Types.cs

/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *--------------------------------------------------------------------------------------------*/

using GitHub.Copilot.Rpc;
using Microsoft.Extensions.AI;
using Microsoft.Extensions.Logging;
using System;
using System.ComponentModel;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Text.Json;
using System.Text.Json.Nodes;
using System.Text.Json.Serialization;
using System.Threading.Tasks;

namespace GitHub.Copilot;

internal static class GeneratedStringEnumJson
{
    internal static string ReadValue(ref Utf8JsonReader reader, Type typeToConvert)
    {
        if (reader.TokenType != JsonTokenType.String)
        {
            throw new JsonException($"Expected a string token when reading {typeToConvert.Name}, but found {reader.TokenType}.");
        }

        var value = reader.GetString();
        if (string.IsNullOrWhiteSpace(value))
        {
            throw new JsonException($"Expected a non-empty string token when reading {typeToConvert.Name}.");
        }

        return value!;
    }

    internal static void WriteValue(Utf8JsonWriter writer, string value, Type typeToConvert)
    {
        if (string.IsNullOrWhiteSpace(value))
        {
            throw new JsonException($"Expected a non-empty string value when writing {typeToConvert.Name}.");
        }

        writer.WriteStringValue(value);
    }
}

/// <summary>Diagnostic IDs for the Copilot SDK.</summary>
internal static class Diagnostics
{
    /// <summary>Indicates an experimental API that may change or be removed.</summary>
    internal const string Experimental = "GHCP001";
}

/// <summary>
/// Log level for the Copilot runtime. Use the well-known values exposed as
/// static members (<see cref="None"/>, <see cref="Error"/>, <see cref="Warning"/>,
/// <see cref="Info"/>, <see cref="Debug"/>, <see cref="All"/>), or construct
/// your own with <see cref="CopilotLogLevel(string)"/> if the runtime accepts
/// additional values. The runtime does not necessarily treat the values as a
/// linear scale, so do not assume <c>&lt;</c>/<c>&gt;</c> comparisons are meaningful.
/// </summary>
[DebuggerDisplay("{Value,nq}")]
public readonly struct CopilotLogLevel : IEquatable<CopilotLogLevel>
{
    /// <summary>Disable logging entirely.</summary>
    public static CopilotLogLevel None { get; } = new("none");

    /// <summary>Log only errors.</summary>
    public static CopilotLogLevel Error { get; } = new("error");

    /// <summary>Log warnings and errors.</summary>
    public static CopilotLogLevel Warning { get; } = new("warning");

    /// <summary>Log informational messages, warnings, and errors.</summary>
    public static CopilotLogLevel Info { get; } = new("info");

    /// <summary>Log debug-level diagnostics in addition to the above.</summary>
    public static CopilotLogLevel Debug { get; } = new("debug");

    /// <summary>Log every diagnostic the runtime emits.</summary>
    public static CopilotLogLevel All { get; } = new("all");

    /// <summary>Gets the underlying string value of this <see cref="CopilotLogLevel"/>.</summary>
    public string Value => _value ?? string.Empty;

    private readonly string? _value;

    /// <summary>Initializes a new instance of the <see cref="CopilotLogLevel"/> struct.</summary>
    /// <param name="value">The wire string value for this log level.</param>
    public CopilotLogLevel(string value) => _value = value;

    /// <inheritdoc/>
    public static bool operator ==(CopilotLogLevel left, CopilotLogLevel right) => left.Equals(right);

    /// <inheritdoc/>
    public static bool operator !=(CopilotLogLevel left, CopilotLogLevel right) => !left.Equals(right);

    /// <inheritdoc/>
    public override bool Equals([NotNullWhen(true)] object? obj) => obj is CopilotLogLevel other && Equals(other);

    /// <inheritdoc/>
    public bool Equals(CopilotLogLevel other) => string.Equals(Value, other.Value, StringComparison.OrdinalIgnoreCase);

    /// <inheritdoc/>
    public override int GetHashCode() => StringComparer.OrdinalIgnoreCase.GetHashCode(Value);

    /// <inheritdoc/>
    public override string ToString() => Value;
}

/// <summary>
/// Configures how a <see cref="CopilotClient"/> connects to the Copilot runtime.
/// Use the factory methods on this class to construct an instance.
/// </summary>
public abstract class RuntimeConnection
{
    internal RuntimeConnection() { }

    /// <summary>
    /// Spawn a runtime child process and communicate over its stdin/stdout.
    /// This is the default if no <see cref="CopilotClientOptions.Connection"/> is set.
    /// </summary>
    /// <param name="path">Path to the runtime executable. When <c>null</c>, the bundled runtime is used.</param>
    /// <param name="args">Extra command-line arguments to pass to the runtime process.</param>
    public static StdioRuntimeConnection ForStdio(string? path = null, IList<string>? args = null)
        => new() { Path = path, Args = args };

    /// <summary>
    /// Spawn a runtime child process that listens on a TCP socket and connect to it.
    /// </summary>
    /// <param name="port">TCP port to listen on. <c>0</c> (the default) auto-allocates a free port.
    /// If the chosen port is already in use, startup fails.</param>
    /// <param name="connectionToken">Optional shared secret the SDK sends to the spawned runtime to authenticate the TCP connection.
    /// When <c>null</c>, a GUID is generated automatically.</param>
    /// <param name="path">Path to the runtime executable. When <c>null</c>, the bundled runtime is used.</param>
    /// <param name="args">Extra command-line arguments to pass to the runtime process.</param>
    public static TcpRuntimeConnection ForTcp(int port = 0, string? connectionToken = null, string? path = null, IList<string>? args = null)
        => new() { Port = port, ConnectionToken = connectionToken, Path = path, Args = args };

    /// <summary>
    /// Connect to an already-running runtime at a given URI.
    /// </summary>
    /// <param name="url">URL of the runtime to connect to. Accepts <c>"port"</c>, <c>"host:port"</c>, or a full URL.</param>
    /// <param name="connectionToken">Optional shared secret to authenticate the connection.</param>
    public static UriRuntimeConnection ForUri(string url, string? connectionToken = null)
        => new() { Url = url, ConnectionToken = connectionToken };

    /// <summary>
    /// Host the runtime in-process by loading its native library and communicating
    /// over the C ABI (FFI) — no child process is spawned by the SDK for JSON-RPC
    /// transport. The bundled runtime is used; to point at a non-default runtime
    /// entrypoint, set the <c>COPILOT_CLI_PATH</c> environment variable.
    /// </summary>
    /// <remarks>
    /// Works across the SDK's target frameworks: modern .NET uses <c>NativeLibrary</c>,
    /// while <c>netstandard2.0</c> consumers use a built-in fallback native loader.
    /// </remarks>
    [Experimental(Diagnostics.Experimental)]
    public static InProcessRuntimeConnection ForInProcess()
        => new();
}

/// <summary>
/// Base for <see cref="RuntimeConnection"/> kinds that spawn a runtime child process.
/// </summary>
public abstract class ChildProcessRuntimeConnection : RuntimeConnection
{
    internal ChildProcessRuntimeConnection() { }

    /// <summary>Path to the runtime executable. When <c>null</c>, the bundled runtime is used.</summary>
    public string? Path { get; set; }

    /// <summary>Extra command-line arguments to pass to the runtime process.</summary>
    public IList<string>? Args { get; set; }

    /// <summary>
    /// Gets or sets the environment variables passed to the spawned runtime process,
    /// replacing the inherited environment.
    /// </summary>
    /// <remarks>
    /// Cannot be combined with <see cref="CopilotClientOptions.Environment"/>; setting both throws
    /// an <see cref="ArgumentException"/> when the client is constructed.
    /// </remarks>
    public IReadOnlyDictionary<string, string>? Environment { get; set; }
}

/// <summary>
/// Spawns a runtime child process and communicates over stdin/stdout. Construct via
/// <see cref="RuntimeConnection.ForStdio(string?, IList{string}?)"/>.
/// </summary>
public sealed class StdioRuntimeConnection : ChildProcessRuntimeConnection
{
    internal StdioRuntimeConnection() { }
}

/// <summary>
/// Hosts the runtime in-process by loading its native library and communicating
/// over the C ABI (FFI). Construct via <see cref="RuntimeConnection.ForInProcess()"/>.
/// Works across the SDK's target frameworks (modern .NET and <c>netstandard2.0</c>).
/// To point at a non-default runtime entrypoint, set the <c>COPILOT_CLI_PATH</c>
/// environment variable.
/// </summary>
[Experimental(Diagnostics.Experimental)]
public sealed class InProcessRuntimeConnection : RuntimeConnection
{
    internal InProcessRuntimeConnection() { }
}

/// <summary>
/// Spawns a runtime child process listening on a TCP socket. Construct via
/// <see cref="RuntimeConnection.ForTcp(int, string?, string?, IList{string}?)"/>.
/// </summary>
public sealed class TcpRuntimeConnection : ChildProcessRuntimeConnection
{
    internal TcpRuntimeConnection() { }

    /// <summary>
    /// TCP port to listen on. <c>0</c> (the default) auto-allocates a free port.
    /// If the chosen port is already in use, startup fails.
    /// </summary>
    public int Port { get; set; }

    /// <summary>
    /// Optional shared secret the SDK sends to the spawned runtime to authenticate
    /// the TCP connection. When <c>null</c>, a GUID is generated automatically.
    /// </summary>
    public string? ConnectionToken { get; set; }
}

/// <summary>
/// Connects to an already-running runtime at the specified URL. Construct via
/// <see cref="RuntimeConnection.ForUri(string, string?)"/>.
/// </summary>
public sealed class UriRuntimeConnection : RuntimeConnection
{
    internal UriRuntimeConnection() { }

    /// <summary>
    /// URL of the runtime to connect to. Accepts <c>"port"</c>, <c>"host:port"</c>,
    /// or a full URL.
    /// </summary>
    public required string Url { get; set; }

    /// <summary>Optional shared secret to authenticate the connection.</summary>
    public string? ConnectionToken { get; set; }
}

/// <summary>
/// Selects the defaulting strategy used by <see cref="CopilotClient"/>.
/// </summary>
public enum CopilotClientMode
{
    /// <summary>
    /// Disables optional features by default. The app must explicitly opt into
    /// anything it needs. Required for any scenario where CLI-like ambient
    /// behavior is unsafe (e.g., multi-user servers).
    /// <para>
    /// When this mode is selected:
    /// </para>
    /// <list type="bullet">
    /// <item>The client constructor requires
    ///     <see cref="CopilotClientOptions.BaseDirectory"/> or
    ///     <see cref="CopilotClientOptions.SessionFs"/> to be set.</item>
    /// <item><see cref="SessionConfigBase.AvailableTools"/> must be supplied on
    ///     every session — no tools are exposed by default.</item>
    /// <item><c>session.create</c> always sets
    ///     <c>toolFilterPrecedence: "excluded"</c> so the allowlist and denylist
    ///     compose naturally.</item>
    /// <item>The SDK injects safe defaults for ambient session features
    ///     (telemetry, custom instructions, plugins, environment context, etc.).</item>
    /// <item><c>COPILOT_DISABLE_KEYTAR=1</c> is set on the spawned runtime so
    ///     credentials are persisted to <c>COPILOT_HOME</c> rather than a
    ///     process-wide system keychain.</item>
    /// </list>
    /// </summary>
    Empty,

    /// <summary>
    /// Uses defaults equivalent to GitHub Copilot CLI. The default. Useful when
    /// building a coding agent that shares sessions with Copilot CLI.
    /// <para>
    /// <b>Do not use this mode for server-based multi-user applications</b> —
    /// the default coding agent has tools and capabilities that operate across
    /// sessions and can access the host OS environment.
    /// </para>
    /// </summary>
    CopilotCli,
}

/// <summary>
/// Configuration options for creating a <see cref="CopilotClient"/> instance.
/// </summary>
public sealed class CopilotClientOptions
{
    /// <summary>
    /// Initializes a new instance of the <see cref="CopilotClientOptions"/> class.
    /// </summary>
    public CopilotClientOptions() { }

    /// <summary>
    /// Initializes a new instance of the <see cref="CopilotClientOptions"/> class
    /// by copying the properties of the specified instance.
    /// </summary>
    private CopilotClientOptions(CopilotClientOptions? other)
    {
        if (other is null) return;

        Connection = other.Connection;
        WorkingDirectory = other.WorkingDirectory;
        BaseDirectory = other.BaseDirectory;
        BuiltinPluginDirectories = other.BuiltinPluginDirectories is null ? null : [.. other.BuiltinPluginDirectories];
        Environment = other.Environment;
        GitHubToken = other.GitHubToken;
        Logger = other.Logger;
        LogLevel = other.LogLevel;
        Telemetry = other.Telemetry;
        UseLoggedInUser = other.UseLoggedInUser;
        OnListModels = other.OnListModels;
        SessionFs = other.SessionFs;
        RequestHandler = other.RequestHandler;
        OnGitHubTelemetry = other.OnGitHubTelemetry;
        SessionIdleTimeoutSeconds = other.SessionIdleTimeoutSeconds;
        EnableRemoteSessions = other.EnableRemoteSessions;
        ClientInfo = other.ClientInfo;
        Mode = other.Mode;
    }

    /// <summary>
    /// Selects the SDK defaulting strategy. See <see cref="CopilotClientMode"/>.
    /// </summary>
    /// <remarks>
    /// When set to <see cref="CopilotClientMode.Empty"/>, the SDK validates that
    /// the app has supplied the required configuration
    /// (<see cref="BaseDirectory"/> or <see cref="SessionFs"/>, plus
    /// <see cref="SessionConfigBase.AvailableTools"/> on each session) and
    /// translates session creation requests into runtime options that flip
    /// tool filter precedence to <c>excluded</c>-wins so exclusions are
    /// expressible.
    /// </remarks>
    public CopilotClientMode Mode { get; set; } = CopilotClientMode.CopilotCli;

    /// <summary>
    /// How to connect to the runtime. When <c>null</c>, the default is
    /// <see cref="RuntimeConnection.ForStdio(string?, IList{string}?)"/> with the bundled runtime.
    /// </summary>
    public RuntimeConnection? Connection { get; set; }

    /// <summary>
    /// Working directory for the runtime process.
    /// </summary>
    public string? WorkingDirectory { get; set; }

    /// <summary>
    /// Base directory for Copilot data (session state, config, etc.).
    /// Sets the <c>COPILOT_HOME</c> environment variable on the spawned runtime.
    /// When <see langword="null"/>, the runtime defaults to <c>~/.copilot</c>.
    /// Ignored when connecting to an existing runtime via
    /// <see cref="RuntimeConnection.ForUri(string, string?)"/>.
    /// </summary>
    public string? BaseDirectory { get; set; }

    /// <summary>
    /// Absolute paths to trusted plugin directories bundled by the host.
    /// When non-empty, the complete set is registered with the runtime during
    /// startup before sessions can be created.
    /// </summary>
    public IList<string>? BuiltinPluginDirectories { get; set; }

    /// <summary>
    /// Log level for the Copilot runtime. Use the well-known values on
    /// <see cref="CopilotLogLevel"/> (<see cref="CopilotLogLevel.None"/>,
    /// <see cref="CopilotLogLevel.Error"/>, <see cref="CopilotLogLevel.Warning"/>,
    /// <see cref="CopilotLogLevel.Info"/>, <see cref="CopilotLogLevel.Debug"/>,
    /// <see cref="CopilotLogLevel.All"/>). When <c>null</c>, the runtime's default
    /// log level is used.
    /// </summary>
    public CopilotLogLevel? LogLevel { get; set; }

    /// <summary>
    /// Gets or sets environment variables passed to the runtime process.
    /// </summary>
    /// <remarks>
    /// Not supported with the in-process transport (<see cref="RuntimeConnection.ForInProcess"/>),
    /// which runs the runtime in the host process; setting this option there throws an
    /// <see cref="ArgumentException"/>. For child-process transports, prefer
    /// <see cref="ChildProcessRuntimeConnection.Environment"/>; setting both throws.
    /// </remarks>
    public IReadOnlyDictionary<string, string>? Environment { get; set; }

    /// <summary>Logger instance for SDK diagnostic output.</summary>
    public ILogger? Logger { get; set; }

    /// <summary>
    /// GitHub token to use for authentication.
    /// When provided, the token is passed to the runtime via environment variable.
    /// This takes priority over other authentication methods.
    /// </summary>
    public string? GitHubToken { get; set; }

    /// <summary>
    /// Whether to use the logged-in user for authentication.
    /// When true, the runtime will attempt to use stored OAuth tokens or gh CLI auth.
    /// When false, only explicit tokens (GitHubToken or environment variables) are used.
    /// Default: true (but defaults to false when GitHubToken is provided).
    /// </summary>
    public bool? UseLoggedInUser { get; set; }

    /// <summary>
    /// Custom handler for listing available models.
    /// When provided, <c>ListModelsAsync()</c> calls this handler instead of
    /// querying the runtime. Useful in BYOK mode to return models
    /// available from your custom provider.
    /// </summary>
    public Func<CancellationToken, Task<IList<ModelInfo>>>? OnListModels { get; set; }

    /// <summary>
    /// Custom session filesystem provider configuration.
    /// When set, the client registers as the session filesystem provider on connect,
    /// routing session-scoped file I/O through per-session handlers created via
    /// <see cref="SessionConfigBase.CreateSessionFsProvider"/>.
    /// </summary>
    public SessionFsConfig? SessionFs { get; set; }

    /// <summary>
    /// Configures interception of the LLM inference requests the runtime would
    /// otherwise issue itself (for both CAPI and BYOK providers). When set, the
    /// client registers a client-global LLM inference handler on connect, so
    /// every model-layer HTTP / WebSocket request is routed to this
    /// <see cref="CopilotRequestHandler"/> subclass instead of the runtime's own
    /// outbound call.
    /// </summary>
    [Experimental(Diagnostics.Experimental)]
    public CopilotRequestHandler? RequestHandler { get; set; }

    /// <summary>
    /// Experimental. Receives GitHub telemetry events the runtime forwards to this
    /// connection; setting a handler opts created/resumed sessions into forwarding.
    /// The SDK awaits the handler task so it may perform asynchronous work.
    /// </summary>
    [Experimental(Diagnostics.Experimental)]
    [EditorBrowsable(EditorBrowsableState.Never)]
    public Func<Rpc.GitHubTelemetryNotification, Task>? OnGitHubTelemetry { get; set; }

    /// <summary>
    /// OpenTelemetry configuration for the runtime.
    /// When set to a non-<see langword="null"/> instance, the runtime is started with OpenTelemetry instrumentation enabled.
    /// </summary>
    public TelemetryConfig? Telemetry { get; set; }

    /// <summary>
    /// Server-wide idle timeout for sessions in seconds.
    /// Sessions without activity for this duration are automatically cleaned up.
    /// Set to <c>0</c> or leave as <see langword="null"/> to disable (sessions live indefinitely).
    /// This option is only used when the SDK spawns the runtime; it is ignored
    /// when connecting to an external runtime via <see cref="RuntimeConnection.ForUri(string, string?)"/>.
    /// </summary>
    public int? SessionIdleTimeoutSeconds { get; set; }

    /// <summary>
    /// Enable remote session support (Mission Control integration).
    /// When true, sessions in a GitHub repository working directory are
    /// accessible from GitHub web and mobile.
    /// This option is only used when the SDK spawns the runtime; it is ignored
    /// when connecting to an external runtime via <see cref="RuntimeConnection.ForUri(string, string?)"/>.
    /// </summary>
    public bool EnableRemoteSessions { get; set; }

    /// <summary>
    /// Declares the integrating application's identity, forwarded to the runtime on the
    /// <c>server.connect</c> handshake. Declaring it lets the telemetry the
    /// runtime emits on this connection be attributed to a consistent surface
    /// (the application and its Copilot integration) instead of the runtime's own
    /// build. All fields are optional; leave it <see langword="null"/> to keep
    /// the runtime's default attribution.
    /// </summary>
    public CopilotClientInfo? ClientInfo { get; set; }

    /// <summary>
    /// Creates a shallow clone of this <see cref="CopilotClientOptions"/> instance.
    /// </summary>
    /// <remarks>
    /// Mutable collection properties are copied into new collection instances so that modifications
    /// to those collections on the clone do not affect the original.
    /// Other reference-type properties (for example delegates and the logger) are not
    /// deep-cloned; the original and the clone will share those objects.
    /// </remarks>
    public CopilotClientOptions Clone() => new(this);
}

/// <summary>
/// OpenTelemetry configuration for the Copilot CLI server.
/// </summary>
public sealed class TelemetryConfig
{
    /// <summary>
    /// OTLP exporter endpoint URL.
    /// </summary>
    /// <remarks>
    /// Maps to the <c>OTEL_EXPORTER_OTLP_ENDPOINT</c> environment variable.
    /// </remarks>
    public string? OtlpEndpoint { get; set; }

    /// <summary>
    /// OTLP HTTP protocol for all signals (<c>"http/json"</c> or <c>"http/protobuf"</c>).
    /// </summary>
    /// <remarks>
    /// Maps to the <c>OTEL_EXPORTER_OTLP_PROTOCOL</c> environment variable.
    /// </remarks>
    public string? OtlpProtocol { get; set; }

    /// <summary>
    /// File path for the file exporter.
    /// </summary>
    /// <remarks>
    /// Maps to the <c>COPILOT_OTEL_FILE_EXPORTER_PATH</c> environment variable.
    /// </remarks>
    public string? FilePath { get; set; }

    /// <summary>
    /// Exporter type (<c>"otlp-http"</c> or <c>"file"</c>).
    /// </summary>
    /// <remarks>
    /// Maps to the <c>COPILOT_OTEL_EXPORTER_TYPE</c> environment variable.
    /// </remarks>
    public string? ExporterType { get; set; }

    /// <summary>
    /// Source name for telemetry spans.
    /// </summary>
    /// <remarks>
    /// Maps to the <c>COPILOT_OTEL_SOURCE_NAME</c> environment variable.
    /// </remarks>
    public string? SourceName { get; set; }

    /// <summary>
    /// Whether to capture message content as part of telemetry.
    /// </summary>
    /// <remarks>
    /// Maps to the <c>OTEL_INSTRUMENTATION_GENAI_CAPTURE_MESSAGE_CONTENT</c> environment variable.
    /// </remarks>
    public bool? CaptureContent { get; set; }
}

/// <summary>
/// Identifies the integrating application on the <c>server.connect</c> handshake.
/// </summary>
/// <remarks>
/// Declaring it lets the telemetry the runtime emits on the connection be
/// attributed to a single, consistent surface instead of the runtime's own
/// build. All properties are optional; an unset property is omitted from the
/// handshake.
/// </remarks>
public sealed class CopilotClientInfo
{
    /// <summary>
    /// Name of the application using the SDK.
    /// </summary>
    public string? ApplicationName { get; set; }

    /// <summary>
    /// Version of the application using the SDK.
    /// </summary>
    public string? ApplicationVersion { get; set; }

    /// <summary>
    /// Optionally specifies a named integration within the application, such as an extension or plugin.
    /// </summary>
    public string? IntegrationName { get; set; }

    /// <summary>
    /// Optionally specifies the version of that integration.
    /// </summary>
    public string? IntegrationVersion { get; set; }
}

/// <summary>
/// Configuration for a custom session filesystem provider.
/// </summary>
public sealed class SessionFsConfig
{
    /// <summary>
    /// Initial working directory for sessions (user's project directory).
    /// </summary>
    [JsonPropertyName("initialCwd")]
    public required string InitialWorkingDirectory { get; init; }

    /// <summary>
    /// Path within each session's SessionFs where the runtime stores
    /// session-scoped files (events, workspace, checkpoints, and temp files).
    /// </summary>
    public required string SessionStatePath { get; init; }

    /// <summary>
    /// Path conventions used by this filesystem provider.
    /// </summary>
    public required SessionFsSetProviderConventions Conventions { get; init; }

    /// <summary>
    /// Optional capabilities that this filesystem provider supports.
    /// When <see cref="SessionFsSetProviderCapabilities.Sqlite"/> is <c>true</c>,
    /// the runtime routes SQLite queries through the provider instead of using a local database file.
    /// </summary>
    public SessionFsSetProviderCapabilities? Capabilities { get; init; }
}

/// <summary>
/// Represents a binary result returned by a tool invocation.
/// </summary>
public sealed class ToolBinaryResult
{
    /// <summary>
    /// Base64-encoded binary data.
    /// </summary>
    [JsonPropertyName("data")]
    public string Data { get; set; } = string.Empty;

    /// <summary>
    /// MIME type of the binary data (e.g., "image/png").
    /// </summary>
    [JsonPropertyName("mimeType")]
    public string MimeType { get; set; } = string.Empty;

    /// <summary>
    /// Type identifier for the binary result. Use the well-known values on
    /// <see cref="ToolBinaryResultType"/> (<c>"image"</c>, <c>"resource"</c>).
    /// </summary>
    [JsonPropertyName("type")]
    public ToolBinaryResultType Type { get; set; }

    /// <summary>
    /// Optional human-readable description of the binary result.
    /// </summary>
    [JsonPropertyName("description")]
    public string? Description { get; set; }
}

/// <summary>Describes the kind of a <see cref="ToolBinaryResult"/>.</summary>
[JsonConverter(typeof(ToolBinaryResultType.Converter))]
[DebuggerDisplay("{Value,nq}")]
public readonly struct ToolBinaryResultType : IEquatable<ToolBinaryResultType>
{
    /// <summary>Gets the kind indicating an inline image result.</summary>
    public static ToolBinaryResultType Image { get; } = new("image");

    /// <summary>Gets the kind indicating an MCP resource result.</summary>
    public static ToolBinaryResultType Resource { get; } = new("resource");

    /// <summary>Gets the underlying string value of this <see cref="ToolBinaryResultType"/>.</summary>
    public string Value => _value ?? string.Empty;

    private readonly string? _value;

    /// <summary>Initializes a new instance of the <see cref="ToolBinaryResultType"/> struct.</summary>
    /// <param name="value">The string value for this type.</param>
    [JsonConstructor]
    public ToolBinaryResultType(string value) => _value = value;

    /// <inheritdoc/>
    public static bool operator ==(ToolBinaryResultType left, ToolBinaryResultType right) => left.Equals(right);

    /// <inheritdoc/>
    public static bool operator !=(ToolBinaryResultType left, ToolBinaryResultType right) => !left.Equals(right);

    /// <inheritdoc/>
    public override bool Equals([NotNullWhen(true)] object? obj) => obj is ToolBinaryResultType other && Equals(other);

    /// <inheritdoc/>
    public bool Equals(ToolBinaryResultType other) => string.Equals(Value, other.Value, StringComparison.OrdinalIgnoreCase);

    /// <inheritdoc/>
    public override int GetHashCode() => StringComparer.OrdinalIgnoreCase.GetHashCode(Value);

    /// <inheritdoc/>
    public override string ToString() => Value;

    /// <summary>Provides a <see cref="JsonConverter{ToolBinaryResultType}"/> for serializing <see cref="ToolBinaryResultType"/> instances.</summary>
    [EditorBrowsable(EditorBrowsableState.Never)]
    public sealed class Converter : JsonConverter<ToolBinaryResultType>
    {
        /// <inheritdoc/>
        public override ToolBinaryResultType Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
        {
            if (reader.TokenType != JsonTokenType.String)
            {
                throw new JsonException("Expected string for ToolBinaryResultType.");
            }

            var value = reader.GetString();
            if (value is null)
            {
                throw new JsonException("ToolBinaryResultType value cannot be null.");
            }

            return new ToolBinaryResultType(value);
        }

        /// <inheritdoc/>
        public override void Write(Utf8JsonWriter writer, ToolBinaryResultType value, JsonSerializerOptions options) =>
            writer.WriteStringValue(value.Value);
    }
}

/// <summary>
/// Represents the structured result of a tool execution.
/// </summary>
public sealed class ToolResultObject
{
    /// <summary>
    /// Text result to be consumed by the language model.
    /// </summary>
    [JsonPropertyName("textResultForLlm")]
    public string TextResultForLlm { get; set; } = string.Empty;

    /// <summary>
    /// Binary results (e.g., images) to be consumed by the language model.
    /// </summary>
    [JsonPropertyName("binaryResultsForLlm")]
    public IList<ToolBinaryResult>? BinaryResultsForLlm { get; set; }

    /// <summary>
    /// Result type indicator.
    /// <list type="bullet">
    /// <item><description><c>"success"</c> — the tool executed successfully.</description></item>
    /// <item><description><c>"failure"</c> — the tool encountered an error.</description></item>
    /// <item><description><c>"rejected"</c> — the tool invocation was rejected.</description></item>
    /// <item><description><c>"denied"</c> — the tool invocation was denied by a permission check.</description></item>
    /// </list>
    /// </summary>
    [JsonPropertyName("resultType")]
    public string ResultType { get; set; } = "success";

    /// <summary>
    /// Error message if the tool execution failed.
    /// </summary>
    [JsonPropertyName("error")]
    public string? Error { get; set; }

    /// <summary>
    /// Log entry for the session history.
    /// </summary>
    [JsonPropertyName("sessionLog")]
    public string? SessionLog { get; set; }

    /// <summary>
    /// Custom telemetry data associated with the tool execution.
    /// </summary>
    [JsonPropertyName("toolTelemetry")]
    public IDictionary<string, object>? ToolTelemetry { get; set; }

    /// <summary>
    /// Names of tools returned by a tool-search tool.
    /// </summary>
    [JsonPropertyName("toolReferences")]
    public IList<string>? ToolReferences { get; set; }

    /// <summary>
    /// Converts the result of an <see cref="AIFunction"/> invocation into a
    /// <see cref="ToolResultObject"/>. Handles <see cref="ToolResultAIContent"/>,
    /// <see cref="AIContent"/>, and falls back to JSON serialization.
    /// </summary>
    internal static ToolResultObject ConvertFromInvocationResult(object? result, JsonSerializerOptions jsonOptions)
    {
        if (result is ToolResultAIContent trac)
        {
            return trac.Result;
        }

        if (TryConvertFromAIContent(result) is { } aiConverted)
        {
            return aiConverted;
        }

        return new ToolResultObject
        {
            ResultType = "success",
            TextResultForLlm = result is JsonElement { ValueKind: JsonValueKind.String } je
                ? je.GetString()!
                : JsonSerializer.Serialize(result, jsonOptions.GetTypeInfo(typeof(object))),
        };
    }

    /// <summary>
    /// Attempts to convert a result from an <see cref="AIFunction"/> invocation into a
    /// <see cref="ToolResultObject"/>. Handles <see cref="TextContent"/>,
    /// <see cref="DataContent"/>, and collections of <see cref="AIContent"/>.
    /// Returns <see langword="null"/> if the value is not a recognized <see cref="AIContent"/> type.
    /// </summary>
    internal static ToolResultObject? TryConvertFromAIContent(object? result)
    {
        if (result is AIContent singleContent)
        {
            return ConvertAIContents([singleContent]);
        }

        if (result is IEnumerable<AIContent> contentList)
        {
            return ConvertAIContents(contentList);
        }

        return null;
    }

    private static ToolResultObject ConvertAIContents(IEnumerable<AIContent> contents)
    {
        List<string>? textParts = null;
        List<ToolBinaryResult>? binaryResults = null;

        foreach (var content in contents)
        {
            switch (content)
            {
                case TextContent textContent:
                    if (textContent.Text is { } text)
                    {
                        (textParts ??= []).Add(text);
                    }
                    break;

                case DataContent dataContent:
                    (binaryResults ??= []).Add(new ToolBinaryResult
                    {
                        Data = dataContent.Base64Data.ToString(),
                        MimeType = dataContent.MediaType ?? "application/octet-stream",
                        Type = dataContent.HasTopLevelMediaType("image") ? ToolBinaryResultType.Image : ToolBinaryResultType.Resource,
                    });
                    break;

                default:
                    (textParts ??= []).Add(SerializeAIContent(content));
                    break;
            }
        }

        return new ToolResultObject
        {
            TextResultForLlm = textParts is not null ? string.Join("\n", textParts) : "",
            ResultType = "success",
            BinaryResultsForLlm = binaryResults,
        };
    }

    private static string SerializeAIContent(AIContent content) =>
        JsonSerializer.Serialize(content, AIJsonUtilities.DefaultOptions.GetTypeInfo(typeof(AIContent)));
}

/// <summary>
/// Contains context for a tool invocation callback.
/// </summary>
public sealed class ToolInvocation
{
    /// <summary>
    /// Identifier of the session that triggered the tool call.
    /// </summary>
    public string SessionId { get; set; } = string.Empty;
    /// <summary>
    /// Unique identifier of this specific tool call.
    /// </summary>
    public string ToolCallId { get; set; } = string.Empty;
    /// <summary>
    /// Name of the tool being invoked.
    /// </summary>
    public string ToolName { get; set; } = string.Empty;
    /// <summary>
    /// Arguments passed to the tool by the language model.
    /// </summary>
    public JsonElement? Arguments { get; set; }
    /// <summary>
    /// Snapshot of the session's currently initialized tools. The SDK populates
    /// this only when the invocation targets the built-in tool-search tool
    /// (<c>tool_search_tool</c>), so a tool-search override can rank/filter the
    /// live catalog — including MCP tools configured in settings — without
    /// issuing its own RPC. <c>null</c> for every other tool invocation.
    /// </summary>
    public IList<CurrentToolMetadata>? AvailableTools { get; set; }
}

/// <summary>
/// Contains context for a permission request callback.
/// </summary>
public sealed class PermissionInvocation
{
    /// <summary>
    /// Identifier of the session that triggered the permission request.
    /// </summary>
    public string SessionId { get; set; } = string.Empty;

    /// <summary>Whether managed settings are enabled for this session.</summary>
    public bool ManagedSettingsEnabled { get; set; }
}

// ============================================================================
// User Input Handler Types
// ============================================================================

/// <summary>
/// Request for user input from the agent.
/// </summary>
public sealed class UserInputRequest
{
    /// <summary>
    /// The question to ask the user.
    /// </summary>
    [JsonPropertyName("question")]
    public string Question { get; set; } = string.Empty;

    /// <summary>
    /// Optional choices for multiple choice questions.
    /// </summary>
    [JsonPropertyName("choices")]
    public IList<string>? Choices { get; set; }

    /// <summary>
    /// Whether freeform text input is allowed.
    /// </summary>
    [JsonPropertyName("allowFreeform")]
    public bool? AllowFreeform { get; set; }
}

/// <summary>
/// Response to a user input request.
/// </summary>
public sealed class UserInputResponse
{
    /// <summary>
    /// The user's answer.
    /// </summary>
    [JsonPropertyName("answer")]
    public string Answer { get; set; } = string.Empty;

    /// <summary>
    /// Whether the answer was freeform (not from the provided choices).
    /// </summary>
    [JsonPropertyName("wasFreeform")]
    public bool WasFreeform { get; set; }
}

/// <summary>
/// Context for a user input request invocation.
/// </summary>
public sealed class UserInputInvocation
{
    /// <summary>
    /// Identifier of the session that triggered the user input request.
    /// </summary>
    public string SessionId { get; set; } = string.Empty;
}

/// <summary>
/// Request to exit plan mode and continue with a selected action.
/// </summary>
public sealed class ExitPlanModeRequest
{
    /// <summary>
    /// Summary of the plan or proposed next step.
    /// </summary>
    [JsonPropertyName("summary")]
    public string Summary { get; set; } = string.Empty;

    /// <summary>
    /// Full plan content, when available.
    /// </summary>
    [JsonPropertyName("planContent")]
    public string? PlanContent { get; set; }

    /// <summary>
    /// Available actions the user can select.
    /// </summary>
    [JsonPropertyName("actions")]
    public IList<string> Actions { get => field ??= []; set; }

    /// <summary>
    /// The action recommended by the runtime.
    /// </summary>
    [JsonPropertyName("recommendedAction")]
    public string RecommendedAction { get; set; } = "autopilot";
}

/// <summary>
/// Response to an exit-plan-mode request.
/// </summary>
public sealed class ExitPlanModeResult
{
    /// <summary>
    /// Whether the user approved exiting plan mode.
    /// </summary>
    [JsonPropertyName("approved")]
    public bool Approved { get; set; } = true;

    /// <summary>
    /// Selected action, if the user chose one.
    /// </summary>
    [JsonPropertyName("selectedAction")]
    public string? SelectedAction { get; set; }

    /// <summary>
    /// Optional feedback provided by the user.
    /// </summary>
    [JsonPropertyName("feedback")]
    public string? Feedback { get; set; }
}

/// <summary>
/// Context for an exit-plan-mode request invocation.
/// </summary>
public sealed class ExitPlanModeInvocation
{
    /// <summary>
    /// Identifier of the session that triggered the request.
    /// </summary>
    public string SessionId { get; set; } = string.Empty;
}

/// <summary>
/// Request to switch to auto mode after an eligible rate limit.
/// </summary>
public sealed class AutoModeSwitchRequest
{
    /// <summary>
    /// The rate-limit error code that triggered the request.
    /// </summary>
    [JsonPropertyName("errorCode")]
    public string? ErrorCode { get; set; }

    /// <summary>
    /// Seconds until the rate limit resets, when known.
    /// </summary>
    [JsonPropertyName("retryAfterSeconds")]
    public double? RetryAfterSeconds { get; set; }
}

/// <summary>
/// Context for an auto-mode-switch request invocation.
/// </summary>
public sealed class AutoModeSwitchInvocation
{
    /// <summary>
    /// Identifier of the session that triggered the request.
    /// </summary>
    public string SessionId { get; set; } = string.Empty;
}

// ============================================================================
// Command Handler Types
// ============================================================================

/// <summary>
/// Defines a slash-command that users can invoke from the CLI TUI.
/// </summary>
public sealed class CommandDefinition
{
    /// <summary>
    /// Command name (without leading <c>/</c>). For example, <c>"deploy"</c>.
    /// </summary>
    public required string Name { get; set; }

    /// <summary>
    /// Human-readable description shown in the command completion UI.
    /// </summary>
    public string? Description { get; set; }

    /// <summary>
    /// Handler invoked when the command is executed.
    /// </summary>
    public required Func<CommandContext, Task> Handler { get; set; }
}

/// <summary>
/// Context passed to a command handler when a command is executed.
/// </summary>
public sealed class CommandContext
{
    /// <summary>
    /// Session ID where the command was invoked.
    /// </summary>
    public string SessionId { get; set; } = string.Empty;

    /// <summary>
    /// The full command text (e.g., <c>/deploy production</c>).
    /// </summary>
    public string Command { get; set; } = string.Empty;

    /// <summary>
    /// Command name without leading <c>/</c>.
    /// </summary>
    public string CommandName { get; set; } = string.Empty;

    /// <summary>
    /// Raw argument string after the command name.
    /// </summary>
    public string Args { get; set; } = string.Empty;
}

// ============================================================================
// Elicitation Types (UI — client → server)
// ============================================================================

/// <summary>
/// JSON Schema describing the form fields to present for an elicitation dialog.
/// </summary>
public sealed class ElicitationSchema
{
    /// <summary>
    /// Schema type indicator (always <c>"object"</c>).
    /// </summary>
    [JsonPropertyName("type")]
    public string Type { get; set; } = "object";

    /// <summary>
    /// Form field definitions, keyed by field name.
    /// </summary>
    [JsonPropertyName("properties")]
    public IDictionary<string, object> Properties { get => field ??= new Dictionary<string, object>(); set; }

    /// <summary>
    /// List of required field names.
    /// </summary>
    [JsonPropertyName("required")]
    public IList<string>? Required { get; set; }
}

/// <summary>
/// Parameters for an elicitation request sent from the SDK to the server.
/// </summary>
public sealed class ElicitationParams
{
    /// <summary>
    /// Message describing what information is needed from the user.
    /// </summary>
    public required string Message { get; set; }

    /// <summary>
    /// JSON Schema describing the form fields to present.
    /// </summary>
    public required ElicitationSchema RequestedSchema { get; set; }
}

/// <summary>
/// Result returned from an elicitation dialog.
/// </summary>
public sealed class ElicitationResult
{
    /// <summary>
    /// User action: <c>"accept"</c> (submitted), <c>"decline"</c> (rejected), or <c>"cancel"</c> (dismissed).
    /// </summary>
    public UIElicitationResponseAction Action { get; set; }

    /// <summary>
    /// Form values submitted by the user (present when <see cref="Action"/> is <c>Accept</c>).
    /// </summary>
    public IDictionary<string, object>? Content { get; set; }
}

/// <summary>
/// Options for the <see cref="ISessionUiApi.InputAsync"/> convenience method.
/// </summary>
public sealed class UiInputOptions
{
    /// <summary>Title label for the input field.</summary>
    public string? Title { get; set; }

    /// <summary>Descriptive text shown below the field.</summary>
    public string? Description { get; set; }

    /// <summary>Minimum character length.</summary>
    public int? MinLength { get; set; }

    /// <summary>Maximum character length.</summary>
    public int? MaxLength { get; set; }

    /// <summary>Semantic format hint (e.g., <c>"email"</c>, <c>"uri"</c>, <c>"date"</c>, <c>"date-time"</c>).</summary>
    public string? Format { get; set; }

    /// <summary>Default value pre-populated in the field.</summary>
    public string? Default { get; set; }
}

/// <summary>
/// Provides UI methods for eliciting information from the user during a session.
/// </summary>
public interface ISessionUiApi
{
    /// <summary>
    /// Shows a generic elicitation dialog with a custom schema.
    /// </summary>
    /// <param name="elicitationParams">The elicitation parameters including message and schema.</param>
    /// <param name="cancellationToken">Optional cancellation token.</param>
    /// <returns>The <see cref="ElicitationResult"/> with the user's response.</returns>
    /// <exception cref="InvalidOperationException">Thrown if the host does not support elicitation.</exception>
    Task<ElicitationResult> ElicitAsync(ElicitationParams elicitationParams, CancellationToken cancellationToken = default);

    /// <summary>
    /// Shows a confirmation dialog and returns the user's boolean answer.
    /// Returns <c>false</c> if the user declines or cancels.
    /// </summary>
    /// <param name="message">The message to display.</param>
    /// <param name="cancellationToken">Optional cancellation token.</param>
    /// <returns><c>true</c> if the user confirmed; otherwise <c>false</c>.</returns>
    /// <exception cref="InvalidOperationException">Thrown if the host does not support elicitation.</exception>
    Task<bool> ConfirmAsync(string message, CancellationToken cancellationToken = default);

    /// <summary>
    /// Shows a selection dialog with the given options.
    /// Returns the selected value, or <c>null</c> if the user declines/cancels.
    /// </summary>
    /// <param name="message">The message to display.</param>
    /// <param name="options">The options to present.</param>
    /// <param name="cancellationToken">Optional cancellation token.</param>
    /// <returns>The selected string, or <c>null</c> if the user declined/cancelled.</returns>
    /// <exception cref="InvalidOperationException">Thrown if the host does not support elicitation.</exception>
    Task<string?> SelectAsync(string message, string[] options, CancellationToken cancellationToken = default);

    /// <summary>
    /// Shows a text input dialog.
    /// Returns the entered text, or <c>null</c> if the user declines/cancels.
    /// </summary>
    /// <param name="message">The message to display.</param>
    /// <param name="options">Optional input field options.</param>
    /// <param name="cancellationToken">Optional cancellation token.</param>
    /// <returns>The entered string, or <c>null</c> if the user declined/cancelled.</returns>
    /// <exception cref="InvalidOperationException">Thrown if the host does not support elicitation.</exception>
    Task<string?> InputAsync(string message, UiInputOptions? options = null, CancellationToken cancellationToken = default);
}

// ============================================================================
// Elicitation Types (server → client callback)
// ============================================================================

/// <summary>
/// Context for an elicitation handler invocation, combining the request data
/// with session context. Mirrors the single-argument pattern of <see cref="CommandContext"/>.
/// </summary>
public sealed class ElicitationContext
{
    /// <summary>Identifier of the session that triggered the elicitation request.</summary>
    public string SessionId { get; set; } = string.Empty;

    /// <summary>Message describing what information is needed from the user.</summary>
    public string Message { get; set; } = string.Empty;

    /// <summary>JSON Schema describing the form fields to present.</summary>
    public ElicitationSchema? RequestedSchema { get; set; }

    /// <summary>Elicitation mode: <c>"form"</c> for structured input, <c>"url"</c> for browser redirect.</summary>
    public ElicitationRequestedMode? Mode { get; set; }

    /// <summary>The source that initiated the request (e.g., MCP server name).</summary>
    public string? ElicitationSource { get; set; }

    /// <summary>URL to open in the user's browser (url mode only).</summary>
    public string? Url { get; set; }
}

/// <summary>
/// Context for an MCP OAuth request callback.
/// </summary>
[Experimental(Diagnostics.Experimental)]
public sealed class McpAuthContext
{
    /// <summary>Identifier of the session that triggered the MCP OAuth request.</summary>
    public string SessionId { get; set; } = string.Empty;

    /// <summary>Identifier of the pending MCP OAuth request.</summary>
    public string RequestId { get; set; } = string.Empty;

    /// <summary>Display name of the MCP server that requires OAuth.</summary>
    public string ServerName { get; set; } = string.Empty;

    /// <summary>URL of the MCP server that requires OAuth.</summary>
    public string ServerUrl { get; set; } = string.Empty;

    /// <summary>Why the runtime is requesting host-provided OAuth credentials.</summary>
    public McpOauthRequestReason Reason { get; set; }

    /// <summary>Parsed WWW-Authenticate parameters from the MCP server, if available.</summary>
    public McpOauthWWWAuthenticateParams? WwwAuthenticateParams { get; set; }

    /// <summary>Raw RFC 9728 protected-resource metadata JSON fetched by the runtime, if available.</summary>
    public string? ResourceMetadata { get; set; }

    /// <summary>Static OAuth client configuration, if the server specifies one.</summary>
    public McpOauthRequiredStaticClientConfig? StaticClientConfig { get; set; }
}

/// <summary>
/// Host-provided OAuth token data for a pending MCP OAuth request.
/// </summary>
[Experimental(Diagnostics.Experimental)]
public sealed class McpAuthToken
{
    /// <summary>Access token acquired by the SDK host.</summary>
    public required string AccessToken { get; set; }

    /// <summary>OAuth token type. Defaults to Bearer when omitted.</summary>
    public string? TokenType { get; set; }

    /// <summary>Token lifetime in seconds, if known.</summary>
    public long? ExpiresIn { get; set; }
}

/// <summary>
/// Result returned by an MCP auth request handler.
/// </summary>
[Experimental(Diagnostics.Experimental)]
public sealed class McpAuthResult
{
    /// <summary>Whether the request should be cancelled instead of resolved with a token.</summary>
    public bool Cancelled { get; set; }

    /// <summary>Host-provided token data. Ignored when <see cref="Cancelled"/> is true.</summary>
    public McpAuthToken? Token { get; set; }

    /// <summary>Create a token result.</summary>
    public static McpAuthResult FromToken(McpAuthToken token) => new() { Token = token };

    /// <summary>Create a cancellation result.</summary>
    public static McpAuthResult Cancel() => new() { Cancelled = true };
}

// ============================================================================
// Session Capabilities
// ============================================================================

/// <summary>
/// Represents the capabilities reported by the host for a session.
/// </summary>
public sealed class SessionCapabilities
{
    /// <summary>
    /// UI-related capabilities.
    /// </summary>
    public SessionUiCapabilities? Ui { get; set; }
}

/// <summary>
/// UI-specific capability flags for a session.
/// </summary>
public sealed class SessionUiCapabilities
{
    /// <summary>
    /// Whether the host supports interactive elicitation dialogs.
    /// </summary>
    public bool? Elicitation { get; set; }

    /// <summary>
    /// Whether the runtime has accepted the session's MCP Apps (SEP-1865) opt-in.
    /// <c>true</c> when the consumer set <see cref="SessionConfigBase.EnableMcpApps"/>
    /// to <c>true</c> on create/resume <b>and</b> the runtime's <c>MCP_APPS</c> feature flag
    /// (or <c>COPILOT_MCP_APPS=true</c> env override) is on. Otherwise absent or
    /// <c>false</c>, indicating the runtime silently dropped the opt-in.
    /// </summary>
    [Experimental(Diagnostics.Experimental)]
    public bool? McpApps { get; set; }
}

// ============================================================================
// Hook Handler Types
// ============================================================================

/// <summary>
/// Context for a hook invocation.
/// </summary>
public sealed class HookInvocation
{
    /// <summary>
    /// Identifier of the session that triggered the hook.
    /// </summary>
    public string SessionId { get; set; } = string.Empty;
}

/// <summary>
/// Input for a pre-tool-use hook.
/// </summary>
public sealed class PreToolUseHookInput
{
    /// <summary>
    /// The runtime session ID of the session that triggered the hook.
    /// </summary>
    [JsonPropertyName("sessionId")]
    public string SessionId { get; set; } = string.Empty;

    /// <summary>
    /// Unix timestamp in milliseconds when the tool use was initiated.
    /// </summary>
    [JsonPropertyName("timestamp")]
    [JsonConverter(typeof(UnixMillisecondsDateTimeOffsetConverter))]
    public DateTimeOffset Timestamp { get; set; }

    /// <summary>
    /// Current working directory of the session.
    /// </summary>
    [JsonPropertyName("cwd")]
    public string WorkingDirectory { get; set; } = string.Empty;

    /// <summary>
    /// Name of the tool about to be executed.
    /// </summary>
    [JsonPropertyName("toolName")]
    public string ToolName { get; set; } = string.Empty;

    /// <summary>
    /// Arguments that will be passed to the tool.
    /// </summary>
    [JsonPropertyName("toolArgs")]
    public JsonElement? ToolArgs { get; set; }
}

/// <summary>
/// Output for a pre-tool-use hook.
/// </summary>
public sealed class PreToolUseHookOutput
{
    /// <summary>
    /// Permission decision for the pending tool call.
    /// <list type="bullet">
    /// <item><description><c>"allow"</c> — permit the tool to execute.</description></item>
    /// <item><description><c>"deny"</c> — block the tool from executing.</description></item>
    /// <item><description><c>"ask"</c> — fall through to the normal permission prompt.</description></item>
    /// </list>
    /// </summary>
    [JsonPropertyName("permissionDecision")]
    public string? PermissionDecision { get; set; }

    /// <summary>
    /// Human-readable reason for the permission decision.
    /// </summary>
    [JsonPropertyName("permissionDecisionReason")]
    public string? PermissionDecisionReason { get; set; }

    /// <summary>
    /// Modified arguments to pass to the tool instead of the original ones.
    /// </summary>
    [JsonPropertyName("modifiedArgs")]
    public object? ModifiedArgs { get; set; }

    /// <summary>
    /// Additional context to inject into the conversation for the language model.
    /// </summary>
    [JsonPropertyName("additionalContext")]
    public string? AdditionalContext { get; set; }

    /// <summary>
    /// Whether to suppress the tool's output from the conversation.
    /// </summary>
    [JsonPropertyName("suppressOutput")]
    public bool? SuppressOutput { get; set; }
}

/// <summary>
/// Input for a pre-MCP-tool-call hook.
/// </summary>
public sealed class PreMcpToolCallHookInput
{
    /// <summary>
    /// The runtime session ID of the session that triggered the hook.
    /// </summary>
    [JsonPropertyName("sessionId")]
    public string SessionId { get; set; } = string.Empty;

    /// <summary>
    /// Unix timestamp in milliseconds when the hook was triggered.
    /// </summary>
    [JsonPropertyName("timestamp")]
    [JsonConverter(typeof(UnixMillisecondsDateTimeOffsetConverter))]
    public DateTimeOffset Timestamp { get; set; }

    /// <summary>
    /// Current working directory of the session.
    /// </summary>
    [JsonPropertyName("cwd")]
    public string WorkingDirectory { get; set; } = string.Empty;

    /// <summary>
    /// Name of the MCP server being called.
    /// </summary>
    [JsonPropertyName("serverName")]
    public string ServerName { get; set; } = string.Empty;

    /// <summary>
    /// Name of the MCP tool being called.
    /// </summary>
    [JsonPropertyName("toolName")]
    public string ToolName { get; set; } = string.Empty;

    /// <summary>
    /// Arguments for the MCP tool call.
    /// </summary>
    [JsonPropertyName("arguments")]
    public JsonElement? Arguments { get; set; }

    /// <summary>
    /// Tool call ID, if available.
    /// </summary>
    [JsonPropertyName("toolCallId")]
    public string? ToolCallId { get; set; }

    /// <summary>
    /// MCP request metadata, if present.
    /// </summary>
    [JsonPropertyName("_meta")]
    public IDictionary<string, JsonElement>? Meta { get; set; }
}

/// <summary>
/// Output for a pre-MCP-tool-call hook.
/// </summary>
/// <remarks>
/// <para>The <see cref="MetaToUse"/> property controls outgoing MCP request metadata:</para>
/// <list type="bullet">
/// <item><description>Return <c>null</c> from the hook handler: preserve existing <c>_meta</c> (no-op).</description></item>
/// <item><description>Return a <see cref="PreMcpToolCallHookOutput"/> with <see cref="MetaToUse"/> left as <c>null</c>: omit <c>_meta</c> from the request.</description></item>
/// <item><description>Return a <see cref="PreMcpToolCallHookOutput"/> with <see cref="MetaToUse"/> set to a <see cref="JsonElement"/> object: replace <c>_meta</c> with that object.</description></item>
/// </list>
/// </remarks>
public sealed class PreMcpToolCallHookOutput
{
    /// <summary>
    /// Hook-controlled metadata to use for the outgoing MCP request.
    /// See class remarks for semantics.
    /// </summary>
    [JsonPropertyName("metaToUse")]
    [JsonIgnore(Condition = JsonIgnoreCondition.Never)]
    public JsonElement? MetaToUse { get; set; }
}

/// <summary>
/// Input for a post-tool-use hook.
/// </summary>
public sealed class PostToolUseHookInput
{
    /// <summary>
    /// The runtime session ID of the session that triggered the hook.
    /// </summary>
    [JsonPropertyName("sessionId")]
    public string SessionId { get; set; } = string.Empty;

    /// <summary>
    /// Unix timestamp in milliseconds when the tool execution completed.
    /// </summary>
    [JsonPropertyName("timestamp")]
    [JsonConverter(typeof(UnixMillisecondsDateTimeOffsetConverter))]
    public DateTimeOffset Timestamp { get; set; }

    /// <summary>
    /// Current working directory of the session.
    /// </summary>
    [JsonPropertyName("cwd")]
    public string WorkingDirectory { get; set; } = string.Empty;

    /// <summary>
    /// Name of the tool that was executed.
    /// </summary>
    [JsonPropertyName("toolName")]
    public string ToolName { get; set; } = string.Empty;

    /// <summary>
    /// Arguments that were passed to the tool.
    /// </summary>
    [JsonPropertyName("toolArgs")]
    public JsonElement? ToolArgs { get; set; }

    /// <summary>
    /// Result returned by the tool execution.
    /// </summary>
    [JsonPropertyName("toolResult")]
    public JsonElement? ToolResult { get; set; }
}

/// <summary>
/// Output for a post-tool-use hook.
/// </summary>
public sealed class PostToolUseHookOutput
{
    /// <summary>
    /// Modified result to replace the original tool result.
    /// </summary>
    [JsonPropertyName("modifiedResult")]
    public object? ModifiedResult { get; set; }

    /// <summary>
    /// Additional context to inject into the conversation for the language model.
    /// </summary>
    [JsonPropertyName("additionalContext")]
    public string? AdditionalContext { get; set; }

    /// <summary>
    /// Whether to suppress the tool's output from the conversation.
    /// </summary>
    [JsonPropertyName("suppressOutput")]
    public bool? SuppressOutput { get; set; }
}

/// <summary>
/// Input for a post-tool-use-failure hook.
///
/// Fires after a tool execution whose result was "failure". The CLI extracts
/// the failure message from the tool result and passes it as the
/// <see cref="Error"/> field (rather than passing the full result object).
/// </summary>
public sealed class PostToolUseFailureHookInput
{
    /// <summary>
    /// The runtime session ID of the session that triggered the hook.
    /// </summary>
    [JsonPropertyName("sessionId")]
    public string SessionId { get; set; } = string.Empty;

    /// <summary>
    /// Unix timestamp in milliseconds when the tool execution completed.
    /// </summary>
    [JsonPropertyName("timestamp")]
    [JsonConverter(typeof(UnixMillisecondsDateTimeOffsetConverter))]
    public DateTimeOffset Timestamp { get; set; }

    /// <summary>
    /// Current working directory of the session.
    /// </summary>
    [JsonPropertyName("cwd")]
    public string WorkingDirectory { get; set; } = string.Empty;

    /// <summary>
    /// Name of the tool that failed.
    /// </summary>
    [JsonPropertyName("toolName")]
    public string ToolName { get; set; } = string.Empty;

    /// <summary>
    /// Arguments that were passed to the tool.
    /// </summary>
    [JsonPropertyName("toolArgs")]
    public JsonElement? ToolArgs { get; set; }

    /// <summary>
    /// Failure message extracted from the tool's result.
    /// </summary>
    [JsonPropertyName("error")]
    public string Error { get; set; } = string.Empty;
}

/// <summary>
/// Output for a post-tool-use-failure hook.
///
/// Only <see cref="AdditionalContext"/> is consumed by the host CLI — it is
/// appended as hidden guidance to the model alongside the failed tool result.
/// </summary>
public sealed class PostToolUseFailureHookOutput
{
    /// <summary>
    /// Additional context to inject into the conversation for the language model.
    /// </summary>
    [JsonPropertyName("additionalContext")]
    public string? AdditionalContext { get; set; }
}

/// <summary>
/// Input for a user-prompt-submitted hook.
/// </summary>
public sealed class UserPromptSubmittedHookInput
{
    /// <summary>
    /// The runtime session ID of the session that triggered the hook.
    /// </summary>
    [JsonPropertyName("sessionId")]
    public string SessionId { get; set; } = string.Empty;

    /// <summary>
    /// Unix timestamp in milliseconds when the prompt was submitted.
    /// </summary>
    [JsonPropertyName("timestamp")]
    [JsonConverter(typeof(UnixMillisecondsDateTimeOffsetConverter))]
    public DateTimeOffset Timestamp { get; set; }

    /// <summary>
    /// Current working directory of the session.
    /// </summary>
    [JsonPropertyName("cwd")]
    public string WorkingDirectory { get; set; } = string.Empty;

    /// <summary>
    /// The user's prompt text.
    /// </summary>
    [JsonPropertyName("prompt")]
    public string Prompt { get; set; } = string.Empty;
}

/// <summary>
/// Output for a user-prompt-submitted hook.
/// </summary>
public sealed class UserPromptSubmittedHookOutput
{
    /// <summary>
    /// Modified prompt to use instead of the original user prompt.
    /// </summary>
    [JsonPropertyName("modifiedPrompt")]
    public string? ModifiedPrompt { get; set; }

    /// <summary>
    /// Additional context to inject into the conversation for the language model.
    /// </summary>
    [JsonPropertyName("additionalContext")]
    public string? AdditionalContext { get; set; }

    /// <summary>
    /// Whether to suppress the prompt's output from the conversation.
    /// </summary>
    [JsonPropertyName("suppressOutput")]
    public bool? SuppressOutput { get; set; }
}

/// <summary>
/// Input for a user-prompt-transformed hook.
/// </summary>
public sealed class UserPromptTransformedHookInput
{
    /// <summary>
    /// The runtime session ID of the session that triggered the hook.
    /// </summary>
    [JsonPropertyName("sessionId")]
    public string SessionId { get; set; } = string.Empty;

    /// <summary>
    /// Unix timestamp in milliseconds when the prompt was transformed.
    /// </summary>
    [JsonPropertyName("timestamp")]
    [JsonConverter(typeof(UnixMillisecondsDateTimeOffsetConverter))]
    public DateTimeOffset Timestamp { get; set; }

    /// <summary>
    /// Current working directory of the session.
    /// </summary>
    [JsonPropertyName("cwd")]
    public string WorkingDirectory { get; set; } = string.Empty;

    /// <summary>
    /// The user prompt after any user-prompt-submitted hooks have run.
    /// </summary>
    [JsonPropertyName("prompt")]
    public string Prompt { get; set; } = string.Empty;

    /// <summary>
    /// The model-facing prompt after runtime transformations.
    /// </summary>
    [JsonPropertyName("transformedPrompt")]
    public string TransformedPrompt { get; set; } = string.Empty;
}

/// <summary>
/// Output for a user-prompt-transformed hook.
/// </summary>
public sealed class UserPromptTransformedHookOutput
{
    /// <summary>
    /// Replacement model-facing prompt to persist and send to the model.
    /// </summary>
    [JsonPropertyName("modifiedTransformedPrompt")]
    public string? ModifiedTransformedPrompt { get; set; }
}

/// <summary>
/// Input for a session-start hook.
/// </summary>
public sealed class SessionStartHookInput
{
    /// <summary>
    /// The runtime session ID of the session that triggered the hook.
    /// </summary>
    [JsonPropertyName("sessionId")]
    public string SessionId { get; set; } = string.Empty;

    /// <summary>
    /// Unix timestamp in milliseconds when the session started.
    /// </summary>
    [JsonPropertyName("timestamp")]
    [JsonConverter(typeof(UnixMillisecondsDateTimeOffsetConverter))]
    public DateTimeOffset Timestamp { get; set; }

    /// <summary>
    /// Current working directory of the session.
    /// </summary>
    [JsonPropertyName("cwd")]
    public string WorkingDirectory { get; set; } = string.Empty;

    /// <summary>
    /// Source of the session start.
    /// <list type="bullet">
    /// <item><description><c>"startup"</c> — initial application startup.</description></item>
    /// <item><description><c>"resume"</c> — resuming a previous session.</description></item>
    /// <item><description><c>"new"</c> — starting a brand new session.</description></item>
    /// </list>
    /// </summary>
    [JsonPropertyName("source")]
    public string Source { get; set; } = string.Empty;

    /// <summary>
    /// Initial prompt provided when the session was started.
    /// </summary>
    [JsonPropertyName("initialPrompt")]
    public string? InitialPrompt { get; set; }
}

/// <summary>
/// Output for a session-start hook.
/// </summary>
public sealed class SessionStartHookOutput
{
    /// <summary>
    /// Additional context to inject into the session for the language model.
    /// </summary>
    [JsonPropertyName("additionalContext")]
    public string? AdditionalContext { get; set; }

    /// <summary>
    /// Modified session configuration to apply at startup.
    /// </summary>
    [JsonPropertyName("modifiedConfig")]
    public IDictionary<string, object>? ModifiedConfig { get; set; }
}

/// <summary>
/// Input for a session-end hook.
/// </summary>
public sealed class SessionEndHookInput
{
    /// <summary>
    /// The runtime session ID of the session that triggered the hook.
    /// </summary>
    [JsonPropertyName("sessionId")]
    public string SessionId { get; set; } = string.Empty;

    /// <summary>
    /// Unix timestamp in milliseconds when the session ended.
    /// </summary>
    [JsonPropertyName("timestamp")]
    [JsonConverter(typeof(UnixMillisecondsDateTimeOffsetConverter))]
    public DateTimeOffset Timestamp { get; set; }

    /// <summary>
    /// Current working directory of the session.
    /// </summary>
    [JsonPropertyName("cwd")]
    public string WorkingDirectory { get; set; } = string.Empty;

    /// <summary>
    /// Reason for session end.
    /// <list type="bullet">
    /// <item><description><c>"complete"</c> — the session finished normally.</description></item>
    /// <item><description><c>"error"</c> — the session ended due to an error.</description></item>
    /// <item><description><c>"abort"</c> — the session was aborted.</description></item>
    /// <item><description><c>"timeout"</c> — the session timed out.</description></item>
    /// <item><description><c>"user_exit"</c> — the user exited the session.</description></item>
    /// </list>
    /// </summary>
    [JsonPropertyName("reason")]
    public string Reason { get; set; } = string.Empty;

    /// <summary>
    /// Final message from the assistant before the session ended.
    /// </summary>
    [JsonPropertyName("finalMessage")]
    public string? FinalMessage { get; set; }

    /// <summary>
    /// Error message if the session ended due to an error.
    /// </summary>
    [JsonPropertyName("error")]
    public string? Error { get; set; }
}

/// <summary>
/// Output for a session-end hook.
/// </summary>
public sealed class SessionEndHookOutput
{
    /// <summary>
    /// Whether to suppress the session end output from the conversation.
    /// </summary>
    [JsonPropertyName("suppressOutput")]
    public bool? SuppressOutput { get; set; }

    /// <summary>
    /// List of cleanup action identifiers to execute after the session ends.
    /// </summary>
    [JsonPropertyName("cleanupActions")]
    public IList<string>? CleanupActions { get; set; }

    /// <summary>
    /// Summary of the session to persist for future reference.
    /// </summary>
    [JsonPropertyName("sessionSummary")]
    public string? SessionSummary { get; set; }
}

/// <summary>
/// Input for an error-occurred hook.
/// </summary>
public sealed class ErrorOccurredHookInput
{
    /// <summary>
    /// The runtime session ID of the session that triggered the hook.
    /// </summary>
    [JsonPropertyName("sessionId")]
    public string SessionId { get; set; } = string.Empty;

    /// <summary>
    /// Unix timestamp in milliseconds when the error occurred.
    /// </summary>
    [JsonPropertyName("timestamp")]
    [JsonConverter(typeof(UnixMillisecondsDateTimeOffsetConverter))]
    public DateTimeOffset Timestamp { get; set; }

    /// <summary>
    /// Current working directory of the session.
    /// </summary>
    [JsonPropertyName("cwd")]
    public string WorkingDirectory { get; set; } = string.Empty;

    /// <summary>
    /// Error message describing what went wrong.
    /// </summary>
    [JsonPropertyName("error")]
    public string Error { get; set; } = string.Empty;

    /// <summary>
    /// Context of the error.
    /// <list type="bullet">
    /// <item><description><c>"model_call"</c> — error during a model API call.</description></item>
    /// <item><description><c>"tool_execution"</c> — error during tool execution.</description></item>
    /// <item><description><c>"system"</c> — internal system error.</description></item>
    /// <item><description><c>"user_input"</c> — error processing user input.</description></item>
    /// </list>
    /// </summary>
    [JsonPropertyName("errorContext")]
    public string ErrorContext { get; set; } = string.Empty;

    /// <summary>
    /// Whether the error is recoverable and the session can continue.
    /// </summary>
    [JsonPropertyName("recoverable")]
    public bool Recoverable { get; set; }
}

/// <summary>
/// Output for an error-occurred hook.
/// </summary>
public sealed class ErrorOccurredHookOutput
{
    /// <summary>
    /// Whether to suppress the error output from the conversation.
    /// </summary>
    [JsonPropertyName("suppressOutput")]
    public bool? SuppressOutput { get; set; }

    /// <summary>
    /// Error handling strategy.
    /// <list type="bullet">
    /// <item><description><c>"retry"</c> — retry the failed operation.</description></item>
    /// <item><description><c>"skip"</c> — skip the failed operation and continue.</description></item>
    /// <item><description><c>"abort"</c> — abort the session.</description></item>
    /// </list>
    /// </summary>
    [JsonPropertyName("errorHandling")]
    public string? ErrorHandling { get; set; }

    /// <summary>
    /// Number of times to retry the failed operation.
    /// </summary>
    [JsonPropertyName("retryCount")]
    public int? RetryCount { get; set; }

    /// <summary>
    /// Message to display to the user about the error.
    /// </summary>
    [JsonPropertyName("userNotification")]
    public string? UserNotification { get; set; }
}

/// <summary>
/// Input for an agent-stop hook.
/// </summary>
public sealed class AgentStopHookInput
{
    /// <summary>
    /// The runtime session ID of the session that triggered the hook.
    /// </summary>
    [JsonPropertyName("sessionId")]
    public string SessionId { get; set; } = string.Empty;

    /// <summary>
    /// Unix timestamp in milliseconds when the agent stopped.
    /// </summary>
    [JsonPropertyName("timestamp")]
    [JsonConverter(typeof(UnixMillisecondsDateTimeOffsetConverter))]
    public DateTimeOffset Timestamp { get; set; }

    /// <summary>
    /// Current working directory of the session.
    /// </summary>
    [JsonPropertyName("cwd")]
    public string WorkingDirectory { get; set; } = string.Empty;

    /// <summary>
    /// Reason the agent stopped.
    /// </summary>
    [JsonPropertyName("stopReason")]
    public string? StopReason { get; set; }

    /// <summary>
    /// Path to the on-disk session transcript.
    /// </summary>
    [JsonPropertyName("transcriptPath")]
    public string? TranscriptPath { get; set; }

    /// <summary>
    /// Whether this stop follows a previous block decision from the hook.
    /// </summary>
    [JsonPropertyName("stop_hook_active")]
    public bool? StopHookActive { get; set; }
}

/// <summary>
/// Output for an agent-stop hook.
/// </summary>
public sealed class AgentStopHookOutput
{
    /// <summary>
    /// Set to <c>"block"</c> to keep the agent running.
    /// </summary>
    [JsonPropertyName("decision")]
    public string? Decision { get; set; }

    /// <summary>
    /// Follow-up instruction supplied when the stop is blocked.
    /// </summary>
    [JsonPropertyName("reason")]
    public string? Reason { get; set; }
}

/// <summary>
/// Hook handlers configuration for a session.
/// </summary>
public sealed class SessionHooks
{
    /// <summary>
    /// Handler called before a tool is executed.
    /// </summary>
    public Func<PreToolUseHookInput, HookInvocation, Task<PreToolUseHookOutput?>>? OnPreToolUse { get; set; }

    /// <summary>
    /// Handler called before an MCP tool is called.
    /// </summary>
    public Func<PreMcpToolCallHookInput, HookInvocation, Task<PreMcpToolCallHookOutput?>>? OnPreMcpToolCall { get; set; }

    /// <summary>
    /// Handler called after a tool has been executed.
    /// </summary>
    public Func<PostToolUseHookInput, HookInvocation, Task<PostToolUseHookOutput?>>? OnPostToolUse { get; set; }

    /// <summary>
    /// Handler called after a tool execution whose result was a failure.
    /// <see cref="OnPostToolUse"/> only fires for successful tool executions;
    /// register this handler in addition to observe failed tool calls.
    /// </summary>
    public Func<PostToolUseFailureHookInput, HookInvocation, Task<PostToolUseFailureHookOutput?>>? OnPostToolUseFailure { get; set; }

    /// <summary>
    /// Handler called when the user submits a prompt.
    /// </summary>
    public Func<UserPromptSubmittedHookInput, HookInvocation, Task<UserPromptSubmittedHookOutput?>>? OnUserPromptSubmitted { get; set; }

    /// <summary>
    /// Handler called after the runtime transforms a submitted prompt and before it is stored.
    /// </summary>
    public Func<UserPromptTransformedHookInput, HookInvocation, Task<UserPromptTransformedHookOutput?>>? OnUserPromptTransformed { get; set; }

    /// <summary>
    /// Handler called when a session starts.
    /// </summary>
    public Func<SessionStartHookInput, HookInvocation, Task<SessionStartHookOutput?>>? OnSessionStart { get; set; }

    /// <summary>
    /// Handler called when a session ends.
    /// </summary>
    public Func<SessionEndHookInput, HookInvocation, Task<SessionEndHookOutput?>>? OnSessionEnd { get; set; }

    /// <summary>
    /// Handler called when an error occurs.
    /// </summary>
    public Func<ErrorOccurredHookInput, HookInvocation, Task<ErrorOccurredHookOutput?>>? OnErrorOccurred { get; set; }

    /// <summary>
    /// Handler called when the top-level agent reaches a natural stop.
    /// </summary>
    public Func<AgentStopHookInput, HookInvocation, Task<AgentStopHookOutput?>>? OnAgentStop { get; set; }
}

/// <summary>
/// Specifies how a custom system message is applied to the session.
/// </summary>
[JsonConverter(typeof(JsonStringEnumConverter<SystemMessageMode>))]
public enum SystemMessageMode
{
    /// <summary>Append the custom system message to the default system message.</summary>
    [JsonStringEnumMemberName("append")]
    Append,
    /// <summary>Replace the default system message entirely.</summary>
    [JsonStringEnumMemberName("replace")]
    Replace,
    /// <summary>Override individual sections of the system prompt.</summary>
    [JsonStringEnumMemberName("customize")]
    Customize
}

/// <summary>
/// The UI mode the agent is in for a given turn.
/// </summary>
/// <remarks>
/// Set on <see cref="MessageOptions.AgentMode"/> to send a message in a specific mode; defaults to the session's current mode.
/// </remarks>
[JsonConverter(typeof(JsonStringEnumConverter<AgentMode>))]
public enum AgentMode
{
    /// <summary>The agent is responding interactively to the user.</summary>
    [JsonStringEnumMemberName("interactive")]
    Interactive,
    /// <summary>The agent is preparing a plan before making changes.</summary>
    [JsonStringEnumMemberName("plan")]
    Plan,
    /// <summary>The agent is working autonomously toward task completion.</summary>
    [JsonStringEnumMemberName("autopilot")]
    Autopilot,
    /// <summary>The agent is in shell-focused UI mode.</summary>
    [JsonStringEnumMemberName("shell")]
    Shell
}

/// <summary>
/// Identifies the origin of a message sent to a session.
/// </summary>
[JsonConverter(typeof(MessageSource.Converter))]
public sealed record MessageSource
{
    /// <summary>The message originates from user input.</summary>
    public static MessageSource User { get; } = new("user");

    /// <summary>The message provides application-generated context.</summary>
    public static MessageSource System { get; } = new("system");

    /// <summary>The string value used in JSON serialization.</summary>
    public string Value { get; }

    private MessageSource(string value) => Value = value;

    /// <summary>Identifies a message from an agent.</summary>
    /// <param name="id">The opaque agent identifier, preserved exactly after <c>agent-</c>.</param>
    /// <returns>The agent message source.</returns>
    /// <exception cref="ArgumentNullException"><paramref name="id"/> is null.</exception>
    public static MessageSource Agent(string id)
    {
        ArgumentNullException.ThrowIfNull(id);
        return new("agent-" + id);
    }

    /// <inheritdoc/>
    public override string ToString() => Value;

    /// <summary>Converts message sources to and from their wire strings.</summary>
    public sealed class Converter : JsonConverter<MessageSource>
    {
        /// <inheritdoc/>
        public override MessageSource Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
        {
            var value = GeneratedStringEnumJson.ReadValue(ref reader, typeToConvert);
            return value switch
            {
                "user" => User,
                "system" => System,
                _ when value.StartsWith("agent-", StringComparison.Ordinal) => new MessageSource(value),
                _ => throw new JsonException($"Unknown MessageSource value: {value}")
            };
        }

        /// <inheritdoc/>
        public override void Write(Utf8JsonWriter writer, MessageSource value, JsonSerializerOptions options) =>
            writer.WriteStringValue(value.Value);
    }
}

/// <summary>
/// Specifies the operation to perform on a system message section.
/// </summary>
[JsonConverter(typeof(JsonStringEnumConverter<SectionOverrideAction>))]
public enum SectionOverrideAction
{
    /// <summary>Replace the section content entirely.</summary>
    [JsonStringEnumMemberName("replace")]
    Replace,
    /// <summary>Remove the section from the prompt.</summary>
    [JsonStringEnumMemberName("remove")]
    Remove,
    /// <summary>Append content after the existing section.</summary>
    [JsonStringEnumMemberName("append")]
    Append,
    /// <summary>Prepend content before the existing section.</summary>
    [JsonStringEnumMemberName("prepend")]
    Prepend,
    /// <summary>
    /// No-op marker that opts an individually-addressable section out of a group-level
    /// remove (e.g. keep <see cref="SystemMessageSection.Tone"/> when removing the
    /// <see cref="SystemMessageSection.Identity"/> group).
    /// </summary>
    [JsonStringEnumMemberName("preserve")]
    Preserve,
    /// <summary>Transform the section content via a callback.</summary>
    [JsonStringEnumMemberName("transform")]
    Transform
}

/// <summary>
/// Override operation for a single system message section.
/// </summary>
public sealed class SectionOverride
{
    /// <summary>
    /// The operation to perform on this section. Ignored when Transform is set.
    /// </summary>
    [JsonPropertyName("action")]
    public SectionOverrideAction? Action { get; set; }

    /// <summary>
    /// Content for the override. Optional for all actions. Ignored for remove.
    /// </summary>
    [JsonPropertyName("content")]
    public string? Content { get; set; }

    /// <summary>
    /// Transform callback. When set, takes precedence over Action.
    /// Receives current section content, returns transformed content.
    /// Not serialized — the SDK handles this locally.
    /// </summary>
    [JsonIgnore]
    public Func<string, Task<string>>? Transform { get; set; }
}

/// <summary>
/// Identifies a system message section for the "customize" mode.
/// </summary>
[JsonConverter(typeof(SystemMessageSection.Converter))]
public readonly struct SystemMessageSection : IEquatable<SystemMessageSection>
{
    /// <summary>Agent identity preamble and mode statement.</summary>
    public static SystemMessageSection Preamble { get; } = new("preamble");
    /// <summary>Section group covering the identity preamble and its sibling sub-sections (tone, tool efficiency, etc.).</summary>
    public static SystemMessageSection Identity { get; } = new("identity");
    /// <summary>Response style, conciseness rules, output formatting preferences.</summary>
    public static SystemMessageSection Tone { get; } = new("tone");
    /// <summary>Tool usage patterns, parallel calling, batching guidelines.</summary>
    public static SystemMessageSection ToolEfficiency { get; } = new("tool_efficiency");
    /// <summary>CWD, OS, git root, directory listing, available tools.</summary>
    public static SystemMessageSection EnvironmentContext { get; } = new("environment_context");
    /// <summary>Coding rules, linting/testing, ecosystem tools, style.</summary>
    public static SystemMessageSection CodeChangeRules { get; } = new("code_change_rules");
    /// <summary>Tips, behavioral best practices, behavioral guidelines.</summary>
    public static SystemMessageSection Guidelines { get; } = new("guidelines");
    /// <summary>Environment limitations, prohibited actions, security policies.</summary>
    public static SystemMessageSection Safety { get; } = new("safety");
    /// <summary>Per-tool usage instructions.</summary>
    public static SystemMessageSection ToolInstructions { get; } = new("tool_instructions");
    /// <summary>Repository and organization custom instructions.</summary>
    public static SystemMessageSection CustomInstructions { get; } = new("custom_instructions");
    /// <summary>Runtime-provided context and instructions (e.g. system notifications, memories, workspace context, mode-specific instructions, content-exclusion policy).</summary>
    public static SystemMessageSection RuntimeInstructions { get; } = new("runtime_instructions");
    /// <summary>End-of-prompt instructions: parallel tool calling, persistence, task completion.</summary>
    public static SystemMessageSection LastInstructions { get; } = new("last_instructions");

    /// <summary>Gets the underlying string value of this <see cref="SystemMessageSection"/>.</summary>
    public string Value => _value ?? string.Empty;

    private readonly string? _value;

    /// <summary>Initializes a new instance of the <see cref="SystemMessageSection"/> struct.</summary>
    /// <param name="value">The string value for this section identifier.</param>
    [JsonConstructor]
    public SystemMessageSection(string value) => _value = value;

    /// <inheritdoc/>
    public static bool operator ==(SystemMessageSection left, SystemMessageSection right) => left.Equals(right);

    /// <inheritdoc/>
    public static bool operator !=(SystemMessageSection left, SystemMessageSection right) => !left.Equals(right);

    /// <inheritdoc/>
    public override bool Equals([NotNullWhen(true)] object? obj) => obj is SystemMessageSection other && Equals(other);

    /// <inheritdoc/>
    public bool Equals(SystemMessageSection other) => string.Equals(Value, other.Value, StringComparison.OrdinalIgnoreCase);

    /// <inheritdoc/>
    public override int GetHashCode() => StringComparer.OrdinalIgnoreCase.GetHashCode(Value);

    /// <inheritdoc/>
    public override string ToString() => Value;

    /// <summary>Provides a <see cref="JsonConverter{SystemMessageSection}"/> for serializing <see cref="SystemMessageSection"/> instances.</summary>
    [EditorBrowsable(EditorBrowsableState.Never)]
    public sealed class Converter : JsonConverter<SystemMessageSection>
    {
        /// <inheritdoc/>
        public override SystemMessageSection Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
        {
            if (reader.TokenType != JsonTokenType.String)
            {
                throw new JsonException("Expected string for SystemMessageSection.");
            }

            var value = reader.GetString();
            if (value is null)
            {
                throw new JsonException("SystemMessageSection value cannot be null.");
            }

            return new SystemMessageSection(value);
        }

        /// <inheritdoc/>
        public override void Write(Utf8JsonWriter writer, SystemMessageSection value, JsonSerializerOptions options) =>
            writer.WriteStringValue(value.Value);

        /// <inheritdoc/>
        public override SystemMessageSection ReadAsPropertyName(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options) =>
            new(reader.GetString()!);

        /// <inheritdoc/>
        public override void WriteAsPropertyName(Utf8JsonWriter writer, SystemMessageSection value, JsonSerializerOptions options) =>
            writer.WritePropertyName(value.Value);
    }
}

/// <summary>
/// Configuration for the system message used in a session.
/// </summary>
public sealed class SystemMessageConfig
{
    /// <summary>
    /// How the system message is applied (append, replace, or customize).
    /// </summary>
    public SystemMessageMode? Mode { get; set; }

    /// <summary>
    /// Content of the system message. Used by append and replace modes.
    /// In customize mode, additional content appended after all sections.
    /// </summary>
    public string? Content { get; set; }

    /// <summary>
    /// Section-level overrides for customize mode.
    /// Keys are section identifiers (see <see cref="SystemMessageSection"/>).
    /// </summary>
    public IDictionary<SystemMessageSection, SectionOverride>? Sections { get; set; }
}

/// <summary>
/// Configuration for a custom model provider.
/// </summary>
public sealed class ProviderConfig
{
    /// <summary>
    /// Provider type identifier (e.g., "openai", "azure").
    /// </summary>
    [JsonPropertyName("type")]
    public string? Type { get; set; }

    /// <summary>
    /// Wire API format to use (e.g., "chat-completions").
    /// </summary>
    [JsonPropertyName("wireApi")]
    public string? WireApi { get; set; }

    /// <summary>
    /// Transport for OpenAI Responses requests ("http" or "websockets"). Defaults to "http".
    /// Set to "websockets" to deliver Responses API requests over a persistent WebSocket
    /// connection instead of HTTP. Applies to OpenAI-compatible providers using
    /// <c>wireApi: "responses"</c>.
    /// </summary>
    [JsonPropertyName("transport")]
    public string? Transport { get; set; }

    /// <summary>
    /// Base URL of the provider's API endpoint.
    /// </summary>
    [JsonPropertyName("baseUrl")]
    public string BaseUrl { get; set; } = string.Empty;

    /// <summary>
    /// API key for authenticating with the provider.
    /// </summary>
    [JsonPropertyName("apiKey")]
    public string? ApiKey { get; set; }

    /// <summary>
    /// Bearer token for authentication. Sets the Authorization header directly.
    /// Use this for services requiring bearer token auth instead of API key.
    /// Takes precedence over ApiKey when both are set.
    /// </summary>
    [JsonPropertyName("bearerToken")]
    public string? BearerToken { get; set; }

    /// <summary>
    /// Wire-only flag, emitted automatically when <see cref="BearerTokenProvider"/> is set, that tells
    /// the runtime to request a token over the session-scoped <c>providerToken.getToken</c> RPC
    /// before each outbound request to this provider. Derived from <see cref="BearerTokenProvider"/>;
    /// internal and never part of the public API.
    /// </summary>
    [JsonInclude]
    [JsonPropertyName("hasBearerTokenProvider")]
    internal bool? HasBearerTokenProvider => BearerTokenProvider is not null ? true : null;

    /// <summary>
    /// Per-request callback that resolves a bearer token on demand for this BYOK provider (for
    /// example via Azure Managed Identity). The Copilot SDK takes no identity dependency: supply a
    /// callback backed by your own identity library. Never serialized — setting it makes the SDK send
    /// <c>hasBearerTokenProvider: true</c> on the wire and answer the runtime's
    /// <c>providerToken.getToken</c> requests. When set alongside <see cref="ApiKey"/>/<see cref="BearerToken"/>, this callback takes precedence:
    /// the runtime applies the token it returns as the Authorization: Bearer header for each request
    /// and does not send the static credential.
    /// </summary>
    [JsonIgnore]
    [Experimental(Diagnostics.Experimental)]
    public Func<ProviderTokenArgs, Task<string>>? BearerTokenProvider { get; set; }

    /// <summary>
    /// Azure-specific configuration options.
    /// </summary>
    [JsonPropertyName("azure")]
    public AzureOptions? Azure { get; set; }

    /// <summary>
    /// Custom HTTP headers to include in outbound provider requests.
    /// </summary>
    [JsonPropertyName("headers")]
    public IDictionary<string, string>? Headers { get; set; }

    /// <summary>
    /// Well-known model name used by the runtime to look up agent configuration
    /// (tools, prompts, reasoning behavior) and default token limits. Also used
    /// as the wire model when <see cref="WireModel"/> is not set.
    /// Falls back to <see cref="SessionConfigBase.Model"/>.
    /// </summary>
    [JsonPropertyName("modelId")]
    public string? ModelId { get; set; }

    /// <summary>
    /// Model name sent to the provider API for inference. Use this when the
    /// provider's model name (e.g. an Azure deployment name or a custom
    /// fine-tune name) differs from <see cref="ModelId"/>.
    /// Falls back to <see cref="ModelId"/>, then <see cref="SessionConfigBase.Model"/>.
    /// </summary>
    [JsonPropertyName("wireModel")]
    public string? WireModel { get; set; }

    /// <summary>
    /// Overrides the resolved model's default max prompt tokens. The runtime
    /// triggers conversation compaction before sending a request when the
    /// prompt (system message, history, tool definitions, user message) would
    /// exceed this limit.
    /// </summary>
    [JsonPropertyName("maxPromptTokens")]
    public int? MaxPromptTokens { get; set; }

    /// <summary>
    /// Overrides the resolved model's default max output tokens. When hit, the
    /// model stops generating and returns a truncated response.
    /// </summary>
    [JsonPropertyName("maxOutputTokens")]
    public int? MaxOutputTokens { get; set; }
}

/// <summary>
/// Provider-scoped options for the Copilot API (CAPI) provider.
/// </summary>
public sealed class CapiSessionOptions
{
    /// <summary>
    /// When <see langword="false"/>, forces the HTTP Responses transport for the CAPI Responses API
    /// instead of the default WebSocket transport.
    /// </summary>
    /// <remarks>
    /// WebSocket transport is the default for CAPI Responses API requests when the model advertises
    /// the <c>ws:/responses</c> endpoint. Set this to <see langword="false"/> for users behind proxies
    /// where WebSockets fail. Setting it to <see langword="false"/> is equivalent to setting the
    /// <c>COPILOT_CLI_DISABLE_WEBSOCKET_RESPONSES</c> environment variable. The option is scoped under
    /// the <c>capi</c> namespace because a single session can host multiple providers, such as CAPI and
    /// BYOK, so transport choice is provider-level.
    /// </remarks>
    [JsonPropertyName("enableWebSocketResponses")]
    public bool? EnableWebSocketResponses { get; set; }

    /// <summary>
    /// Routing tier for model <c>auto</c> with V2 Auto.
    /// </summary>
    /// <remarks>
    /// Requires a runtime that supports Auto tiers; it has no effect outside V2 Auto.
    /// When omitted, the runtime uses its default on create and restores the last committed
    /// tier on cold resume. On resident resume, a different tier requests a safe switch that
    /// takes effect after resume succeeds and never disturbs a turn that is already running.
    /// To change the preference on a live session, use
    /// <see cref="CopilotSession.SetAutoTierAsync"/>.
    /// </remarks>
    [JsonPropertyName("autoTier")]
    public AutoTier? AutoTier { get; set; }
}

/// <summary>
/// Azure OpenAI-specific provider options.
/// </summary>
public sealed class AzureOptions
{
    /// <summary>
    /// Azure OpenAI API version. When omitted, the runtime uses the GA versionless v1 route.
    /// </summary>
    [JsonPropertyName("apiVersion")]
    public string? ApiVersion { get; set; }
}

/// <summary>
/// A named BYOK provider connection (transport + credentials only), referenced by
/// <see cref="ProviderModelConfig"/> entries via <see cref="Name"/>.
/// <para>
/// Unlike the singular, whole-session <see cref="ProviderConfig"/> — which bypasses
/// Copilot API authentication — named providers are additive and coexist with Copilot
/// API auth, so models from CAPI and one or more BYOK providers can be mixed within a
/// single session and across sub-agents. Combining named providers/models with
/// <see cref="SessionConfigBase.Provider"/> is rejected.
/// </para>
/// </summary>
[Experimental(Diagnostics.Experimental)]
public sealed class NamedProviderConfig
{
    /// <summary>
    /// Stable identifier referenced by <see cref="ProviderModelConfig.Provider"/>.
    /// Must not contain '/'.
    /// </summary>
    [JsonPropertyName("name")]
    public string Name { get; set; } = string.Empty;

    /// <summary>
    /// Provider type. Defaults to "openai" for generic OpenAI-compatible APIs.
    /// </summary>
    [JsonPropertyName("type")]
    public string? Type { get; set; }

    /// <summary>
    /// Wire API format (openai/azure only). Defaults to "completions".
    /// </summary>
    [JsonPropertyName("wireApi")]
    public string? WireApi { get; set; }

    /// <summary>
    /// API endpoint URL.
    /// </summary>
    [JsonPropertyName("baseUrl")]
    public string BaseUrl { get; set; } = string.Empty;

    /// <summary>
    /// API key. Optional for local providers like Ollama.
    /// </summary>
    [JsonPropertyName("apiKey")]
    public string? ApiKey { get; set; }

    /// <summary>
    /// Bearer token for authentication. Sets the Authorization header directly.
    /// Takes precedence over <see cref="ApiKey"/> when both are set.
    /// </summary>
    [JsonPropertyName("bearerToken")]
    public string? BearerToken { get; set; }

    /// <summary>
    /// Wire-only flag, emitted automatically when <see cref="BearerTokenProvider"/> is set, that tells
    /// the runtime to request a token over the session-scoped <c>providerToken.getToken</c> RPC
    /// before each outbound request to this provider. Derived from <see cref="BearerTokenProvider"/>;
    /// internal and never part of the public API.
    /// </summary>
    [JsonInclude]
    [JsonPropertyName("hasBearerTokenProvider")]
    internal bool? HasBearerTokenProvider => BearerTokenProvider is not null ? true : null;

    /// <summary>
    /// Per-request callback that resolves a bearer token on demand for this BYOK provider (for
    /// example via Azure Managed Identity). The Copilot SDK takes no identity dependency: supply a
    /// callback backed by your own identity library. Never serialized — setting it makes the SDK send
    /// <c>hasBearerTokenProvider: true</c> on the wire and answer the runtime's
    /// <c>providerToken.getToken</c> requests. When set alongside <see cref="ApiKey"/>/<see cref="BearerToken"/>, this callback takes precedence:
    /// the runtime applies the token it returns as the Authorization: Bearer header for each request
    /// and does not send the static credential.
    /// </summary>
    [JsonIgnore]
    [Experimental(Diagnostics.Experimental)]
    public Func<ProviderTokenArgs, Task<string>>? BearerTokenProvider { get; set; }

    /// <summary>
    /// Azure-specific configuration options.
    /// </summary>
    [JsonPropertyName("azure")]
    public AzureOptions? Azure { get; set; }

    /// <summary>
    /// Custom HTTP headers to include in all outbound requests to the provider.
    /// </summary>
    [JsonPropertyName("headers")]
    public IDictionary<string, string>? Headers { get; set; }
}

/// <summary>
/// A BYOK model definition that references a <see cref="NamedProviderConfig"/> by name
/// and is added to the session's selectable model list. The session-wide selection id
/// (shown in the model list and passed to model switching) is the provider-qualified
/// <c>provider/id</c>, so BYOK ids never collide with bare CAPI ids.
/// </summary>
[Experimental(Diagnostics.Experimental)]
public sealed class ProviderModelConfig
{
    /// <summary>
    /// Provider-local model id, unique within its provider.
    /// </summary>
    [JsonPropertyName("id")]
    public string Id { get; set; } = string.Empty;

    /// <summary>
    /// Name of the <see cref="NamedProviderConfig"/> that serves this model.
    /// </summary>
    [JsonPropertyName("provider")]
    public string Provider { get; set; } = string.Empty;

    /// <summary>
    /// The model name sent to the provider API for inference. Defaults to <see cref="Id"/>.
    /// </summary>
    [JsonPropertyName("wireModel")]
    public string? WireModel { get; set; }

    /// <summary>
    /// Well-known base model id used for behavior/capability/config lookup. Defaults to <see cref="Id"/>.
    /// </summary>
    [JsonPropertyName("modelId")]
    public string? ModelId { get; set; }

    /// <summary>
    /// Display name for model pickers. Defaults to the provider-qualified selection id.
    /// </summary>
    [JsonPropertyName("name")]
    public string? Name { get; set; }

    /// <summary>
    /// Maximum prompt/input tokens for the model.
    /// </summary>
    [JsonPropertyName("maxPromptTokens")]
    public int? MaxPromptTokens { get; set; }

    /// <summary>
    /// Maximum context window tokens for the model.
    /// </summary>
    [JsonPropertyName("maxContextWindowTokens")]
    public int? MaxContextWindowTokens { get; set; }

    /// <summary>
    /// Maximum output tokens for the model.
    /// </summary>
    [JsonPropertyName("maxOutputTokens")]
    public int? MaxOutputTokens { get; set; }

    /// <summary>
    /// Optional capability overrides (vision, tool_calls, reasoning, etc.) for the synthesized model.
    /// </summary>
    [JsonPropertyName("capabilities")]
    public ModelCapabilitiesOverride? Capabilities { get; set; }
}

// ============================================================================
// MCP Server Configuration Types
// ============================================================================

/// <summary>
/// OAuth grant type for a remote MCP server.
/// </summary>
[JsonConverter(typeof(JsonStringEnumConverter<McpHttpServerConfigOauthGrantType>))]
public enum McpHttpServerConfigOauthGrantType
{
    /// <summary>Use the authorization code OAuth flow.</summary>
    [JsonStringEnumMemberName("authorization_code")]
    AuthorizationCode,

    /// <summary>Use the client credentials OAuth flow.</summary>
    [JsonStringEnumMemberName("client_credentials")]
    ClientCredentials
}

/// <summary>
/// Controls how MCP OAuth tokens are stored for a session.
/// </summary>
[JsonConverter(typeof(JsonStringEnumConverter<McpOAuthTokenStorageMode>))]
public enum McpOAuthTokenStorageMode
{
    /// <summary>Tokens are stored in the OS keychain, shared across sessions.</summary>
    [JsonStringEnumMemberName("persistent")]
    Persistent,

    /// <summary>Tokens are stored in memory and discarded when the session ends.</summary>
    [JsonStringEnumMemberName("in-memory")]
    InMemory
}

/// <summary>
/// Controls how the embedding cache is stored for a session.
/// </summary>
[JsonConverter(typeof(JsonStringEnumConverter<EmbeddingCacheStorageMode>))]
public enum EmbeddingCacheStorageMode
{
    /// <summary>Embeddings are cached on disk, shared across sessions and restarts.</summary>
    [JsonStringEnumMemberName("persistent")]
    Persistent,

    /// <summary>Embeddings are cached in memory only and discarded when the session ends.</summary>
    [JsonStringEnumMemberName("in-memory")]
    InMemory
}

/// <summary>
/// Abstract base class for MCP server configurations.
/// </summary>
[JsonPolymorphic(
    TypeDiscriminatorPropertyName = "type",
    IgnoreUnrecognizedTypeDiscriminators = true)]
[JsonDerivedType(typeof(McpStdioServerConfig), "stdio")]
[JsonDerivedType(typeof(McpHttpServerConfig), "http")]
public abstract class McpServerConfig
{
    private protected McpServerConfig() { }

    /// <summary>
    /// List of tools to include from this server. <c>null</c> (the default)
    /// means include all tools. An empty list means include none.
    /// </summary>
    [JsonPropertyName("tools")]
    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
    public IList<string>? Tools { get; set; }

    /// <summary>
    /// The server type discriminator.
    /// </summary>
    [JsonIgnore]
    public virtual string Type => "unknown";

    /// <summary>
    /// Optional timeout in milliseconds for tool calls to this server.
    /// </summary>
    [JsonPropertyName("timeout")]
    public int? Timeout { get; set; }
}

/// <summary>
/// Configuration for a local/stdio MCP server.
/// </summary>
public sealed class McpStdioServerConfig : McpServerConfig
{
    /// <inheritdoc />
    [JsonIgnore]
    public override string Type => "stdio";

    /// <summary>
    /// Command to run the MCP server.
    /// </summary>
    [JsonPropertyName("command")]
    public string Command { get; set; } = string.Empty;

    /// <summary>
    /// Arguments to pass to the command.
    /// </summary>
    [JsonPropertyName("args")]
    public IList<string>? Args { get; set; }

    /// <summary>
    /// Environment variables to pass to the server.
    /// </summary>
    [JsonPropertyName("env")]
    public IDictionary<string, string>? Env { get; set; }

    /// <summary>
    /// Working directory for the server process.
    /// </summary>
    [JsonPropertyName("cwd")]
    public string? WorkingDirectory { get; set; }
}

/// <summary>
/// Configuration for a remote MCP server (HTTP or SSE).
/// </summary>
public sealed class McpHttpServerConfig : McpServerConfig
{
    /// <inheritdoc />
    [JsonIgnore]
    public override string Type => "http";

    /// <summary>
    /// URL of the remote server.
    /// </summary>
    [JsonPropertyName("url")]
    public string Url { get; set; } = string.Empty;

    /// <summary>
    /// Optional HTTP headers to include in requests.
    /// </summary>
    [JsonPropertyName("headers")]
    public IDictionary<string, string>? Headers { get; set; }

    /// <summary>
    /// Optional OAuth client ID for the remote server.
    /// </summary>
    [JsonPropertyName("oauthClientId")]
    public string? OauthClientId { get; set; }

    /// <summary>
    /// Whether this is a public OAuth client.
    /// </summary>
    [JsonPropertyName("oauthPublicClient")]
    public bool? OauthPublicClient { get; set; }

    /// <summary>
    /// Optional OAuth grant type for the remote server.
    /// </summary>
    [JsonPropertyName("oauthGrantType")]
    public McpHttpServerConfigOauthGrantType? OauthGrantType { get; set; }
}

// ============================================================================
// Custom Agent Configuration Types
// ============================================================================

/// <summary>
/// Configuration for a custom agent.
/// </summary>
public sealed class CustomAgentConfig
{
    /// <summary>
    /// Unique name of the custom agent.
    /// </summary>
    [JsonPropertyName("name")]
    public string Name { get; set; } = string.Empty;

    /// <summary>
    /// Display name for UI purposes.
    /// </summary>
    [JsonPropertyName("displayName")]
    public string? DisplayName { get; set; }

    /// <summary>
    /// Description of what the agent does.
    /// </summary>
    [JsonPropertyName("description")]
    public string? Description { get; set; }

    /// <summary>
    /// List of tool names the agent can use. Null for all tools.
    /// </summary>
    [JsonPropertyName("tools")]
    public IList<string>? Tools { get; set; }

    /// <summary>
    /// The prompt content for the agent.
    /// </summary>
    [JsonPropertyName("prompt")]
    public string Prompt { get; set; } = string.Empty;

    /// <summary>
    /// MCP servers specific to this agent.
    /// </summary>
    [JsonPropertyName("mcpServers")]
    public IDictionary<string, McpServerConfig>? McpServers { get; set; }

    /// <summary>
    /// Whether the agent should be available for model inference.
    /// </summary>
    [JsonPropertyName("infer")]
    public bool? Infer { get; set; }

    /// <summary>
    /// List of skill names to preload into this agent's context.
    /// When set, the full content of each listed skill is eagerly injected into
    /// the agent's context at startup. Skills are resolved by name from the
    /// session's configured skill directories (<see cref="SessionConfigBase.SkillDirectories"/>).
    /// When omitted, no skills are injected (opt-in model).
    /// </summary>
    [JsonPropertyName("skills")]
    public IList<string>? Skills { get; set; }

    /// <summary>
    /// Model identifier for this agent (e.g. "claude-haiku-4.5").
    /// When set, the runtime will attempt to use this model for the agent,
    /// falling back to the parent session model if unavailable.
    /// </summary>
    [JsonPropertyName("model")]
    public string? Model { get; set; }

    /// <summary>
    /// Reasoning effort level for this agent's model.
    /// When omitted, the runtime resolves model configuration, then inherits
    /// the parent effort only if this agent uses the same model.
    /// </summary>
    [JsonPropertyName("reasoningEffort")]
    public string? ReasoningEffort { get; set; }
}

/// <summary>
/// Configuration for the default agent (the built-in agent that handles turns when no custom agent is selected).
/// Use <see cref="ExcludedTools"/> to hide specific tools from the default agent
/// while keeping them available to custom sub-agents.
/// </summary>
public sealed class DefaultAgentConfig
{
    /// <summary>
    /// List of tool names to exclude from the default agent.
    /// These tools remain available to custom sub-agents that reference them
    /// in their <see cref="CustomAgentConfig.Tools"/> list.
    /// </summary>
    public IList<string>? ExcludedTools { get; set; }
}

/// <summary>
/// Configuration for infinite sessions with automatic context compaction and workspace persistence.
/// When enabled, sessions automatically manage context window limits through background compaction
/// and persist state to a workspace directory.
/// </summary>
public sealed class InfiniteSessionConfig
{
    /// <summary>
    /// Whether infinite sessions are enabled. Default: true
    /// </summary>
    [JsonPropertyName("enabled")]
    public bool? Enabled { get; set; }

    /// <summary>
    /// Context utilization threshold (0.0-1.0) at which background compaction starts.
    /// Compaction runs asynchronously, allowing the session to continue processing.
    /// Default: 0.80
    /// </summary>
    [JsonPropertyName("backgroundCompactionThreshold")]
    public double? BackgroundCompactionThreshold { get; set; }

    /// <summary>
    /// Context utilization threshold (0.0-1.0) at which the session blocks until compaction completes.
    /// This prevents context overflow when compaction hasn't finished in time.
    /// Default: 0.95
    /// </summary>
    [JsonPropertyName("bufferExhaustionThreshold")]
    public double? BufferExhaustionThreshold { get; set; }
}

/// <summary>
/// Configuration for handling large tool outputs.
/// </summary>
/// <remarks>
/// When a tool produces output exceeding the configured size, the output is
/// written to a temp file and a reference is returned to the model instead of
/// returning to it the full payload.
/// </remarks>
public sealed class LargeToolOutputConfig
{
    /// <summary>
    /// Whether large output handling is enabled.
    /// </summary>
    /// <remarks>The default value is <see langword="true"/>.</remarks>
    [JsonPropertyName("enabled")]
    public bool? Enabled { get; set; }

    /// <summary>
    /// Maximum size in bytes before output is written to a temp file.
    /// </summary>
    [JsonPropertyName("maxSizeBytes")]
    public long? MaxSizeBytes { get; set; }

    /// <summary>
    /// Directory to write temp files to.
    /// </summary>
    /// <remarks>The default value is the OS temp directory.</remarks>
    [JsonPropertyName("outputDir")]
    public string? OutputDirectory { get; set; }
}

/// <summary>
/// Overrides the runtime's built-in tool-search behavior.
/// Defers tools to keep the model's active tool set small.
/// To override the tool-search tool's implementation, register a tool
/// named "tool_search_tool" with <c>OverridesBuiltInTool</c> set to
/// <see langword="true"/>.
/// </summary>
public sealed class ToolSearchConfig
{
    /// <summary>
    /// Enable or disable tool search.
    /// </summary>
    [JsonPropertyName("enabled")]
    public bool? Enabled { get; set; }

    /// <summary>
    /// The tool count above which MCP and external tools are deferred behind
    /// tool search. When <see langword="null"/>, the runtime default (30)
    /// applies.
    /// </summary>
    [JsonPropertyName("deferThreshold")]
    public int? DeferThreshold { get; set; }
}

/// <summary>
/// Configuration for session memory.
/// </summary>
public sealed class MemoryConfiguration
{
    /// <summary>
    /// Whether memory is enabled for the session.
    /// </summary>
    [JsonPropertyName("enabled")]
    public bool Enabled { get; set; }
}

/// <summary>
/// GitHub repository metadata to associate with a cloud session.
/// </summary>
public sealed class CloudSessionRepository
{
    /// <summary>Repository owner.</summary>
    public required string Owner { get; set; }

    /// <summary>Repository name.</summary>
    public required string Name { get; set; }

    /// <summary>Optional branch name.</summary>
    public string? Branch { get; set; }
}

/// <summary>
/// Options for creating a remote session in the cloud.
/// </summary>
public sealed class CloudSessionOptions
{
    /// <summary>
    /// Optional GitHub repository metadata to associate with the cloud session.
    /// </summary>
    public CloudSessionRepository? Repository { get; set; }
}

/// <summary>
/// Optional settings for <see cref="CopilotSession.SetModelAsync(string, SetModelOptions, CancellationToken)"/>.
/// </summary>
public struct SetModelOptions
{
    /// <summary>
    /// Reasoning effort level for the new model.
    /// </summary>
    public string? ReasoningEffort { get; set; }

    /// <summary>
    /// Reasoning summary mode for models that support configurable reasoning summaries.
    /// </summary>
    /// <remarks>
    /// Use <see cref="ReasoningSummary.None"/> to suppress summary output regardless of whether reasoning is enabled.
    /// </remarks>
    public ReasoningSummary? ReasoningSummary { get; set; }

    /// <summary>
    /// Explicit context window tier for models that support it.
    /// Leave unset to use normal model behavior with no explicit tier.
    /// </summary>
    public ContextTier? ContextTier { get; set; }

    /// <summary>Per-property overrides for model capabilities, deep-merged over runtime defaults.</summary>
    public ModelCapabilitiesOverride? ModelCapabilities { get; set; }

    /// <summary>
    /// Routing preference to stage atomically with selecting the <c>auto</c> model.
    /// </summary>
    /// <remarks>
    /// Leave unset to leave the current preference alone. Set
    /// <see cref="ResetAutoTier"/> instead to return to the provider's default Auto
    /// routing. The runtime rejects this option when the model is anything other than
    /// <c>auto</c>; use <see cref="CopilotSession.SetAutoTierAsync"/> to change the
    /// preference without changing the selected model.
    /// </remarks>
    [Experimental(Diagnostics.Experimental)]
    public AutoTier? AutoTier { get; set; }

    /// <summary>
    /// Returns to the provider's default Auto routing as part of this switch.
    /// Mutually exclusive with <see cref="AutoTier"/>.
    /// </summary>
    [Experimental(Diagnostics.Experimental)]
    public bool ResetAutoTier { get; set; }
}

/// <summary>
/// A single configuration entry in a <see cref="CopilotExpAssignmentResponse"/>.
/// Each entry carries an identifier and a bag of typed parameter values.
/// </summary>
public sealed class ExpConfigEntry
{
    /// <summary>Identifier of the configuration entry.</summary>
    [JsonPropertyName("Id")]
    public string Id { get; set; } = string.Empty;

    /// <summary>
    /// Parameter values keyed by parameter name. Each value is a scalar string,
    /// number, boolean, or <c>null</c>.
    /// </summary>
    [JsonPropertyName("Parameters")]
    public IDictionary<string, JsonValue?> Parameters { get; set; } = new Dictionary<string, JsonValue?>();
}

/// <summary>
/// ExP ("flight") assignment data, in the same JSON shape the Copilot CLI
/// fetches from the experimentation service. Property names serialize as
/// PascalCase (<c>Features</c>, <c>Flights</c>, ...) to match the on-the-wire
/// contract consumed by the runtime.
/// </summary>
public sealed class CopilotExpAssignmentResponse
{
    /// <summary>Enabled feature names.</summary>
    [JsonPropertyName("Features")]
    public IList<string> Features { get; set; } = new List<string>();

    /// <summary>Assigned flights keyed by flight name.</summary>
    [JsonPropertyName("Flights")]
    public IDictionary<string, string> Flights { get; set; } = new Dictionary<string, string>();

    /// <summary>Configuration entries carrying typed parameter values.</summary>
    [JsonPropertyName("Configs")]
    public IList<ExpConfigEntry> Configs { get; set; } = new List<ExpConfigEntry>();

    /// <summary>Opaque parameter-group payload passed through untouched. Optional.</summary>
    [JsonPropertyName("ParameterGroups")]
    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
    public JsonNode? ParameterGroups { get; set; }

    /// <summary>Version of the flighting configuration. Optional.</summary>
    [JsonPropertyName("FlightingVersion")]
    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
    public int? FlightingVersion { get; set; }

    /// <summary>Impression identifier for the assignment. Optional.</summary>
    [JsonPropertyName("ImpressionId")]
    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
    public string? ImpressionId { get; set; }

    /// <summary>Assignment context string forwarded to CAPI and telemetry.</summary>
    [JsonPropertyName("AssignmentContext")]
    public string AssignmentContext { get; set; } = string.Empty;
}

/// <summary>
/// Configuration for the built-in GitHub MCP server.
/// </summary>
public sealed class GitHubMcpToolConfig
{
    /// <summary>Enables all GitHub MCP tools.</summary>
    [JsonPropertyName("enableAllTools")]
    public bool? EnableAllTools { get; set; }

    /// <summary>Additional GitHub MCP toolsets to enable.</summary>
    [JsonPropertyName("additionalToolsets")]
    public IList<string>? AdditionalToolsets { get; set; }

    /// <summary>Additional GitHub MCP tools to enable.</summary>
    [JsonPropertyName("additionalTools")]
    public IList<string>? AdditionalTools { get; set; }

    /// <summary>Enables GitHub MCP insiders-mode tools.</summary>
    [JsonPropertyName("enableInsidersMode")]
    public bool? EnableInsidersMode { get; set; }

    /// <summary>
    /// Disables form deferral for GitHub MCP tools. This only applies to the
    /// built-in GitHub MCP server and only has an effect when MCP Apps and
    /// form-backed GitHub tools are enabled.
    /// </summary>
    [JsonPropertyName("disableFormDeferral")]
    public bool? DisableFormDeferral { get; set; }
}

/// <summary>Well-known managed bypass-permissions policies.</summary>
public static class DisableBypassPermissionsModes
{
    /// <summary>Turns off bypass-permissions mode entirely.</summary>
    public const string Disable = "disable";

    /// <summary>Permits automatic bypass but blocks full allow-all.</summary>
    public const string AllowAutoOnly = "allow-auto-only";
}

/// <summary>
/// Permission rules injected as a managed-settings layer at session bootstrap.
/// All fields are optional; omitted fields impose no constraint from this layer.
/// </summary>
/// <remarks>
/// This layer composes restrictively with any server- or device-level managed
/// settings: <see cref="Deny"/> and <see cref="Ask"/> rules are unioned across
/// layers, every present <see cref="Allow"/> list must admit a tool for it to be
/// allowed, and <see cref="DisableBypassPermissionsMode"/> policies compose to
/// the most restrictive setting.
/// </remarks>
public sealed class ManagedSettingsPermissions
{
    /// <summary>
    /// Restricts bypass-permissions mode for the session regardless of other
    /// layers. See <see cref="DisableBypassPermissionsModes"/> for well-known
    /// values. Unknown values are forwarded so newer runtime policies fail closed.
    /// Serialized as <c>disableBypassPermissionsMode</c>.
    /// </summary>
    [JsonPropertyName("disableBypassPermissionsMode")]
    public string? DisableBypassPermissionsMode { get; set; }

    /// <summary>Tool-permission patterns that are always denied.</summary>
    [JsonPropertyName("deny")]
    public IList<string>? Deny { get; set; }

    /// <summary>Tool-permission patterns that require an explicit ask.</summary>
    [JsonPropertyName("ask")]
    public IList<string>? Ask { get; set; }

    /// <summary>Tool-permission patterns that are allowed without prompting.</summary>
    [JsonPropertyName("allow")]
    public IList<string>? Allow { get; set; }
}

/// <summary>
/// Managed-settings layer injected at session startup. Currently carries only a
/// <see cref="Permissions"/> object.
/// </summary>
/// <remarks>
/// This layer is startup-only and is not persisted with the session. It must be
/// re-supplied on <see cref="CopilotClient.ResumeSessionAsync"/> to remain in
/// effect; omitting it on resume clears the previously injected layer. It can be
/// combined with <see cref="SessionConfigBase.EnableManagedSettings"/>. Older
/// runtimes may ignore this additive field, so hosts must not rely on injected
/// policy until they ship a compatible runtime.
/// </remarks>
public sealed class ManagedSettings
{
    /// <summary>Permission rules for this managed-settings layer.</summary>
    [JsonPropertyName("permissions")]
    public ManagedSettingsPermissions? Permissions { get; set; }
}

/// <summary>
/// Selects the model-facing shape of the built-in <c>ask_user</c> tool.
/// </summary>
[JsonConverter(typeof(JsonStringEnumConverter<AskUserVariant>))]
public enum AskUserVariant
{
    /// <summary>Use the legacy user-input request flow.</summary>
    [JsonStringEnumMemberName("legacy")]
    Legacy,

    /// <summary>Use the elicitation request flow.</summary>
    [JsonStringEnumMemberName("elicitation")]
    Elicitation
}

/// <summary>
/// Shared configuration properties for creating or resuming a Copilot session.
/// Use <see cref="SessionConfig"/> when creating a new session, or
/// <see cref="ResumeSessionConfig"/> when resuming an existing one.
/// </summary>
public abstract class SessionConfigBase
{
    /// <summary>Initializes a new instance of the <see cref="SessionConfigBase"/> class.</summary>
    protected SessionConfigBase() { }

    /// <summary>
    /// Initializes a new instance of <see cref="SessionConfigBase"/> by copying the
    /// properties of the specified instance.
    /// </summary>
    protected SessionConfigBase(SessionConfigBase? other)
    {
        if (other is null) return;

        AvailableTools = other.AvailableTools is not null ? [.. other.AvailableTools] : null;
        ClientName = other.ClientName;
        Commands = other.Commands is not null ? [.. other.Commands] : null;
        ConfigDirectory = other.ConfigDirectory;
        CustomAgents = other.CustomAgents is not null ? [.. other.CustomAgents] : null;
        DefaultAgent = other.DefaultAgent;
        Agent = other.Agent;
        DisabledSkills = other.DisabledSkills is not null ? [.. other.DisabledSkills] : null;
        IncludedBuiltinSkills = other.IncludedBuiltinSkills is not null ? [.. other.IncludedBuiltinSkills] : null;
        DisabledMcpServers = other.DisabledMcpServers is not null ? [.. other.DisabledMcpServers] : null;
        EnableCitations = other.EnableCitations;
        EnableFileChangeTracking = other.EnableFileChangeTracking;
        EnableConfigDiscovery = other.EnableConfigDiscovery;
        SkipEmbeddingRetrieval = other.SkipEmbeddingRetrieval;
        EmbeddingCacheStorage = other.EmbeddingCacheStorage;
        OrganizationCustomInstructions = other.OrganizationCustomInstructions;
        EnableOnDemandInstructionDiscovery = other.EnableOnDemandInstructionDiscovery;
        EnableFileHooks = other.EnableFileHooks;
        EnableHostGitOperations = other.EnableHostGitOperations;
        EnableSessionStore = other.EnableSessionStore;
        EnableSkills = other.EnableSkills;
        EnableMcpApps = other.EnableMcpApps;
        GitHubMcpToolConfig = other.GitHubMcpToolConfig is null
            ? null
            : new GitHubMcpToolConfig
            {
                EnableAllTools = other.GitHubMcpToolConfig.EnableAllTools,
                AdditionalToolsets = other.GitHubMcpToolConfig.AdditionalToolsets is not null
                    ? [.. other.GitHubMcpToolConfig.AdditionalToolsets]
                    : null,
                AdditionalTools = other.GitHubMcpToolConfig.AdditionalTools is not null
                    ? [.. other.GitHubMcpToolConfig.AdditionalTools]
                    : null,
                EnableInsidersMode = other.GitHubMcpToolConfig.EnableInsidersMode,
                DisableFormDeferral = other.GitHubMcpToolConfig.DisableFormDeferral,
            };
        ExcludedBuiltInAgents = other.ExcludedBuiltInAgents is not null ? [.. other.ExcludedBuiltInAgents] : null;
        ExcludedTools = other.ExcludedTools is not null ? [.. other.ExcludedTools] : null;
        Hooks = other.Hooks;
        InfiniteSessions = other.InfiniteSessions;
        LargeOutput = other.LargeOutput;
        ToolSearch = other.ToolSearch;
        Memory = other.Memory;
        McpServers = other.McpServers is not null
            ? (other.McpServers is Dictionary<string, McpServerConfig> dict
                ? new Dictionary<string, McpServerConfig>(dict, dict.Comparer)
                : new Dictionary<string, McpServerConfig>(other.McpServers))
            : null;
        McpOAuthTokenStorage = other.McpOAuthTokenStorage;
        AuthClientIdMetadataUrl = other.AuthClientIdMetadataUrl;
        Model = other.Model;
        ModelCapabilities = other.ModelCapabilities;
        OnAutoModeSwitchRequest = other.OnAutoModeSwitchRequest;
        OnElicitationRequest = other.OnElicitationRequest;
        OnEvent = other.OnEvent;
        OnExitPlanModeRequest = other.OnExitPlanModeRequest;
        OnMcpAuthRequest = other.OnMcpAuthRequest;
        OnPermissionRequest = other.OnPermissionRequest;
        OnUserInputRequest = other.OnUserInputRequest;
        Provider = other.Provider;
        Capi = other.Capi;
        Providers = other.Providers is not null ? [.. other.Providers] : null;
        Models = other.Models is not null ? [.. other.Models] : null;
        EnableSessionTelemetry = other.EnableSessionTelemetry;
        EnableExperimentalMode = other.EnableExperimentalMode;
        SkipCustomInstructions = other.SkipCustomInstructions;
        CustomAgentsLocalOnly = other.CustomAgentsLocalOnly;
        CoauthorEnabled = other.CoauthorEnabled;
        ManageScheduleEnabled = other.ManageScheduleEnabled;
        ReasoningEffort = other.ReasoningEffort;
        ReasoningSummary = other.ReasoningSummary;
        ContextTier = other.ContextTier;
        AskUserVariant = other.AskUserVariant;
        CreateSessionFsProvider = other.CreateSessionFsProvider;
        GitHubToken = other.GitHubToken;
        GitHubTokenProvider = other.GitHubTokenProvider;
        RemoteSession = other.RemoteSession;
        FeatureFlags = other.FeatureFlags is not null
            ? new Dictionary<string, bool>(other.FeatureFlags)
            : null;
        ExpAssignments = other.ExpAssignments;
        EnableManagedSettings = other.EnableManagedSettings;
        ManagedSettings = other.ManagedSettings;
#pragma warning disable GHCP001
        Canvases = other.Canvases is not null ? [.. other.Canvases] : null;
        RequestCanvasRenderer = other.RequestCanvasRenderer;
        RequestExtensions = other.RequestExtensions;
        ExtensionSdkPath = other.ExtensionSdkPath;
        ExtensionInfo = other.ExtensionInfo;
        CanvasProvider = other.CanvasProvider;
        CanvasHandler = other.CanvasHandler;
#pragma warning restore GHCP001
        SkillDirectories = other.SkillDirectories is not null ? [.. other.SkillDirectories] : null;
        PluginDirectories = other.PluginDirectories is not null ? [.. other.PluginDirectories] : null;
        InstructionDirectories = other.InstructionDirectories is not null ? [.. other.InstructionDirectories] : null;
        SessionLimits = other.SessionLimits;
        Streaming = other.Streaming;
        IncludeSubAgentStreamingEvents = other.IncludeSubAgentStreamingEvents;
        SystemMessage = other.SystemMessage;
        Tools = other.Tools is not null ? [.. other.Tools] : null;
        WorkingDirectory = other.WorkingDirectory;
        AdditionalDirectories = other.AdditionalDirectories is not null ? [.. other.AdditionalDirectories] : null;
    }

    /// <summary>Client name to identify the application using the SDK.</summary>
    public string? ClientName { get; set; }

    /// <summary>Model identifier to use for this session (e.g., "gpt-4o").</summary>
    public string? Model { get; set; }

    /// <summary>
    /// Reasoning effort level for models that support it.
    /// Valid values: "low", "medium", "high", "xhigh", "max".
    /// Only applies to models where capabilities.supports.reasoningEffort is true.
    /// </summary>
    public string? ReasoningEffort { get; set; }

    /// <summary>
    /// Reasoning summary mode for models that support configurable reasoning summaries.
    /// </summary>
    /// <remarks>
    /// Use <see cref="ReasoningSummary.None"/> to suppress summary output regardless of whether reasoning is enabled.
    /// </remarks>
    public ReasoningSummary? ReasoningSummary { get; set; }

    /// <summary>
    /// Context window tier for models that support it.
    /// Use <see cref="ContextTier.Default"/> or <see cref="ContextTier.LongContext"/>
    /// for the currently known tiers.
    /// </summary>
    public ContextTier? ContextTier { get; set; }

    /// <summary>Per-property overrides for model capabilities, deep-merged over runtime defaults.</summary>
    public ModelCapabilitiesOverride? ModelCapabilities { get; set; }

    /// <summary>
    /// Enables native model citations for models that support them.
    /// </summary>
    /// <remarks>
    /// Citations are experimental, off by default, and currently available for Anthropic models.
    /// This option may change or be removed while citation support is experimental.
    /// </remarks>
    [Experimental(Diagnostics.Experimental)]
    public bool? EnableCitations { get; set; }

    /// <summary>
    /// Opts in to capturing file changes for session rewind and cumulative
    /// session diff.
    /// </summary>
    /// <remarks>
    /// On create, capture starts with the first turn. On resume, tracking can be
    /// enabled only when the session still has a valid baseline; earlier untracked
    /// changes cannot be reconstructed.
    /// </remarks>
    public bool? EnableFileChangeTracking { get; set; }

    /// <summary>
    /// Override the default configuration directory location.
    /// When specified, the session will use this directory for storing config and state.
    /// </summary>
    public string? ConfigDirectory { get; set; }

    /// <summary>
    /// Enables runtime discovery of supported configuration. Explicitly supplied
    /// configuration takes precedence over discovered values.
    /// </summary>
    public bool? EnableConfigDiscovery { get; set; }

    /// <summary>
    /// When <see langword="true"/>, skips embedding-based retrieval for this session.
    /// Use in multitenant deployments to prevent cross-session information leakage
    /// through the shared embedding cache.
    /// </summary>
    public bool? SkipEmbeddingRetrieval { get; set; }

    /// <summary>
    /// Controls how the embedding cache is stored for this session.
    /// <see cref="EmbeddingCacheStorageMode.Persistent"/>: Embeddings are cached on disk and shared across sessions/restarts.
    /// <see cref="EmbeddingCacheStorageMode.InMemory"/>: Embeddings are cached in memory only and discarded when the session ends.
    /// </summary>
    public EmbeddingCacheStorageMode? EmbeddingCacheStorage { get; set; }

    /// <summary>
    /// Organization-level custom instructions to include in the system prompt.
    /// Allows hosts to inject organization-specific guidance without relying on
    /// filesystem-based instruction discovery.
    /// </summary>
    public string? OrganizationCustomInstructions { get; set; }

    /// <summary>
    /// When <see langword="true"/>, enables on-demand discovery of instruction files
    /// (for example <c>AGENTS.md</c> and <c>.github/copilot-instructions.md</c>)
    /// after successful file views.
    /// </summary>
    public bool? EnableOnDemandInstructionDiscovery { get; set; }

    /// <summary>
    /// When <see langword="true"/>, enables loading of file-based hooks from
    /// <c>.github/hooks/</c>. This is separate from <see cref="Hooks"/>, which
    /// controls SDK hook callback registration.
    /// </summary>
    public bool? EnableFileHooks { get; set; }

    /// <summary>
    /// When <see langword="true"/>, enables git operations on the host filesystem
    /// such as branch detection, file status, and commit history. When
    /// <see langword="false"/>, no git context is surfaced in the system prompt.
    /// </summary>
    public bool? EnableHostGitOperations { get; set; }

    /// <summary>
    /// When <see langword="true"/>, enables the cross-session store for search and
    /// retrieval across sessions. When <see langword="false"/>, session content is
    /// not written to or read from the shared session store.
    /// </summary>
    public bool? EnableSessionStore { get; set; }

    /// <summary>
    /// When <see langword="true"/>, enables skill loading, including built-in
    /// skills and discovered skill directories. When <see langword="false"/>, no
    /// skills are loaded regardless of <see cref="SkillDirectories"/> or
    /// <see cref="EnableConfigDiscovery"/>.
    /// </summary>
    public bool? EnableSkills { get; set; }

    /// <summary>
    /// Built-in skill names to include in the session. In
    /// <see cref="CopilotClientMode.Empty"/>, omitting this option excludes all
    /// runtime-bundled skills; specifying names opts those built-ins back in.
    /// Skills from other sources remain eligible.
    /// </summary>
    public IList<string>? IncludedBuiltinSkills { get; set; }

    /// <summary>
    /// Custom tool declarations available to the language model during the session.
    /// Declarations backed by an <see cref="AIFunction"/> are invoked automatically; declarations without one
    /// are left for the client to handle via external tool request events.
    /// </summary>
    public ICollection<AIFunctionDeclaration>? Tools { get; set; }

    /// <summary>System message configuration for the session.</summary>
    public SystemMessageConfig? SystemMessage { get; set; }

    /// <summary>
    /// Selects the model-facing shape of the built-in <c>ask_user</c> tool.
    /// The default is <see cref="GitHub.Copilot.AskUserVariant.Legacy"/>. To use
    /// <see cref="GitHub.Copilot.AskUserVariant.Elicitation"/>, also provide
    /// <see cref="OnElicitationRequest"/> so the host can answer structured forms.
    /// The runtime resolves this option when it creates or cold-resumes the session.
    /// </summary>
    public AskUserVariant? AskUserVariant { get; set; }

    /// <summary>List of tool names to allow; only these tools will be available when specified.</summary>
    public IList<string>? AvailableTools { get; set; }

    /// <summary>List of tool names to exclude from the session.</summary>
    public IList<string>? ExcludedTools { get; set; }

    /// <summary>
    /// Built-in subagent names to exclude from this session.
    /// </summary>
    /// <remarks>
    /// Excluded built-ins are hidden from agent discovery and cannot be dispatched unless a
    /// custom agent with the same name is available.
    /// </remarks>
    [JsonPropertyName("excludedBuiltinAgents")]
    public IList<string>? ExcludedBuiltInAgents { get; set; }

    /// <summary>Custom model provider configuration for the session.</summary>
    public ProviderConfig? Provider { get; set; }

    /// <summary>
    /// CAPI (Copilot API) provider-scoped configuration for the session.
    /// </summary>
    public CapiSessionOptions? Capi { get; set; }

    /// <summary>
    /// Named BYOK provider connections (transport + credentials). Additive to Copilot
    /// API authentication (unlike <see cref="Provider"/>); combine with <see cref="Models"/>.
    /// Cannot be combined with <see cref="Provider"/>.
    /// </summary>
    [Experimental(Diagnostics.Experimental)]
    public IList<NamedProviderConfig>? Providers { get; set; }

    /// <summary>
    /// BYOK model definitions added to the session's selectable model list, each
    /// referencing a <see cref="Providers"/> entry by name.
    /// </summary>
    [Experimental(Diagnostics.Experimental)]
    public IList<ProviderModelConfig>? Models { get; set; }

    /// <summary>
    /// Enables or disables internal session telemetry for this session.
    /// When <c>false</c>, disables session telemetry. When <c>null</c> (the default) or <c>true</c>,
    /// telemetry is enabled for GitHub-authenticated sessions.
    /// When a custom <see cref="Provider"/> (BYOK) is configured, session telemetry is
    /// always disabled regardless of this setting.
    /// This is independent of <see cref="CopilotClientOptions.Telemetry"/>, which configures
    /// OpenTelemetry export for observability.
    /// </summary>
    public bool? EnableSessionTelemetry { get; set; }

    /// <summary>
    /// Controls whether the session enables experimental features.
    /// </summary>
    /// <remarks>
    /// Defaults to <see langword="false"/> in <see cref="CopilotClientMode.Empty"/>.
    /// Otherwise, the runtime decides when left <see langword="null"/>.
    /// </remarks>
    public bool? EnableExperimentalMode { get; set; }

    /// <summary>
    /// When <see langword="true"/>, suppresses loading of custom instruction files
    /// (e.g. <c>.github/copilot-instructions.md</c>, <c>AGENTS.md</c>) from the working directory.
    /// When <see langword="null"/>, the SDK chooses based on
    /// <see cref="CopilotClientOptions.Mode"/>: <c>true</c> under
    /// <see cref="CopilotClientMode.Empty"/> (instructions are not loaded
    /// unless the app explicitly opts in), <c>null</c> otherwise.
    /// </summary>
    public bool? SkipCustomInstructions { get; set; }

    /// <summary>
    /// When <see langword="true"/>, custom-agent discovery is restricted to the
    /// session's local working directory (no organisation-level discovery).
    /// When <see langword="null"/>, the SDK chooses based on
    /// <see cref="CopilotClientOptions.Mode"/>: <c>true</c> under
    /// <see cref="CopilotClientMode.Empty"/>, <c>null</c> otherwise.
    /// </summary>
    public bool? CustomAgentsLocalOnly { get; set; }

    /// <summary>
    /// When <see langword="true"/>, allows the runtime to append a
    /// <c>Co-authored-by</c> trailer when it commits on behalf of the user.
    /// When <see langword="null"/>, the SDK chooses based on
    /// <see cref="CopilotClientOptions.Mode"/>: <c>false</c> under
    /// <see cref="CopilotClientMode.Empty"/>, <c>null</c> otherwise.
    /// </summary>
    public bool? CoauthorEnabled { get; set; }

    /// <summary>
    /// When <see langword="true"/>, enables the <c>manage_schedule</c> tool
    /// (host scheduler integration). When <see langword="null"/>, the SDK
    /// chooses based on <see cref="CopilotClientOptions.Mode"/>: <c>false</c>
    /// under <see cref="CopilotClientMode.Empty"/>, <c>null</c> otherwise.
    /// </summary>
    public bool? ManageScheduleEnabled { get; set; }

    /// <summary>Handler for permission requests from the server.</summary>
    public Func<PermissionRequest, PermissionInvocation, Task<PermissionDecision>>? OnPermissionRequest { get; set; }

    /// <summary>
    /// Handler for user input requests from the agent. When provided with the default
    /// <see cref="GitHub.Copilot.AskUserVariant.Legacy"/> variant, enables the
    /// question-and-answer form of the <c>ask_user</c> tool.
    /// </summary>
    public Func<UserInputRequest, UserInputInvocation, Task<UserInputResponse>>? OnUserInputRequest { get; set; }

    /// <summary>Slash commands registered for this session.</summary>
    public IList<CommandDefinition>? Commands { get; set; }

    /// <summary>Handler for elicitation requests from the server or MCP tools.</summary>
    public Func<ElicitationContext, Task<ElicitationResult>>? OnElicitationRequest { get; set; }

    /// <summary>Handler for exit-plan-mode requests from the server.</summary>
    public Func<ExitPlanModeRequest, ExitPlanModeInvocation, Task<ExitPlanModeResult>>? OnExitPlanModeRequest { get; set; }

    /// <summary>Handler for auto-mode-switch requests from the server.</summary>
    public Func<AutoModeSwitchRequest, AutoModeSwitchInvocation, Task<AutoModeSwitchResponse>>? OnAutoModeSwitchRequest { get; set; }

    /// <summary>
    /// Enable MCP Apps (SEP-1865) UI passthrough on this session.
    /// <para>
    /// When <c>true</c> <b>and</b> the runtime has MCP Apps enabled (via the
    /// <c>MCP_APPS</c> feature flag or <c>COPILOT_MCP_APPS=true</c> environment override), the
    /// runtime adds the <c>mcp-apps</c> capability to the session, which causes it to advertise
    /// the <c>extensions.io.modelcontextprotocol/ui</c> extension to MCP servers (so they expose
    /// <c>_meta.ui.resourceUri</c> on tools) and to expose the
    /// <c>session.rpc.mcp.apps.{listTools,callTool,readResource,setHostContext,getHostContext,diagnose}</c>
    /// JSON-RPC methods.
    /// </para>
    /// <para>
    /// If the runtime gate is off, the opt-in is silently dropped server-side (the runtime logs a
    /// warning); the session is created normally but the MCP Apps surface is unavailable. Inspect
    /// the runtime's <c>capabilities.ui.mcpApps</c> on the create/resume response to detect this.
    /// </para>
    /// <para>
    /// SDK consumers MUST set this to <c>true</c> only when they have an iframe renderer that can
    /// display <c>ui://</c> MCP App bundles. Setting it without a renderer will cause MCP servers
    /// to register UI-enabled tool variants the consumer cannot display.
    /// </para>
    /// </summary>
    [Experimental(Diagnostics.Experimental)]
    public bool EnableMcpApps { get; set; }

    /// <summary>
    /// Configuration for the built-in GitHub MCP server.
    /// <c>DisableFormDeferral</c> only applies to that server and only has an
    /// effect when MCP Apps and form-backed GitHub tools are enabled.
    /// </summary>
    public GitHubMcpToolConfig? GitHubMcpToolConfig { get; set; }

    /// <summary>Hook handlers for session lifecycle events.</summary>
    public SessionHooks? Hooks { get; set; }

    /// <summary>Working directory for the session.</summary>
    public string? WorkingDirectory { get; set; }

    /// <summary>
    /// Additional directories the agent may access beyond <see cref="WorkingDirectory"/>.
    /// Relative paths resolve against the session working directory. Re-supply them when resuming.
    /// </summary>
    public IList<string>? AdditionalDirectories { get; set; }

    /// <summary>
    /// Enable streaming of assistant message and reasoning chunks.
    /// When true, assistant.message_delta and assistant.reasoning_delta events
    /// with deltaContent are sent as the response is generated.
    /// </summary>
    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
    public bool? Streaming { get; set; }

    /// <summary>
    /// Include sub-agent streaming events in the event stream. When true, streaming
    /// delta events from sub-agents (e.g., <c>assistant.message_delta</c>,
    /// <c>assistant.reasoning_delta</c>, <c>assistant.streaming_delta</c> with
    /// <c>agentId</c> set) are forwarded to this connection. When false, only
    /// non-streaming sub-agent events and <c>subagent.*</c> lifecycle events are
    /// forwarded; streaming deltas from sub-agents are suppressed.
    /// Default: true.
    /// </summary>
    public bool IncludeSubAgentStreamingEvents { get; set; } = true;

    /// <summary>
    /// MCP server configurations for the session.
    /// Keys are server names, values are server configurations (<see cref="McpStdioServerConfig"/> or <see cref="McpHttpServerConfig"/>).
    /// </summary>
    public IDictionary<string, McpServerConfig>? McpServers { get; set; }

    /// <summary>
    /// Controls how MCP OAuth tokens are stored for this session.
    /// Default: <see cref="McpOAuthTokenStorageMode.InMemory"/> for safe multitenant behavior.
    /// </summary>
    public McpOAuthTokenStorageMode? McpOAuthTokenStorage { get; set; }

    /// <summary>
    /// OAuth Client ID Metadata Document URL identifying the host for MCP authorization.
    /// When unset, no host identity is supplied.
    /// </summary>
    public string? AuthClientIdMetadataUrl { get; set; }

    /// <summary>Custom agent configurations for the session.</summary>
    public IList<CustomAgentConfig>? CustomAgents { get; set; }

    /// <summary>
    /// Configuration for the default agent (the built-in agent that handles turns when no custom agent is selected).
    /// Use <see cref="DefaultAgentConfig.ExcludedTools"/> to hide specific tools from the default agent
    /// while keeping them available to custom sub-agents.
    /// </summary>
    public DefaultAgentConfig? DefaultAgent { get; set; }

    /// <summary>
    /// Name of the custom agent to activate when the session starts.
    /// Must match the <see cref="CustomAgentConfig.Name"/> of one of the agents in <see cref="CustomAgents"/>.
    /// </summary>
    public string? Agent { get; set; }

    /// <summary>Directories to load skills from.</summary>
    public IList<string>? SkillDirectories { get; set; }

    /// <summary>
    /// Local filesystem paths to Open Plugins-format directories
    /// (https://open-plugins.com/) to load for this session.
    /// </summary>
    /// <remarks>
    /// Relative paths resolve against <see cref="WorkingDirectory"/> (or the
    /// runtime cwd if unset). Treated as an explicit opt-in: plugin agents
    /// and rules load even when <see cref="EnableConfigDiscovery"/> is false.
    /// </remarks>
    public IList<string>? PluginDirectories { get; set; }

    /// <summary>Additional directories to search for custom instruction files.</summary>
    public IList<string>? InstructionDirectories { get; set; }

    /// <summary>List of skill names to disable.</summary>
    public IList<string>? DisabledSkills { get; set; }

    /// <summary>
    /// Exact MCP server names to disable for this session. Disabled servers are not
    /// started or authenticated on create or cold resume; a resident resume cannot
    /// stop servers that are already running.
    /// </summary>
    public IList<string>? DisabledMcpServers { get; set; }

    /// <summary>
    /// Infinite session configuration for persistent workspaces and automatic compaction.
    /// When enabled (default), sessions automatically manage context limits and persist state.
    /// </summary>
    public InfiniteSessionConfig? InfiniteSessions { get; set; }

    /// <summary>
    /// Optional limits for the session's current accounting window.
    /// </summary>
    /// <remarks>
    /// These settings only model the caller's configured limits. Enforcement and
    /// limit-exhaustion behavior are handled by the runtime.
    /// </remarks>
    [Experimental(Diagnostics.Experimental)]
    public SessionLimitsConfig? SessionLimits { get; set; }

    /// <summary>
    /// Configuration for handling large tool outputs. When a tool produces
    /// output exceeding the configured size, the output is written to a temp
    /// file and a reference is returned to the model instead of the full
    /// payload.
    /// </summary>
    public LargeToolOutputConfig? LargeOutput { get; set; }

    /// <summary>
    /// Overrides the runtime's built-in tool-search behavior.
    /// Tool search defers tools to keep the model's active tool set small. When <see langword="null"/>,
    /// the runtime default applies.
    /// </summary>
    public ToolSearchConfig? ToolSearch { get; set; }

    /// <summary>
    /// Configuration for session memory. When set, controls whether the
    /// session can read and write persistent memory.
    /// </summary>
    public MemoryConfiguration? Memory { get; set; }

    /// <summary>
    /// Optional event handler registered on the session before the session.create / session.resume
    /// RPC is issued, ensuring early events are delivered.
    /// </summary>
    public Action<SessionEvent>? OnEvent { get; set; }

    /// <summary>
    /// Supplies a handler for session filesystem operations.
    /// This is used only when <see cref="CopilotClientOptions.SessionFs"/> is configured.
    /// </summary>
    public Func<CopilotSession, SessionFsProvider>? CreateSessionFsProvider { get; set; }

    /// <summary>
    /// GitHub token for per-session authentication.
    /// When provided, the runtime resolves this token into a full GitHub identity
    /// and stores it on the session for content exclusion, model routing, and quota checks.
    /// </summary>
    public string? GitHubToken { get; set; }

    /// <summary>
    /// Gets or sets a callback that acquires session-scoped GitHub tokens on
    /// demand. Initial cancellation, callback errors, and invalid token responses
    /// reject session creation or resume instead of falling back to ambient
    /// authentication. This cannot be combined with <see cref="GitHubToken"/>.
    /// </summary>
    [Experimental(Diagnostics.Experimental)]
    [JsonIgnore]
    public Func<GitHubTokenProviderArgs, Task<GitHubTokenProviderResult>>? GitHubTokenProvider { get; set; }

    /// <summary>
    /// Per-session remote behavior control:
    /// <list type="bullet">
    /// <item><description><c>"off"</c> — local only, no remote export (default)</description></item>
    /// <item><description><c>"export"</c> — export session events to GitHub without enabling remote steering</description></item>
    /// <item><description><c>"on"</c> — export to GitHub AND enable remote steering</description></item>
    /// </list>
    /// </summary>
    public RemoteSessionMode? RemoteSession { get; set; }

    /// <summary>
    /// ExP assignment ("flight") data injected by a trusted integrator, in the
    /// same JSON shape the Copilot CLI fetches from the experimentation service
    /// (<c>CopilotExpAssignmentResponse</c>). When provided, the runtime feeds it
    /// into the same feature-flag path as CLI-fetched assignments and stamps it
    /// onto telemetry and the CAPI request header. When unset, the session does
    /// not block on ExP. Intended for out-of-process integrators that fetch ExP
    /// data themselves; malformed payloads are dropped by the runtime (fail-open).
    /// Serialized on the wire as <c>expAssignments</c>.
    /// </summary>
    /// <remarks>
    /// This is an internal/trusted-integrator option and is hidden from editor
    /// completion. It is not part of the broadly advertised public surface.
    /// </remarks>
    [EditorBrowsable(EditorBrowsableState.Never)]
    public CopilotExpAssignmentResponse? ExpAssignments { get; set; }

    /// <summary>
    /// Feature-flag values resolved by the host for this session.
    /// Re-supply them when resuming after a runtime restart.
    /// </summary>
    public IDictionary<string, bool>? FeatureFlags { get; set; }

    /// <summary>
    /// Opt-in: when <c>true</c>, the runtime self-fetches enterprise managed
    /// settings (bypass-permissions policy) at session bootstrap using the
    /// session's <see cref="GitHubToken"/>. Requires <see cref="GitHubToken"/> to
    /// be set; if omitted, the runtime is expected to reject session creation
    /// (fail-closed). When unset, behaves exactly as before. Serialized on the
    /// wire as <c>enableManagedSettings</c>.
    /// </summary>
    public bool? EnableManagedSettings { get; set; }

    /// <summary>
    /// Optional managed-settings layer injected at session bootstrap. Currently
    /// carries a permissions object that composes restrictively with any
    /// server- or device-level managed settings. This layer is startup-only and
    /// is not persisted: it must be re-supplied on resume to remain in effect,
    /// and omitting it on resume clears the previously injected layer. Can be
    /// combined with <see cref="EnableManagedSettings"/>. Serialized on the wire
    /// as <c>managedSettings</c>.
    /// </summary>
    public ManagedSettings? ManagedSettings { get; set; }

#pragma warning disable GHCP001
    /// <summary>
    /// Canvas declarations advertised by this connection. The runtime forwards
    /// these to the agent and routes inbound <c>canvas.*</c> requests for any
    /// declared canvas to <see cref="CanvasHandler"/>.
    /// </summary>
    [Experimental(Diagnostics.Experimental)]
    public IList<CanvasDeclaration>? Canvases { get; set; }

    /// <summary>
    /// When <see langword="true"/>, asks the host to expose canvas renderer tools
    /// for this session. The host typically grants this only to trusted clients.
    /// </summary>
    [Experimental(Diagnostics.Experimental)]
    public bool? RequestCanvasRenderer { get; set; }

    /// <summary>
    /// When <see langword="true"/>, asks the host to expose extension-discovery
    /// tools for this session. The host typically grants this only to trusted clients.
    /// </summary>
    [Experimental(Diagnostics.Experimental)]
    public bool? RequestExtensions { get; set; }

    /// <summary>
    /// Optional override path to a <c>copilot-sdk/</c> folder to inject into
    /// extension subprocesses for this session in place of the bundled SDK.
    /// When unset or invalid (missing folder, or missing <c>index.js</c> /
    /// <c>extension.js</c>), the runtime falls back to the bundled SDK
    /// without throwing. Takes precedence over any server-level default.
    /// </summary>
    [Experimental(Diagnostics.Experimental)]
    public string? ExtensionSdkPath { get; set; }

    /// <summary>
    /// Stable extension identity for canvas/tool providers on this connection.
    /// Required when <see cref="Canvases"/> is set so the runtime can attribute
    /// declared canvases back to this provider.
    /// </summary>
    [Experimental(Diagnostics.Experimental)]
    public ExtensionInfo? ExtensionInfo { get; set; }

    /// <summary>
    /// Stable identity for a host/SDK connection that supplies built-in
    /// canvases. When set, the runtime uses <see cref="CanvasProviderIdentity.Id"/>
    /// verbatim as the agent-facing canvas extension id, so canvases declared on
    /// a control connection survive reconnect and CLI restart. Honored on
    /// session create and resume.
    /// </summary>
    [Experimental(Diagnostics.Experimental)]
    public CanvasProviderIdentity? CanvasProvider { get; set; }

    /// <summary>
    /// Provider-side canvas lifecycle handler. The SDK routes inbound
    /// <c>canvas.open</c> / <c>canvas.close</c> / <c>canvas.action.invoke</c>
    /// requests to this handler.
    /// </summary>
    [Experimental(Diagnostics.Experimental)]
    [JsonIgnore]
    public ICanvasHandler? CanvasHandler { get; set; }
#pragma warning restore GHCP001

    /// <summary>
    /// Optional handler for MCP OAuth requests from MCP servers.
    /// When provided, the SDK can satisfy MCP server OAuth requests with host-provided token data or cancellation.
    /// </summary>
    [Experimental(Diagnostics.Experimental)]
    [JsonIgnore]
    public Func<McpAuthContext, Task<McpAuthResult?>>? OnMcpAuthRequest { get; set; }
}

/// <summary>
/// Configuration options for creating a new Copilot session.
/// </summary>
public sealed class SessionConfig : SessionConfigBase
{
    /// <summary>Initializes a new instance of the <see cref="SessionConfig"/> class.</summary>
    public SessionConfig() { }

    /// <summary>
    /// Initializes a new instance of <see cref="SessionConfig"/> by copying the
    /// properties of the specified instance.
    /// </summary>
    private SessionConfig(SessionConfig? other) : base(other)
    {
        if (other is null) return;

        SessionId = other.SessionId;
        Cloud = other.Cloud;
    }

    /// <summary>Optional session identifier; a new ID is generated if not provided.</summary>
    public string? SessionId { get; set; }

    /// <summary>
    /// Creates a remote session in the cloud instead of a local session.
    /// The optional repository is associated with the cloud session.
    /// </summary>
    public CloudSessionOptions? Cloud { get; set; }

    /// <summary>
    /// Creates a shallow clone of this <see cref="SessionConfig"/> instance.
    /// </summary>
    /// <remarks>
    /// Mutable collection properties are copied into new collection instances so that modifications
    /// to those collections on the clone do not affect the original.
    /// Other reference-type properties (for example provider configuration, system messages,
    /// hooks, infinite session configuration, and delegates) are not deep-cloned; the original
    /// and the clone will share those nested objects, and changes to them may affect both.
    /// </remarks>
    public SessionConfig Clone() => new(this);
}

/// <summary>
/// Configuration options for resuming an existing Copilot session.
/// </summary>
public sealed class ResumeSessionConfig : SessionConfigBase
{
    /// <summary>Initializes a new instance of the <see cref="ResumeSessionConfig"/> class.</summary>
    public ResumeSessionConfig() { }

    /// <summary>
    /// Initializes a new instance of <see cref="ResumeSessionConfig"/> by copying the
    /// properties of the specified instance.
    /// </summary>
    private ResumeSessionConfig(ResumeSessionConfig? other) : base(other)
    {
        if (other is null) return;

        SuppressResumeEvent = other.SuppressResumeEvent;
        ContinuePendingWork = other.ContinuePendingWork;
        OpenCanvases = other.OpenCanvases is not null ? [.. other.OpenCanvases] : null;
    }

    /// <summary>
    /// When true, the session.resume event is not emitted.
    /// Default: false (resume event is emitted).
    /// </summary>
    public bool SuppressResumeEvent { get; set; }

    /// <summary>
    /// When <see langword="true"/>, instructs the runtime to continue any tool calls
    /// or permission prompts that were still pending when the session was last suspended.
    /// When <see langword="false"/> (the default), the runtime treats pending work as
    /// interrupted on resume.
    /// <para>
    /// For permission requests, the runtime re-emits <c>permission.requested</c> so the
    /// registered <see cref="SessionConfigBase.OnPermissionRequest"/> handler can re-prompt;
    /// for external tool calls, the consumer is expected to supply the result via the
    /// corresponding low-level RPC method.
    /// </para>
    /// </summary>
    public bool? ContinuePendingWork { get; set; }

#pragma warning disable GHCP001
    /// <summary>
    /// Snapshot of canvases that were already open when the session was suspended.
    /// When provided on resume, the runtime can rehydrate canvas state so consumers
    /// do not need to re-open canvases that were active before the previous shutdown.
    /// </summary>
    [Experimental(Diagnostics.Experimental)]
    public IList<OpenCanvasInstance>? OpenCanvases { get; set; }
#pragma warning restore GHCP001

    /// <summary>
    /// Creates a shallow clone of this <see cref="ResumeSessionConfig"/> instance.
    /// </summary>
    /// <remarks>
    /// Mutable collection properties are copied into new collection instances so that modifications
    /// to those collections on the clone do not affect the original.
    /// Other reference-type properties (for example provider configuration, system messages,
    /// hooks, infinite session configuration, and delegates) are not deep-cloned; the original
    /// and the clone will share those nested objects, and changes to them may affect both.
    /// </remarks>
    public ResumeSessionConfig Clone() => new(this);
}

/// <summary>
/// Options for sending a message in a Copilot session.
/// </summary>
public sealed class MessageOptions
{
    /// <summary>
    /// Initializes a new instance of the <see cref="MessageOptions"/> class.
    /// </summary>
    public MessageOptions() { }

    /// <summary>
    /// Initializes a new instance of the <see cref="MessageOptions"/> class
    /// by copying the properties of the specified instance.
    /// </summary>
    private MessageOptions(MessageOptions? other)
    {
        if (other is null) return;

        Attachments = other.Attachments is not null ? [.. other.Attachments] : null;
        Mode = other.Mode;
        AgentMode = other.AgentMode;
        Source = other.Source;
        Prompt = other.Prompt;
        DisplayPrompt = other.DisplayPrompt;
        RequestHeaders = other.RequestHeaders is not null
            ? new Dictionary<string, string>(other.RequestHeaders)
            : null;
    }

    /// <summary>
    /// The prompt text to send to the assistant.
    /// </summary>
    public string Prompt { get; set; } = string.Empty;
    /// <summary>
    /// File or data attachments to include with the message.
    /// </summary>
    public IList<Attachment>? Attachments { get; set; }
    /// <summary>
    /// How to deliver the message. <c>"enqueue"</c> (default) appends to the message queue;
    /// <c>"immediate"</c> interjects during an in-progress turn.
    /// </summary>
    public string? Mode { get; set; }
    /// <summary>
    /// The UI mode the agent was in when this message was sent (for example "plan", "autopilot").
    /// Defaults to the session's current mode when unset.
    /// </summary>
    public AgentMode? AgentMode { get; set; }
    /// <summary>
    /// The message's origin. When unset, the field is omitted and the runtime defaults to user input.
    /// This tags message provenance; it does not replace the session's system prompt or change delivery mode.
    /// </summary>
    public MessageSource? Source { get; set; }
    /// <summary>
    /// Custom per-turn HTTP headers for outbound model requests.
    /// </summary>
    public IDictionary<string, string>? RequestHeaders { get; set; }
    /// <summary>
    /// If provided, this is shown in the timeline instead of <see cref="Prompt"/>.
    /// </summary>
    public string? DisplayPrompt { get; set; }

    /// <summary>
    /// Creates a shallow clone of this <see cref="MessageOptions"/> instance.
    /// </summary>
    /// <remarks>
    /// Mutable collection properties are copied into new collection instances so that modifications
    /// to those collections on the clone do not affect the original.
    /// Other reference-type properties (for example attachment items) are not deep-cloned;
    /// the original and the clone will share those nested objects.
    /// </remarks>
    public MessageOptions Clone()
    {
        return new(this);
    }
}

/// <summary>
/// Working directory context for a session.
/// </summary>
public sealed class SessionContext
{
    /// <summary>Working directory where the session was created.</summary>
    [JsonPropertyName("cwd")]
    public string WorkingDirectory { get; set; } = string.Empty;
    /// <summary>Git repository root (if in a git repo).</summary>
    public string? GitRoot { get; set; }
    /// <summary>GitHub repository in "owner/repo" format.</summary>
    public string? Repository { get; set; }
    /// <summary>Current git branch.</summary>
    public string? Branch { get; set; }
}

/// <summary>
/// Filter options for listing sessions.
/// </summary>
public sealed class SessionListFilter
{
    /// <summary>Filter by exact working directory match.</summary>
    public string? WorkingDirectory { get; set; }
    /// <summary>Filter by git root.</summary>
    public string? GitRoot { get; set; }
    /// <summary>Filter by repository (owner/repo format).</summary>
    public string? Repository { get; set; }
    /// <summary>Filter by branch.</summary>
    public string? Branch { get; set; }
}

/// <summary>
/// Metadata describing a Copilot session.
/// </summary>
public sealed class SessionMetadata
{
    /// <summary>
    /// Unique identifier of the session.
    /// </summary>
    public string SessionId { get; set; } = string.Empty;
    /// <summary>
    /// Time when the session was created.
    /// </summary>
    public DateTimeOffset StartTime { get; set; }
    /// <summary>
    /// Time when the session was last modified.
    /// </summary>
    public DateTimeOffset ModifiedTime { get; set; }
    /// <summary>
    /// Human-readable summary of the session.
    /// </summary>
    public string? Summary { get; set; }
    /// <summary>
    /// Whether the session is running on a remote server.
    /// </summary>
    public bool IsRemote { get; set; }
    /// <summary>Working directory context (cwd, git info) from session creation.</summary>
    public SessionContext? Context { get; set; }
}

internal class PingRequest
{
    public string? Message { get; set; }
}

/// <summary>
/// Response from a server ping request.
/// </summary>
public sealed class PingResponse
{
    /// <summary>
    /// Echo of the ping message.
    /// </summary>
    public string Message { get; set; } = string.Empty;
    /// <summary>
    /// ISO 8601 timestamp when the ping was processed.
    /// </summary>
    public DateTimeOffset Timestamp { get; set; }
    /// <summary>
    /// Protocol version supported by the server.
    /// </summary>
    public int? ProtocolVersion { get; set; }
}

/// <summary>
/// Response from status.get
/// </summary>
public sealed class GetStatusResponse
{
    /// <summary>Package version (e.g., "1.0.0")</summary>
    [JsonPropertyName("version")]
    public string Version { get; set; } = string.Empty;

    /// <summary>Protocol version for SDK compatibility</summary>
    [JsonPropertyName("protocolVersion")]
    public int ProtocolVersion { get; set; }
}

/// <summary>
/// Response from auth.getStatus
/// </summary>
public sealed class GetAuthStatusResponse
{
    /// <summary>Whether the user is authenticated</summary>
    [JsonPropertyName("isAuthenticated")]
    public bool IsAuthenticated { get; set; }

    /// <summary>
    /// Authentication type.
    /// <list type="bullet">
    /// <item><description><c>"user"</c> — authenticated via user login.</description></item>
    /// <item><description><c>"env"</c> — authenticated via environment variable.</description></item>
    /// <item><description><c>"gh-cli"</c> — authenticated via the GitHub CLI.</description></item>
    /// <item><description><c>"hmac"</c> — authenticated via HMAC signature.</description></item>
    /// <item><description><c>"api-key"</c> — authenticated via API key.</description></item>
    /// <item><description><c>"token"</c> — authenticated via explicit token.</description></item>
    /// </list>
    /// </summary>
    [JsonPropertyName("authType")]
    public string? AuthType { get; set; }

    /// <summary>GitHub host URL</summary>
    [JsonPropertyName("host")]
    public string? Host { get; set; }

    /// <summary>User login name</summary>
    [JsonPropertyName("login")]
    public string? Login { get; set; }

    /// <summary>Human-readable status message</summary>
    [JsonPropertyName("statusMessage")]
    public string? StatusMessage { get; set; }
}

/// <summary>
/// Model vision-specific limits
/// </summary>
public sealed class ModelVisionLimits
{
    /// <summary>
    /// List of supported image MIME types (e.g., "image/png", "image/jpeg").
    /// </summary>
    [JsonPropertyName("supported_media_types")]
    public IList<string> SupportedMediaTypes { get => field ??= []; set; }

    /// <summary>
    /// Maximum number of images allowed in a single prompt.
    /// </summary>
    [JsonPropertyName("max_prompt_images")]
    public int MaxPromptImages { get; set; }

    /// <summary>
    /// Maximum size in bytes for a single prompt image.
    /// </summary>
    [JsonPropertyName("max_prompt_image_size")]
    public int MaxPromptImageSize { get; set; }
}

/// <summary>
/// Model limits
/// </summary>
public sealed class ModelLimits
{
    /// <summary>
    /// Maximum number of tokens allowed in the prompt.
    /// </summary>
    [JsonPropertyName("max_prompt_tokens")]
    public int? MaxPromptTokens { get; set; }

    /// <summary>
    /// Maximum total tokens in the context window.
    /// </summary>
    [JsonPropertyName("max_context_window_tokens")]
    public int MaxContextWindowTokens { get; set; }

    /// <summary>
    /// Vision-specific limits for the model.
    /// </summary>
    [JsonPropertyName("vision")]
    public ModelVisionLimits? Vision { get; set; }
}

/// <summary>
/// Model support flags
/// </summary>
public sealed class ModelSupports
{
    /// <summary>
    /// Whether this model supports image/vision inputs.
    /// </summary>
    [JsonPropertyName("vision")]
    public bool Vision { get; set; }

    /// <summary>
    /// Whether this model supports reasoning effort configuration.
    /// </summary>
    [JsonPropertyName("reasoningEffort")]
    public bool ReasoningEffort { get; set; }
}

/// <summary>
/// Model capabilities and limits
/// </summary>
public sealed class ModelCapabilities
{
    /// <summary>
    /// Feature support flags for the model.
    /// </summary>
    [JsonPropertyName("supports")]
    public ModelSupports Supports { get; set; } = new();

    /// <summary>
    /// Token and resource limits for the model.
    /// </summary>
    [JsonPropertyName("limits")]
    public ModelLimits Limits { get; set; } = new();
}

/// <summary>
/// Model policy state
/// </summary>
public sealed class ModelPolicy
{
    /// <summary>
    /// Policy state of the model (e.g., "enabled", "disabled").
    /// </summary>
    [JsonPropertyName("state")]
    public string State { get; set; } = string.Empty;

    /// <summary>
    /// Terms or conditions associated with using the model.
    /// </summary>
    [JsonPropertyName("terms")]
    public string Terms { get; set; } = string.Empty;
}

/// <summary>
/// Model billing information
/// </summary>
public sealed class ModelBilling
{
    /// <summary>
    /// Billing cost multiplier relative to the base model rate.
    /// </summary>
    [JsonPropertyName("multiplier")]
    public double? Multiplier { get; set; }

    /// <summary>
    /// Token-level pricing information for this model.
    /// </summary>
    [JsonPropertyName("tokenPrices")]
    public ModelBillingTokenPrices? TokenPrices { get; set; }
}

/// <summary>
/// Information about an available model
/// </summary>
public sealed class ModelInfo
{
    /// <summary>Model identifier (e.g., "claude-sonnet-4.5")</summary>
    [JsonPropertyName("id")]
    public string Id { get; set; } = string.Empty;

    /// <summary>Display name</summary>
    [JsonPropertyName("name")]
    public string Name { get; set; } = string.Empty;

    /// <summary>Model capabilities and limits</summary>
    [JsonPropertyName("capabilities")]
    public ModelCapabilities Capabilities { get; set; } = new();

    /// <summary>Policy state</summary>
    [JsonPropertyName("policy")]
    public ModelPolicy? Policy { get; set; }

    /// <summary>Billing information</summary>
    [JsonPropertyName("billing")]
    public ModelBilling? Billing { get; set; }

    /// <summary>Supported reasoning effort levels (only present if model supports reasoning effort)</summary>
    [JsonPropertyName("supportedReasoningEfforts")]
    public IList<string>? SupportedReasoningEfforts { get; set; }

    /// <summary>Default reasoning effort level (only present if model supports reasoning effort)</summary>
    [JsonPropertyName("defaultReasoningEffort")]
    public string? DefaultReasoningEffort { get; set; }
}

/// <summary>
/// Response from models.list
/// </summary>
public sealed class GetModelsResponse
{
    /// <summary>
    /// List of available models.
    /// </summary>
    [JsonPropertyName("models")]
    public IList<ModelInfo> Models { get => field ??= []; set; }
}

// ============================================================================
// Session Lifecycle Types (for TUI+server mode)
// ============================================================================

/// <summary>
/// Metadata for session lifecycle events.
/// </summary>
public sealed class SessionLifecycleEventMetadata
{
    /// <summary>
    /// Timestamp when the session was created.
    /// </summary>
    [JsonPropertyName("startTime")]
    public DateTimeOffset StartTime { get; set; }

    /// <summary>
    /// Timestamp when the session was last modified.
    /// </summary>
    [JsonPropertyName("modifiedTime")]
    public DateTimeOffset ModifiedTime { get; set; }

    /// <summary>
    /// Human-readable summary of the session.
    /// </summary>
    [JsonPropertyName("summary")]
    public string? Summary { get; set; }
}

/// <summary>
/// Session lifecycle event notification. Use derived types
/// (<see cref="SessionCreatedEvent"/>, <see cref="SessionDeletedEvent"/>,
/// <see cref="SessionUpdatedEvent"/>, <see cref="SessionForegroundEvent"/>,
/// <see cref="SessionBackgroundEvent"/>) for known kinds. The base type is
/// instantiated when the runtime emits an event kind not known to this SDK
/// version, so consumers can still inspect <see cref="Type"/> for forward
/// compatibility.
/// </summary>
public class SessionLifecycleEvent
{
    /// <summary>
    /// Wire-format type discriminator (e.g., <c>"session.created"</c>). Useful
    /// when the runtime emits an event kind not yet known to this SDK; for
    /// known kinds, prefer pattern-matching on the derived type instead.
    /// </summary>
    [JsonPropertyName("type")]
    public string Type { get; set; } = string.Empty;

    /// <summary>
    /// Identifier of the session this event pertains to.
    /// </summary>
    [JsonPropertyName("sessionId")]
    public string SessionId { get; set; } = string.Empty;

    /// <summary>
    /// Metadata associated with the session lifecycle event.
    /// </summary>
    [JsonPropertyName("metadata")]
    public SessionLifecycleEventMetadata? Metadata { get; set; }
}

/// <summary>Raised when a new session is created.</summary>
public sealed class SessionCreatedEvent : SessionLifecycleEvent { }

/// <summary>Raised when a session is deleted.</summary>
public sealed class SessionDeletedEvent : SessionLifecycleEvent { }

/// <summary>Raised when a session's metadata is updated.</summary>
public sealed class SessionUpdatedEvent : SessionLifecycleEvent { }

/// <summary>Raised when a session is brought to the foreground (TUI+server mode).</summary>
public sealed class SessionForegroundEvent : SessionLifecycleEvent { }

/// <summary>Raised when a session moves to the background (TUI+server mode).</summary>
public sealed class SessionBackgroundEvent : SessionLifecycleEvent { }

/// <summary>
/// Response from session.getForeground
/// </summary>
public sealed class GetForegroundSessionResponse
{
    /// <summary>
    /// Identifier of the current foreground session, or null if none.
    /// </summary>
    [JsonPropertyName("sessionId")]
    public string? SessionId { get; set; }

    /// <summary>
    /// Workspace path associated with the foreground session.
    /// </summary>
    [JsonPropertyName("workspacePath")]
    public string? WorkspacePath { get; set; }
}

/// <summary>
/// Response from session.setForeground
/// </summary>
public sealed class SetForegroundSessionResponse
{
    /// <summary>
    /// Whether the foreground session was set successfully.
    /// </summary>
    [JsonPropertyName("success")]
    public bool Success { get; set; }

    /// <summary>
    /// Error message if the operation failed.
    /// </summary>
    [JsonPropertyName("error")]
    public string? Error { get; set; }
}

/// <summary>
/// Content data for a single system message section in a transform RPC call.
/// </summary>
public sealed class SystemMessageTransformSection
{
    /// <summary>
    /// The content of the section.
    /// </summary>
    [JsonPropertyName("content")]
    public string? Content { get; set; }
}

/// <summary>
/// Response to a systemMessage.transform RPC call.
/// </summary>
public sealed class SystemMessageTransformRpcResponse
{
    /// <summary>
    /// The transformed sections keyed by section identifier.
    /// </summary>
    [JsonPropertyName("sections")]
    public IDictionary<string, SystemMessageTransformSection>? Sections { get; set; }
}

[JsonSourceGenerationOptions(
    JsonSerializerDefaults.Web,
    AllowOutOfOrderMetadataProperties = true,
    NumberHandling = JsonNumberHandling.AllowReadingFromString,
    DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull)]
[JsonSerializable(typeof(AzureOptions))]
[JsonSerializable(typeof(AutoModeSwitchRequest))]
[JsonSerializable(typeof(AutoModeSwitchResponse))]
[JsonSerializable(typeof(CustomAgentConfig))]
[JsonSerializable(typeof(CopilotExpAssignmentResponse))]
[JsonSerializable(typeof(ExpConfigEntry))]
[JsonSerializable(typeof(ExitPlanModeRequest))]
[JsonSerializable(typeof(ExitPlanModeResult))]
[JsonSerializable(typeof(GetAuthStatusResponse))]
[JsonSerializable(typeof(GetForegroundSessionResponse))]
[JsonSerializable(typeof(GetModelsResponse))]
[JsonSerializable(typeof(GetStatusResponse))]
[JsonSerializable(typeof(McpServerConfig))]
[JsonSerializable(typeof(MessageOptions))]
[JsonSerializable(typeof(ModelBilling))]
[JsonSerializable(typeof(GitHub.Copilot.Rpc.ModelBillingTokenPrices))]
[JsonSerializable(typeof(GitHub.Copilot.Rpc.ModelBillingTokenPricesLongContext))]
[JsonSerializable(typeof(ModelCapabilities))]
[JsonSerializable(typeof(ModelCapabilitiesOverride))]
[JsonSerializable(typeof(ModelInfo))]
[JsonSerializable(typeof(ModelLimits))]
[JsonSerializable(typeof(ModelPolicy))]
[JsonSerializable(typeof(ModelSupports))]
[JsonSerializable(typeof(ModelVisionLimits))]
[JsonSerializable(typeof(PingRequest))]
[JsonSerializable(typeof(PingResponse))]
[JsonSerializable(typeof(ProviderConfig))]
[JsonSerializable(typeof(CapiSessionOptions))]
[JsonSerializable(typeof(SessionContext))]
[JsonSerializable(typeof(SessionLifecycleEvent))]
[JsonSerializable(typeof(SessionLifecycleEventMetadata))]
[JsonSerializable(typeof(SessionListFilter))]
[JsonSerializable(typeof(SectionOverride))]
[JsonSerializable(typeof(SessionMetadata))]
[JsonSerializable(typeof(SetForegroundSessionResponse))]
[JsonSerializable(typeof(SystemMessageConfig))]
[JsonSerializable(typeof(ToolBinaryResult))]
[JsonSerializable(typeof(ToolBinaryResultType))]
[JsonSerializable(typeof(ToolInvocation))]
[JsonSerializable(typeof(ToolResultObject))]
[JsonSerializable(typeof(JsonElement))]
[JsonSerializable(typeof(JsonElement?))]
[JsonSerializable(typeof(JsonObject))]
[JsonSerializable(typeof(object))]
[JsonSerializable(typeof(Dictionary<string, object>))]
[JsonSerializable(typeof(string[]))]
#pragma warning disable GHCP001
[JsonSerializable(typeof(CanvasDeclaration))]
[JsonSerializable(typeof(CanvasProviderOpenResult))]
[JsonSerializable(typeof(CanvasHostContext))]
[JsonSerializable(typeof(ExtensionInfo))]
[JsonSerializable(typeof(CanvasProviderIdentity))]
#pragma warning restore GHCP001
internal partial class TypesJsonContext : JsonSerializerContext;