessionValueMapper(new Microsoft.Extensions.Logging.Abstractions.NullLogger<SessionValueMapper>());
-    }
-
-    [Fact]
-    public void GetValue_ReturnsNull_WhenKeyNotFound()
-    {
-        // Arrange
-        var mapper = GetSessionValueMapper();
-        var httpContext = CreateHttpContextWithSession();
-        mapper.SetRequestContext(httpContext);
-
-        // Act
-        var result = mapper.GetValue("nonexistent", typeof(string));
-
-        // Assert
-        Assert.Null(result);
-    }
-
-    [Fact]
-    public void GetValue_ReturnsDeserializedValue_WhenKeyExists()
-    {
-        // Arrange
-        var mapper = GetSessionValueMapper();
-        var httpContext = CreateHttpContextWithSession();
-        httpContext.Session.SetString("email", "\"test@example.com\"");
-        mapper.SetRequestContext(httpContext);
-
-        // Act
-        var result = mapper.GetValue("email", typeof(string));
-
-        // Assert
-        Assert.Equal("test@example.com", result);
-    }
-
-    [Fact]
-    public void GetValue_DeserializesComplexType()
-    {
-        // Arrange
-        var mapper = GetSessionValueMapper();
-        var httpContext = CreateHttpContextWithSession();
-        httpContext.Session.SetString("user", "{\"name\":\"John\",\"age\":30}");
-        mapper.SetRequestContext(httpContext);
-
-        // Act
-        var result = mapper.GetValue("user", typeof(TestUser));
-
-        // Assert
-        var user = Assert.IsType<TestUser>(result);
-        Assert.Equal("John", user.Name);
-        Assert.Equal(30, user.Age);
-    }
-
-    [Fact]
-    public void RegisterValueCallback_AddsCallbackToList()
-    {
-        // Arrange
-        var mapper = GetSessionValueMapper();
-        var callCount = 0;
-
-        // Act
-        mapper.RegisterValueCallback("key", () => { callCount++; return "value"; });
-
-        // Assert
-        Assert.Equal(0, callCount);
-    }
-
-    [Fact]
-    public void RegisterValueCallback_ThrowsForDuplicateKey()
-    {
-        // Arrange
-        var mapper = GetSessionValueMapper();
-        mapper.RegisterValueCallback("key", () => "value1");
-
-        // Act & Assert
-        var ex = Assert.Throws<InvalidOperationException>(() =>
-            mapper.RegisterValueCallback("key", () => "value2"));
-        Assert.Contains("key", ex.Message);
-    }
-
-    [Fact]
-    public async Task PersistAllValues_PersistsValue()
-    {
-        // Arrange
-        var mapper = GetSessionValueMapper();
-        var httpContext = CreateHttpContextWithSession(out var responseFeature);
-        mapper.SetRequestContext(httpContext);
-
-        mapper.RegisterValueCallback("email", () => "test@example.com");
-
-        // Act
-        await responseFeature.FireOnStartingAsync();
-
-        // Assert
-        Assert.Equal("\"test@example.com\"", httpContext.Session.GetString("email"));
-    }
-
-    [Fact]
-    public async Task PersistAllValues_RemovesKey_WhenCallbackReturnsNull()
-    {
-        // Arrange
-        var mapper = GetSessionValueMapper();
-        var httpContext = CreateHttpContextWithSession(out var responseFeature);
-        httpContext.Session.SetString("email", "\"existing@example.com\"");
-        mapper.SetRequestContext(httpContext);
-
-        mapper.RegisterValueCallback("email", () => null);
-
-        // Act
-        await responseFeature.FireOnStartingAsync();
-
-        // Assert
-        Assert.Null(httpContext.Session.GetString("email"));
-    }
-
-    [Fact]
-    public async Task PersistAllValues_HandlesMultipleKeys()
-    {
-        // Arrange
-        var mapper = GetSessionValueMapper();
-        var httpContext = CreateHttpContextWithSession(out var responseFeature);
-        mapper.SetRequestContext(httpContext);
-
-        mapper.RegisterValueCallback("key1", () => "value1");
-        mapper.RegisterValueCallback("key2", () => "value2");
-
-        // Act
-        await responseFeature.FireOnStartingAsync();
-
-        // Assert
-        Assert.Equal("\"value1\"", httpContext.Session.GetString("key1"));
-        Assert.Equal("\"value2\"", httpContext.Session.GetString("key2"));
-    }
-
-    [Fact]
-    public async Task PersistAllValues_SerializesComplexTypes()
-    {
-        // Arrange
-        var mapper = GetSessionValueMapper();
-        var httpContext = CreateHttpContextWithSession(out var responseFeature);
-        mapper.SetRequestContext(httpContext);
-
-        mapper.RegisterValueCallback("user", () => new TestUser { Name = "Jane", Age = 25 });
-
-        // Act
-        await responseFeature.FireOnStartingAsync();
-
-        // Assert
-        var json = httpContext.Session.GetString("user");
-        Assert.NotNull(json);
-        Assert.Contains("\"name\":\"Jane\"", json);
-        Assert.Contains("\"age\":25", json);
-    }
-
-    [Fact]
-    public async Task HandlesIncorrectValuesInSession()
-    {
-        // Arrange
-        var mapper = GetSessionValueMapper();
-        var httpContext = CreateHttpContextWithSession(out var responseFeature);
-        mapper.SetRequestContext(httpContext);
-
-        mapper.RegisterValueCallback("number", () => "not-a-number");
-
-        // Act
-        await responseFeature.FireOnStartingAsync();
-        var result = mapper.GetValue("number", typeof(int));
-
-        // Assert
-        Assert.Null(result);
-    }
-
-    [Fact]
-    public async Task HandlesCallbackThrowing()
-    {
-        // Arrange
-        var mapper = GetSessionValueMapper();
-        var httpContext = CreateHttpContextWithSession(out var responseFeature);
-        mapper.SetRequestContext(httpContext);
-
-        mapper.RegisterValueCallback("number", () => throw new Exception("Callback exception"));
-
-        // Act
-        await responseFeature.FireOnStartingAsync();
-        var result = mapper.GetValue("number", typeof(int));
-
-        // Assert
-        Assert.Null(result);
-    }
-
-    private static DefaultHttpContext CreateHttpContextWithSession()
-    {
-        return CreateHttpContextWithSession(out _);
-    }
-
-    private static DefaultHttpContext CreateHttpContextWithSession(out TestHttpResponseFeature responseFeature)
-    {
-        var httpContext = new DefaultHttpContext();
-        var session = new TestSession();
-        httpContext.Features.Set<ISessionFeature>(new TestSessionFeature(session));
-
-        responseFeature = new TestHttpResponseFeature();
-        httpContext.Features.Set<IHttpResponseFeature>(responseFeature);
-
-        return httpContext;
-    }
-
-    private class TestUser
-    {
-        public string? Name { get; set; }
-        public int Age { get; set; }
-    }
-
-    private class TestSession : ISession
-    {
-        private readonly Dictionary<string, byte[]> _store = new();
-
-        public bool IsAvailable => true;
-        public string Id => "test-session";
-        public IEnumerable<string> Keys => _store.Keys;
-
-        public void Clear() => _store.Clear();
-        public Task CommitAsync(CancellationToken cancellationToken = default) => Task.CompletedTask;
-        public Task LoadAsync(CancellationToken cancellationToken = default) => Task.CompletedTask;
-        public void Remove(string key) => _store.Remove(key);
-        public void Set(string key, byte[] value) => _store[key] = value;
-        public bool TryGetValue(string key, [System.Diagnostics.CodeAnalysis.NotNullWhen(true)] out byte[]? value) => _store.TryGetValue(key, out value);
-    }
-
-    private class TestSessionFeature : ISessionFeature
-    {
-        public TestSessionFeature(ISession session)
-        {
-            Session = session;
-        }
-
-        public ISession Session { get; set; }
-    }
-
-    private class TestHttpResponseFeature : IHttpResponseFeature
-    {
-        private readonly Stack<(Func<object, Task> Callback, object State)> _onStarting = new();
-
-        public int StatusCode { get; set; } = 200;
-        public string? ReasonPhrase { get; set; }
-        public IHeaderDictionary Headers { get; set; } = new HeaderDictionary();
-        public Stream Body { get; set; } = new MemoryStream();
-        public bool HasStarted { get; private set; }
-
-        public void OnCompleted(Func<object, Task> callback, object state)
-        {
-        }
-
-        public void OnStarting(Func<object, Task> callback, object state)
-        {
-            _onStarting.Push((callback, state));
-        }
-
-        public async Task FireOnStartingAsync()
-        {
-            foreach (var (callback, state) in _onStarting)
-            {
-                await callback(state);
-            }
-            HasStarted = true;
-        }
-    }
-}
-
diff --git a/src/Components/Web/src/PublicAPI.Unshipped.txt b/src/Components/Web/src/PublicAPI.Unshipped.txt
index 3e6daf94f47d..2478b8813484 100644
--- a/src/Components/Web/src/PublicAPI.Unshipped.txt
+++ b/src/Components/Web/src/PublicAPI.Unshipped.txt
@@ -80,6 +80,10 @@ Microsoft.AspNetCore.Components.Web.Media.MediaSource.MediaSource(byte[]! data,
 Microsoft.AspNetCore.Components.Web.Media.MediaSource.MediaSource(System.IO.Stream! stream, string! mimeType, string! cacheKey) -> void
 Microsoft.AspNetCore.Components.Web.Media.MediaSource.MimeType.get -> string!
 Microsoft.AspNetCore.Components.Web.Media.MediaSource.Stream.get -> System.IO.Stream!
+Microsoft.AspNetCore.Components.Web.SupplyParameterFromSessionAttribute
+Microsoft.AspNetCore.Components.Web.SupplyParameterFromSessionAttribute.Name.get -> string?
+Microsoft.AspNetCore.Components.Web.SupplyParameterFromSessionAttribute.Name.set -> void
+Microsoft.AspNetCore.Components.Web.SupplyParameterFromSessionAttribute.SupplyParameterFromSessionAttribute() -> void
 Microsoft.AspNetCore.Components.Web.SupplyParameterFromTempDataAttribute
 Microsoft.AspNetCore.Components.Web.SupplyParameterFromTempDataAttribute.Name.get -> string?
 Microsoft.AspNetCore.Components.Web.SupplyParameterFromTempDataAttribute.Name.set -> void
diff --git a/src/Components/Components/src/SupplyParameterFromSessionAttribute.cs b/src/Components/Web/src/SupplyParameterFromSessionAttribute.cs
similarity index 93%
rename from src/Components/Components/src/SupplyParameterFromSessionAttribute.cs
rename to src/Components/Web/src/SupplyParameterFromSessionAttribute.cs
index 50faa0b4dd4d..945615560414 100644
--- a/src/Components/Components/src/SupplyParameterFromSessionAttribute.cs
+++ b/src/Components/Web/src/SupplyParameterFromSessionAttribute.cs
@@ -1,7 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-namespace Microsoft.AspNetCore.Components;
+namespace Microsoft.AspNetCore.Components.Web;
 
 /// <summary>
 /// Indicates that the value of the associated property should be supplied from

From e5692c65e442c8cc6fb9d1b06edd58ec8318ad29 Mon Sep 17 00:00:00 2001
From: Daria Tiurina <dariatiurina@microsoft.com>
Date: Mon, 20 Apr 2026 16:31:28 +0200
Subject: [PATCH 11/11] Clean-up

---
 .../SessionCascadingValueSupplier.cs          | 39 ++++++-------------
 .../SessionCascadingValueSupplierTest.cs      | 32 +++++++--------
 .../test/Session/SessionSubscriptionTest.cs   | 26 -------------
 ...SupplyParameterFromSessionAttributeTest.cs |  2 +-
 4 files changed, 26 insertions(+), 73 deletions(-)
 rename src/Components/Endpoints/src/{Session => }/SessionCascadingValueSupplier.cs (86%)

diff --git a/src/Components/Endpoints/src/Session/SessionCascadingValueSupplier.cs b/src/Components/Endpoints/src/SessionCascadingValueSupplier.cs
similarity index 86%
rename from src/Components/Endpoints/src/Session/SessionCascadingValueSupplier.cs
rename to src/Components/Endpoints/src/SessionCascadingValueSupplier.cs
index 877d65c45773..b9e364c148d8 100644
--- a/src/Components/Endpoints/src/Session/SessionCascadingValueSupplier.cs
+++ b/src/Components/Endpoints/src/SessionCascadingValueSupplier.cs
@@ -28,16 +28,6 @@ public SessionCascadingValueSupplier(ILogger<SessionCascadingValueSupplier> logg
 
     internal void SetRequestContext(HttpContext httpContext)
     {
-        if (ReferenceEquals(_httpContext, httpContext))
-        {
-            return;
-        }
-
-        if (_httpContext is not null)
-        {
-            throw new InvalidOperationException($"{nameof(SessionCascadingValueSupplier)} is already associated with a different {nameof(HttpContext)}.");
-        }
-
         _httpContext = httpContext;
         _httpContext.Response.OnStarting(PersistAllValues);
     }
@@ -91,26 +81,23 @@ internal Task PersistAllValues()
 
         foreach (var (key, valueGetter) in _valueCallbacks)
         {
-            object? value = null;
+            var sessionKey = key.ToLowerInvariant();
             try
             {
-                value = valueGetter();
+                var value = valueGetter();
+                if (value is not null)
+                {
+                    var json = JsonSerializer.Serialize(value, value.GetType(), _jsonOptions);
+                    session.SetString(sessionKey, json);
+                }
+                else
+                {
+                    session.Remove(sessionKey);
+                }
             }
             catch (Exception ex)
             {
                 Log.SessionPersistFail(_logger, ex);
-                continue;
-            }
-
-            var sessionKey = key.ToLowerInvariant();
-            if (value is not null)
-            {
-                var json = JsonSerializer.Serialize(value, value.GetType(), _jsonOptions);
-                session.SetString(sessionKey, json);
-            }
-            else
-            {
-                session.Remove(sessionKey);
             }
         }
         return Task.CompletedTask;
@@ -154,13 +141,10 @@ public SessionSubscription(
         {
             if (_delivered)
             {
-                // After the first delivery, return the component's current property value
-                // to avoid overriding modifications the component made during rendering.
                 return _currentValueGetter();
             }
 
             _delivered = true;
-
             var session = _owner.GetSession();
             if (session is null)
             {
@@ -174,7 +158,6 @@ public SessionSubscription(
                 {
                     return null;
                 }
-
                 return JsonSerializer.Deserialize(json, _propertyType, _jsonOptions);
             }
             catch (Exception ex)
diff --git a/src/Components/Endpoints/test/Session/SessionCascadingValueSupplierTest.cs b/src/Components/Endpoints/test/Session/SessionCascadingValueSupplierTest.cs
index cbe73efb0581..15b7a597dedb 100644
--- a/src/Components/Endpoints/test/Session/SessionCascadingValueSupplierTest.cs
+++ b/src/Components/Endpoints/test/Session/SessionCascadingValueSupplierTest.cs
@@ -101,6 +101,20 @@ public async Task PersistAllValues_ContinuesOnCallbackException()
         Assert.Equal("\"value2\"", httpContext.Session.GetString("key2"));
     }
 
+    [Fact]
+    public async Task PersistAllValues_ContinuesOnSerializationException()
+    {
+        _supplier.RegisterValueCallback("key1", () => new IntPtr(42));
+        _supplier.RegisterValueCallback("key2", () => "value2");
+
+        var httpContext = CreateHttpContextWithSession();
+        _supplier.SetRequestContext(httpContext);
+        await _supplier.PersistAllValues();
+
+        Assert.Null(httpContext.Session.GetString("key1"));
+        Assert.Equal("\"value2\"", httpContext.Session.GetString("key2"));
+    }
+
     [Fact]
     public async Task PersistAllValues_LowercasesSessionKey()
     {
@@ -158,24 +172,6 @@ public async Task SetRequestContext_RegistersOnStartingCallback()
         Assert.Equal("\"value\"", httpContext.Session.GetString("key"));
     }
 
-    [Fact]
-    public void SetRequestContext_IsIdempotent_ForSameHttpContext()
-    {
-        var httpContext = CreateHttpContextWithSession();
-        _supplier.SetRequestContext(httpContext);
-        _supplier.SetRequestContext(httpContext);
-    }
-
-    [Fact]
-    public void SetRequestContext_Throws_ForDifferentHttpContext()
-    {
-        var first = CreateHttpContextWithSession();
-        var second = CreateHttpContextWithSession();
-        _supplier.SetRequestContext(first);
-
-        Assert.Throws<InvalidOperationException>(() => _supplier.SetRequestContext(second));
-    }
-
     internal static DefaultHttpContext CreateHttpContextWithSession()
     {
         return CreateHttpContextWithSession(out _);
diff --git a/src/Components/Endpoints/test/Session/SessionSubscriptionTest.cs b/src/Components/Endpoints/test/Session/SessionSubscriptionTest.cs
index e2b5e56a28e5..443b0bb3cf8d 100644
--- a/src/Components/Endpoints/test/Session/SessionSubscriptionTest.cs
+++ b/src/Components/Endpoints/test/Session/SessionSubscriptionTest.cs
@@ -82,20 +82,6 @@ public void GetValue_LowercasesSessionKey()
 
     [Fact]
     public void GetValue_DeserializesEnum()
-    {
-        var httpContext = CreateHttpContextWithSession();
-        httpContext.Session.SetString("status", "1");
-        _supplier.SetRequestContext(httpContext);
-
-        var subscription = CreateSubscription("status", typeof(TestEnum));
-        var result = subscription.GetCurrentValue();
-
-        Assert.IsType<TestEnum>(result);
-        Assert.Equal(TestEnum.Active, result);
-    }
-
-    [Fact]
-    public void GetValue_DeserializesNullableEnum()
     {
         var httpContext = CreateHttpContextWithSession();
         httpContext.Session.SetString("status", "2");
@@ -108,18 +94,6 @@ public void GetValue_DeserializesNullableEnum()
         Assert.Equal(TestEnum.Inactive, result);
     }
 
-    [Fact]
-    public void GetValue_ReturnsNull_WhenKeyNotFound_ForEnumType()
-    {
-        var httpContext = CreateHttpContextWithSession();
-        _supplier.SetRequestContext(httpContext);
-
-        var subscription = CreateSubscription("missing", typeof(TestEnum));
-        var result = subscription.GetCurrentValue();
-
-        Assert.Null(result);
-    }
-
     [Fact]
     public void GetValue_ReturnsNull_WhenDeserializationFails()
     {
diff --git a/src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs b/src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs
index f8537fd2ba23..b86f1de1576f 100644
--- a/src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs
+++ b/src/Components/test/E2ETest/Tests/SupplyParameterFromSessionAttributeTest.cs
@@ -12,7 +12,7 @@
 using TestServer;
 using Xunit.Abstractions;
 
-namespace Microsoft.AspNetCore.Components.E2ETests.Tests;
+namespace Microsoft.AspNetCore.Components.E2ETest.Tests;
 
 public class SupplyParameterFromSessionAttributeTest : ServerTestBase<BasicTestAppServerSiteFixture<RazorComponentEndpointsNoInteractivityStartup<App>>>
 {