github_copilot_sdk/

types.rs

//! Protocol types shared between the SDK and the GitHub Copilot CLI.
//!
//! These types map directly to the JSON-RPC request/response payloads
//! defined by the GitHub Copilot CLI protocol. They are used for session
//! configuration, event handling, tool invocations, and model queries.

use std::collections::HashMap;
use std::path::{Path, PathBuf};
use std::sync::Arc;
use std::time::Duration;

use serde::{Deserialize, Serialize};
use serde_json::Value;

use crate::handler::SessionHandler;
use crate::hooks::SessionHooks;
pub use crate::session_fs::{
    DirEntry, DirEntryKind, FileInfo, FsError, SessionFsConfig, SessionFsConventions,
    SessionFsProvider,
};
pub use crate::trace_context::{TraceContext, TraceContextProvider};
use crate::transforms::SystemMessageTransform;

/// Lifecycle state of a [`Client`](crate::Client) connection to the CLI.
///
/// The state advances from `Connecting` → `Connected` during construction,
/// transitions to `Disconnected` after [`Client::stop`](crate::Client::stop) or
/// [`Client::force_stop`](crate::Client::force_stop), and lands in
/// `Error` if startup fails or the underlying transport tears down
/// unexpectedly.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[serde(rename_all = "lowercase")]
#[non_exhaustive]
pub enum ConnectionState {
    /// No CLI process is attached or the process has exited cleanly.
    Disconnected,
    /// The client is starting up (spawning the CLI, negotiating protocol).
    Connecting,
    /// The client is connected and ready to handle RPC traffic.
    Connected,
    /// Startup failed or the connection encountered an unrecoverable error.
    Error,
}

/// Type of [`SessionLifecycleEvent`] received via [`Client::subscribe_lifecycle`](crate::Client::subscribe_lifecycle).
///
/// Values serialize as the dotted JSON strings the CLI sends (e.g.
/// `"session.created"`).
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[non_exhaustive]
pub enum SessionLifecycleEventType {
    /// A new session was created.
    #[serde(rename = "session.created")]
    Created,
    /// A session was deleted.
    #[serde(rename = "session.deleted")]
    Deleted,
    /// A session's metadata was updated (e.g. summary regenerated).
    #[serde(rename = "session.updated")]
    Updated,
    /// A session moved into the foreground.
    #[serde(rename = "session.foreground")]
    Foreground,
    /// A session moved into the background.
    #[serde(rename = "session.background")]
    Background,
}

/// Optional metadata attached to a [`SessionLifecycleEvent`].
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct SessionLifecycleEventMetadata {
    /// ISO-8601 timestamp the session was created.
    #[serde(rename = "startTime")]
    pub start_time: String,
    /// ISO-8601 timestamp the session was last modified.
    #[serde(rename = "modifiedTime")]
    pub modified_time: String,
    /// Optional generated summary of the session conversation so far.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub summary: Option<String>,
}

/// A `session.lifecycle` notification dispatched to subscribers obtained via
/// [`Client::subscribe_lifecycle`](crate::Client::subscribe_lifecycle).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct SessionLifecycleEvent {
    /// The kind of lifecycle change this event represents.
    #[serde(rename = "type")]
    pub event_type: SessionLifecycleEventType,
    /// Identifier of the session this event refers to.
    #[serde(rename = "sessionId")]
    pub session_id: SessionId,
    /// Optional metadata describing the session at the time of the event.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub metadata: Option<SessionLifecycleEventMetadata>,
}

/// Opaque session identifier assigned by the CLI.
///
/// A newtype wrapper around `String` that provides type safety — prevents
/// accidentally passing a workspace ID or request ID where a session ID
/// is expected. Derefs to `str` for zero-friction borrowing.
#[derive(Debug, Clone, Default, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[serde(transparent)]
pub struct SessionId(String);

impl SessionId {
    /// Create a new session ID from any string-like value.
    pub fn new(id: impl Into<String>) -> Self {
        Self(id.into())
    }

    /// Borrow the inner string.
    pub fn as_str(&self) -> &str {
        &self.0
    }

    /// Consume the wrapper, returning the inner string.
    pub fn into_inner(self) -> String {
        self.0
    }
}

impl std::ops::Deref for SessionId {
    type Target = str;

    fn deref(&self) -> &str {
        &self.0
    }
}

impl std::fmt::Display for SessionId {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_str(&self.0)
    }
}

impl From<String> for SessionId {
    fn from(s: String) -> Self {
        Self(s)
    }
}

impl From<&str> for SessionId {
    fn from(s: &str) -> Self {
        Self(s.to_owned())
    }
}

impl AsRef<str> for SessionId {
    fn as_ref(&self) -> &str {
        &self.0
    }
}

impl std::borrow::Borrow<str> for SessionId {
    fn borrow(&self) -> &str {
        &self.0
    }
}

impl From<SessionId> for String {
    fn from(id: SessionId) -> String {
        id.0
    }
}

impl PartialEq<str> for SessionId {
    fn eq(&self, other: &str) -> bool {
        self.0 == other
    }
}

impl PartialEq<String> for SessionId {
    fn eq(&self, other: &String) -> bool {
        &self.0 == other
    }
}

impl PartialEq<SessionId> for String {
    fn eq(&self, other: &SessionId) -> bool {
        self == &other.0
    }
}

impl PartialEq<&str> for SessionId {
    fn eq(&self, other: &&str) -> bool {
        self.0 == *other
    }
}

impl PartialEq<&SessionId> for SessionId {
    fn eq(&self, other: &&SessionId) -> bool {
        self.0 == other.0
    }
}

impl PartialEq<SessionId> for &SessionId {
    fn eq(&self, other: &SessionId) -> bool {
        self.0 == other.0
    }
}

/// Opaque request identifier for pending CLI requests (permission, user-input, etc.).
///
/// A newtype wrapper around `String` that provides type safety — prevents
/// accidentally passing a session ID or workspace ID where a request ID
/// is expected. Derefs to `str` for zero-friction borrowing.
#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[serde(transparent)]
pub struct RequestId(String);

impl RequestId {
    /// Create a new request ID from any string-like value.
    pub fn new(id: impl Into<String>) -> Self {
        Self(id.into())
    }

    /// Consume the wrapper, returning the inner string.
    pub fn into_inner(self) -> String {
        self.0
    }
}

impl std::ops::Deref for RequestId {
    type Target = str;

    fn deref(&self) -> &str {
        &self.0
    }
}

impl std::fmt::Display for RequestId {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_str(&self.0)
    }
}

impl From<String> for RequestId {
    fn from(s: String) -> Self {
        Self(s)
    }
}

impl From<&str> for RequestId {
    fn from(s: &str) -> Self {
        Self(s.to_owned())
    }
}

impl AsRef<str> for RequestId {
    fn as_ref(&self) -> &str {
        &self.0
    }
}

impl std::borrow::Borrow<str> for RequestId {
    fn borrow(&self) -> &str {
        &self.0
    }
}

impl From<RequestId> for String {
    fn from(id: RequestId) -> String {
        id.0
    }
}

impl PartialEq<str> for RequestId {
    fn eq(&self, other: &str) -> bool {
        self.0 == other
    }
}

impl PartialEq<String> for RequestId {
    fn eq(&self, other: &String) -> bool {
        &self.0 == other
    }
}

impl PartialEq<RequestId> for String {
    fn eq(&self, other: &RequestId) -> bool {
        self == &other.0
    }
}

impl PartialEq<&str> for RequestId {
    fn eq(&self, other: &&str) -> bool {
        self.0 == *other
    }
}

/// A tool that the client exposes to the Copilot agent.
///
/// Sent to the CLI as part of [`SessionConfig::tools`] / [`ResumeSessionConfig::tools`]
/// at session creation/resume time. The Rust SDK hand-authors this struct
/// (rather than using the schema-generated form) so it can carry runtime
/// hints — `overrides_built_in_tool`, `skip_permission` — that don't appear
/// in the wire schema but are honored by the CLI.
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
#[non_exhaustive]
pub struct Tool {
    /// Tool identifier (e.g., `"bash"`, `"grep"`, `"str_replace_editor"`).
    pub name: String,
    /// Optional namespaced name for declarative filtering (e.g., `"playwright/navigate"`
    /// for MCP tools).
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub namespaced_name: Option<String>,
    /// Description of what the tool does.
    #[serde(default)]
    pub description: String,
    /// Optional instructions for how to use this tool effectively.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub instructions: Option<String>,
    /// JSON Schema for the tool's input parameters.
    #[serde(default, skip_serializing_if = "HashMap::is_empty")]
    pub parameters: HashMap<String, Value>,
    /// When `true`, this tool replaces a built-in tool of the same name
    /// (e.g. supplying a custom `grep` that the agent uses in place of the
    /// CLI's built-in implementation).
    #[serde(default, skip_serializing_if = "is_false")]
    pub overrides_built_in_tool: bool,
    /// When `true`, the CLI does not request permission before invoking
    /// this tool. Use with caution — the tool is responsible for any
    /// access control.
    #[serde(default, skip_serializing_if = "is_false")]
    pub skip_permission: bool,
}

#[inline]
fn is_false(b: &bool) -> bool {
    !*b
}

impl Tool {
    /// Construct a new [`Tool`] with the given name and otherwise default
    /// values. The struct is `#[non_exhaustive]`, so external callers
    /// cannot use struct-literal syntax — use this builder or
    /// [`Default::default`] plus mut-let.
    ///
    /// # Example
    ///
    /// ```
    /// # use github_copilot_sdk::types::Tool;
    /// # use serde_json::json;
    /// let tool = Tool::new("greet")
    ///     .with_description("Say hello to a user")
    ///     .with_parameters(json!({
    ///         "type": "object",
    ///         "properties": { "name": { "type": "string" } },
    ///         "required": ["name"]
    ///     }));
    /// # let _ = tool;
    /// ```
    pub fn new(name: impl Into<String>) -> Self {
        Self {
            name: name.into(),
            ..Default::default()
        }
    }

    /// Set the namespaced name for declarative filtering (e.g.
    /// `"playwright/navigate"` for MCP tools).
    pub fn with_namespaced_name(mut self, namespaced_name: impl Into<String>) -> Self {
        self.namespaced_name = Some(namespaced_name.into());
        self
    }

    /// Set the human-readable description of what the tool does.
    pub fn with_description(mut self, description: impl Into<String>) -> Self {
        self.description = description.into();
        self
    }

    /// Set optional instructions for how to use this tool effectively.
    pub fn with_instructions(mut self, instructions: impl Into<String>) -> Self {
        self.instructions = Some(instructions.into());
        self
    }

    /// Set the JSON Schema for the tool's input parameters.
    ///
    /// Accepts anything that converts into a JSON object, including a
    /// `serde_json::Value` produced by `json!({...})`. Non-object values
    /// are stored as an empty parameter map; callers that need direct
    /// control over the field can construct a `HashMap<String, Value>`
    /// and assign it to [`Tool::parameters`] via [`Default::default`].
    pub fn with_parameters(mut self, parameters: Value) -> Self {
        self.parameters = parameters
            .as_object()
            .map(|m| m.iter().map(|(k, v)| (k.clone(), v.clone())).collect())
            .unwrap_or_default();
        self
    }

    /// Mark this tool as overriding a built-in tool of the same name.
    /// E.g. supplying a custom `grep` that the agent uses in place of the
    /// CLI's built-in implementation.
    pub fn with_overrides_built_in_tool(mut self, overrides: bool) -> Self {
        self.overrides_built_in_tool = overrides;
        self
    }

    /// When `true`, the CLI will not request permission before invoking
    /// this tool. Use with caution — the tool is responsible for any
    /// access control.
    pub fn with_skip_permission(mut self, skip: bool) -> Self {
        self.skip_permission = skip;
        self
    }
}

/// Context passed to a [`CommandHandler`] when a registered slash command
/// is executed by the user.
#[non_exhaustive]
#[derive(Debug, Clone)]
pub struct CommandContext {
    /// Session ID where the command was invoked.
    pub session_id: SessionId,
    /// The full command text (e.g. `"/deploy production"`).
    pub command: String,
    /// Command name without the leading `/` (e.g. `"deploy"`).
    pub command_name: String,
    /// Raw argument string after the command name (e.g. `"production"`).
    pub args: String,
}

/// Handler invoked when a registered slash command is executed.
///
/// Returning `Err(_)` causes the SDK to forward the error message back to
/// the CLI via `session.commands.handlePendingCommand` so the TUI can
/// surface it. Returning `Ok(())` reports success.
#[async_trait::async_trait]
pub trait CommandHandler: Send + Sync {
    /// Called when the user invokes the command this handler is registered for.
    async fn on_command(&self, ctx: CommandContext) -> Result<(), crate::Error>;
}

/// Definition of a slash command registered with the session.
///
/// When the CLI is running with a TUI, registered commands appear as
/// `/name` for the user to invoke. Only `name` and `description` are sent
/// over the wire — the handler is local to this SDK process.
#[non_exhaustive]
#[derive(Clone)]
pub struct CommandDefinition {
    /// Command name (without leading `/`).
    pub name: String,
    /// Human-readable description shown in command-completion UI.
    pub description: Option<String>,
    /// Handler invoked when the command is executed.
    pub handler: Arc<dyn CommandHandler>,
}

impl CommandDefinition {
    /// Construct a new command definition. Use [`with_description`](Self::with_description)
    /// to add a description.
    pub fn new(name: impl Into<String>, handler: Arc<dyn CommandHandler>) -> Self {
        Self {
            name: name.into(),
            description: None,
            handler,
        }
    }

    /// Set the human-readable description shown in the CLI's command-completion UI.
    pub fn with_description(mut self, description: impl Into<String>) -> Self {
        self.description = Some(description.into());
        self
    }
}

impl std::fmt::Debug for CommandDefinition {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("CommandDefinition")
            .field("name", &self.name)
            .field("description", &self.description)
            .field("handler", &"<set>")
            .finish()
    }
}

impl Serialize for CommandDefinition {
    fn serialize<S: serde::Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
        use serde::ser::SerializeStruct;
        let len = if self.description.is_some() { 2 } else { 1 };
        let mut state = serializer.serialize_struct("CommandDefinition", len)?;
        state.serialize_field("name", &self.name)?;
        if let Some(description) = &self.description {
            state.serialize_field("description", description)?;
        }
        state.end()
    }
}

/// Configures a custom agent (sub-agent) for the session.
///
/// Custom agents have their own prompt, tool allowlist, and optionally
/// their own MCP servers and skill set. The agent named in
/// [`SessionConfig::agent`] (or the runtime default) is the active one
/// when the session starts.
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
#[non_exhaustive]
pub struct CustomAgentConfig {
    /// Unique name of the custom agent.
    pub name: String,
    /// Display name for UI purposes.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub display_name: Option<String>,
    /// Description of what the agent does.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub description: Option<String>,
    /// List of tool names the agent can use. `None` means all tools.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub tools: Option<Vec<String>>,
    /// Prompt content for the agent.
    pub prompt: String,
    /// MCP servers specific to this agent.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub mcp_servers: Option<HashMap<String, McpServerConfig>>,
    /// Whether the agent is available for model inference.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub infer: Option<bool>,
    /// Skill names to preload into this agent's context at startup.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub skills: Option<Vec<String>>,
}

impl CustomAgentConfig {
    /// Construct a custom agent configuration with the required `name`
    /// and `prompt` fields populated.
    ///
    /// All other fields default to unset; use the `with_*` chain to
    /// customize them. Fields are also `pub` if direct assignment is
    /// preferred for `Option<T>` pass-through.
    pub fn new(name: impl Into<String>, prompt: impl Into<String>) -> Self {
        Self {
            name: name.into(),
            prompt: prompt.into(),
            ..Self::default()
        }
    }

    /// Set the display name shown in the CLI's agent-selection UI.
    pub fn with_display_name(mut self, display_name: impl Into<String>) -> Self {
        self.display_name = Some(display_name.into());
        self
    }

    /// Set the description of what the agent does.
    pub fn with_description(mut self, description: impl Into<String>) -> Self {
        self.description = Some(description.into());
        self
    }

    /// Restrict the agent to a specific tool allowlist. When unset, the
    /// agent inherits the parent session's tool set.
    pub fn with_tools<I, S>(mut self, tools: I) -> Self
    where
        I: IntoIterator<Item = S>,
        S: Into<String>,
    {
        self.tools = Some(tools.into_iter().map(Into::into).collect());
        self
    }

    /// Configure agent-specific MCP servers.
    pub fn with_mcp_servers(mut self, mcp_servers: HashMap<String, McpServerConfig>) -> Self {
        self.mcp_servers = Some(mcp_servers);
        self
    }

    /// Whether the agent participates in model inference.
    pub fn with_infer(mut self, infer: bool) -> Self {
        self.infer = Some(infer);
        self
    }

    /// Set the skills preloaded into the agent's context at startup.
    pub fn with_skills<I, S>(mut self, skills: I) -> Self
    where
        I: IntoIterator<Item = S>,
        S: Into<String>,
    {
        self.skills = Some(skills.into_iter().map(Into::into).collect());
        self
    }
}

/// Configures the default (built-in) agent that handles turns when no
/// custom agent is selected.
///
/// Use [`Self::excluded_tools`] to hide tools from the default agent
/// while keeping them available to custom sub-agents that list them in
/// their [`CustomAgentConfig::tools`].
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct DefaultAgentConfig {
    /// Tool names to exclude from the default agent.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub excluded_tools: Option<Vec<String>>,
}

/// Configures infinite sessions: persistent workspaces with automatic
/// context-window compaction.
///
/// When enabled (default), sessions automatically manage context limits
/// through background compaction and persist state to a workspace
/// directory.
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
#[non_exhaustive]
pub struct InfiniteSessionConfig {
    /// Whether infinite sessions are enabled. Defaults to `true` on the CLI.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub enabled: Option<bool>,
    /// Context utilization (0.0–1.0) at which background compaction starts.
    /// Default: 0.80.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub background_compaction_threshold: Option<f64>,
    /// Context utilization (0.0–1.0) at which the session blocks until
    /// compaction completes. Default: 0.95.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub buffer_exhaustion_threshold: Option<f64>,
}

impl InfiniteSessionConfig {
    /// Construct an empty [`InfiniteSessionConfig`]; all fields default to
    /// unset (the CLI applies its own defaults).
    pub fn new() -> Self {
        Self::default()
    }

    /// Toggle infinite sessions on or off. Defaults to `true` on the CLI
    /// when unset.
    pub fn with_enabled(mut self, enabled: bool) -> Self {
        self.enabled = Some(enabled);
        self
    }

    /// Set the context utilization (0.0–1.0) at which background
    /// compaction starts.
    pub fn with_background_compaction_threshold(mut self, threshold: f64) -> Self {
        self.background_compaction_threshold = Some(threshold);
        self
    }

    /// Set the context utilization (0.0–1.0) at which the session blocks
    /// until compaction completes.
    pub fn with_buffer_exhaustion_threshold(mut self, threshold: f64) -> Self {
        self.buffer_exhaustion_threshold = Some(threshold);
        self
    }
}

/// Configuration for a single MCP server.
///
/// MCP (Model Context Protocol) servers expose external tools to the
/// agent. Local servers run as a subprocess over stdio; remote servers
/// speak HTTP or Server-Sent Events.
///
/// Serialized as a JSON object with a `type` discriminator (`"stdio"` |
/// `"http"` | `"sse"`).
///
/// # Example
///
/// ```
/// # use github_copilot_sdk::types::{McpServerConfig, McpStdioServerConfig, McpHttpServerConfig};
/// # use std::collections::HashMap;
/// let mut servers = HashMap::new();
/// servers.insert(
///     "playwright".to_string(),
///     McpServerConfig::Stdio(McpStdioServerConfig {
///         tools: vec!["*".to_string()],
///         command: "npx".to_string(),
///         args: vec!["-y".to_string(), "@playwright/mcp".to_string()],
///         ..Default::default()
///     }),
/// );
/// servers.insert(
///     "weather".to_string(),
///     McpServerConfig::Http(McpHttpServerConfig {
///         tools: vec!["forecast".to_string()],
///         url: "https://example.com/mcp".to_string(),
///         ..Default::default()
///     }),
/// );
/// ```
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(tag = "type", rename_all = "lowercase")]
#[non_exhaustive]
pub enum McpServerConfig {
    /// Local MCP server launched as a subprocess and addressed over stdio.
    /// On the wire this serializes as `{"type": "stdio", ...}`. The CLI
    /// also accepts `"local"` as an alias on input.
    #[serde(alias = "local")]
    Stdio(McpStdioServerConfig),
    /// Remote MCP server addressed over HTTP.
    Http(McpHttpServerConfig),
    /// Remote MCP server addressed over Server-Sent Events.
    Sse(McpHttpServerConfig),
}

/// Configuration for a local/stdio MCP server.
///
/// See [`McpServerConfig::Stdio`].
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct McpStdioServerConfig {
    /// Tools to expose from this server. `["*"]` exposes all; `[]` exposes none.
    #[serde(default)]
    pub tools: Vec<String>,
    /// Optional timeout in milliseconds for tool calls to this server.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub timeout: Option<i64>,
    /// Subprocess executable.
    pub command: String,
    /// Arguments to pass to the subprocess.
    #[serde(default)]
    pub args: Vec<String>,
    /// Environment variables to set on the subprocess. Values are passed
    /// through literally to the child process.
    #[serde(default, skip_serializing_if = "HashMap::is_empty")]
    pub env: HashMap<String, String>,
    /// Working directory for the subprocess.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub cwd: Option<String>,
}

/// Configuration for a remote MCP server (HTTP or SSE).
///
/// See [`McpServerConfig::Http`] and [`McpServerConfig::Sse`].
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct McpHttpServerConfig {
    /// Tools to expose from this server. `["*"]` exposes all; `[]` exposes none.
    #[serde(default)]
    pub tools: Vec<String>,
    /// Optional timeout in milliseconds for tool calls to this server.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub timeout: Option<i64>,
    /// Server URL.
    pub url: String,
    /// Optional HTTP headers to include on every request.
    #[serde(default, skip_serializing_if = "HashMap::is_empty")]
    pub headers: HashMap<String, String>,
}

/// Configures a custom inference provider (BYOK — Bring Your Own Key).
///
/// Routes session requests through an alternative model provider
/// (OpenAI-compatible, Azure, Anthropic, or local) instead of GitHub
/// Copilot's default routing.
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
#[non_exhaustive]
pub struct ProviderConfig {
    /// Provider type: `"openai"`, `"azure"`, or `"anthropic"`. Defaults to
    /// `"openai"` on the CLI.
    #[serde(default, skip_serializing_if = "Option::is_none", rename = "type")]
    pub provider_type: Option<String>,
    /// API format (openai/azure only): `"completions"` or `"responses"`.
    /// Defaults to `"completions"`.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub wire_api: Option<String>,
    /// API endpoint URL.
    pub base_url: String,
    /// API key. Optional for local providers like Ollama.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub api_key: Option<String>,
    /// Bearer token for authentication. Sets the `Authorization` header
    /// directly. Use for services requiring bearer-token auth instead of
    /// API key. Takes precedence over `api_key` when both are set.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub bearer_token: Option<String>,
    /// Azure-specific options.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub azure: Option<AzureProviderOptions>,
    /// Custom HTTP headers included in outbound provider requests.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub headers: Option<HashMap<String, String>>,
    /// Well-known model ID used to look up agent config and default token
    /// limits. Also used as the wire model when [`wire_model`](Self::wire_model)
    /// is unset. Falls back to [`SessionConfig::model`](crate::SessionConfig::model).
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub model_id: Option<String>,
    /// 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
    /// [`model_id`](Self::model_id). Falls back to
    /// [`model_id`](Self::model_id), then to
    /// [`SessionConfig::model`](crate::SessionConfig::model).
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub wire_model: Option<String>,
    /// 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.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub max_prompt_tokens: Option<i64>,
    /// Overrides the resolved model's default max output tokens. When
    /// hit, the model stops generating and returns a truncated response.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub max_output_tokens: Option<i64>,
}

impl ProviderConfig {
    /// Construct a [`ProviderConfig`] with the required `base_url` set;
    /// all other fields default to unset.
    pub fn new(base_url: impl Into<String>) -> Self {
        Self {
            base_url: base_url.into(),
            ..Self::default()
        }
    }

    /// Set the provider type (`"openai"`, `"azure"`, or `"anthropic"`).
    pub fn with_provider_type(mut self, provider_type: impl Into<String>) -> Self {
        self.provider_type = Some(provider_type.into());
        self
    }

    /// Set the API format (`"completions"` or `"responses"`; openai/azure only).
    pub fn with_wire_api(mut self, wire_api: impl Into<String>) -> Self {
        self.wire_api = Some(wire_api.into());
        self
    }

    /// Set the API key. Optional for local providers like Ollama.
    pub fn with_api_key(mut self, api_key: impl Into<String>) -> Self {
        self.api_key = Some(api_key.into());
        self
    }

    /// Set the bearer token used to populate the `Authorization` header.
    /// Takes precedence over `api_key` when both are set.
    pub fn with_bearer_token(mut self, bearer_token: impl Into<String>) -> Self {
        self.bearer_token = Some(bearer_token.into());
        self
    }

    /// Set Azure-specific options.
    pub fn with_azure(mut self, azure: AzureProviderOptions) -> Self {
        self.azure = Some(azure);
        self
    }

    /// Set the custom HTTP headers attached to outbound provider requests.
    pub fn with_headers(mut self, headers: HashMap<String, String>) -> Self {
        self.headers = Some(headers);
        self
    }

    /// Set the well-known model ID used to look up agent config and default
    /// token limits. Falls back to the session's configured model when unset.
    pub fn with_model_id(mut self, model_id: impl Into<String>) -> Self {
        self.model_id = Some(model_id.into());
        self
    }

    /// Set the 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
    /// [`model_id`](Self::model_id).
    pub fn with_wire_model(mut self, wire_model: impl Into<String>) -> Self {
        self.wire_model = Some(wire_model.into());
        self
    }

    /// Override the resolved model's default max prompt tokens. The
    /// runtime triggers conversation compaction when the prompt would
    /// exceed this limit.
    pub fn with_max_prompt_tokens(mut self, max: i64) -> Self {
        self.max_prompt_tokens = Some(max);
        self
    }

    /// Override the resolved model's default max output tokens. When
    /// hit, the model stops generating and returns a truncated response.
    pub fn with_max_output_tokens(mut self, max: i64) -> Self {
        self.max_output_tokens = Some(max);
        self
    }
}

/// Azure-specific provider options.
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct AzureProviderOptions {
    /// Azure API version. Defaults to `"2024-10-21"`.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub api_version: Option<String>,
}

/// Wire default for [`SessionConfig::env_value_mode`] /
/// [`ResumeSessionConfig::env_value_mode`]. The runtime understands
/// `"direct"` (literal values) or `"indirect"` (env-var lookup); the SDK
/// only ever sends `"direct"`.
fn default_env_value_mode() -> String {
    "direct".into()
}

/// Configuration for creating a new session via the `session.create` RPC.
///
/// All fields are optional — the CLI applies sensible defaults.
///
/// # Construction
///
/// Two equivalent shapes are supported:
///
/// 1. **Chained builder** (preferred for compile-time-known values):
///
///    ```
///    # use github_copilot_sdk::types::SessionConfig;
///    let cfg = SessionConfig::default()
///        .with_client_name("my-app")
///        .with_streaming(true)
///        .with_enable_config_discovery(true);
///    ```
///
/// 2. **Direct field assignment** (preferred when forwarding `Option<T>`
///    from upstream code, since `with_<field>` setters take the inner
///    `T`, not `Option<T>`):
///
///    ```
///    # use github_copilot_sdk::types::SessionConfig;
///    # let upstream_model: Option<String> = None;
///    # let upstream_system_message: Option<github_copilot_sdk::types::SystemMessageConfig> = None;
///    let mut cfg = SessionConfig::default()
///        .with_client_name("my-app")
///        .with_streaming(true);
///    cfg.model = upstream_model;
///    cfg.system_message = upstream_system_message;
///    ```
///
///    Mixing the two is fine: chain the fields you know at compile time,
///    then assign the `Option<T>` pass-through fields directly. All
///    fields on this struct are `pub`. This pattern matches the
///    `http::request::Parts` / `hyper::Body::Builder` convention in the
///    wider Rust ecosystem.
///
/// # Field naming across SDKs
///
/// Rust field names are snake_case (`available_tools`, `system_message`);
/// they round-trip to the camelCase wire protocol via `#[serde(rename_all =
/// "camelCase")]`. When porting code from the TypeScript, Go, Python, or
/// .NET SDKs — or reading the raw JSON-RPC traces — fields appear as
/// `availableTools`, `systemMessage`, etc.
#[derive(Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
#[non_exhaustive]
pub struct SessionConfig {
    /// Custom session ID. When unset, the CLI generates one.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub session_id: Option<SessionId>,
    /// Model to use (e.g. `"gpt-4"`, `"claude-sonnet-4"`).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub model: Option<String>,
    /// Application name sent as `User-Agent` context.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub client_name: Option<String>,
    /// Reasoning effort level (e.g. `"low"`, `"medium"`, `"high"`).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub reasoning_effort: Option<String>,
    /// Enable streaming token deltas via `assistant.message_delta` events.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub streaming: Option<bool>,
    /// Custom system message configuration.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub system_message: Option<SystemMessageConfig>,
    /// Client-defined tools to expose to the agent.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub tools: Option<Vec<Tool>>,
    /// Allowlist of built-in tool names the agent may use.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub available_tools: Option<Vec<String>>,
    /// Blocklist of built-in tool names the agent must not use.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub excluded_tools: Option<Vec<String>>,
    /// MCP server configurations passed through to the CLI.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub mcp_servers: Option<HashMap<String, McpServerConfig>>,
    /// Wire-format hint for MCP `env` map values. The runtime understands
    /// `"direct"` (literal values) and `"indirect"` (env-var lookup); the
    /// SDK only ever sends `"direct"` and consumers don't have a knob.
    #[serde(default = "default_env_value_mode", skip_deserializing)]
    pub(crate) env_value_mode: String,
    /// When true, the CLI runs config discovery (MCP config files, skills, plugins).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub enable_config_discovery: Option<bool>,
    /// Enable the `ask_user` tool for interactive user input. Defaults to
    /// `Some(true)` via [`SessionConfig::default`].
    #[serde(skip_serializing_if = "Option::is_none")]
    pub request_user_input: Option<bool>,
    /// Enable `permission.request` JSON-RPC calls from the CLI. Defaults
    /// to `Some(true)` via [`SessionConfig::default`]; the default
    /// [`DenyAllHandler`](crate::handler::DenyAllHandler) refuses all
    /// requests so the wire surface is safe out-of-the-box.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub request_permission: Option<bool>,
    /// Enable `exitPlanMode.request` JSON-RPC calls for plan approval.
    /// Defaults to `Some(true)` via [`SessionConfig::default`].
    #[serde(skip_serializing_if = "Option::is_none")]
    pub request_exit_plan_mode: Option<bool>,
    /// Enable `autoModeSwitch.request` JSON-RPC calls. When `true`, the CLI
    /// asks the handler whether to switch to auto model when an eligible
    /// rate limit is hit. Defaults to `Some(true)` via
    /// [`SessionConfig::default`]. Without this flag, the CLI surfaces the
    /// rate-limit error directly without offering the auto-mode switch.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub request_auto_mode_switch: Option<bool>,
    /// Advertise elicitation provider capability. When true, the CLI sends
    /// `elicitation.requested` events that the handler can respond to.
    /// Defaults to `Some(true)` via [`SessionConfig::default`].
    #[serde(skip_serializing_if = "Option::is_none")]
    pub request_elicitation: Option<bool>,
    /// Skill directory paths passed through to the GitHub Copilot CLI.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub skill_directories: Option<Vec<PathBuf>>,
    /// Additional directories to search for custom instruction files.
    /// Forwarded to the CLI; not the same as [`skill_directories`](Self::skill_directories).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub instruction_directories: Option<Vec<PathBuf>>,
    /// Skill names to disable. Skills in this set will not be available
    /// even if found in skill directories.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub disabled_skills: Option<Vec<String>>,
    /// Enable session hooks. When `true`, the CLI sends `hooks.invoke`
    /// RPC requests at key lifecycle points (pre/post tool use, prompt
    /// submission, session start/end, errors).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub hooks: Option<bool>,
    /// Custom agents (sub-agents) configured for this session.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub custom_agents: Option<Vec<CustomAgentConfig>>,
    /// Configures the built-in default agent. Use `excluded_tools` to
    /// hide tools from the default agent while keeping them available
    /// to custom sub-agents that reference them in their `tools` list.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub default_agent: Option<DefaultAgentConfig>,
    /// Name of the custom agent to activate when the session starts.
    /// Must match the `name` of one of the agents in [`Self::custom_agents`].
    #[serde(skip_serializing_if = "Option::is_none")]
    pub agent: Option<String>,
    /// Configures infinite sessions: persistent workspace + automatic
    /// context-window compaction. Enabled by default on the CLI.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub infinite_sessions: Option<InfiniteSessionConfig>,
    /// Custom model provider (BYOK). When set, the session routes
    /// requests through this provider instead of the default Copilot
    /// routing.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub provider: Option<ProviderConfig>,
    /// Enables or disables internal session telemetry for this session.
    ///
    /// When `Some(false)`, disables session telemetry. When `None` or
    /// `Some(true)`, telemetry is enabled for GitHub-authenticated sessions.
    /// When a custom [`provider`](Self::provider) is configured, session
    /// telemetry is always disabled regardless of this setting. This is
    /// independent of [`ClientOptions::telemetry`](crate::ClientOptions::telemetry).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub enable_session_telemetry: Option<bool>,
    /// Per-property overrides for model capabilities, deep-merged over
    /// runtime defaults.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub model_capabilities: Option<crate::generated::api_types::ModelCapabilitiesOverride>,
    /// Override the default configuration directory location. When set,
    /// the session uses this directory for storing config and state.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub config_dir: Option<PathBuf>,
    /// Working directory for the session. Tool operations resolve
    /// relative paths against this directory.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub working_directory: Option<PathBuf>,
    /// Per-session GitHub token. Distinct from
    /// [`ClientOptions::github_token`](crate::ClientOptions::github_token),
    /// which authenticates the CLI process itself; this token determines
    /// the GitHub identity used for content exclusion, model routing, and
    /// quota checks for *this session*.
    #[serde(rename = "gitHubToken", skip_serializing_if = "Option::is_none")]
    pub github_token: Option<String>,
    /// Forward sub-agent streaming events to this connection. When false,
    /// only non-streaming sub-agent events and `subagent.*` lifecycle events
    /// are delivered. Defaults to true on the CLI.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub include_sub_agent_streaming_events: Option<bool>,
    /// Slash commands registered for this session. When the CLI has a TUI,
    /// each command appears as `/name` for the user to invoke and the
    /// associated [`CommandHandler`] is called when executed.
    #[serde(skip_serializing_if = "Option::is_none", skip_deserializing)]
    pub commands: Option<Vec<CommandDefinition>>,
    /// Custom session filesystem provider for this session. Required when
    /// the [`Client`](crate::Client) was started with
    /// [`ClientOptions::session_fs`](crate::ClientOptions::session_fs) set.
    /// See [`SessionFsProvider`].
    #[serde(skip)]
    pub session_fs_provider: Option<Arc<dyn SessionFsProvider>>,
    /// Session-level event handler. The default is
    /// [`DenyAllHandler`](crate::handler::DenyAllHandler) — permission
    /// requests are denied; other events are no-ops. Use
    /// [`with_handler`](Self::with_handler) to install a custom handler.
    #[serde(skip)]
    pub handler: Option<Arc<dyn SessionHandler>>,
    /// Session lifecycle hook handler (pre/post tool use, session
    /// start/end, etc.). When set, the SDK auto-enables the wire-level
    /// `hooks` flag. Use [`with_hooks`](Self::with_hooks) to install one.
    #[serde(skip)]
    pub hooks_handler: Option<Arc<dyn SessionHooks>>,
    /// System-message transform. When set, the SDK injects the matching
    /// `action: "transform"` sections into the system message and routes
    /// `systemMessage.transform` RPC callbacks to it during the session.
    /// Use [`with_transform`](Self::with_transform) to install one.
    #[serde(skip)]
    pub transform: Option<Arc<dyn SystemMessageTransform>>,
}

impl std::fmt::Debug for SessionConfig {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("SessionConfig")
            .field("session_id", &self.session_id)
            .field("model", &self.model)
            .field("client_name", &self.client_name)
            .field("reasoning_effort", &self.reasoning_effort)
            .field("streaming", &self.streaming)
            .field("system_message", &self.system_message)
            .field("tools", &self.tools)
            .field("available_tools", &self.available_tools)
            .field("excluded_tools", &self.excluded_tools)
            .field("mcp_servers", &self.mcp_servers)
            .field("enable_config_discovery", &self.enable_config_discovery)
            .field("request_user_input", &self.request_user_input)
            .field("request_permission", &self.request_permission)
            .field("request_exit_plan_mode", &self.request_exit_plan_mode)
            .field("request_auto_mode_switch", &self.request_auto_mode_switch)
            .field("request_elicitation", &self.request_elicitation)
            .field("skill_directories", &self.skill_directories)
            .field("instruction_directories", &self.instruction_directories)
            .field("disabled_skills", &self.disabled_skills)
            .field("hooks", &self.hooks)
            .field("custom_agents", &self.custom_agents)
            .field("default_agent", &self.default_agent)
            .field("agent", &self.agent)
            .field("infinite_sessions", &self.infinite_sessions)
            .field("provider", &self.provider)
            .field("enable_session_telemetry", &self.enable_session_telemetry)
            .field("model_capabilities", &self.model_capabilities)
            .field("config_dir", &self.config_dir)
            .field("working_directory", &self.working_directory)
            .field(
                "github_token",
                &self.github_token.as_ref().map(|_| "<redacted>"),
            )
            .field(
                "include_sub_agent_streaming_events",
                &self.include_sub_agent_streaming_events,
            )
            .field("commands", &self.commands)
            .field(
                "session_fs_provider",
                &self.session_fs_provider.as_ref().map(|_| "<set>"),
            )
            .field("handler", &self.handler.as_ref().map(|_| "<set>"))
            .field(
                "hooks_handler",
                &self.hooks_handler.as_ref().map(|_| "<set>"),
            )
            .field("transform", &self.transform.as_ref().map(|_| "<set>"))
            .finish()
    }
}

impl Default for SessionConfig {
    /// Permission and elicitation flows are enabled by default. With
    /// Rust's trait-based handlers, the SDK installs `DenyAllHandler` when
    /// no handler is provided, so these flags being `Some(true)` means the
    /// wire surface advertises the capabilities — and the default handler
    /// safely refuses requests. Callers that want the wire surface fully
    /// disabled set these explicitly to `Some(false)`.
    fn default() -> Self {
        Self {
            session_id: None,
            model: None,
            client_name: None,
            reasoning_effort: None,
            streaming: None,
            system_message: None,
            tools: None,
            available_tools: None,
            excluded_tools: None,
            mcp_servers: None,
            env_value_mode: default_env_value_mode(),
            enable_config_discovery: None,
            request_user_input: Some(true),
            request_permission: Some(true),
            request_exit_plan_mode: Some(true),
            request_auto_mode_switch: Some(true),
            request_elicitation: Some(true),
            skill_directories: None,
            instruction_directories: None,
            disabled_skills: None,
            hooks: None,
            custom_agents: None,
            default_agent: None,
            agent: None,
            infinite_sessions: None,
            provider: None,
            enable_session_telemetry: None,
            model_capabilities: None,
            config_dir: None,
            working_directory: None,
            github_token: None,
            include_sub_agent_streaming_events: None,
            commands: None,
            session_fs_provider: None,
            handler: None,
            hooks_handler: None,
            transform: None,
        }
    }
}

impl SessionConfig {
    /// Install a custom [`SessionHandler`] for this session.
    pub fn with_handler(mut self, handler: Arc<dyn SessionHandler>) -> Self {
        self.handler = Some(handler);
        self
    }

    /// Register slash commands for this session. Each command appears as
    /// `/name` in the CLI's TUI; the handler is invoked when the user
    /// executes the command. Replaces any commands previously set on this
    /// config. See [`CommandDefinition`].
    pub fn with_commands(mut self, commands: Vec<CommandDefinition>) -> Self {
        self.commands = Some(commands);
        self
    }

    /// Install a [`SessionFsProvider`] backing the session's filesystem.
    /// Required when the [`Client`](crate::Client) was started with
    /// [`ClientOptions::session_fs`](crate::ClientOptions::session_fs).
    pub fn with_session_fs_provider(mut self, provider: Arc<dyn SessionFsProvider>) -> Self {
        self.session_fs_provider = Some(provider);
        self
    }

    /// Install a [`SessionHooks`] handler. Automatically enables the
    /// wire-level `hooks` flag on session creation.
    pub fn with_hooks(mut self, hooks: Arc<dyn SessionHooks>) -> Self {
        self.hooks_handler = Some(hooks);
        self
    }

    /// Install a [`SystemMessageTransform`]. The SDK injects the matching
    /// `action: "transform"` sections into the system message and routes
    /// `systemMessage.transform` RPC callbacks to it during the session.
    pub fn with_transform(mut self, transform: Arc<dyn SystemMessageTransform>) -> Self {
        self.transform = Some(transform);
        self
    }

    /// Wrap the configured handler so every permission request is
    /// auto-approved. Forwards every non-permission event to the inner
    /// handler unchanged.
    ///
    /// If no handler has been installed via [`with_handler`](Self::with_handler),
    /// wraps a [`DenyAllHandler`](crate::handler::DenyAllHandler) — useful
    /// when you only care about permission policy and want the trait
    /// fallback responses for everything else.
    ///
    /// Order-independent: `with_handler(...).approve_all_permissions()` and
    /// `approve_all_permissions().with_handler(...)` are NOT equivalent —
    /// the second form discards the wrap because `with_handler` overwrites
    /// the handler field. Always call `approve_all_permissions` *after*
    /// `with_handler`.
    pub fn approve_all_permissions(mut self) -> Self {
        let inner = self
            .handler
            .take()
            .unwrap_or_else(|| Arc::new(crate::handler::DenyAllHandler));
        self.handler = Some(crate::permission::approve_all(inner));
        self
    }

    /// Wrap the configured handler so every permission request is
    /// auto-denied. See [`approve_all_permissions`](Self::approve_all_permissions)
    /// for ordering and default-handler semantics.
    pub fn deny_all_permissions(mut self) -> Self {
        let inner = self
            .handler
            .take()
            .unwrap_or_else(|| Arc::new(crate::handler::DenyAllHandler));
        self.handler = Some(crate::permission::deny_all(inner));
        self
    }

    /// Wrap the configured handler with a closure-based permission policy:
    /// `predicate` is called for each permission request; `true` approves,
    /// `false` denies. See
    /// [`approve_all_permissions`](Self::approve_all_permissions) for
    /// ordering and default-handler semantics.
    pub fn approve_permissions_if<F>(mut self, predicate: F) -> Self
    where
        F: Fn(&crate::types::PermissionRequestData) -> bool + Send + Sync + 'static,
    {
        let inner = self
            .handler
            .take()
            .unwrap_or_else(|| Arc::new(crate::handler::DenyAllHandler));
        self.handler = Some(crate::permission::approve_if(inner, predicate));
        self
    }

    /// Set a custom session ID (when unset, the CLI generates one).
    pub fn with_session_id(mut self, id: impl Into<SessionId>) -> Self {
        self.session_id = Some(id.into());
        self
    }

    /// Set the model identifier (e.g. `"claude-sonnet-4"`).
    pub fn with_model(mut self, model: impl Into<String>) -> Self {
        self.model = Some(model.into());
        self
    }

    /// Set the application name sent as `User-Agent` context.
    pub fn with_client_name(mut self, name: impl Into<String>) -> Self {
        self.client_name = Some(name.into());
        self
    }

    /// Set the reasoning effort level (e.g. `"low"`, `"medium"`, `"high"`).
    pub fn with_reasoning_effort(mut self, effort: impl Into<String>) -> Self {
        self.reasoning_effort = Some(effort.into());
        self
    }

    /// Enable streaming token deltas via `assistant.message_delta` events.
    pub fn with_streaming(mut self, streaming: bool) -> Self {
        self.streaming = Some(streaming);
        self
    }

    /// Set a custom system message configuration.
    pub fn with_system_message(mut self, system_message: SystemMessageConfig) -> Self {
        self.system_message = Some(system_message);
        self
    }

    /// Set the client-defined tools to expose to the agent.
    pub fn with_tools<I: IntoIterator<Item = Tool>>(mut self, tools: I) -> Self {
        self.tools = Some(tools.into_iter().collect());
        self
    }

    /// Set the allowlist of built-in tool names the agent may use.
    pub fn with_available_tools<I, S>(mut self, tools: I) -> Self
    where
        I: IntoIterator<Item = S>,
        S: Into<String>,
    {
        self.available_tools = Some(tools.into_iter().map(Into::into).collect());
        self
    }

    /// Set the blocklist of built-in tool names the agent must not use.
    pub fn with_excluded_tools<I, S>(mut self, tools: I) -> Self
    where
        I: IntoIterator<Item = S>,
        S: Into<String>,
    {
        self.excluded_tools = Some(tools.into_iter().map(Into::into).collect());
        self
    }

    /// Set MCP server configurations passed through to the CLI.
    pub fn with_mcp_servers(mut self, servers: HashMap<String, McpServerConfig>) -> Self {
        self.mcp_servers = Some(servers);
        self
    }

    /// Enable or disable CLI config discovery (MCP config files, skills, plugins).
    pub fn with_enable_config_discovery(mut self, enable: bool) -> Self {
        self.enable_config_discovery = Some(enable);
        self
    }

    /// Enable the `ask_user` tool. Defaults to `Some(true)` via [`Self::default`].
    pub fn with_request_user_input(mut self, enable: bool) -> Self {
        self.request_user_input = Some(enable);
        self
    }

    /// Enable `permission.request` JSON-RPC calls. Defaults to `Some(true)`.
    pub fn with_request_permission(mut self, enable: bool) -> Self {
        self.request_permission = Some(enable);
        self
    }

    /// Enable `exitPlanMode.request` JSON-RPC calls. Defaults to `Some(true)`.
    pub fn with_request_exit_plan_mode(mut self, enable: bool) -> Self {
        self.request_exit_plan_mode = Some(enable);
        self
    }

    /// Enable `autoModeSwitch.request` JSON-RPC calls. Defaults to `Some(true)`.
    pub fn with_request_auto_mode_switch(mut self, enable: bool) -> Self {
        self.request_auto_mode_switch = Some(enable);
        self
    }

    /// Advertise elicitation provider capability. Defaults to `Some(true)`.
    pub fn with_request_elicitation(mut self, enable: bool) -> Self {
        self.request_elicitation = Some(enable);
        self
    }

    /// Set skill directory paths passed through to the CLI.
    pub fn with_skill_directories<I, P>(mut self, paths: I) -> Self
    where
        I: IntoIterator<Item = P>,
        P: Into<PathBuf>,
    {
        self.skill_directories = Some(paths.into_iter().map(Into::into).collect());
        self
    }

    /// Set additional directories to search for custom instruction files.
    /// Forwarded to the CLI on session create; not the same as
    /// [`with_skill_directories`](Self::with_skill_directories).
    pub fn with_instruction_directories<I, P>(mut self, paths: I) -> Self
    where
        I: IntoIterator<Item = P>,
        P: Into<PathBuf>,
    {
        self.instruction_directories = Some(paths.into_iter().map(Into::into).collect());
        self
    }

    /// Set the names of skills to disable (overrides skill discovery).
    pub fn with_disabled_skills<I, S>(mut self, names: I) -> Self
    where
        I: IntoIterator<Item = S>,
        S: Into<String>,
    {
        self.disabled_skills = Some(names.into_iter().map(Into::into).collect());
        self
    }

    /// Set the custom agents (sub-agents) configured for this session.
    pub fn with_custom_agents<I: IntoIterator<Item = CustomAgentConfig>>(
        mut self,
        agents: I,
    ) -> Self {
        self.custom_agents = Some(agents.into_iter().collect());
        self
    }

    /// Configure the built-in default agent.
    pub fn with_default_agent(mut self, agent: DefaultAgentConfig) -> Self {
        self.default_agent = Some(agent);
        self
    }

    /// Activate a named custom agent on session start. Must match the
    /// `name` of one of the agents in [`Self::custom_agents`].
    pub fn with_agent(mut self, name: impl Into<String>) -> Self {
        self.agent = Some(name.into());
        self
    }

    /// Configure infinite sessions (persistent workspace + automatic
    /// context-window compaction).
    pub fn with_infinite_sessions(mut self, config: InfiniteSessionConfig) -> Self {
        self.infinite_sessions = Some(config);
        self
    }

    /// Configure a custom model provider (BYOK).
    pub fn with_provider(mut self, provider: ProviderConfig) -> Self {
        self.provider = Some(provider);
        self
    }

    /// Enable or disable internal session telemetry.
    ///
    /// See [`Self::enable_session_telemetry`] for default and BYOK behavior.
    pub fn with_enable_session_telemetry(mut self, enable: bool) -> Self {
        self.enable_session_telemetry = Some(enable);
        self
    }

    /// Set per-property overrides for model capabilities.
    pub fn with_model_capabilities(
        mut self,
        capabilities: crate::generated::api_types::ModelCapabilitiesOverride,
    ) -> Self {
        self.model_capabilities = Some(capabilities);
        self
    }

    /// Override the default configuration directory location.
    pub fn with_config_dir(mut self, dir: impl Into<PathBuf>) -> Self {
        self.config_dir = Some(dir.into());
        self
    }

    /// Set the per-session working directory. Tool operations resolve
    /// relative paths against this directory.
    pub fn with_working_directory(mut self, dir: impl Into<PathBuf>) -> Self {
        self.working_directory = Some(dir.into());
        self
    }

    /// Set the per-session GitHub token. Distinct from
    /// [`ClientOptions::github_token`](crate::ClientOptions::github_token);
    /// this token determines the GitHub identity used for content exclusion,
    /// model routing, and quota checks for this session only.
    pub fn with_github_token(mut self, token: impl Into<String>) -> Self {
        self.github_token = Some(token.into());
        self
    }

    /// Forward sub-agent streaming events to this connection. Defaults
    /// to true on the CLI when unset.
    pub fn with_include_sub_agent_streaming_events(mut self, include: bool) -> Self {
        self.include_sub_agent_streaming_events = Some(include);
        self
    }
}

/// Configuration for resuming an existing session via the `session.resume` RPC.
///
/// See [`SessionConfig`] for the construction patterns (chained `with_*`
/// builder vs. direct field assignment for `Option<T>` pass-through) and
/// the note on snake_case vs. camelCase field naming.
#[derive(Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
#[non_exhaustive]
pub struct ResumeSessionConfig {
    /// ID of the session to resume.
    pub session_id: SessionId,
    /// Application name sent as User-Agent context.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub client_name: Option<String>,
    /// Desired reasoning effort to apply after resuming the session.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub reasoning_effort: Option<String>,
    /// Enable streaming token deltas.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub streaming: Option<bool>,
    /// Re-supply the system message so the agent retains workspace context
    /// across CLI process restarts.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub system_message: Option<SystemMessageConfig>,
    /// Client-defined tools to re-supply on resume.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub tools: Option<Vec<Tool>>,
    /// Allowlist of tool names the agent may use.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub available_tools: Option<Vec<String>>,
    /// Blocklist of built-in tool names.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub excluded_tools: Option<Vec<String>>,
    /// Re-supply MCP servers so they remain available after app restart.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub mcp_servers: Option<HashMap<String, McpServerConfig>>,
    /// See [`SessionConfig::env_value_mode`]. Always `"direct"` on the wire.
    #[serde(default = "default_env_value_mode", skip_deserializing)]
    pub(crate) env_value_mode: String,
    /// Enable config discovery on resume.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub enable_config_discovery: Option<bool>,
    /// Enable the ask_user tool.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub request_user_input: Option<bool>,
    /// Enable permission request RPCs.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub request_permission: Option<bool>,
    /// Enable exit-plan-mode request RPCs.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub request_exit_plan_mode: Option<bool>,
    /// Enable auto-mode-switch request RPCs on resume. Defaults to
    /// `Some(true)` via [`ResumeSessionConfig::new`]. See
    /// [`SessionConfig::request_auto_mode_switch`] for details.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub request_auto_mode_switch: Option<bool>,
    /// Advertise elicitation provider capability on resume.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub request_elicitation: Option<bool>,
    /// Skill directory paths passed through to the GitHub Copilot CLI on resume.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub skill_directories: Option<Vec<PathBuf>>,
    /// Additional directories to search for custom instruction files on
    /// resume. Forwarded to the CLI; not the same as [`skill_directories`](Self::skill_directories).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub instruction_directories: Option<Vec<PathBuf>>,
    /// Skill names to disable on resume.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub disabled_skills: Option<Vec<String>>,
    /// Enable session hooks on resume.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub hooks: Option<bool>,
    /// Custom agents to re-supply on resume.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub custom_agents: Option<Vec<CustomAgentConfig>>,
    /// Configures the built-in default agent on resume.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub default_agent: Option<DefaultAgentConfig>,
    /// Name of the custom agent to activate.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub agent: Option<String>,
    /// Re-supply infinite session configuration on resume.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub infinite_sessions: Option<InfiniteSessionConfig>,
    /// Re-supply BYOK provider configuration on resume.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub provider: Option<ProviderConfig>,
    /// Enables or disables internal session telemetry for this session.
    ///
    /// When `Some(false)`, disables session telemetry. When `None` or
    /// `Some(true)`, telemetry is enabled for GitHub-authenticated sessions.
    /// When a custom [`provider`](Self::provider) is configured, session
    /// telemetry is always disabled regardless of this setting. This is
    /// independent of [`ClientOptions::telemetry`](crate::ClientOptions::telemetry).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub enable_session_telemetry: Option<bool>,
    /// Per-property model capability overrides on resume.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub model_capabilities: Option<crate::generated::api_types::ModelCapabilitiesOverride>,
    /// Override the default configuration directory location on resume.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub config_dir: Option<PathBuf>,
    /// Per-session working directory on resume.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub working_directory: Option<PathBuf>,
    /// Per-session GitHub token on resume. See
    /// [`SessionConfig::github_token`].
    #[serde(rename = "gitHubToken", skip_serializing_if = "Option::is_none")]
    pub github_token: Option<String>,
    /// Forward sub-agent streaming events to this connection on resume.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub include_sub_agent_streaming_events: Option<bool>,
    /// Slash commands registered for this session on resume. See
    /// [`SessionConfig::commands`] — commands are not persisted server-side,
    /// so the resume payload re-supplies the registration.
    #[serde(skip_serializing_if = "Option::is_none", skip_deserializing)]
    pub commands: Option<Vec<CommandDefinition>>,
    /// Custom session filesystem provider. Required on resume when the
    /// [`Client`](crate::Client) was started with
    /// [`ClientOptions::session_fs`](crate::ClientOptions::session_fs).
    /// See [`SessionConfig::session_fs_provider`].
    #[serde(skip)]
    pub session_fs_provider: Option<Arc<dyn SessionFsProvider>>,
    /// Force-fail resume if the session does not exist on disk, instead of
    /// silently starting a new session.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub disable_resume: Option<bool>,
    /// When `true`, instructs the runtime to continue any tool calls or
    /// permission requests that were pending when the previous connection
    /// was dropped. Use this together with [`Client::force_stop`] to hand
    /// off a session from one process to another without losing in-flight
    /// work.
    ///
    /// [`Client::force_stop`]: crate::Client::force_stop
    #[serde(skip_serializing_if = "Option::is_none")]
    pub continue_pending_work: Option<bool>,
    /// Session-level event handler. See [`SessionConfig::handler`].
    #[serde(skip)]
    pub handler: Option<Arc<dyn SessionHandler>>,
    /// Session hook handler. See [`SessionConfig::hooks_handler`].
    #[serde(skip)]
    pub hooks_handler: Option<Arc<dyn SessionHooks>>,
    /// System-message transform. See [`SessionConfig::transform`].
    #[serde(skip)]
    pub transform: Option<Arc<dyn SystemMessageTransform>>,
}

impl std::fmt::Debug for ResumeSessionConfig {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("ResumeSessionConfig")
            .field("session_id", &self.session_id)
            .field("client_name", &self.client_name)
            .field("reasoning_effort", &self.reasoning_effort)
            .field("streaming", &self.streaming)
            .field("system_message", &self.system_message)
            .field("tools", &self.tools)
            .field("available_tools", &self.available_tools)
            .field("excluded_tools", &self.excluded_tools)
            .field("mcp_servers", &self.mcp_servers)
            .field("enable_config_discovery", &self.enable_config_discovery)
            .field("request_user_input", &self.request_user_input)
            .field("request_permission", &self.request_permission)
            .field("request_exit_plan_mode", &self.request_exit_plan_mode)
            .field("request_auto_mode_switch", &self.request_auto_mode_switch)
            .field("request_elicitation", &self.request_elicitation)
            .field("skill_directories", &self.skill_directories)
            .field("instruction_directories", &self.instruction_directories)
            .field("disabled_skills", &self.disabled_skills)
            .field("hooks", &self.hooks)
            .field("custom_agents", &self.custom_agents)
            .field("default_agent", &self.default_agent)
            .field("agent", &self.agent)
            .field("infinite_sessions", &self.infinite_sessions)
            .field("provider", &self.provider)
            .field("enable_session_telemetry", &self.enable_session_telemetry)
            .field("model_capabilities", &self.model_capabilities)
            .field("config_dir", &self.config_dir)
            .field("working_directory", &self.working_directory)
            .field(
                "github_token",
                &self.github_token.as_ref().map(|_| "<redacted>"),
            )
            .field(
                "include_sub_agent_streaming_events",
                &self.include_sub_agent_streaming_events,
            )
            .field("commands", &self.commands)
            .field(
                "session_fs_provider",
                &self.session_fs_provider.as_ref().map(|_| "<set>"),
            )
            .field("handler", &self.handler.as_ref().map(|_| "<set>"))
            .field(
                "hooks_handler",
                &self.hooks_handler.as_ref().map(|_| "<set>"),
            )
            .field("transform", &self.transform.as_ref().map(|_| "<set>"))
            .field("disable_resume", &self.disable_resume)
            .field("continue_pending_work", &self.continue_pending_work)
            .finish()
    }
}

impl ResumeSessionConfig {
    /// Construct a `ResumeSessionConfig` with the given session ID and all
    /// other fields left unset. Combine with `.with_*` builders or struct
    /// update syntax (`..ResumeSessionConfig::new(id)`) to populate the
    /// fields you need.
    pub fn new(session_id: SessionId) -> Self {
        Self {
            session_id,
            client_name: None,
            reasoning_effort: None,
            streaming: None,
            system_message: None,
            tools: None,
            available_tools: None,
            excluded_tools: None,
            mcp_servers: None,
            env_value_mode: default_env_value_mode(),
            enable_config_discovery: None,
            request_user_input: Some(true),
            request_permission: Some(true),
            request_exit_plan_mode: Some(true),
            request_auto_mode_switch: Some(true),
            request_elicitation: Some(true),
            skill_directories: None,
            instruction_directories: None,
            disabled_skills: None,
            hooks: None,
            custom_agents: None,
            default_agent: None,
            agent: None,
            infinite_sessions: None,
            provider: None,
            enable_session_telemetry: None,
            model_capabilities: None,
            config_dir: None,
            working_directory: None,
            github_token: None,
            include_sub_agent_streaming_events: None,
            commands: None,
            session_fs_provider: None,
            disable_resume: None,
            continue_pending_work: None,
            handler: None,
            hooks_handler: None,
            transform: None,
        }
    }

    /// Install a custom [`SessionHandler`] for this session.
    pub fn with_handler(mut self, handler: Arc<dyn SessionHandler>) -> Self {
        self.handler = Some(handler);
        self
    }

    /// Install a [`SessionHooks`] handler. Automatically enables the
    /// wire-level `hooks` flag on session resumption.
    pub fn with_hooks(mut self, hooks: Arc<dyn SessionHooks>) -> Self {
        self.hooks_handler = Some(hooks);
        self
    }

    /// Install a [`SystemMessageTransform`].
    pub fn with_transform(mut self, transform: Arc<dyn SystemMessageTransform>) -> Self {
        self.transform = Some(transform);
        self
    }

    /// Register slash commands for the resumed session. See
    /// [`SessionConfig::with_commands`] — commands are not persisted
    /// server-side, so the resume payload re-supplies the registration.
    pub fn with_commands(mut self, commands: Vec<CommandDefinition>) -> Self {
        self.commands = Some(commands);
        self
    }

    /// Install a [`SessionFsProvider`] backing the resumed session's
    /// filesystem. See [`SessionConfig::with_session_fs_provider`].
    pub fn with_session_fs_provider(mut self, provider: Arc<dyn SessionFsProvider>) -> Self {
        self.session_fs_provider = Some(provider);
        self
    }

    /// Wrap the configured handler so every permission request is
    /// auto-approved. See
    /// [`SessionConfig::approve_all_permissions`] for semantics.
    pub fn approve_all_permissions(mut self) -> Self {
        let inner = self
            .handler
            .take()
            .unwrap_or_else(|| Arc::new(crate::handler::DenyAllHandler));
        self.handler = Some(crate::permission::approve_all(inner));
        self
    }

    /// Wrap the configured handler so every permission request is
    /// auto-denied. See
    /// [`SessionConfig::deny_all_permissions`] for semantics.
    pub fn deny_all_permissions(mut self) -> Self {
        let inner = self
            .handler
            .take()
            .unwrap_or_else(|| Arc::new(crate::handler::DenyAllHandler));
        self.handler = Some(crate::permission::deny_all(inner));
        self
    }

    /// Wrap the configured handler with a predicate-based permission policy.
    /// See [`SessionConfig::approve_permissions_if`] for semantics.
    pub fn approve_permissions_if<F>(mut self, predicate: F) -> Self
    where
        F: Fn(&crate::types::PermissionRequestData) -> bool + Send + Sync + 'static,
    {
        let inner = self
            .handler
            .take()
            .unwrap_or_else(|| Arc::new(crate::handler::DenyAllHandler));
        self.handler = Some(crate::permission::approve_if(inner, predicate));
        self
    }

    /// Set the application name sent as `User-Agent` context.
    pub fn with_client_name(mut self, name: impl Into<String>) -> Self {
        self.client_name = Some(name.into());
        self
    }

    /// Set the reasoning effort to apply on resume.
    pub fn with_reasoning_effort(mut self, effort: impl Into<String>) -> Self {
        self.reasoning_effort = Some(effort.into());
        self
    }

    /// Enable streaming token deltas via `assistant.message_delta` events.
    pub fn with_streaming(mut self, streaming: bool) -> Self {
        self.streaming = Some(streaming);
        self
    }

    /// Re-supply the system message so the agent retains workspace context
    /// across CLI process restarts.
    pub fn with_system_message(mut self, system_message: SystemMessageConfig) -> Self {
        self.system_message = Some(system_message);
        self
    }

    /// Re-supply client-defined tools on resume.
    pub fn with_tools<I: IntoIterator<Item = Tool>>(mut self, tools: I) -> Self {
        self.tools = Some(tools.into_iter().collect());
        self
    }

    /// Set the allowlist of tool names the agent may use.
    pub fn with_available_tools<I, S>(mut self, tools: I) -> Self
    where
        I: IntoIterator<Item = S>,
        S: Into<String>,
    {
        self.available_tools = Some(tools.into_iter().map(Into::into).collect());
        self
    }

    /// Set the blocklist of built-in tool names the agent must not use.
    pub fn with_excluded_tools<I, S>(mut self, tools: I) -> Self
    where
        I: IntoIterator<Item = S>,
        S: Into<String>,
    {
        self.excluded_tools = Some(tools.into_iter().map(Into::into).collect());
        self
    }

    /// Re-supply MCP server configurations on resume.
    pub fn with_mcp_servers(mut self, servers: HashMap<String, McpServerConfig>) -> Self {
        self.mcp_servers = Some(servers);
        self
    }

    /// Enable or disable CLI config discovery on resume.
    pub fn with_enable_config_discovery(mut self, enable: bool) -> Self {
        self.enable_config_discovery = Some(enable);
        self
    }

    /// Enable the `ask_user` tool. Defaults to `Some(true)` via [`Self::new`].
    pub fn with_request_user_input(mut self, enable: bool) -> Self {
        self.request_user_input = Some(enable);
        self
    }

    /// Enable `permission.request` JSON-RPC calls. Defaults to `Some(true)`.
    pub fn with_request_permission(mut self, enable: bool) -> Self {
        self.request_permission = Some(enable);
        self
    }

    /// Enable `exitPlanMode.request` JSON-RPC calls. Defaults to `Some(true)`.
    pub fn with_request_exit_plan_mode(mut self, enable: bool) -> Self {
        self.request_exit_plan_mode = Some(enable);
        self
    }

    /// Enable `autoModeSwitch.request` JSON-RPC calls. Defaults to `Some(true)`.
    pub fn with_request_auto_mode_switch(mut self, enable: bool) -> Self {
        self.request_auto_mode_switch = Some(enable);
        self
    }

    /// Advertise elicitation provider capability on resume. Defaults to `Some(true)`.
    pub fn with_request_elicitation(mut self, enable: bool) -> Self {
        self.request_elicitation = Some(enable);
        self
    }

    /// Set skill directory paths passed through to the CLI on resume.
    pub fn with_skill_directories<I, P>(mut self, paths: I) -> Self
    where
        I: IntoIterator<Item = P>,
        P: Into<PathBuf>,
    {
        self.skill_directories = Some(paths.into_iter().map(Into::into).collect());
        self
    }

    /// Set additional directories to search for custom instruction files
    /// on resume. Forwarded to the CLI; not the same as
    /// [`with_skill_directories`](Self::with_skill_directories).
    pub fn with_instruction_directories<I, P>(mut self, paths: I) -> Self
    where
        I: IntoIterator<Item = P>,
        P: Into<PathBuf>,
    {
        self.instruction_directories = Some(paths.into_iter().map(Into::into).collect());
        self
    }

    /// Set the names of skills to disable on resume.
    pub fn with_disabled_skills<I, S>(mut self, names: I) -> Self
    where
        I: IntoIterator<Item = S>,
        S: Into<String>,
    {
        self.disabled_skills = Some(names.into_iter().map(Into::into).collect());
        self
    }

    /// Re-supply custom agents on resume.
    pub fn with_custom_agents<I: IntoIterator<Item = CustomAgentConfig>>(
        mut self,
        agents: I,
    ) -> Self {
        self.custom_agents = Some(agents.into_iter().collect());
        self
    }

    /// Configure the built-in default agent on resume.
    pub fn with_default_agent(mut self, agent: DefaultAgentConfig) -> Self {
        self.default_agent = Some(agent);
        self
    }

    /// Activate a named custom agent on resume.
    pub fn with_agent(mut self, name: impl Into<String>) -> Self {
        self.agent = Some(name.into());
        self
    }

    /// Re-supply infinite session configuration on resume.
    pub fn with_infinite_sessions(mut self, config: InfiniteSessionConfig) -> Self {
        self.infinite_sessions = Some(config);
        self
    }

    /// Re-supply BYOK provider configuration on resume.
    pub fn with_provider(mut self, provider: ProviderConfig) -> Self {
        self.provider = Some(provider);
        self
    }

    /// Enable or disable internal session telemetry on resume.
    ///
    /// See [`Self::enable_session_telemetry`] for default and BYOK behavior.
    pub fn with_enable_session_telemetry(mut self, enable: bool) -> Self {
        self.enable_session_telemetry = Some(enable);
        self
    }

    /// Set per-property model capability overrides on resume.
    pub fn with_model_capabilities(
        mut self,
        capabilities: crate::generated::api_types::ModelCapabilitiesOverride,
    ) -> Self {
        self.model_capabilities = Some(capabilities);
        self
    }

    /// Override the default configuration directory location on resume.
    pub fn with_config_dir(mut self, dir: impl Into<PathBuf>) -> Self {
        self.config_dir = Some(dir.into());
        self
    }

    /// Set the per-session working directory on resume.
    pub fn with_working_directory(mut self, dir: impl Into<PathBuf>) -> Self {
        self.working_directory = Some(dir.into());
        self
    }

    /// Set the per-session GitHub token on resume. See
    /// [`SessionConfig::github_token`] for distinction from the
    /// client-level token.
    pub fn with_github_token(mut self, token: impl Into<String>) -> Self {
        self.github_token = Some(token.into());
        self
    }

    /// Forward sub-agent streaming events to this connection on resume.
    pub fn with_include_sub_agent_streaming_events(mut self, include: bool) -> Self {
        self.include_sub_agent_streaming_events = Some(include);
        self
    }

    /// Force-fail resume if the session does not exist on disk, instead
    /// of silently starting a new session.
    pub fn with_disable_resume(mut self, disable: bool) -> Self {
        self.disable_resume = Some(disable);
        self
    }

    /// When `true`, instructs the runtime to continue any tool calls or
    /// permission requests that were pending when the previous connection
    /// was dropped. Use this together with
    /// [`Client::force_stop`](crate::Client::force_stop) to hand off a
    /// session from one process to another without losing in-flight work.
    pub fn with_continue_pending_work(mut self, continue_pending: bool) -> Self {
        self.continue_pending_work = Some(continue_pending);
        self
    }
}

/// Controls how the system message is constructed.
///
/// Use `mode: "append"` (default) to add content after the built-in system
/// message, `"replace"` to substitute it entirely, or `"customize"` for
/// section-level overrides.
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
#[non_exhaustive]
pub struct SystemMessageConfig {
    /// How content is applied: `"append"` (default), `"replace"`, or `"customize"`.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub mode: Option<String>,
    /// Content string to append or replace.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub content: Option<String>,
    /// Section-level overrides (used with `mode: "customize"`).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub sections: Option<HashMap<String, SectionOverride>>,
}

impl SystemMessageConfig {
    /// Construct an empty [`SystemMessageConfig`]; all fields default to
    /// unset.
    pub fn new() -> Self {
        Self::default()
    }

    /// Set the application mode: `"append"` (default), `"replace"`, or
    /// `"customize"`.
    pub fn with_mode(mut self, mode: impl Into<String>) -> Self {
        self.mode = Some(mode.into());
        self
    }

    /// Set the system message content (used by `"append"` and `"replace"`
    /// modes).
    pub fn with_content(mut self, content: impl Into<String>) -> Self {
        self.content = Some(content.into());
        self
    }

    /// Set the section-level overrides (used with `mode: "customize"`).
    pub fn with_sections(mut self, sections: HashMap<String, SectionOverride>) -> Self {
        self.sections = Some(sections);
        self
    }
}

/// An override operation for a single system prompt section.
///
/// Used within [`SystemMessageConfig::sections`] when `mode` is `"customize"`.
/// The `action` field determines the operation: `"replace"`, `"remove"`,
/// `"append"`, `"prepend"`, or `"transform"`.
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct SectionOverride {
    /// Override action: `"replace"`, `"remove"`, `"append"`, `"prepend"`, or `"transform"`.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub action: Option<String>,
    /// Content for the override operation.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub content: Option<String>,
}

/// Response from `session.create`.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct CreateSessionResult {
    /// The CLI-assigned session ID.
    pub session_id: SessionId,
    /// Workspace directory for the session (infinite sessions).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub workspace_path: Option<PathBuf>,
    /// Remote session URL, if the session is running remotely.
    #[serde(default, alias = "remote_url")]
    pub remote_url: Option<String>,
    /// Capabilities negotiated with the CLI for this session.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub capabilities: Option<SessionCapabilities>,
}

/// Severity level for [`Session::log`](crate::session::Session::log) messages.
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "lowercase")]
pub enum LogLevel {
    /// Informational message (default).
    #[default]
    Info,
    /// Warning message.
    Warning,
    /// Error message.
    Error,
}

/// Options for [`Session::log`](crate::session::Session::log).
///
/// Pass `None` to `log` for defaults (info level, persisted to the session
/// event log on disk).
#[derive(Debug, Clone, Default, PartialEq, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct LogOptions {
    /// Log severity. `None` lets the server pick (defaults to `info`).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub level: Option<LogLevel>,
    /// When `Some(true)`, the message is transient and not persisted to the
    /// session event log on disk. `None` lets the server pick.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub ephemeral: Option<bool>,
}

impl LogOptions {
    /// Set [`level`](Self::level).
    pub fn with_level(mut self, level: LogLevel) -> Self {
        self.level = Some(level);
        self
    }

    /// Set [`ephemeral`](Self::ephemeral).
    pub fn with_ephemeral(mut self, ephemeral: bool) -> Self {
        self.ephemeral = Some(ephemeral);
        self
    }
}

/// Options for [`Session::set_model`](crate::session::Session::set_model).
///
/// Pass `None` to `set_model` to switch model without any overrides.
#[derive(Debug, Clone, Default)]
pub struct SetModelOptions {
    /// Reasoning effort for the new model (e.g. `"low"`, `"medium"`,
    /// `"high"`, `"xhigh"`).
    pub reasoning_effort: Option<String>,
    /// Override individual model capabilities resolved by the runtime. Only
    /// fields set on the override are applied; the rest fall back to the
    /// runtime-resolved values for the model.
    pub model_capabilities: Option<crate::generated::api_types::ModelCapabilitiesOverride>,
}

impl SetModelOptions {
    /// Set [`reasoning_effort`](Self::reasoning_effort).
    pub fn with_reasoning_effort(mut self, effort: impl Into<String>) -> Self {
        self.reasoning_effort = Some(effort.into());
        self
    }

    /// Set [`model_capabilities`](Self::model_capabilities).
    pub fn with_model_capabilities(
        mut self,
        caps: crate::generated::api_types::ModelCapabilitiesOverride,
    ) -> Self {
        self.model_capabilities = Some(caps);
        self
    }
}

/// Response from the top-level `ping` RPC.
///
/// The `protocol_version` field is the most commonly-inspected piece —
/// see [`Client::verify_protocol_version`].
///
/// [`Client::verify_protocol_version`]: crate::Client::verify_protocol_version
#[derive(Debug, Clone, Default, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct PingResponse {
    /// The message echoed back by the CLI.
    #[serde(default)]
    pub message: String,
    /// Server-side timestamp (Unix epoch milliseconds).
    #[serde(default)]
    pub timestamp: i64,
    /// The protocol version negotiated by the CLI, if reported.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub protocol_version: Option<u32>,
}

/// Line range for file attachments.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct AttachmentLineRange {
    /// First line (1-based).
    pub start: u32,
    /// Last line (inclusive).
    pub end: u32,
}

/// Cursor position within a file selection.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct AttachmentSelectionPosition {
    /// Line number (0-based).
    pub line: u32,
    /// Character offset (0-based).
    pub character: u32,
}

/// Range of selected text within a file.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct AttachmentSelectionRange {
    /// Start position.
    pub start: AttachmentSelectionPosition,
    /// End position.
    pub end: AttachmentSelectionPosition,
}

/// Type of GitHub reference attachment.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
#[non_exhaustive]
pub enum GitHubReferenceType {
    /// GitHub issue.
    Issue,
    /// GitHub pull request.
    Pr,
    /// GitHub discussion.
    Discussion,
}

/// An attachment included with a user message.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[serde(
    tag = "type",
    rename_all = "camelCase",
    rename_all_fields = "camelCase"
)]
#[non_exhaustive]
pub enum Attachment {
    /// A file path, optionally with a line range.
    File {
        /// Absolute path to the file.
        path: PathBuf,
        /// Label shown in the UI.
        #[serde(skip_serializing_if = "Option::is_none")]
        display_name: Option<String>,
        /// Optional line range to focus on.
        #[serde(skip_serializing_if = "Option::is_none")]
        line_range: Option<AttachmentLineRange>,
    },
    /// A directory path.
    Directory {
        /// Absolute path to the directory.
        path: PathBuf,
        /// Label shown in the UI.
        #[serde(skip_serializing_if = "Option::is_none")]
        display_name: Option<String>,
    },
    /// A text selection within a file.
    Selection {
        /// Path to the file containing the selection.
        file_path: PathBuf,
        /// The selected text content.
        text: String,
        /// Label shown in the UI.
        #[serde(skip_serializing_if = "Option::is_none")]
        display_name: Option<String>,
        /// Character range of the selection.
        selection: AttachmentSelectionRange,
    },
    /// Raw binary data (e.g. an image).
    Blob {
        /// Base64-encoded data.
        data: String,
        /// MIME type of the data.
        mime_type: String,
        /// Label shown in the UI.
        #[serde(skip_serializing_if = "Option::is_none")]
        display_name: Option<String>,
    },
    /// A reference to a GitHub issue, PR, or discussion.
    #[serde(rename = "github_reference")]
    GitHubReference {
        /// Issue/PR/discussion number.
        number: u64,
        /// Title of the referenced item.
        title: String,
        /// Kind of reference.
        reference_type: GitHubReferenceType,
        /// Current state (e.g. "open", "closed").
        state: String,
        /// URL to the referenced item.
        url: String,
    },
}

impl Attachment {
    /// Returns the display name, if set.
    pub fn display_name(&self) -> Option<&str> {
        match self {
            Self::File { display_name, .. }
            | Self::Directory { display_name, .. }
            | Self::Selection { display_name, .. }
            | Self::Blob { display_name, .. } => display_name.as_deref(),
            Self::GitHubReference { .. } => None,
        }
    }

    /// Returns a human-readable label, deriving one from the path if needed.
    pub fn label(&self) -> Option<String> {
        if let Some(display_name) = self
            .display_name()
            .map(str::trim)
            .filter(|name| !name.is_empty())
        {
            return Some(display_name.to_string());
        }

        match self {
            Self::GitHubReference { number, title, .. } => Some(if title.trim().is_empty() {
                format!("#{}", number)
            } else {
                title.trim().to_string()
            }),
            _ => self.derived_display_name(),
        }
    }

    /// Ensure `display_name` is populated when the variant supports one.
    pub fn ensure_display_name(&mut self) {
        if self
            .display_name()
            .map(str::trim)
            .is_some_and(|name| !name.is_empty())
        {
            return;
        }

        let Some(derived_display_name) = self.derived_display_name() else {
            return;
        };

        match self {
            Self::File { display_name, .. }
            | Self::Directory { display_name, .. }
            | Self::Selection { display_name, .. }
            | Self::Blob { display_name, .. } => *display_name = Some(derived_display_name),
            Self::GitHubReference { .. } => {}
        }
    }

    fn derived_display_name(&self) -> Option<String> {
        match self {
            Self::File { path, .. } | Self::Directory { path, .. } => {
                Some(attachment_name_from_path(path))
            }
            Self::Selection { file_path, .. } => Some(attachment_name_from_path(file_path)),
            Self::Blob { .. } => Some("attachment".to_string()),
            Self::GitHubReference { .. } => None,
        }
    }
}

fn attachment_name_from_path(path: &Path) -> String {
    path.file_name()
        .map(|name| name.to_string_lossy().into_owned())
        .filter(|name| !name.is_empty())
        .unwrap_or_else(|| {
            let full = path.to_string_lossy();
            if full.is_empty() {
                "attachment".to_string()
            } else {
                full.into_owned()
            }
        })
}

/// Normalize a list of attachments so every entry has a `display_name`.
pub fn ensure_attachment_display_names(attachments: &mut [Attachment]) {
    for attachment in attachments {
        attachment.ensure_display_name();
    }
}

/// Message delivery mode for [`MessageOptions::mode`].
///
/// Controls how a prompt is delivered relative to in-flight session work.
/// Wire values: `"enqueue"` and `"immediate"`.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[serde(rename_all = "lowercase")]
#[non_exhaustive]
pub enum DeliveryMode {
    /// Queue the prompt behind any in-flight work (default).
    Enqueue,
    /// Interrupt the session and run the prompt immediately.
    Immediate,
}

/// Options for sending a user message to the agent.
///
/// Used by both [`Session::send`](crate::session::Session::send) and
/// [`Session::send_and_wait`](crate::session::Session::send_and_wait); the
/// `wait_timeout` field is honored only by `send_and_wait` and is ignored by
/// `send`.
///
/// `MessageOptions` is `#[non_exhaustive]` and constructed via [`MessageOptions::new`]
/// plus the `with_*` chain so future fields can land without breaking callers.
/// For the trivial case, both `&str` and `String` implement `Into<MessageOptions>`,
/// so:
///
/// ```no_run
/// # use github_copilot_sdk::session::Session;
/// # async fn run(session: Session) -> Result<(), github_copilot_sdk::Error> {
/// session.send("hello").await?;
/// # Ok(()) }
/// ```
///
/// is equivalent to:
///
/// ```no_run
/// # use github_copilot_sdk::session::Session;
/// # use github_copilot_sdk::types::MessageOptions;
/// # async fn run(session: Session) -> Result<(), github_copilot_sdk::Error> {
/// session.send(MessageOptions::new("hello")).await?;
/// # Ok(()) }
/// ```
#[derive(Debug, Clone)]
#[non_exhaustive]
pub struct MessageOptions {
    /// The user prompt to send.
    pub prompt: String,
    /// Optional message delivery mode for this turn.
    ///
    /// Controls whether the prompt is queued behind in-flight work
    /// ([`DeliveryMode::Enqueue`], default) or interrupts the session and
    /// runs immediately ([`DeliveryMode::Immediate`]).
    pub mode: Option<DeliveryMode>,
    /// Optional attachments to include with the message.
    pub attachments: Option<Vec<Attachment>>,
    /// Maximum time to wait for the session to go idle. Honored only by
    /// `send_and_wait`. Defaults to 60 seconds when unset.
    pub wait_timeout: Option<Duration>,
    /// Custom HTTP headers to include in outbound model requests for this
    /// turn. When `None` or empty, no `requestHeaders` field is sent on
    /// the wire.
    pub request_headers: Option<HashMap<String, String>>,
    /// W3C Trace Context `traceparent` header for this turn.
    ///
    /// Per-turn override that takes precedence over
    /// [`ClientOptions::on_get_trace_context`](crate::ClientOptions::on_get_trace_context).
    /// When `None`, the SDK falls back to the provider (if configured)
    /// before omitting the field.
    pub traceparent: Option<String>,
    /// W3C Trace Context `tracestate` header for this turn.
    ///
    /// Per-turn override paired with [`traceparent`](Self::traceparent).
    pub tracestate: Option<String>,
}

impl MessageOptions {
    /// Build a new `MessageOptions` with just a prompt.
    pub fn new(prompt: impl Into<String>) -> Self {
        Self {
            prompt: prompt.into(),
            mode: None,
            attachments: None,
            wait_timeout: None,
            request_headers: None,
            traceparent: None,
            tracestate: None,
        }
    }

    /// Set the message delivery mode for this turn.
    ///
    /// Pass [`DeliveryMode::Immediate`] to interrupt the session and run
    /// the prompt now; the default ([`DeliveryMode::Enqueue`]) queues the
    /// prompt behind in-flight work.
    pub fn with_mode(mut self, mode: DeliveryMode) -> Self {
        self.mode = Some(mode);
        self
    }

    /// Attach files / selections / blobs to the message.
    pub fn with_attachments(mut self, attachments: Vec<Attachment>) -> Self {
        self.attachments = Some(attachments);
        self
    }

    /// Override the default 60-second wait timeout for `send_and_wait`.
    pub fn with_wait_timeout(mut self, timeout: Duration) -> Self {
        self.wait_timeout = Some(timeout);
        self
    }

    /// Set custom HTTP headers for outbound model requests for this turn.
    pub fn with_request_headers(mut self, headers: HashMap<String, String>) -> Self {
        self.request_headers = Some(headers);
        self
    }

    /// Set both `traceparent` and `tracestate` from a [`TraceContext`].
    /// Either field may remain `None` if the [`TraceContext`] has no value
    /// for it. Use [`with_traceparent`](Self::with_traceparent) or
    /// [`with_tracestate`](Self::with_tracestate) to set them individually.
    pub fn with_trace_context(mut self, ctx: TraceContext) -> Self {
        self.traceparent = ctx.traceparent;
        self.tracestate = ctx.tracestate;
        self
    }

    /// Set the W3C `traceparent` header for this turn.
    pub fn with_traceparent(mut self, traceparent: impl Into<String>) -> Self {
        self.traceparent = Some(traceparent.into());
        self
    }

    /// Set the W3C `tracestate` header for this turn.
    pub fn with_tracestate(mut self, tracestate: impl Into<String>) -> Self {
        self.tracestate = Some(tracestate.into());
        self
    }
}

impl From<&str> for MessageOptions {
    fn from(prompt: &str) -> Self {
        Self::new(prompt)
    }
}

impl From<String> for MessageOptions {
    fn from(prompt: String) -> Self {
        Self::new(prompt)
    }
}

impl From<&String> for MessageOptions {
    fn from(prompt: &String) -> Self {
        Self::new(prompt.clone())
    }
}

/// Response from [`Client::get_status`](crate::Client::get_status).
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
#[non_exhaustive]
pub struct GetStatusResponse {
    /// Package version (e.g. `"1.0.0"`).
    pub version: String,
    /// Protocol version for SDK compatibility.
    pub protocol_version: u32,
}

/// Response from [`Client::get_auth_status`](crate::Client::get_auth_status).
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
#[non_exhaustive]
pub struct GetAuthStatusResponse {
    /// Whether the user is authenticated.
    pub is_authenticated: bool,
    /// Authentication type (e.g. `"user"`, `"env"`, `"gh-cli"`, `"hmac"`,
    /// `"api-key"`, `"token"`).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub auth_type: Option<String>,
    /// GitHub host URL.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub host: Option<String>,
    /// User login name.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub login: Option<String>,
    /// Human-readable status message.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub status_message: Option<String>,
}

/// Wrapper for session event notifications received from the CLI.
///
/// The CLI sends these as JSON-RPC notifications on the `session.event` method.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct SessionEventNotification {
    /// The session this event belongs to.
    pub session_id: SessionId,
    /// The event payload.
    pub event: SessionEvent,
}

/// A single event in a session's timeline.
///
/// Events form a linked chain via `parent_id`. The `event_type` string
/// identifies the kind (e.g. `"assistant.message_delta"`, `"session.idle"`,
/// `"tool.execution_start"`). Event-specific payload is in `data` as
/// untyped JSON.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct SessionEvent {
    /// Unique event ID (UUID v4).
    pub id: String,
    /// ISO 8601 timestamp.
    pub timestamp: String,
    /// ID of the preceding event in the chain.
    pub parent_id: Option<String>,
    /// Transient events that are not persisted to disk.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub ephemeral: Option<bool>,
    /// Sub-agent instance identifier. Absent for events emitted by the
    /// root/main agent and for session-level events.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub agent_id: Option<String>,
    /// Debug timestamp: when the CLI received this event (ms since epoch).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub debug_cli_received_at_ms: Option<i64>,
    /// Debug timestamp: when the event was forwarded over WebSocket.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub debug_ws_forwarded_at_ms: Option<i64>,
    /// Event type string (e.g. `"assistant.message"`, `"session.idle"`).
    #[serde(rename = "type")]
    pub event_type: String,
    /// Event-specific data. Structure depends on `event_type`.
    pub data: Value,
}

impl SessionEvent {
    /// Parse the string `event_type` into a typed [`SessionEventType`](crate::generated::SessionEventType) enum.
    ///
    /// Returns `SessionEventType::Unknown` for unrecognized event types,
    /// ensuring forward compatibility with newer CLI versions.
    pub fn parsed_type(&self) -> crate::generated::SessionEventType {
        use serde::de::IntoDeserializer;
        let deserializer: serde::de::value::StrDeserializer<'_, serde::de::value::Error> =
            self.event_type.as_str().into_deserializer();
        crate::generated::SessionEventType::deserialize(deserializer)
            .unwrap_or(crate::generated::SessionEventType::Unknown)
    }

    /// Deserialize the event `data` field into a typed struct.
    ///
    /// Returns `None` if deserialization fails (e.g. unknown event type
    /// or schema mismatch). Prefer typed data accessors for specific
    /// event types where you need strongly-typed field access.
    pub fn typed_data<T: serde::de::DeserializeOwned>(&self) -> Option<T> {
        serde_json::from_value(self.data.clone()).ok()
    }

    /// `model_call` errors are transient — the CLI agent loop continues
    /// after them and may succeed on the next turn. These should not be
    /// treated as session-ending errors.
    pub fn is_transient_error(&self) -> bool {
        self.event_type == "session.error"
            && self.data.get("errorType").and_then(|v| v.as_str()) == Some("model_call")
    }
}

/// A request from the CLI to invoke a client-defined tool.
///
/// Received as a JSON-RPC request on the `tool.call` method. The client
/// must respond with a [`ToolResultResponse`].
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
#[non_exhaustive]
pub struct ToolInvocation {
    /// Session that owns this tool call.
    pub session_id: SessionId,
    /// Unique ID for this tool call, used to correlate the response.
    pub tool_call_id: String,
    /// Name of the tool being invoked.
    pub tool_name: String,
    /// Tool arguments as JSON.
    pub arguments: Value,
    /// W3C Trace Context `traceparent` header propagated from the CLI's
    /// `execute_tool` span. Pass through to OpenTelemetry-aware code so
    /// child spans created inside the handler are parented to the CLI
    /// span. `None` when the CLI has no trace context for this call.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub traceparent: Option<String>,
    /// W3C Trace Context `tracestate` paired with
    /// [`traceparent`](Self::traceparent).
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub tracestate: Option<String>,
}

impl ToolInvocation {
    /// Deserialize this invocation's [`arguments`](Self::arguments) into a
    /// strongly-typed parameter struct.
    ///
    /// Idiomatic way to extract typed parameters when implementing
    /// [`ToolHandler`](crate::tool::ToolHandler) directly. Equivalent to
    /// `serde_json::from_value(invocation.arguments.clone())` with the SDK's
    /// error type.
    ///
    /// # Example
    ///
    /// ```rust,no_run
    /// # use github_copilot_sdk::{Error, types::ToolInvocation, ToolResult};
    /// # use serde::Deserialize;
    /// # #[derive(Deserialize)] struct MyParams { city: String }
    /// # async fn example(inv: ToolInvocation) -> Result<ToolResult, Error> {
    /// let params: MyParams = inv.params()?;
    /// // …use `inv.session_id` / `inv.tool_call_id` alongside `params`…
    /// # let _ = params; Ok(ToolResult::Text(String::new()))
    /// # }
    /// ```
    pub fn params<P: serde::de::DeserializeOwned>(&self) -> Result<P, crate::Error> {
        serde_json::from_value(self.arguments.clone()).map_err(crate::Error::from)
    }

    /// Returns the propagated [`TraceContext`] for this invocation, or
    /// [`TraceContext::default()`] when the CLI sent no headers.
    pub fn trace_context(&self) -> TraceContext {
        TraceContext {
            traceparent: self.traceparent.clone(),
            tracestate: self.tracestate.clone(),
        }
    }
}

/// Binary content returned by a tool.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct ToolBinaryResult {
    /// Base64-encoded binary data.
    pub data: String,
    /// MIME type for the binary data.
    pub mime_type: String,
    /// Type identifier for the binary result.
    pub r#type: String,
    /// Optional description shown alongside the binary result.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub description: Option<String>,
}

/// Expanded tool result with metadata for the LLM and session log.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct ToolResultExpanded {
    /// Result text sent back to the LLM.
    pub text_result_for_llm: String,
    /// `"success"` or `"failure"`.
    pub result_type: String,
    /// Binary payloads sent back to the LLM.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub binary_results_for_llm: Option<Vec<ToolBinaryResult>>,
    /// Optional log message for the session timeline.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub session_log: Option<String>,
    /// Error message, if the tool failed.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub error: Option<String>,
    /// Tool-specific telemetry emitted with the result.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub tool_telemetry: Option<HashMap<String, Value>>,
}

/// Result of a tool invocation — either a plain text string or an expanded result.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(untagged)]
#[non_exhaustive]
pub enum ToolResult {
    /// Simple text result passed directly to the LLM.
    Text(String),
    /// Structured result with metadata.
    Expanded(ToolResultExpanded),
}

/// JSON-RPC response wrapper for a tool result, sent back to the CLI.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct ToolResultResponse {
    /// The tool result payload.
    pub result: ToolResult,
}

/// Metadata for a persisted session, returned by `session.list`.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct SessionMetadata {
    /// The session's unique identifier.
    pub session_id: SessionId,
    /// ISO 8601 timestamp when the session was created.
    pub start_time: String,
    /// ISO 8601 timestamp of the last modification.
    pub modified_time: String,
    /// Agent-generated session summary.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub summary: Option<String>,
    /// Whether the session is running remotely.
    pub is_remote: bool,
}

/// Response from `session.list`.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct ListSessionsResponse {
    /// The list of session metadata entries.
    pub sessions: Vec<SessionMetadata>,
}

/// Filter options for [`Client::list_sessions`](crate::Client::list_sessions).
///
/// All fields are optional; unset fields don't constrain the result.
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct SessionListFilter {
    /// Filter by exact `cwd` match.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub cwd: Option<String>,
    /// Filter by git root path.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub git_root: Option<String>,
    /// Filter by repository in `owner/repo` form.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub repository: Option<String>,
    /// Filter by git branch name.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub branch: Option<String>,
}

/// Response from `session.getMetadata`.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct GetSessionMetadataResponse {
    /// The session metadata, or `None` if the session was not found.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub session: Option<SessionMetadata>,
}

/// Response from `session.getLastId`.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct GetLastSessionIdResponse {
    /// The most recently updated session ID, or `None` if no sessions exist.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub session_id: Option<SessionId>,
}

/// Response from `session.getForeground`.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct GetForegroundSessionResponse {
    /// The current foreground session ID, or `None` if no foreground session.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub session_id: Option<SessionId>,
}

/// Response from `session.getMessages`.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct GetMessagesResponse {
    /// Timeline events for the session.
    pub events: Vec<SessionEvent>,
}

/// Result of an elicitation (interactive UI form) request.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct ElicitationResult {
    /// User's action: `"accept"`, `"decline"`, or `"cancel"`.
    pub action: String,
    /// Form data submitted by the user (present when action is `"accept"`).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub content: Option<Value>,
}

/// Elicitation display mode.
///
/// New modes may be added by the CLI in future protocol versions; the
/// `Unknown` variant keeps deserialization from failing on unrecognised
/// values so the SDK can still surface the request to callers.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
#[non_exhaustive]
pub enum ElicitationMode {
    /// Structured form input rendered by the host.
    Form,
    /// Browser redirect to a URL.
    Url,
    /// A mode not yet known to this SDK version.
    #[serde(other)]
    Unknown,
}

/// An incoming elicitation request from the CLI (provider side).
///
/// Received via `elicitation.requested` session event when the session was
/// created with `request_elicitation: true`. The provider should render a
/// form or dialog and return an [`ElicitationResult`].
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct ElicitationRequest {
    /// Message describing what information is needed from the user.
    pub message: String,
    /// JSON Schema describing the form fields to present.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub requested_schema: Option<Value>,
    /// Elicitation display mode.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub mode: Option<ElicitationMode>,
    /// The source that initiated the request (e.g. MCP server name).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub elicitation_source: Option<String>,
    /// URL to open in the user's browser (url mode only).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub url: Option<String>,
}

/// Session-level capabilities reported by the CLI after session creation.
///
/// Capabilities indicate which features the CLI host supports for this session.
/// Updated at runtime via `capabilities.changed` events.
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct SessionCapabilities {
    /// UI capabilities (elicitation support, etc.).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub ui: Option<UiCapabilities>,
}

/// UI-specific capabilities for a session.
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct UiCapabilities {
    /// Whether the host supports interactive elicitation dialogs.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub elicitation: Option<bool>,
}

/// Options for the [`SessionUi::input`](crate::session::SessionUi::input) convenience method.
#[derive(Debug, Clone, Default)]
pub struct InputOptions<'a> {
    /// Title label for the input field.
    pub title: Option<&'a str>,
    /// Descriptive text shown below the field.
    pub description: Option<&'a str>,
    /// Minimum character length.
    pub min_length: Option<u64>,
    /// Maximum character length.
    pub max_length: Option<u64>,
    /// Semantic format hint.
    pub format: Option<InputFormat>,
    /// Default value pre-populated in the field.
    pub default: Option<&'a str>,
}

/// Semantic format hints for text input fields.
#[derive(Debug, Clone, Copy)]
#[non_exhaustive]
pub enum InputFormat {
    /// Email address.
    Email,
    /// URI.
    Uri,
    /// Calendar date.
    Date,
    /// Date and time.
    DateTime,
}

impl InputFormat {
    /// Returns the JSON Schema format string for this variant.
    pub fn as_str(&self) -> &'static str {
        match self {
            Self::Email => "email",
            Self::Uri => "uri",
            Self::Date => "date",
            Self::DateTime => "date-time",
        }
    }
}

/// Re-exports of generated protocol types that are part of the SDK's
/// public API surface. The canonical definitions live in
/// [`crate::generated::api_types`]; they live here so the crate-root
/// `pub use types::*` surfaces them alongside hand-written SDK types.
pub use crate::generated::api_types::{
    Model, ModelBilling, ModelCapabilities, ModelCapabilitiesLimits, ModelCapabilitiesLimitsVision,
    ModelCapabilitiesSupports, ModelList, ModelPolicy,
};

/// Permission categories the CLI may request approval for.
///
/// Wire values are the lower-kebab strings the CLI sends as the `kind`
/// discriminator on a permission request. Marked `#[non_exhaustive]`
/// because the CLI may add new kinds; matches must include a `_` arm.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[serde(rename_all = "kebab-case")]
#[non_exhaustive]
pub enum PermissionRequestKind {
    /// Run a shell command.
    Shell,
    /// Write to a file.
    Write,
    /// Read a file.
    Read,
    /// Open a URL.
    Url,
    /// Invoke an MCP server tool.
    Mcp,
    /// Invoke a client-defined custom tool.
    CustomTool,
    /// Update agent memory.
    Memory,
    /// Run a hook callback.
    Hook,
    /// Unrecognized kind. The original wire string is available in
    /// [`PermissionRequestData::extra`] under the `kind` key.
    #[serde(other)]
    Unknown,
}

/// Data sent by the CLI for permission-related events.
///
/// Used for both the `permission.request` RPC call (which expects a response)
/// and `permission.requested` notifications (fire-and-forget). Contains the
/// full params object. Note that `requestId` is also available as a separate
/// field on `HandlerEvent::PermissionRequest`.
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct PermissionRequestData {
    /// The permission category being requested. `None` means the CLI did
    /// not include a `kind` field. Use this to branch on common cases
    /// (shell, write, etc.) without parsing [`extra`](Self::extra).
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub kind: Option<PermissionRequestKind>,
    /// The originating tool-call ID, if this permission request is tied
    /// to a specific tool invocation.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub tool_call_id: Option<String>,
    /// The full permission request params from the CLI. The shape varies by
    /// permission type and CLI version, so we preserve it as `Value`.
    #[serde(flatten)]
    pub extra: Value,
}

/// Data sent by the CLI with an `exitPlanMode.request` RPC call.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct ExitPlanModeData {
    /// Markdown summary of the plan presented to the user.
    #[serde(default)]
    pub summary: String,
    /// Full plan content (e.g. the plan.md body), if available.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub plan_content: Option<String>,
    /// Allowed exit actions (e.g. "interactive", "autopilot", "autopilot_fleet").
    #[serde(default)]
    pub actions: Vec<String>,
    /// Which action the CLI recommends, defaults to "autopilot".
    #[serde(default = "default_recommended_action")]
    pub recommended_action: String,
}

fn default_recommended_action() -> String {
    "autopilot".to_string()
}

impl Default for ExitPlanModeData {
    fn default() -> Self {
        Self {
            summary: String::new(),
            plan_content: None,
            actions: Vec::new(),
            recommended_action: default_recommended_action(),
        }
    }
}

#[cfg(test)]
mod tests {
    use std::path::PathBuf;

    use serde_json::json;

    use super::{
        Attachment, AttachmentLineRange, AttachmentSelectionPosition, AttachmentSelectionRange,
        ConnectionState, CustomAgentConfig, DeliveryMode, GitHubReferenceType,
        InfiniteSessionConfig, ProviderConfig, ResumeSessionConfig, SessionConfig, SessionEvent,
        SessionId, SystemMessageConfig, Tool, ToolBinaryResult, ToolResult, ToolResultExpanded,
        ToolResultResponse, ensure_attachment_display_names,
    };
    use crate::generated::session_events::TypedSessionEvent;

    #[test]
    fn tool_builder_composes() {
        let tool = Tool::new("greet")
            .with_description("Say hello")
            .with_namespaced_name("hello/greet")
            .with_instructions("Pass the user's name")
            .with_parameters(json!({
                "type": "object",
                "properties": { "name": { "type": "string" } },
                "required": ["name"]
            }))
            .with_overrides_built_in_tool(true)
            .with_skip_permission(true);
        assert_eq!(tool.name, "greet");
        assert_eq!(tool.description, "Say hello");
        assert_eq!(tool.namespaced_name.as_deref(), Some("hello/greet"));
        assert_eq!(tool.instructions.as_deref(), Some("Pass the user's name"));
        assert_eq!(tool.parameters.get("type").unwrap(), &json!("object"));
        assert!(tool.overrides_built_in_tool);
        assert!(tool.skip_permission);
    }

    #[test]
    fn tool_with_parameters_handles_non_object_value() {
        let tool = Tool::new("noop").with_parameters(json!(null));
        assert!(tool.parameters.is_empty());
    }

    #[test]
    fn tool_result_expanded_serializes_binary_results_for_llm() {
        let response = ToolResultResponse {
            result: ToolResult::Expanded(ToolResultExpanded {
                text_result_for_llm: "rendered chart".to_string(),
                result_type: "success".to_string(),
                binary_results_for_llm: Some(vec![ToolBinaryResult {
                    data: "aW1n".to_string(),
                    mime_type: "image/png".to_string(),
                    r#type: "image".to_string(),
                    description: Some("chart preview".to_string()),
                }]),
                session_log: None,
                error: None,
                tool_telemetry: None,
            }),
        };

        let wire = serde_json::to_value(&response).unwrap();

        assert_eq!(
            wire,
            json!({
                "result": {
                    "textResultForLlm": "rendered chart",
                    "resultType": "success",
                    "binaryResultsForLlm": [
                        {
                            "data": "aW1n",
                            "mimeType": "image/png",
                            "type": "image",
                            "description": "chart preview"
                        }
                    ]
                }
            })
        );
    }

    #[test]
    fn tool_result_expanded_omits_binary_results_for_llm_when_none() {
        let response = ToolResultResponse {
            result: ToolResult::Expanded(ToolResultExpanded {
                text_result_for_llm: "ok".to_string(),
                result_type: "success".to_string(),
                binary_results_for_llm: None,
                session_log: None,
                error: None,
                tool_telemetry: None,
            }),
        };

        let wire = serde_json::to_value(&response).unwrap();

        assert_eq!(wire["result"]["textResultForLlm"], "ok");
        assert!(wire["result"].get("binaryResultsForLlm").is_none());
    }

    #[test]
    fn session_config_default_enables_permission_flow_flags() {
        let cfg = SessionConfig::default();
        assert_eq!(cfg.request_user_input, Some(true));
        assert_eq!(cfg.request_permission, Some(true));
        assert_eq!(cfg.request_elicitation, Some(true));
        assert_eq!(cfg.request_exit_plan_mode, Some(true));
        assert_eq!(cfg.request_auto_mode_switch, Some(true));
    }

    #[test]
    fn resume_session_config_new_enables_permission_flow_flags() {
        let cfg = ResumeSessionConfig::new(SessionId::from("test-id"));
        assert_eq!(cfg.request_user_input, Some(true));
        assert_eq!(cfg.request_permission, Some(true));
        assert_eq!(cfg.request_elicitation, Some(true));
        assert_eq!(cfg.request_exit_plan_mode, Some(true));
        assert_eq!(cfg.request_auto_mode_switch, Some(true));
    }

    #[test]
    fn session_config_builder_composes() {
        use std::collections::HashMap;

        let cfg = SessionConfig::default()
            .with_session_id(SessionId::from("sess-1"))
            .with_model("claude-sonnet-4")
            .with_client_name("test-app")
            .with_reasoning_effort("medium")
            .with_streaming(true)
            .with_tools([Tool::new("greet")])
            .with_available_tools(["bash", "view"])
            .with_excluded_tools(["dangerous"])
            .with_mcp_servers(HashMap::new())
            .with_enable_config_discovery(true)
            .with_request_user_input(false)
            .with_request_exit_plan_mode(false)
            .with_request_auto_mode_switch(false)
            .with_skill_directories([PathBuf::from("/tmp/skills")])
            .with_disabled_skills(["broken-skill"])
            .with_agent("researcher")
            .with_config_dir(PathBuf::from("/tmp/config"))
            .with_working_directory(PathBuf::from("/tmp/work"))
            .with_github_token("ghp_test")
            .with_enable_session_telemetry(false)
            .with_include_sub_agent_streaming_events(false);

        assert_eq!(cfg.session_id.as_ref().map(|s| s.as_str()), Some("sess-1"));
        assert_eq!(cfg.model.as_deref(), Some("claude-sonnet-4"));
        assert_eq!(cfg.client_name.as_deref(), Some("test-app"));
        assert_eq!(cfg.reasoning_effort.as_deref(), Some("medium"));
        assert_eq!(cfg.streaming, Some(true));
        assert_eq!(cfg.tools.as_ref().map(|t| t.len()), Some(1));
        assert_eq!(
            cfg.available_tools.as_deref(),
            Some(&["bash".to_string(), "view".to_string()][..])
        );
        assert_eq!(
            cfg.excluded_tools.as_deref(),
            Some(&["dangerous".to_string()][..])
        );
        assert!(cfg.mcp_servers.is_some());
        assert_eq!(cfg.enable_config_discovery, Some(true));
        assert_eq!(cfg.request_user_input, Some(false)); // overrode default
        assert_eq!(cfg.request_permission, Some(true)); // default preserved
        assert_eq!(cfg.request_exit_plan_mode, Some(false));
        assert_eq!(cfg.request_auto_mode_switch, Some(false));
        assert_eq!(
            cfg.skill_directories.as_deref(),
            Some(&[PathBuf::from("/tmp/skills")][..])
        );
        assert_eq!(
            cfg.disabled_skills.as_deref(),
            Some(&["broken-skill".to_string()][..])
        );
        assert_eq!(cfg.agent.as_deref(), Some("researcher"));
        assert_eq!(cfg.config_dir, Some(PathBuf::from("/tmp/config")));
        assert_eq!(cfg.working_directory, Some(PathBuf::from("/tmp/work")));
        assert_eq!(cfg.github_token.as_deref(), Some("ghp_test"));
        assert_eq!(cfg.enable_session_telemetry, Some(false));
        assert_eq!(cfg.include_sub_agent_streaming_events, Some(false));
    }

    #[test]
    fn resume_session_config_builder_composes() {
        use std::collections::HashMap;

        let cfg = ResumeSessionConfig::new(SessionId::from("sess-2"))
            .with_client_name("test-app")
            .with_streaming(true)
            .with_tools([Tool::new("greet")])
            .with_available_tools(["bash", "view"])
            .with_excluded_tools(["dangerous"])
            .with_mcp_servers(HashMap::new())
            .with_enable_config_discovery(true)
            .with_request_user_input(false)
            .with_request_exit_plan_mode(false)
            .with_request_auto_mode_switch(false)
            .with_skill_directories([PathBuf::from("/tmp/skills")])
            .with_disabled_skills(["broken-skill"])
            .with_agent("researcher")
            .with_config_dir(PathBuf::from("/tmp/config"))
            .with_working_directory(PathBuf::from("/tmp/work"))
            .with_github_token("ghp_test")
            .with_enable_session_telemetry(false)
            .with_include_sub_agent_streaming_events(true)
            .with_disable_resume(true)
            .with_continue_pending_work(true);

        assert_eq!(cfg.session_id.as_str(), "sess-2");
        assert_eq!(cfg.client_name.as_deref(), Some("test-app"));
        assert_eq!(cfg.streaming, Some(true));
        assert_eq!(cfg.tools.as_ref().map(|t| t.len()), Some(1));
        assert_eq!(
            cfg.available_tools.as_deref(),
            Some(&["bash".to_string(), "view".to_string()][..])
        );
        assert_eq!(
            cfg.excluded_tools.as_deref(),
            Some(&["dangerous".to_string()][..])
        );
        assert!(cfg.mcp_servers.is_some());
        assert_eq!(cfg.enable_config_discovery, Some(true));
        assert_eq!(cfg.request_user_input, Some(false)); // overrode default
        assert_eq!(cfg.request_permission, Some(true)); // default preserved
        assert_eq!(cfg.request_exit_plan_mode, Some(false));
        assert_eq!(cfg.request_auto_mode_switch, Some(false));
        assert_eq!(
            cfg.skill_directories.as_deref(),
            Some(&[PathBuf::from("/tmp/skills")][..])
        );
        assert_eq!(
            cfg.disabled_skills.as_deref(),
            Some(&["broken-skill".to_string()][..])
        );
        assert_eq!(cfg.agent.as_deref(), Some("researcher"));
        assert_eq!(cfg.config_dir, Some(PathBuf::from("/tmp/config")));
        assert_eq!(cfg.working_directory, Some(PathBuf::from("/tmp/work")));
        assert_eq!(cfg.github_token.as_deref(), Some("ghp_test"));
        assert_eq!(cfg.enable_session_telemetry, Some(false));
        assert_eq!(cfg.include_sub_agent_streaming_events, Some(true));
        assert_eq!(cfg.disable_resume, Some(true));
        assert_eq!(cfg.continue_pending_work, Some(true));
    }

    /// `continue_pending_work` must serialize to wire as `continuePendingWork`
    /// — the runtime keys off this exact field name to opt into the
    /// pending-work-handoff pattern.
    #[test]
    fn resume_session_config_serializes_continue_pending_work_to_camel_case() {
        let cfg =
            ResumeSessionConfig::new(SessionId::from("sess-1")).with_continue_pending_work(true);
        let wire = serde_json::to_value(&cfg).unwrap();
        assert_eq!(wire["continuePendingWork"], true);

        // Unset case — skip_serializing_if must omit the field.
        let cfg = ResumeSessionConfig::new(SessionId::from("sess-2"));
        let wire = serde_json::to_value(&cfg).unwrap();
        assert!(wire.get("continuePendingWork").is_none());
    }

    /// `instruction_directories` must serialize to wire as
    /// `instructionDirectories` on `SessionConfig`.
    #[test]
    fn session_config_serializes_instruction_directories_to_camel_case() {
        let cfg =
            SessionConfig::default().with_instruction_directories([PathBuf::from("/tmp/instr")]);
        let wire = serde_json::to_value(&cfg).unwrap();
        assert_eq!(
            wire["instructionDirectories"],
            serde_json::json!(["/tmp/instr"])
        );

        // Unset case — skip_serializing_if must omit the field.
        let cfg = SessionConfig::default();
        let wire = serde_json::to_value(&cfg).unwrap();
        assert!(wire.get("instructionDirectories").is_none());
    }

    /// Same check on the resume path. Forwarded to the CLI on
    /// `session.resume`.
    #[test]
    fn resume_session_config_serializes_instruction_directories_to_camel_case() {
        let cfg = ResumeSessionConfig::new(SessionId::from("sess-1"))
            .with_instruction_directories([PathBuf::from("/tmp/instr")]);
        let wire = serde_json::to_value(&cfg).unwrap();
        assert_eq!(
            wire["instructionDirectories"],
            serde_json::json!(["/tmp/instr"])
        );

        let cfg = ResumeSessionConfig::new(SessionId::from("sess-2"));
        let wire = serde_json::to_value(&cfg).unwrap();
        assert!(wire.get("instructionDirectories").is_none());
    }

    #[test]
    fn custom_agent_config_builder_composes() {
        use std::collections::HashMap;

        let cfg = CustomAgentConfig::new("researcher", "You are a research assistant.")
            .with_display_name("Research Assistant")
            .with_description("Investigates technical questions.")
            .with_tools(["bash", "view"])
            .with_mcp_servers(HashMap::new())
            .with_infer(true)
            .with_skills(["rust-coding-skill"]);

        assert_eq!(cfg.name, "researcher");
        assert_eq!(cfg.prompt, "You are a research assistant.");
        assert_eq!(cfg.display_name.as_deref(), Some("Research Assistant"));
        assert_eq!(
            cfg.description.as_deref(),
            Some("Investigates technical questions.")
        );
        assert_eq!(
            cfg.tools.as_deref(),
            Some(&["bash".to_string(), "view".to_string()][..])
        );
        assert!(cfg.mcp_servers.is_some());
        assert_eq!(cfg.infer, Some(true));
        assert_eq!(
            cfg.skills.as_deref(),
            Some(&["rust-coding-skill".to_string()][..])
        );
    }

    #[test]
    fn infinite_session_config_builder_composes() {
        let cfg = InfiniteSessionConfig::new()
            .with_enabled(true)
            .with_background_compaction_threshold(0.75)
            .with_buffer_exhaustion_threshold(0.92);

        assert_eq!(cfg.enabled, Some(true));
        assert_eq!(cfg.background_compaction_threshold, Some(0.75));
        assert_eq!(cfg.buffer_exhaustion_threshold, Some(0.92));
    }

    #[test]
    fn provider_config_builder_composes() {
        use std::collections::HashMap;

        let mut headers = HashMap::new();
        headers.insert("X-Custom".to_string(), "value".to_string());

        let cfg = ProviderConfig::new("https://api.example.com")
            .with_provider_type("openai")
            .with_wire_api("completions")
            .with_api_key("sk-test")
            .with_bearer_token("bearer-test")
            .with_headers(headers)
            .with_model_id("gpt-4")
            .with_wire_model("azure-gpt-4-deployment")
            .with_max_prompt_tokens(8192)
            .with_max_output_tokens(2048);

        assert_eq!(cfg.base_url, "https://api.example.com");
        assert_eq!(cfg.provider_type.as_deref(), Some("openai"));
        assert_eq!(cfg.wire_api.as_deref(), Some("completions"));
        assert_eq!(cfg.api_key.as_deref(), Some("sk-test"));
        assert_eq!(cfg.bearer_token.as_deref(), Some("bearer-test"));
        assert_eq!(
            cfg.headers
                .as_ref()
                .and_then(|h| h.get("X-Custom"))
                .map(String::as_str),
            Some("value"),
        );
        assert_eq!(cfg.model_id.as_deref(), Some("gpt-4"));
        assert_eq!(cfg.wire_model.as_deref(), Some("azure-gpt-4-deployment"));
        assert_eq!(cfg.max_prompt_tokens, Some(8192));
        assert_eq!(cfg.max_output_tokens, Some(2048));

        // Wire-shape: camelCase, skip_serializing_if when unset.
        let wire = serde_json::to_value(&cfg).unwrap();
        assert_eq!(wire["modelId"], "gpt-4");
        assert_eq!(wire["wireModel"], "azure-gpt-4-deployment");
        assert_eq!(wire["maxPromptTokens"], 8192);
        assert_eq!(wire["maxOutputTokens"], 2048);

        let unset = ProviderConfig::new("https://api.example.com");
        let wire_unset = serde_json::to_value(&unset).unwrap();
        assert!(wire_unset.get("modelId").is_none());
        assert!(wire_unset.get("wireModel").is_none());
        assert!(wire_unset.get("maxPromptTokens").is_none());
        assert!(wire_unset.get("maxOutputTokens").is_none());
    }

    #[test]
    fn system_message_config_builder_composes() {
        use std::collections::HashMap;

        let cfg = SystemMessageConfig::new()
            .with_mode("replace")
            .with_content("Custom system message.")
            .with_sections(HashMap::new());

        assert_eq!(cfg.mode.as_deref(), Some("replace"));
        assert_eq!(cfg.content.as_deref(), Some("Custom system message."));
        assert!(cfg.sections.is_some());
    }

    #[test]
    fn delivery_mode_serializes_to_kebab_case_strings() {
        assert_eq!(
            serde_json::to_string(&DeliveryMode::Enqueue).unwrap(),
            "\"enqueue\""
        );
        assert_eq!(
            serde_json::to_string(&DeliveryMode::Immediate).unwrap(),
            "\"immediate\""
        );
        let parsed: DeliveryMode = serde_json::from_str("\"immediate\"").unwrap();
        assert_eq!(parsed, DeliveryMode::Immediate);
    }

    #[test]
    fn connection_state_error_serializes_to_match_go() {
        let json = serde_json::to_string(&ConnectionState::Error).unwrap();
        assert_eq!(json, "\"error\"");
        let parsed: ConnectionState = serde_json::from_str("\"error\"").unwrap();
        assert_eq!(parsed, ConnectionState::Error);
    }

    /// `agentId` is the sub-agent attribution field added in copilot-sdk
    /// commit f8cf846 ("Derive session event envelopes from schema").
    /// Every other SDK (Node, Python, Go, .NET) carries it on the event
    /// envelope; Rust must too or sub-agent events lose attribution at
    /// the deserialization boundary. Cross-SDK parity test.
    #[test]
    fn session_event_round_trips_agent_id_on_envelope() {
        let wire = json!({
            "id": "evt-1",
            "timestamp": "2026-04-30T12:00:00Z",
            "parentId": null,
            "agentId": "sub-agent-42",
            "type": "assistant.message",
            "data": { "message": "hi" }
        });

        let event: SessionEvent = serde_json::from_value(wire.clone()).unwrap();
        assert_eq!(event.agent_id.as_deref(), Some("sub-agent-42"));

        // Round-trip preserves the field on the wire.
        let roundtripped = serde_json::to_value(&event).unwrap();
        assert_eq!(roundtripped["agentId"], "sub-agent-42");

        // Absent agentId remains absent (skip_serializing_if).
        let main_agent_event: SessionEvent = serde_json::from_value(json!({
            "id": "evt-2",
            "timestamp": "2026-04-30T12:00:01Z",
            "parentId": null,
            "type": "session.idle",
            "data": {}
        }))
        .unwrap();
        assert!(main_agent_event.agent_id.is_none());
        let roundtripped = serde_json::to_value(&main_agent_event).unwrap();
        assert!(roundtripped.get("agentId").is_none());
    }

    /// Same parity for the typed event envelope produced by the codegen.
    #[test]
    fn typed_session_event_round_trips_agent_id_on_envelope() {
        let wire = json!({
            "id": "evt-1",
            "timestamp": "2026-04-30T12:00:00Z",
            "parentId": null,
            "agentId": "sub-agent-42",
            "type": "session.idle",
            "data": {}
        });

        let event: TypedSessionEvent = serde_json::from_value(wire).unwrap();
        assert_eq!(event.agent_id.as_deref(), Some("sub-agent-42"));

        let roundtripped = serde_json::to_value(&event).unwrap();
        assert_eq!(roundtripped["agentId"], "sub-agent-42");
    }

    #[test]
    fn connection_state_other_variants_serialize_as_lowercase() {
        assert_eq!(
            serde_json::to_string(&ConnectionState::Disconnected).unwrap(),
            "\"disconnected\""
        );
        assert_eq!(
            serde_json::to_string(&ConnectionState::Connecting).unwrap(),
            "\"connecting\""
        );
        assert_eq!(
            serde_json::to_string(&ConnectionState::Connected).unwrap(),
            "\"connected\""
        );
    }

    #[test]
    fn deserializes_runtime_attachment_variants() {
        let attachments: Vec<Attachment> = serde_json::from_value(json!([
            {
                "type": "file",
                "path": "/tmp/file.rs",
                "displayName": "file.rs",
                "lineRange": { "start": 7, "end": 12 }
            },
            {
                "type": "directory",
                "path": "/tmp/project",
                "displayName": "project"
            },
            {
                "type": "selection",
                "filePath": "/tmp/lib.rs",
                "displayName": "lib.rs",
                "text": "fn main() {}",
                "selection": {
                    "start": { "line": 1, "character": 2 },
                    "end": { "line": 3, "character": 4 }
                }
            },
            {
                "type": "blob",
                "data": "Zm9v",
                "mimeType": "image/png",
                "displayName": "image.png"
            },
            {
                "type": "github_reference",
                "number": 42,
                "title": "Fix rendering",
                "referenceType": "issue",
                "state": "open",
                "url": "https://github.com/example/repo/issues/42"
            }
        ]))
        .expect("attachments should deserialize");

        assert_eq!(attachments.len(), 5);
        assert!(matches!(
            &attachments[0],
            Attachment::File {
                path,
                display_name,
                line_range: Some(AttachmentLineRange { start: 7, end: 12 }),
            } if path == &PathBuf::from("/tmp/file.rs") && display_name.as_deref() == Some("file.rs")
        ));
        assert!(matches!(
            &attachments[1],
            Attachment::Directory { path, display_name }
                if path == &PathBuf::from("/tmp/project") && display_name.as_deref() == Some("project")
        ));
        assert!(matches!(
            &attachments[2],
            Attachment::Selection {
                file_path,
                display_name,
                selection:
                    AttachmentSelectionRange {
                        start: AttachmentSelectionPosition { line: 1, character: 2 },
                        end: AttachmentSelectionPosition { line: 3, character: 4 },
                    },
                ..
            } if file_path == &PathBuf::from("/tmp/lib.rs") && display_name.as_deref() == Some("lib.rs")
        ));
        assert!(matches!(
            &attachments[3],
            Attachment::Blob {
                data,
                mime_type,
                display_name,
            } if data == "Zm9v" && mime_type == "image/png" && display_name.as_deref() == Some("image.png")
        ));
        assert!(matches!(
            &attachments[4],
            Attachment::GitHubReference {
                number: 42,
                title,
                reference_type: GitHubReferenceType::Issue,
                state,
                url,
            } if title == "Fix rendering"
                && state == "open"
                && url == "https://github.com/example/repo/issues/42"
        ));
    }

    #[test]
    fn ensures_display_names_for_variants_that_support_them() {
        let mut attachments = vec![
            Attachment::File {
                path: PathBuf::from("/tmp/file.rs"),
                display_name: None,
                line_range: None,
            },
            Attachment::Selection {
                file_path: PathBuf::from("/tmp/src/lib.rs"),
                display_name: None,
                text: "fn main() {}".to_string(),
                selection: AttachmentSelectionRange {
                    start: AttachmentSelectionPosition {
                        line: 0,
                        character: 0,
                    },
                    end: AttachmentSelectionPosition {
                        line: 0,
                        character: 10,
                    },
                },
            },
            Attachment::Blob {
                data: "Zm9v".to_string(),
                mime_type: "image/png".to_string(),
                display_name: None,
            },
            Attachment::GitHubReference {
                number: 7,
                title: "Track regressions".to_string(),
                reference_type: GitHubReferenceType::Issue,
                state: "open".to_string(),
                url: "https://example.com/issues/7".to_string(),
            },
        ];

        ensure_attachment_display_names(&mut attachments);

        assert_eq!(attachments[0].display_name(), Some("file.rs"));
        assert_eq!(attachments[1].display_name(), Some("lib.rs"));
        assert_eq!(attachments[2].display_name(), Some("attachment"));
        assert_eq!(attachments[3].display_name(), None);
        assert_eq!(
            attachments[3].label(),
            Some("Track regressions".to_string())
        );
    }
}

#[cfg(test)]
mod permission_builder_tests {
    use std::sync::Arc;

    use crate::handler::{
        ApproveAllHandler, HandlerEvent, HandlerResponse, PermissionResult, SessionHandler,
    };
    use crate::types::{
        PermissionRequestData, RequestId, ResumeSessionConfig, SessionConfig, SessionId,
    };

    fn permission_event() -> HandlerEvent {
        HandlerEvent::PermissionRequest {
            session_id: SessionId::from("s1"),
            request_id: RequestId::new("1"),
            data: PermissionRequestData {
                extra: serde_json::json!({"tool": "shell"}),
                ..Default::default()
            },
        }
    }

    async fn dispatch(handler: &Arc<dyn SessionHandler>) -> HandlerResponse {
        handler.on_event(permission_event()).await
    }

    #[tokio::test]
    async fn session_config_approve_all_wraps_existing_handler() {
        let cfg = SessionConfig::default()
            .with_handler(Arc::new(ApproveAllHandler))
            .approve_all_permissions();
        let handler = cfg.handler.expect("handler should be set");
        match dispatch(&handler).await {
            HandlerResponse::Permission(PermissionResult::Approved) => {}
            other => panic!("expected Approved, got {other:?}"),
        }
    }

    #[tokio::test]
    async fn session_config_approve_all_defaults_to_deny_inner() {
        // Without with_handler, the wrap defaults to DenyAllHandler. The
        // approve-all wrap intercepts permission events, so they're still
        // approved -- the inner handler is consulted only for other events.
        let cfg = SessionConfig::default().approve_all_permissions();
        let handler = cfg.handler.expect("handler should be set");
        match dispatch(&handler).await {
            HandlerResponse::Permission(PermissionResult::Approved) => {}
            other => panic!("expected Approved, got {other:?}"),
        }
    }

    #[tokio::test]
    async fn session_config_deny_all_denies() {
        let cfg = SessionConfig::default()
            .with_handler(Arc::new(ApproveAllHandler))
            .deny_all_permissions();
        let handler = cfg.handler.expect("handler should be set");
        match dispatch(&handler).await {
            HandlerResponse::Permission(PermissionResult::Denied) => {}
            other => panic!("expected Denied, got {other:?}"),
        }
    }

    #[tokio::test]
    async fn session_config_approve_permissions_if_consults_predicate() {
        let cfg = SessionConfig::default()
            .with_handler(Arc::new(ApproveAllHandler))
            .approve_permissions_if(|data| {
                data.extra.get("tool").and_then(|v| v.as_str()) != Some("shell")
            });
        let handler = cfg.handler.expect("handler should be set");
        match dispatch(&handler).await {
            HandlerResponse::Permission(PermissionResult::Denied) => {}
            other => panic!("expected Denied for shell, got {other:?}"),
        }
    }

    #[tokio::test]
    async fn resume_session_config_approve_all_wraps_existing_handler() {
        let cfg = ResumeSessionConfig::new(SessionId::from("s1"))
            .with_handler(Arc::new(ApproveAllHandler))
            .approve_all_permissions();
        let handler = cfg.handler.expect("handler should be set");
        match dispatch(&handler).await {
            HandlerResponse::Permission(PermissionResult::Approved) => {}
            other => panic!("expected Approved, got {other:?}"),
        }
    }
}