krubenok · July 29, 2026 04:28
diff --git a/README.md b/README.md
diff --git a/AppElicitationExample.csproj b/AppElicitationExample.csproj
 <Project Sdk="Microsoft.NET.Sdk.Web">
  <PropertyGroup>
    <TargetFramework>net10.0</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
    <NoWarn>$(NoWarn);MCPEXP003;MCPAELICITATION001</NoWarn>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="ModelContextProtocol.AspNetCore" Version="2.0.0-rc.2" />
    <PackageReference Include="Krubenok.ModelContextProtocol.Extensions.Apps.Elicitation"
                      Version="0.3.0-preview.4" />
  </ItemGroup>

  <ItemGroup>
    <Content Include="ui\choose-option.html" CopyToOutputDirectory="PreserveNewest" />
  </ItemGroup>
 </Project>
diff --git a/ChoiceResources.cs b/ChoiceResources.cs
 using ModelContextProtocol.Extensions.Apps;
 using ModelContextProtocol.Server;
 using System.ComponentModel;

 [McpServerResourceType]
 public sealed class ChoiceResources
 {
    public const string AppResourceUri = "ui://examples/choose-option";

    [McpServerResource(
        UriTemplate = AppResourceUri,
        Name = "choose-option",
        MimeType = McpApps.HtmlMimeType)]
    [McpMeta("ui", """{"prefersBorder":true}""")]
    [Description("MCP App that renders the choose-option form elicitation.")]
    public static string GetChooseOptionApp() =>
        File.ReadAllText(Path.Combine(AppContext.BaseDirectory, "ui", "choose-option.html"));
 }
diff --git a/ChoiceTools.cs b/ChoiceTools.cs
 using ModelContextProtocol.Extensions.Apps.Elicitation;
 using ModelContextProtocol.Protocol;
 using ModelContextProtocol.Server;
 using System.ComponentModel;
 using System.Text.Json.Serialization;

 [McpServerToolType]
 public sealed class ChoiceTools
 {
    [McpServerTool(Name = "choose_option")]
    [Description("Ask the user to choose and confirm one of two options.")]
    public static string ChooseOption(
        McpServer server,
        RequestContext<CallToolRequestParams> context)
    {
        var elicitation = McpAppElicitation.SetAppUiIfSupported(
            new ElicitRequestParams
            {
                Message = "Choose an option and confirm your selection.",
                RequestedSchema = new ElicitRequestParams.RequestSchema
                {
                    Properties = new Dictionary<string, ElicitRequestParams.PrimitiveSchemaDefinition>
                    {
                        ["selectedOption"] = new ElicitRequestParams.UntitledSingleSelectEnumSchema
                        {
                            Title = "Option",
                            Enum = ["standard", "priority"],
                            Default = "standard",
                        },
                        ["confirmed"] = new ElicitRequestParams.BooleanSchema
                        {
                            Title = "Confirm selection",
                            Default = true,
                        },
                    },
                    Required = ["selectedOption", "confirmed"],
                },
            },
            context,
            ChoiceResources.AppResourceUri);

        var response = McpAppElicitation.ResolveOrRequest(
            server,
            context.Params,
            inputKey: "option-choice",
            elicitation,
            ExampleJsonContext.Default.OptionChoice,
            requestState: "choose-option:v1");

        if (!response.IsAccepted || response.Content is null)
        {
            var disposition = response.Action switch
            {
                "decline" => "declined",
                "cancel" => "canceled",
                _ => response.Action,
            };
            return $"The user {disposition} the choice.";
        }

        return response.Content.Confirmed
            ? $"The user selected and confirmed '{response.Content.SelectedOption}'."
            : $"The user selected '{response.Content.SelectedOption}' without confirming it.";
    }
 }

 public sealed class OptionChoice
 {
    public string SelectedOption { get; set; } = string.Empty;

    public bool Confirmed { get; set; }
 }

 [JsonSourceGenerationOptions(PropertyNamingPolicy = JsonKnownNamingPolicy.CamelCase)]
 [JsonSerializable(typeof(OptionChoice))]
 internal sealed partial class ExampleJsonContext : JsonSerializerContext
 {
 }
diff --git a/choose-option.html b/choose-option.html
 <!doctype html>
 <html lang="en">
 <head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Choose an option</title>
 </head>
 <body>
  <p id="message">Choose an option.</p>
  <label><input type="radio" name="option" value="standard" checked> Standard</label>
  <label><input type="radio" name="option" value="priority"> Priority</label>
  <button id="confirm">Confirm</button>
  <button id="cancel">Cancel</button>

  <script>
    const initializeRequestId = "app-init";
    let elicitationRequestId;

    function send(message) {
      window.parent.postMessage(message, "*");
    }

    window.addEventListener("message", event => {
      const message = event.data;
      if (!message || message.jsonrpc !== "2.0") return;

      if (message.id === initializeRequestId && message.result) {
        send({ jsonrpc: "2.0", method: "ui/notifications/initialized" });
        return;
      }

      if (message.method === "elicitation/create") {
        elicitationRequestId = message.id;
        document.getElementById("message").textContent = message.params.message;
      }
    });

    document.getElementById("confirm").addEventListener("click", () => {
      const selectedOption =
        document.querySelector('input[name="option"]:checked').value;

      send({
        jsonrpc: "2.0",
        id: elicitationRequestId,
        result: {
          action: "accept",
          content: { selectedOption, confirmed: true }
        }
      });
    });

    document.getElementById("cancel").addEventListener("click", () => {
      send({
        jsonrpc: "2.0",
        id: elicitationRequestId,
        result: { action: "cancel" }
      });
    });

    send({
      jsonrpc: "2.0",
      id: initializeRequestId,
      method: "ui/initialize",
      params: {
        appInfo: { name: "choose-option-app", version: "1.0.0" },
        appCapabilities: { elicitation: {} }
      }
    });
  </script>
 </body>
 </html>
diff --git a/inspector-testing.md b/inspector-testing.md
diff --git a/Program.cs b/Program.cs
 using ModelContextProtocol.AspNetCore;
 using ModelContextProtocol.Extensions.Apps.Elicitation;
 using ModelContextProtocol.Protocol;

 var builder = WebApplication.CreateBuilder(args);

 builder.Services
    .AddMcpServer(options =>
    {
        options.ProtocolVersion = "2026-07-28";
        options.ServerInfo = new Implementation
        {
            Name = "app-elicitation-example",
            Version = "1.0.0",
        };
        options.Capabilities = new ServerCapabilities
        {
            Tools = new ToolsCapability(),
            Resources = new ResourcesCapability(),
        };
    })
    .WithHttpTransport(options => options.Stateless = true)
    .WithTools<ChoiceTools>()
    .WithResources<ChoiceResources>()
    .WithMcpAppElicitation();

 var app = builder.Build();
 app.MapMcp("/mcp");
 app.Run();
diff --git a/typescript-client.md b/typescript-client.md
	<Project Sdk="Microsoft.NET.Sdk.Web">
	<PropertyGroup>
	<TargetFramework>net10.0</TargetFramework>
	<Nullable>enable</Nullable>
	<ImplicitUsings>enable</ImplicitUsings>
	<NoWarn>$(NoWarn);MCPEXP003;MCPAELICITATION001</NoWarn>
	</PropertyGroup>

	<ItemGroup>
	<PackageReference Include="ModelContextProtocol.AspNetCore" Version="2.0.0-rc.2" />
	<PackageReference Include="Krubenok.ModelContextProtocol.Extensions.Apps.Elicitation"
	Version="0.3.0-preview.4" />
	</ItemGroup>

	<ItemGroup>
	<Content Include="ui\choose-option.html" CopyToOutputDirectory="PreserveNewest" />
	</ItemGroup>
	</Project>
	using ModelContextProtocol.Extensions.Apps;
	using ModelContextProtocol.Server;
	using System.ComponentModel;

	[McpServerResourceType]
	public sealed class ChoiceResources
	{
	public const string AppResourceUri = "ui://examples/choose-option";

	[McpServerResource(
	UriTemplate = AppResourceUri,
	Name = "choose-option",
	MimeType = McpApps.HtmlMimeType)]
	[McpMeta("ui", """{"prefersBorder":true}""")]
	[Description("MCP App that renders the choose-option form elicitation.")]
	public static string GetChooseOptionApp() =>
	File.ReadAllText(Path.Combine(AppContext.BaseDirectory, "ui", "choose-option.html"));
	}
	using ModelContextProtocol.Extensions.Apps.Elicitation;
	using ModelContextProtocol.Protocol;
	using ModelContextProtocol.Server;
	using System.ComponentModel;
	using System.Text.Json.Serialization;

	[McpServerToolType]
	public sealed class ChoiceTools
	{
	[McpServerTool(Name = "choose_option")]
	[Description("Ask the user to choose and confirm one of two options.")]
	public static string ChooseOption(
	McpServer server,
	RequestContext<CallToolRequestParams> context)
	{
	var elicitation = McpAppElicitation.SetAppUiIfSupported(
	new ElicitRequestParams
	{
	Message = "Choose an option and confirm your selection.",
	RequestedSchema = new ElicitRequestParams.RequestSchema
	{
	Properties = new Dictionary<string, ElicitRequestParams.PrimitiveSchemaDefinition>
	{
	["selectedOption"] = new ElicitRequestParams.UntitledSingleSelectEnumSchema
	{
	Title = "Option",
	Enum = ["standard", "priority"],
	Default = "standard",
	},
	["confirmed"] = new ElicitRequestParams.BooleanSchema
	{
	Title = "Confirm selection",
	Default = true,
	},
	},
	Required = ["selectedOption", "confirmed"],
	},
	},
	context,
	ChoiceResources.AppResourceUri);

	var response = McpAppElicitation.ResolveOrRequest(
	server,
	context.Params,
	inputKey: "option-choice",
	elicitation,
	ExampleJsonContext.Default.OptionChoice,
	requestState: "choose-option:v1");

	if (!response.IsAccepted \|\| response.Content is null)
	{
	var disposition = response.Action switch
	{
	"decline" => "declined",
	"cancel" => "canceled",
	_ => response.Action,
	};
	return $"The user {disposition} the choice.";
	}

	return response.Content.Confirmed
	? $"The user selected and confirmed '{response.Content.SelectedOption}'."
	: $"The user selected '{response.Content.SelectedOption}' without confirming it.";
	}
	}

	public sealed class OptionChoice
	{
	public string SelectedOption { get; set; } = string.Empty;

	public bool Confirmed { get; set; }
	}

	[JsonSourceGenerationOptions(PropertyNamingPolicy = JsonKnownNamingPolicy.CamelCase)]
	[JsonSerializable(typeof(OptionChoice))]
	internal sealed partial class ExampleJsonContext : JsonSerializerContext
	{
	}
	<!doctype html>
	<html lang="en">
	<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title>Choose an option</title>
	</head>
	<body>
	<p id="message">Choose an option.</p>
	<label><input type="radio" name="option" value="standard" checked> Standard</label>
	<label><input type="radio" name="option" value="priority"> Priority</label>
	<button id="confirm">Confirm</button>
	<button id="cancel">Cancel</button>

	<script>
	const initializeRequestId = "app-init";
	let elicitationRequestId;

	function send(message) {
	window.parent.postMessage(message, "*");
	}

	window.addEventListener("message", event => {
	const message = event.data;
	if (!message \|\| message.jsonrpc !== "2.0") return;

	if (message.id === initializeRequestId && message.result) {
	send({ jsonrpc: "2.0", method: "ui/notifications/initialized" });
	return;
	}

	if (message.method === "elicitation/create") {
	elicitationRequestId = message.id;
	document.getElementById("message").textContent = message.params.message;
	}
	});

	document.getElementById("confirm").addEventListener("click", () => {
	const selectedOption =
	document.querySelector('input[name="option"]:checked').value;

	send({
	jsonrpc: "2.0",
	id: elicitationRequestId,
	result: {
	action: "accept",
	content: { selectedOption, confirmed: true }
	}
	});
	});

	document.getElementById("cancel").addEventListener("click", () => {
	send({
	jsonrpc: "2.0",
	id: elicitationRequestId,
	result: { action: "cancel" }
	});
	});

	send({
	jsonrpc: "2.0",
	id: initializeRequestId,
	method: "ui/initialize",
	params: {
	appInfo: { name: "choose-option-app", version: "1.0.0" },
	appCapabilities: { elicitation: {} }
	}
	});
	</script>
	</body>
	</html>
	using ModelContextProtocol.AspNetCore;
	using ModelContextProtocol.Extensions.Apps.Elicitation;
	using ModelContextProtocol.Protocol;

	var builder = WebApplication.CreateBuilder(args);

	builder.Services
	.AddMcpServer(options =>
	{
	options.ProtocolVersion = "2026-07-28";
	options.ServerInfo = new Implementation
	{
	Name = "app-elicitation-example",
	Version = "1.0.0",
	};
	options.Capabilities = new ServerCapabilities
	{
	Tools = new ToolsCapability(),
	Resources = new ResourcesCapability(),
	};
	})
	.WithHttpTransport(options => options.Stateless = true)
	.WithTools<ChoiceTools>()
	.WithResources<ChoiceResources>()
	.WithMcpAppElicitation();

	var app = builder.Build();
	app.MapMcp("/mcp");
	app.Run();
Client capability input	Server behavior
Nested-only canonical shape from a future main MCP Apps client	App-rendered elicitation enabled
Dual canonical + prototype shape from this preview.5 package	App-rendered elicitation enabled
Canonical shape plus a malformed or unknown prototype gate	App-rendered elicitation enabled; gate ignored
Prototype gate only	Native form fallback
Base MCP Apps MIME type without nested `elicitation`	Native form fallback
Missing core `elicitation.form` or MCP App MIME type	Native form fallback
Malformed MCP Apps settings or malformed nested `elicitation`	Native form fallback
API	Purpose
`withAppElicitationClientCapabilities()`	Adds core form, canonical MCP Apps elicitation, MIME type, and the default-on prototype gate.
`withAppElicitationBridgeCapabilities()`	Adds `elicitation: {}` to app or host bridge capabilities without replacing other settings.
`supportsAppElicitationBridgeCapability()`	Checks the negotiated app or host bridge member.
`registerAppElicitationClient()`	Registers legacy and MRTR client handling with native fallback.
`registerAppElicitationApp()`	Registers the standard app-side `elicitation/create` handler.
`preserveAppElicitationCapability()`	Preserves app capabilities through ext-apps 1.7.5 `ui/initialize`.
`preserveHostAppElicitationCapability()`	Preserves host capabilities through ext-apps 1.7.5 `ui/initialize`.
`waitForAppInitialized()` / `onAppInitialized()`	Race-safe app readiness APIs.
`adaptExtAppsBridge()`	Adapts the ext-apps bridge to a request-bound session.
`validateAppElicitationResult()`	Validates the core result and accepted content schema.
`getAppElicitationResourceUri()`	Reads and validates an absolute `ui://` form hint.