hanzo_protocol/

protocol.rs

//! Defines the protocol for a Codex session between a client and an agent.
//!
//! Uses a SQ (Submission Queue) / EQ (Event Queue) pattern to asynchronously communicate
//! between user and agent.

use std::collections::HashMap;
use std::fmt;
use std::path::Path;
use std::path::PathBuf;
use std::str::FromStr;
use std::time::Duration;

use crate::ConversationId;
use crate::config_types::ReasoningEffort as ReasoningEffortConfig;
use crate::config_types::ReasoningSummary as ReasoningSummaryConfig;
use crate::custom_prompts::CustomPrompt;
use crate::message_history::HistoryEntry;
use crate::models::ContentItem;
use crate::models::ResponseItem;
use crate::num_format::format_with_separators;
use crate::parse_command::ParsedCommand;
use crate::plan_tool::UpdatePlanArgs;
use crate::skills::Skill;
use mcp_types::CallToolResult;
use mcp_types::Tool as McpTool;
use serde::Deserialize;
use serde::Serialize;
use serde_json::Value;
use serde_with::serde_as;
use strum_macros::Display;
use ts_rs::TS;

/// Open/close tags for special user-input blocks. Used across crates to avoid
/// duplicated hardcoded strings.
pub const USER_INSTRUCTIONS_OPEN_TAG: &str = "<user_instructions>";
pub const USER_INSTRUCTIONS_CLOSE_TAG: &str = "</user_instructions>";
pub const ENVIRONMENT_CONTEXT_OPEN_TAG: &str = "<environment_context>";
pub const ENVIRONMENT_CONTEXT_CLOSE_TAG: &str = "</environment_context>";
pub const ENVIRONMENT_CONTEXT_DELTA_OPEN_TAG: &str = "<environment_context_delta>";
pub const ENVIRONMENT_CONTEXT_DELTA_CLOSE_TAG: &str = "</environment_context_delta>";
pub const BROWSER_SNAPSHOT_OPEN_TAG: &str = "<browser_snapshot>";
pub const BROWSER_SNAPSHOT_CLOSE_TAG: &str = "</browser_snapshot>";
pub const USER_MESSAGE_BEGIN: &str = "## My request for Codex:";

/// Submission Queue Entry - requests from user
#[derive(Debug, Clone, Deserialize, Serialize)]
pub struct Submission {
    /// Unique id for this Submission to correlate with Events
    pub id: String,
    /// Payload
    pub op: Op,
}

/// Submission operation
#[derive(Debug, Clone, Deserialize, Serialize, PartialEq)]
#[serde(tag = "type", rename_all = "snake_case")]
#[allow(clippy::large_enum_variant)]
#[non_exhaustive]
pub enum Op {
    /// Abort current task.
    /// This server sends [`EventMsg::TurnAborted`] in response.
    Interrupt,

    /// Input from the user
    UserInput {
        /// User input items, see `InputItem`
        items: Vec<InputItem>,
        /// Optional JSON Schema used to constrain the final assistant message for this turn.
        #[serde(skip_serializing_if = "Option::is_none")]
        final_output_json_schema: Option<Value>,
    },

    /// Queue user input to be appended to the next model request without
    /// interrupting the current turn.
    QueueUserInput {
        /// User input items, see `InputItem`
        items: Vec<InputItem>,
    },

    /// Similar to [`Op::UserInput`], but contains additional context required
    /// for a turn of a [`crate::code_conversation::CodexConversation`].
    UserTurn {
        /// User input items, see `InputItem`
        items: Vec<InputItem>,

        /// `cwd` to use with the [`SandboxPolicy`] and potentially tool calls
        /// such as `local_shell`.
        cwd: PathBuf,

        /// Policy to use for command approval.
        approval_policy: AskForApproval,

        /// Policy to use for tool calls such as `local_shell`.
        sandbox_policy: SandboxPolicy,

        /// Must be a valid model slug for the [`crate::client::ModelClient`]
        /// associated with this conversation.
        model: String,

        /// Will only be honored if the model is configured to use reasoning.
        #[serde(skip_serializing_if = "Option::is_none")]
        effort: Option<ReasoningEffortConfig>,

        /// Will only be honored if the model is configured to use reasoning.
        summary: ReasoningSummaryConfig,
        // The JSON schema to use for the final assistant message
        final_output_json_schema: Option<Value>,
    },

    /// Override parts of the persistent turn context for subsequent turns.
    ///
    /// All fields are optional; when omitted, the existing value is preserved.
    /// This does not enqueue any input – it only updates defaults used for
    /// future `UserInput` turns.
    OverrideTurnContext {
        /// Updated `cwd` for sandbox/tool calls.
        #[serde(skip_serializing_if = "Option::is_none")]
        cwd: Option<PathBuf>,

        /// Updated command approval policy.
        #[serde(skip_serializing_if = "Option::is_none")]
        approval_policy: Option<AskForApproval>,

        /// Updated sandbox policy for tool calls.
        #[serde(skip_serializing_if = "Option::is_none")]
        sandbox_policy: Option<SandboxPolicy>,

        /// Updated model slug. When set, the model family is derived
        /// automatically.
        #[serde(skip_serializing_if = "Option::is_none")]
        model: Option<String>,

        /// Updated reasoning effort (honored only for reasoning-capable models).
        ///
        /// Use `Some(Some(_))` to set a specific effort, `Some(None)` to clear
        /// the effort, or `None` to leave the existing value unchanged.
        #[serde(skip_serializing_if = "Option::is_none")]
        effort: Option<Option<ReasoningEffortConfig>>,

        /// Updated reasoning summary preference (honored only for reasoning-capable models).
        #[serde(skip_serializing_if = "Option::is_none")]
        summary: Option<ReasoningSummaryConfig>,
    },

    /// Approve a command execution
    ExecApproval {
        /// The id of the submission we are approving
        id: String,
        /// The user's decision in response to the request.
        decision: ReviewDecision,
    },

    /// Register a command pattern as approved for the remainder of the session.
    RegisterApprovedCommand {
        command: Vec<String>,
        match_kind: ApprovedCommandMatchKind,
        #[serde(skip_serializing_if = "Option::is_none")]
        #[serde(default)]
        semantic_prefix: Option<Vec<String>>,
    },

    /// Approve a code patch
    PatchApproval {
        /// The id of the submission we are approving
        id: String,
        /// The user's decision in response to the request.
        decision: ReviewDecision,
    },

    /// Append an entry to the persistent cross-session message history.
    ///
    /// Note the entry is not guaranteed to be logged if the user has
    /// history disabled, it matches the list of "sensitive" patterns, etc.
    AddToHistory {
        /// The message text to be stored.
        text: String,
    },

    /// Persist the full chat history snapshot for the current session.
    PersistHistorySnapshot { snapshot: serde_json::Value },

    /// Request a single history entry identified by `log_id` + `offset`.
    GetHistoryEntryRequest { offset: usize, log_id: u64 },

    /// Request the full in-memory conversation transcript for the current session.
    /// Reply is delivered via `EventMsg::ConversationHistory`.
    GetPath,

    /// Request the list of MCP tools available across all configured servers.
    /// Reply is delivered via `EventMsg::McpListToolsResponse`.
    ListMcpTools,

    /// Request the list of available custom prompts.
    ListCustomPrompts,

    /// Request the list of available skills.
    /// Reply is delivered via `EventMsg::ListSkillsResponse`.
    ListSkills,

    /// Request the agent to summarize the current conversation context.
    /// The agent will use its existing context (either conversation history or previous response id)
    /// to generate a summary which will be returned as an AgentMessage event.
    Compact,

    /// Request a code review from the agent.
    Review { review_request: ReviewRequest },

    /// Request to shut down codex instance.
    Shutdown,
}

/// Determines the conditions under which the user is consulted to approve
/// running the command proposed by Codex.
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Hash, Serialize, Deserialize, Display, TS)]
#[serde(rename_all = "kebab-case")]
#[strum(serialize_all = "kebab-case")]
pub enum AskForApproval {
    /// Under this policy, only "known safe" commands—as determined by
    /// `is_safe_command()`—that **only read files** are auto‑approved.
    /// Everything else will ask the user to approve.
    #[serde(rename = "untrusted")]
    #[strum(serialize = "untrusted")]
    UnlessTrusted,

    /// *All* commands are auto‑approved, but they are expected to run inside a
    /// sandbox where network access is disabled and writes are confined to a
    /// specific set of paths. If the command fails, it will be escalated to
    /// the user to approve execution without a sandbox.
    OnFailure,

    /// The model decides when to ask the user for approval.
    #[default]
    OnRequest,

    /// Never ask the user to approve commands. Failures are immediately returned
    /// to the model, and never escalated to the user for approval.
    Never,
}

#[derive(Debug, Clone, Copy, Deserialize, Serialize, PartialEq, Eq, Hash, TS)]
#[serde(rename_all = "kebab-case")]
pub enum ApprovedCommandMatchKind {
    Exact,
    Prefix,
}

/// Determines execution restrictions for model shell commands.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Display, TS)]
#[strum(serialize_all = "kebab-case")]
#[serde(tag = "mode", rename_all = "kebab-case")]
pub enum SandboxPolicy {
    /// No restrictions whatsoever. Use with caution.
    #[serde(rename = "danger-full-access")]
    DangerFullAccess,

    /// Read-only access to the entire file-system.
    #[serde(rename = "read-only")]
    ReadOnly,

    /// Same as `ReadOnly` but additionally grants write access to the current
    /// working directory ("workspace").
    #[serde(rename = "workspace-write")]
    WorkspaceWrite {
        /// Additional folders (beyond cwd and possibly TMPDIR) that should be
        /// writable from within the sandbox.
        #[serde(default, skip_serializing_if = "Vec::is_empty")]
        writable_roots: Vec<PathBuf>,

        /// When set to `true`, outbound network access is allowed. `false` by
        /// default.
        #[serde(default)]
        network_access: bool,

        /// When set to `true`, will NOT include the per-user `TMPDIR`
        /// environment variable among the default writable roots. Defaults to
        /// `false`.
        #[serde(default)]
        exclude_tmpdir_env_var: bool,

        /// When set to `true`, will NOT include the `/tmp` among the default
        /// writable roots on UNIX. Defaults to `false`.
        #[serde(default)]
        exclude_slash_tmp: bool,

        /// When true, do not protect the top-level `.git` folder under a writable root.
        /// Defaults to true to match historical behavior that permits Git writes.
        #[serde(default = "default_true_bool")]
        allow_git_writes: bool,
    },
}

const fn default_true_bool() -> bool {
    true
}

/// A writable root path accompanied by a list of subpaths that should remain
/// read‑only even when the root is writable. This is primarily used to ensure
/// top‑level VCS metadata directories (e.g. `.git`) under a writable root are
/// not modified by the agent.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct WritableRoot {
    /// Absolute path, by construction.
    pub root: PathBuf,

    /// Also absolute paths, by construction.
    pub read_only_subpaths: Vec<PathBuf>,
}

impl WritableRoot {
    pub fn is_path_writable(&self, path: &Path) -> bool {
        // Check if the path is under the root.
        if !path.starts_with(&self.root) {
            return false;
        }

        // Check if the path is under any of the read-only subpaths.
        for subpath in &self.read_only_subpaths {
            if path.starts_with(subpath) {
                return false;
            }
        }

        true
    }
}

impl FromStr for SandboxPolicy {
    type Err = serde_json::Error;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        serde_json::from_str(s)
    }
}

impl SandboxPolicy {
    /// Returns a policy with read-only disk access and no network.
    pub fn new_read_only_policy() -> Self {
        SandboxPolicy::ReadOnly
    }

    /// Returns a policy that can read the entire disk, but can only write to
    /// the current working directory and the per-user tmp dir on macOS. It does
    /// not allow network access.
    pub fn new_workspace_write_policy() -> Self {
        SandboxPolicy::WorkspaceWrite {
            writable_roots: vec![],
            network_access: false,
            exclude_tmpdir_env_var: false,
            exclude_slash_tmp: false,
            allow_git_writes: true,
        }
    }

    /// Always returns `true`; restricting read access is not supported.
    pub fn has_full_disk_read_access(&self) -> bool {
        true
    }

    pub fn has_full_disk_write_access(&self) -> bool {
        match self {
            SandboxPolicy::DangerFullAccess => true,
            SandboxPolicy::ReadOnly => false,
            SandboxPolicy::WorkspaceWrite { .. } => false,
        }
    }

    pub fn has_full_network_access(&self) -> bool {
        match self {
            SandboxPolicy::DangerFullAccess => true,
            SandboxPolicy::ReadOnly => false,
            SandboxPolicy::WorkspaceWrite { network_access, .. } => *network_access,
        }
    }

    /// Returns the list of writable roots (tailored to the current working
    /// directory) together with subpaths that should remain read‑only under
    /// each writable root.
    pub fn get_writable_roots_with_cwd(&self, cwd: &Path) -> Vec<WritableRoot> {
        match self {
            SandboxPolicy::DangerFullAccess => Vec::new(),
            SandboxPolicy::ReadOnly => Vec::new(),
            SandboxPolicy::WorkspaceWrite {
                writable_roots,
                exclude_tmpdir_env_var,
                exclude_slash_tmp,
                allow_git_writes,
                network_access: _,
            } => {
                // Start from explicitly configured writable roots.
                let mut roots: Vec<PathBuf> = writable_roots.clone();

                // Always include defaults: cwd, /tmp (if present on Unix), and
                // on macOS, the per-user TMPDIR unless explicitly excluded.
                roots.push(cwd.to_path_buf());

                // Include /tmp on Unix unless explicitly excluded.
                if cfg!(unix) && !exclude_slash_tmp {
                    let slash_tmp = PathBuf::from("/tmp");
                    if slash_tmp.is_dir() {
                        roots.push(slash_tmp);
                    }
                }

                // Include $TMPDIR unless explicitly excluded. On macOS, TMPDIR
                // is per-user, so writes to TMPDIR should not be readable by
                // other users on the system.
                //
                // By comparison, TMPDIR is not guaranteed to be defined on
                // Linux or Windows, but supporting it here gives users a way to
                // provide the model with their own temporary directory without
                // having to hardcode it in the config.
                if !exclude_tmpdir_env_var
                    && let Some(tmpdir) = std::env::var_os("TMPDIR")
                    && !tmpdir.is_empty()
                {
                    roots.push(PathBuf::from(tmpdir));
                }

                // For each root, compute subpaths that should remain read-only.
                roots
                    .into_iter()
                    .map(|writable_root| {
                        let mut subpaths = Vec::new();
                        if !allow_git_writes {
                            let top_level_git = writable_root.join(".git");
                            if top_level_git.is_dir() {
                                subpaths.push(top_level_git);
                            }
                        }
                        WritableRoot {
                            root: writable_root,
                            read_only_subpaths: subpaths,
                        }
                    })
                    .collect()
            }
        }
    }
}

/// User input
#[non_exhaustive]
#[derive(Debug, Clone, Deserialize, Serialize, PartialEq)]
#[serde(tag = "type", rename_all = "snake_case")]
pub enum InputItem {
    Text {
        text: String,
    },
    /// Pre‑encoded data: URI image.
    Image {
        image_url: String,
    },

    /// Local image path provided by the user.  This will be converted to an
    /// `Image` variant (base64 data URL) during request serialization.
    LocalImage {
        path: std::path::PathBuf,
    },
}

/// Event Queue Entry - events from agent
#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct Event {
    /// Submission `id` that this event is correlated with.
    pub id: String,
    /// Monotonic, per-turn sequence for ordering within a submission id.
    /// Resets to 0 at TaskStarted and increments for each subsequent event.
    pub event_seq: u64,
    /// Payload
    pub msg: EventMsg,
    /// Optional model-provided ordering metadata (when applicable)
    #[serde(skip_serializing_if = "Option::is_none")]
    pub order: Option<OrderMeta>,
}

/// Lightweight representation of an event suitable for persistence and replay.
#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct RecordedEvent {
    pub id: String,
    pub event_seq: u64,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub order: Option<OrderMeta>,
    pub msg: EventMsg,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct OrderMeta {
    /// 1-based ordinal of this request/turn in the session
    pub request_ordinal: u64,
    /// Model-provided output_index for the top-level item
    #[serde(skip_serializing_if = "Option::is_none")]
    pub output_index: Option<u32>,
    /// Model-provided sequence_number within the output_index stream
    #[serde(skip_serializing_if = "Option::is_none")]
    pub sequence_number: Option<u64>,
}

/// Response event from the agent
/// NOTE: Make sure none of these values have optional types, as it will mess up the extension code-gen.
#[derive(Debug, Clone, Deserialize, Serialize, Display, TS)]
#[serde(tag = "type", rename_all = "snake_case")]
#[strum(serialize_all = "snake_case")]
pub enum EventMsg {
    /// Error while executing a submission
    Error(ErrorEvent),

    /// Agent has started a task
    TaskStarted(TaskStartedEvent),

    /// Agent has completed all actions
    TaskComplete(TaskCompleteEvent),

    /// Usage update for the current session, including totals and last turn.
    /// Optional means unknown — UIs should not display when `None`.
    TokenCount(TokenCountEvent),

    /// Agent text output message
    AgentMessage(AgentMessageEvent),

    /// User/system input message (what was sent to the model)
    UserMessage(UserMessageEvent),

    /// Agent text output delta message
    AgentMessageDelta(AgentMessageDeltaEvent),

    /// Reasoning event from agent.
    AgentReasoning(AgentReasoningEvent),

    /// Agent reasoning delta event from agent.
    AgentReasoningDelta(AgentReasoningDeltaEvent),

    /// Raw chain-of-thought from agent.
    AgentReasoningRawContent(AgentReasoningRawContentEvent),

    /// Agent reasoning content delta event from agent.
    AgentReasoningRawContentDelta(AgentReasoningRawContentDeltaEvent),
    /// Signaled when the model begins a new reasoning summary section (e.g., a new titled block).
    AgentReasoningSectionBreak(AgentReasoningSectionBreakEvent),

    /// Full environment context snapshot emitted to the model.
    EnvironmentContextFull(EnvironmentContextFullEvent),

    /// Environment context delta emitted to the model.
    EnvironmentContextDelta(EnvironmentContextDeltaEvent),

    /// Browser snapshot metadata emitted alongside environment context.
    BrowserSnapshot(BrowserSnapshotEvent),

    /// Warning that the platform compacted conversation history to stay within limits.
    CompactionCheckpointWarning(CompactionCheckpointWarningEvent),

    /// Ack the client's configure message.
    SessionConfigured(SessionConfiguredEvent),

    McpToolCallBegin(McpToolCallBeginEvent),

    McpToolCallEnd(McpToolCallEndEvent),

    WebSearchBegin(WebSearchBeginEvent),

    WebSearchEnd(WebSearchEndEvent),

    /// Notification that the server is about to execute a command.
    ExecCommandBegin(ExecCommandBeginEvent),

    /// Incremental chunk of output from a running command.
    ExecCommandOutputDelta(ExecCommandOutputDeltaEvent),

    ExecCommandEnd(ExecCommandEndEvent),

    /// Notification that the agent attached a local image via the image_view tool.
    ViewImageToolCall(ViewImageToolCallEvent),

    ExecApprovalRequest(ExecApprovalRequestEvent),

    ApplyPatchApprovalRequest(ApplyPatchApprovalRequestEvent),

    BackgroundEvent(BackgroundEventEvent),

    /// Notification that a model stream experienced an error or disconnect
    /// and the system is handling it (e.g., retrying with backoff).
    StreamError(StreamErrorEvent),

    /// Notification that the agent is about to apply a code patch. Mirrors
    /// `ExecCommandBegin` so front‑ends can show progress indicators.
    PatchApplyBegin(PatchApplyBeginEvent),

    /// Notification that a patch application has finished.
    PatchApplyEnd(PatchApplyEndEvent),

    TurnDiff(TurnDiffEvent),

    /// Response to GetHistoryEntryRequest.
    GetHistoryEntryResponse(GetHistoryEntryResponseEvent),

    /// List of MCP tools available to the agent.
    McpListToolsResponse(McpListToolsResponseEvent),

    /// List of custom prompts available to the agent.
    ListCustomPromptsResponse(ListCustomPromptsResponseEvent),

    /// List of skills available to the agent.
    ListSkillsResponse(ListSkillsResponseEvent),

    PlanUpdate(UpdatePlanArgs),

    TurnAborted(TurnAbortedEvent),

    /// Notification that the agent is shutting down.
    ShutdownComplete,

    ConversationPath(ConversationPathResponseEvent),

    /// Entered review mode.
    EnteredReviewMode(ReviewRequest),

    /// Exited review mode with an optional final result to apply.
    ExitedReviewMode(ExitedReviewModeEvent),
}

/// Codex errors that we expose to clients.
#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, Eq, TS)]
#[serde(rename_all = "snake_case")]
#[ts(rename_all = "snake_case")]
pub enum CodexErrorInfo {
    ContextWindowExceeded,
    UsageLimitExceeded,
    HttpConnectionFailed {
        http_status_code: Option<u16>,
    },
    /// Failed to connect to the response SSE stream.
    ResponseStreamConnectionFailed {
        http_status_code: Option<u16>,
    },
    InternalServerError,
    Unauthorized,
    BadRequest,
    SandboxError,
    /// The response SSE stream disconnected in the middle of a turnbefore completion.
    ResponseStreamDisconnected {
        http_status_code: Option<u16>,
    },
    /// Reached the retry limit for responses.
    ResponseTooManyFailedAttempts {
        http_status_code: Option<u16>,
    },
    Other,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct ExitedReviewModeEvent {
    pub review_output: Option<ReviewOutputEvent>,
    #[serde(skip_serializing_if = "Option::is_none")]
    #[ts(optional)]
    pub snapshot: Option<ReviewSnapshotInfo>,
}

/// Git/worktree context captured at review time.
#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, TS)]
pub struct ReviewSnapshotInfo {
    #[serde(skip_serializing_if = "Option::is_none")]
    #[ts(optional)]
    pub snapshot_commit: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    #[ts(optional)]
    pub branch: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    #[ts(optional)]
    pub worktree_path: Option<std::path::PathBuf>,
    #[serde(skip_serializing_if = "Option::is_none")]
    #[ts(optional)]
    pub repo_root: Option<std::path::PathBuf>,
}

// Individual event payload types matching each `EventMsg` variant.

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct ErrorEvent {
    pub message: String,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct TaskCompleteEvent {
    pub last_agent_message: Option<String>,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct TaskStartedEvent {
    pub model_context_window: Option<u64>,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct CompactionCheckpointWarningEvent {
    pub message: String,
}

#[derive(Debug, Clone, Default, PartialEq, Eq, Deserialize, Serialize, TS)]
pub struct TokenUsage {
    pub input_tokens: u64,
    pub cached_input_tokens: u64,
    pub output_tokens: u64,
    pub reasoning_output_tokens: u64,
    pub total_tokens: u64,
}

#[derive(Debug, Clone, PartialEq, Eq, Deserialize, Serialize, TS)]
pub struct TokenUsageInfo {
    pub total_token_usage: TokenUsage,
    pub last_token_usage: TokenUsage,
    pub model_context_window: Option<u64>,
}

impl TokenUsageInfo {
    pub fn new_or_append(
        info: &Option<TokenUsageInfo>,
        last: &Option<TokenUsage>,
        model_context_window: Option<u64>,
    ) -> Option<Self> {
        if info.is_none() && last.is_none() {
            return None;
        }

        let mut info = match info {
            Some(info) => info.clone(),
            None => Self {
                total_token_usage: TokenUsage::default(),
                last_token_usage: TokenUsage::default(),
                model_context_window,
            },
        };
        if let Some(last) = last {
            info.append_last_usage(last);
        }
        Some(info)
    }

    pub fn append_last_usage(&mut self, last: &TokenUsage) {
        self.total_token_usage.add_assign(last);
        self.last_token_usage = last.clone();
    }
}

#[derive(Debug, Clone, PartialEq, Deserialize, Serialize, TS)]
pub struct TokenCountEvent {
    pub info: Option<TokenUsageInfo>,
    pub rate_limits: Option<RateLimitSnapshot>,
}

#[derive(Debug, Clone, PartialEq, Deserialize, Serialize, TS)]
pub struct RateLimitSnapshot {
    pub primary: Option<RateLimitWindow>,
    pub secondary: Option<RateLimitWindow>,
}

#[derive(Debug, Clone, PartialEq, Deserialize, Serialize, TS)]
pub struct RateLimitWindow {
    /// Percentage (0-100) of the window that has been consumed.
    pub used_percent: f64,
    /// Rolling window duration, in minutes.
    pub window_minutes: Option<u64>,
    /// Seconds until the window resets.
    pub resets_in_seconds: Option<u64>,
}

/// Payload for `ReplayHistory` containing prior `ResponseItem`s.
#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct ReplayHistoryEvent {
    pub items: Vec<crate::models::ResponseItem>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub history_snapshot: Option<serde_json::Value>,
}

// Includes prompts, tools and space to call compact.
const BASELINE_TOKENS: u64 = 12000;

impl TokenUsage {
    pub fn is_zero(&self) -> bool {
        self.total_tokens == 0
    }

    pub fn cached_input(&self) -> u64 {
        self.cached_input_tokens
    }

    pub fn non_cached_input(&self) -> u64 {
        self.input_tokens.saturating_sub(self.cached_input())
    }

    /// Primary count for display as a single absolute value: non-cached input + output.
    pub fn blended_total(&self) -> u64 {
        self.non_cached_input() + self.output_tokens
    }

    /// For estimating what % of the model's context window is used, we need to account
    /// for reasoning output tokens from prior turns being dropped from the context window.
    /// We approximate this here by subtracting reasoning output tokens from the total.
    /// This will be off for the current turn and pending function calls.
    pub fn tokens_in_context_window(&self) -> u64 {
        self.total_tokens
            .saturating_sub(self.reasoning_output_tokens)
    }

    /// Estimate the remaining user-controllable percentage of the model's context window.
    ///
    /// `context_window` is the total size of the model's context window.
    /// `BASELINE_TOKENS` should capture tokens that are always present in
    /// the context (e.g., system prompt and fixed tool instructions) so that
    /// the percentage reflects the portion the user can influence.
    ///
    /// This normalizes both the numerator and denominator by subtracting the
    /// baseline, so immediately after the first prompt the UI shows 100% left
    /// and trends toward 0% as the user fills the effective window.
    pub fn percent_of_context_window_remaining(&self, context_window: u64) -> u8 {
        if context_window <= BASELINE_TOKENS {
            return 0;
        }

        let effective_window = context_window - BASELINE_TOKENS;
        let used = self
            .tokens_in_context_window()
            .saturating_sub(BASELINE_TOKENS);
        let remaining = effective_window.saturating_sub(used);
        ((remaining as f32 / effective_window as f32) * 100.0).clamp(0.0, 100.0) as u8
    }

    /// In-place element-wise sum of token counts.
    pub fn add_assign(&mut self, other: &TokenUsage) {
        self.input_tokens += other.input_tokens;
        self.cached_input_tokens += other.cached_input_tokens;
        self.output_tokens += other.output_tokens;
        self.reasoning_output_tokens += other.reasoning_output_tokens;
        self.total_tokens += other.total_tokens;
    }
}

#[derive(Debug, Clone, Deserialize, Serialize)]
pub struct FinalOutput {
    pub token_usage: TokenUsage,
}

impl From<TokenUsage> for FinalOutput {
    fn from(token_usage: TokenUsage) -> Self {
        Self { token_usage }
    }
}

impl fmt::Display for FinalOutput {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let token_usage = &self.token_usage;

        write!(
            f,
            "Token usage: total={} input={}{} output={}{}",
            format_with_separators(token_usage.blended_total()),
            format_with_separators(token_usage.non_cached_input()),
            if token_usage.cached_input() > 0 {
                format!(
                    " (+ {} cached)",
                    format_with_separators(token_usage.cached_input())
                )
            } else {
                String::new()
            },
            format_with_separators(token_usage.output_tokens),
            if token_usage.reasoning_output_tokens > 0 {
                format!(
                    " (reasoning {})",
                    format_with_separators(token_usage.reasoning_output_tokens)
                )
            } else {
                String::new()
            }
        )
    }
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct AgentMessageEvent {
    pub message: String,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
#[serde(rename_all = "snake_case")]
pub enum InputMessageKind {
    /// Plain user text (default)
    Plain,
    /// XML-wrapped user instructions (<user_instructions>...)
    UserInstructions,
    /// XML-wrapped environment context (<environment_context>...)
    EnvironmentContext,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct UserMessageEvent {
    pub message: String,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub kind: Option<InputMessageKind>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub images: Option<Vec<String>>,
}

impl<T, U> From<(T, U)> for InputMessageKind
where
    T: AsRef<str>,
    U: AsRef<str>,
{
    fn from(value: (T, U)) -> Self {
        let (_role, message) = value;
        let message = message.as_ref();
        let trimmed = message.trim();
        if starts_with_ignore_ascii_case(trimmed, ENVIRONMENT_CONTEXT_OPEN_TAG)
            && ends_with_ignore_ascii_case(trimmed, ENVIRONMENT_CONTEXT_CLOSE_TAG)
        {
            InputMessageKind::EnvironmentContext
        } else if starts_with_ignore_ascii_case(trimmed, USER_INSTRUCTIONS_OPEN_TAG)
            && ends_with_ignore_ascii_case(trimmed, USER_INSTRUCTIONS_CLOSE_TAG)
        {
            InputMessageKind::UserInstructions
        } else {
            InputMessageKind::Plain
        }
    }
}

fn starts_with_ignore_ascii_case(text: &str, prefix: &str) -> bool {
    let text_bytes = text.as_bytes();
    let prefix_bytes = prefix.as_bytes();
    text_bytes.len() >= prefix_bytes.len()
        && text_bytes
            .iter()
            .zip(prefix_bytes.iter())
            .all(|(a, b)| a.eq_ignore_ascii_case(b))
}

fn ends_with_ignore_ascii_case(text: &str, suffix: &str) -> bool {
    let text_bytes = text.as_bytes();
    let suffix_bytes = suffix.as_bytes();
    text_bytes.len() >= suffix_bytes.len()
        && text_bytes[text_bytes.len() - suffix_bytes.len()..]
            .iter()
            .zip(suffix_bytes.iter())
            .all(|(a, b)| a.eq_ignore_ascii_case(b))
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct AgentMessageDeltaEvent {
    pub delta: String,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct AgentReasoningEvent {
    pub text: String,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct AgentReasoningRawContentEvent {
    pub text: String,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct AgentReasoningRawContentDeltaEvent {
    pub delta: String,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct AgentReasoningSectionBreakEvent {}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct AgentReasoningDeltaEvent {
    pub delta: String,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct McpInvocation {
    /// Name of the MCP server as defined in the config.
    pub server: String,
    /// Name of the tool as given by the MCP server.
    pub tool: String,
    /// Arguments to the tool call.
    pub arguments: Option<serde_json::Value>,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct McpToolCallBeginEvent {
    /// Identifier so this can be paired with the McpToolCallEnd event.
    pub call_id: String,
    pub invocation: McpInvocation,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct McpToolCallEndEvent {
    /// Identifier for the corresponding McpToolCallBegin that finished.
    pub call_id: String,
    pub invocation: McpInvocation,
    #[ts(type = "string")]
    pub duration: Duration,
    /// Result of the tool call. Note this could be an error.
    pub result: Result<CallToolResult, String>,
}

impl McpToolCallEndEvent {
    pub fn is_success(&self) -> bool {
        match &self.result {
            Ok(result) => !result.is_error.unwrap_or(false),
            Err(_) => false,
        }
    }
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct WebSearchBeginEvent {
    pub call_id: String,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct WebSearchEndEvent {
    pub call_id: String,
    pub query: String,
}

/// Response payload for `Op::GetHistory` containing the current session's
/// in-memory transcript.
#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct ConversationPathResponseEvent {
    pub conversation_id: ConversationId,
    pub path: PathBuf,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct ResumedHistory {
    pub conversation_id: ConversationId,
    pub history: Vec<RolloutItem>,
    pub rollout_path: PathBuf,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub enum InitialHistory {
    New,
    Resumed(ResumedHistory),
    Forked(Vec<RolloutItem>),
}

impl InitialHistory {
    pub fn get_rollout_items(&self) -> Vec<RolloutItem> {
        match self {
            InitialHistory::New => Vec::new(),
            InitialHistory::Resumed(resumed) => resumed.history.clone(),
            InitialHistory::Forked(items) => items.clone(),
        }
    }

    pub fn get_event_msgs(&self) -> Option<Vec<EventMsg>> {
        match self {
            InitialHistory::New => None,
            InitialHistory::Resumed(resumed) => Some(
                resumed
                    .history
                    .iter()
                    .filter_map(|ri| match ri {
                        RolloutItem::Event(ev) => Some(ev.msg.clone()),
                        _ => None,
                    })
                    .collect(),
            ),
            InitialHistory::Forked(items) => Some(
                items
                    .iter()
                    .filter_map(|ri| match ri {
                        RolloutItem::Event(ev) => Some(ev.msg.clone()),
                        _ => None,
                    })
                    .collect(),
            ),
        }
    }
}

#[derive(Serialize, Deserialize, Copy, Clone, Debug, PartialEq, Eq, TS, Default)]
#[serde(rename_all = "lowercase")]
#[ts(rename_all = "lowercase")]
pub enum SessionSource {
    Cli,
    #[default]
    VSCode,
    Exec,
    Mcp,
    #[serde(other)]
    Unknown,
}

#[derive(Serialize, Deserialize, Clone, Debug, TS)]
pub struct SessionMeta {
    pub id: ConversationId,
    pub timestamp: String,
    pub cwd: PathBuf,
    pub originator: String,
    pub cli_version: String,
    pub instructions: Option<String>,
    #[serde(default)]
    pub source: SessionSource,
}

impl Default for SessionMeta {
    fn default() -> Self {
        SessionMeta {
            id: ConversationId::default(),
            timestamp: String::new(),
            cwd: PathBuf::new(),
            originator: String::new(),
            cli_version: String::new(),
            instructions: None,
            source: SessionSource::default(),
        }
    }
}

#[derive(Serialize, Deserialize, Debug, Clone, TS)]
pub struct SessionMetaLine {
    #[serde(flatten)]
    pub meta: SessionMeta,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub git: Option<GitInfo>,
}

#[derive(Serialize, Deserialize, Debug, Clone, TS)]
#[serde(tag = "type", content = "payload", rename_all = "snake_case")]
pub enum RolloutItem {
    SessionMeta(SessionMetaLine),
    ResponseItem(ResponseItem),
    Compacted(CompactedItem),
    TurnContext(TurnContextItem),
    Event(RecordedEvent),
}

#[derive(Serialize, Deserialize, Clone, Debug, TS)]
pub struct CompactedItem {
    pub message: String,
}

impl From<CompactedItem> for ResponseItem {
    fn from(value: CompactedItem) -> Self {
        ResponseItem::Message {
            id: None,
            role: "assistant".to_string(),
            content: vec![ContentItem::OutputText {
                text: value.message,
            }],
        }
    }
}

#[derive(Serialize, Deserialize, Clone, Debug, TS)]
pub struct TurnContextItem {
    pub cwd: PathBuf,
    pub approval_policy: AskForApproval,
    pub sandbox_policy: SandboxPolicy,
    pub model: String,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub effort: Option<ReasoningEffortConfig>,
    pub summary: ReasoningSummaryConfig,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub base_instructions: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub user_instructions: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub developer_instructions: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub final_output_json_schema: Option<Value>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub truncation_policy: Option<TruncationPolicy>,
}

#[derive(Debug, Clone, Copy, Deserialize, Serialize, PartialEq, Eq, TS)]
#[serde(tag = "mode", content = "limit", rename_all = "snake_case")]
pub enum TruncationPolicy {
    Bytes(usize),
    Tokens(usize),
}

#[derive(Serialize, Deserialize, Clone)]
pub struct RolloutLine {
    pub timestamp: String,
    #[serde(flatten)]
    pub item: RolloutItem,
}

#[derive(Serialize, Deserialize, Clone, Debug, TS)]
pub struct GitInfo {
    /// Current commit hash (SHA)
    #[serde(skip_serializing_if = "Option::is_none")]
    pub commit_hash: Option<String>,
    /// Current branch name
    #[serde(skip_serializing_if = "Option::is_none")]
    pub branch: Option<String>,
    /// Repository URL (if available from remote)
    #[serde(skip_serializing_if = "Option::is_none")]
    pub repository_url: Option<String>,
}

/// Review request sent to the review session.
#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, TS)]
pub struct ReviewRequest {
    pub prompt: String,
    pub user_facing_hint: String,
    #[serde(skip_serializing_if = "Option::is_none")]
    #[ts(optional)]
    pub metadata: Option<ReviewContextMetadata>,
}

#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, TS, Default)]
pub struct ReviewContextMetadata {
    #[serde(skip_serializing_if = "Option::is_none")]
    #[ts(optional)]
    pub scope: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    #[ts(optional)]
    pub commit: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    #[ts(optional)]
    pub base_branch: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    #[ts(optional)]
    pub current_branch: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    #[ts(optional)]
    pub auto_review: Option<bool>,
}

/// Structured review result produced by a child review session.
#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, TS)]
pub struct ReviewOutputEvent {
    pub findings: Vec<ReviewFinding>,
    pub overall_correctness: String,
    pub overall_explanation: String,
    pub overall_confidence_score: f32,
}

impl Default for ReviewOutputEvent {
    fn default() -> Self {
        Self {
            findings: Vec::new(),
            overall_correctness: String::default(),
            overall_explanation: String::default(),
            overall_confidence_score: 0.0,
        }
    }
}

/// A single review finding describing an observed issue or recommendation.
#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, TS)]
pub struct ReviewFinding {
    pub title: String,
    pub body: String,
    pub confidence_score: f32,
    pub priority: i32,
    pub code_location: ReviewCodeLocation,
}

/// Location of the code related to a review finding.
#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, TS)]
pub struct ReviewCodeLocation {
    pub absolute_file_path: PathBuf,
    pub line_range: ReviewLineRange,
}

/// Inclusive line range in a file associated with the finding.
#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, TS)]
pub struct ReviewLineRange {
    pub start: u32,
    pub end: u32,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct ExecCommandBeginEvent {
    /// Identifier so this can be paired with the ExecCommandEnd event.
    pub call_id: String,
    /// The command to be executed.
    pub command: Vec<String>,
    /// The command's working directory if not the default cwd for the agent.
    pub cwd: PathBuf,
    pub parsed_cmd: Vec<ParsedCommand>,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct ExecCommandEndEvent {
    /// Identifier for the ExecCommandBegin that finished.
    pub call_id: String,
    /// Captured stdout
    pub stdout: String,
    /// Captured stderr
    pub stderr: String,
    /// Captured aggregated output
    #[serde(default)]
    pub aggregated_output: String,
    /// The command's exit code.
    pub exit_code: i32,
    /// The duration of the command execution.
    #[ts(type = "string")]
    pub duration: Duration,
    /// Formatted output from the command, as seen by the model.
    pub formatted_output: String,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct ViewImageToolCallEvent {
    /// Identifier for the originating tool call.
    pub call_id: String,
    /// Local filesystem path provided to the tool.
    pub path: PathBuf,
}

#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, TS)]
#[serde(rename_all = "snake_case")]
pub enum ExecOutputStream {
    Stdout,
    Stderr,
}

#[serde_as]
#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, TS)]
pub struct ExecCommandOutputDeltaEvent {
    /// Identifier for the ExecCommandBegin that produced this chunk.
    pub call_id: String,
    /// Which stream produced this chunk.
    pub stream: ExecOutputStream,
    /// Raw bytes from the stream (may not be valid UTF-8).
    #[serde_as(as = "serde_with::base64::Base64")]
    #[ts(type = "string")]
    pub chunk: Vec<u8>,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct ExecApprovalRequestEvent {
    /// Identifier for the associated exec call, if available.
    pub call_id: String,
    /// The command to be executed.
    pub command: Vec<String>,
    /// The command's working directory.
    pub cwd: PathBuf,
    /// Optional human-readable reason for the approval (e.g. retry without sandbox).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub reason: Option<String>,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct ApplyPatchApprovalRequestEvent {
    /// Responses API call id for the associated patch apply call, if available.
    pub call_id: String,
    pub changes: HashMap<PathBuf, FileChange>,
    /// Optional explanatory reason (e.g. request for extra write access).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub reason: Option<String>,
    /// When set, the agent is asking the user to allow writes under this root for the remainder of the session.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub grant_root: Option<PathBuf>,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct BackgroundEventEvent {
    pub message: String,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct StreamErrorEvent {
    pub message: String,
    #[serde(default)]
    pub codex_error_info: Option<CodexErrorInfo>,
    /// Optional details about the underlying stream failure (often the same
    /// human-readable message that is surfaced as the terminal error if retries
    /// are exhausted).
    #[serde(default)]
    pub additional_details: Option<String>,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct PatchApplyBeginEvent {
    /// Identifier so this can be paired with the PatchApplyEnd event.
    pub call_id: String,
    /// If true, there was no ApplyPatchApprovalRequest for this patch.
    pub auto_approved: bool,
    /// The changes to be applied.
    pub changes: HashMap<PathBuf, FileChange>,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct PatchApplyEndEvent {
    /// Identifier for the PatchApplyBegin that finished.
    pub call_id: String,
    /// Captured stdout (summary printed by apply_patch).
    pub stdout: String,
    /// Captured stderr (parser errors, IO failures, etc.).
    pub stderr: String,
    /// Whether the patch was applied successfully.
    pub success: bool,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct TurnDiffEvent {
    pub unified_diff: String,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct GetHistoryEntryResponseEvent {
    pub offset: usize,
    pub log_id: u64,
    /// The entry at the requested offset, if available and parseable.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub entry: Option<HistoryEntry>,
}

/// Response payload for `Op::ListMcpTools`.
#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct McpListToolsResponseEvent {
    /// Fully qualified tool name -> tool definition.
    pub tools: std::collections::HashMap<String, McpTool>,
}

/// Response payload for `Op::ListCustomPrompts`.
#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct ListCustomPromptsResponseEvent {
    pub custom_prompts: Vec<CustomPrompt>,
}

/// Response payload for `Op::ListSkills`.
#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct ListSkillsResponseEvent {
    pub skills: Vec<Skill>,
}

#[derive(Debug, Default, Clone, Deserialize, Serialize, TS)]
pub struct SessionConfiguredEvent {
    /// Name left as session_id instead of conversation_id for backwards compatibility.
    pub session_id: ConversationId,

    /// Tell the client what model is being queried.
    pub model: String,

    /// The effort the model is putting into reasoning about the user's request.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub reasoning_effort: Option<ReasoningEffortConfig>,

    /// Identifier of the history log file (inode on Unix, 0 otherwise).
    pub history_log_id: u64,

    /// Current number of entries in the history log.
    pub history_entry_count: usize,

    /// Optional initial messages (as events) for resumed sessions.
    /// When present, UIs can use these to seed the history.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub initial_messages: Option<Vec<EventMsg>>,

    pub rollout_path: PathBuf,
}

/// User's decision in response to an ExecApprovalRequest.
#[derive(Debug, Default, Clone, Copy, Deserialize, Serialize, PartialEq, Eq, Display, TS)]
#[serde(rename_all = "snake_case")]
pub enum ReviewDecision {
    /// User has approved this command and the agent should execute it.
    Approved,

    /// User has approved this command and wants to automatically approve any
    /// future identical instances (`command` and `cwd` match exactly) for the
    /// remainder of the session.
    ApprovedForSession,

    /// User has denied this command and the agent should not execute it, but
    /// it should continue the session and try something else.
    #[default]
    Denied,

    /// User has denied this command and the agent should not do anything until
    /// the user's next command.
    Abort,
}

#[derive(Debug, Clone, PartialEq, Eq, Deserialize, Serialize, TS)]
#[serde(rename_all = "snake_case")]
pub enum FileChange {
    Add {
        content: String,
    },
    Delete {
        content: String,
    },
    Update {
        unified_diff: String,
        move_path: Option<PathBuf>,
        original_content: String,
        new_content: String,
    },
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct Chunk {
    /// 1-based line index of the first line in the original file
    pub orig_index: u32,
    pub deleted_lines: Vec<String>,
    pub inserted_lines: Vec<String>,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct EnvironmentContextFullEvent {
    /// JSON serialization of the environment context snapshot.
    pub snapshot: serde_json::Value,
    /// Sequence number associated with the snapshot emission.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub sequence: Option<u64>,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct EnvironmentContextDeltaEvent {
    /// JSON serialization of the environment context delta.
    pub delta: serde_json::Value,
    /// Sequence number associated with the delta emission.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub sequence: Option<u64>,
    /// Fingerprint of the baseline snapshot for this delta.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub base_fingerprint: Option<String>,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct BrowserSnapshotEvent {
    /// JSON serialization of the browser snapshot metadata.
    pub snapshot: serde_json::Value,
    /// URL associated with the snapshot, if available.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub url: Option<String>,
    /// Timestamp when the snapshot was captured.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub captured_at: Option<String>,
}

#[derive(Debug, Clone, Deserialize, Serialize, TS)]
pub struct TurnAbortedEvent {
    pub reason: TurnAbortReason,
}

#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, TS)]
#[serde(rename_all = "snake_case")]
pub enum TurnAbortReason {
    Interrupted,
    Replaced,
    ReviewEnded,
}

#[cfg(test)]
mod tests {
    use super::*;
    use anyhow::Result;
    use serde_json::json;
    use tempfile::NamedTempFile;

    /// Serialize Event to verify that its JSON representation has the expected
    /// amount of nesting.
    #[test]
    fn serialize_event() -> Result<()> {
        let conversation_id = ConversationId::from_string("67e55044-10b1-426f-9247-bb680e5fe0c8")?;
        let rollout_file = NamedTempFile::new()?;
        let event = Event {
            id: "1234".to_string(),
            event_seq: 1,
            msg: EventMsg::SessionConfigured(SessionConfiguredEvent {
                session_id: conversation_id,
                model: "codex-mini-latest".to_string(),
                reasoning_effort: Some(ReasoningEffortConfig::default()),
                history_log_id: 0,
                history_entry_count: 0,
                initial_messages: None,
                rollout_path: rollout_file.path().to_path_buf(),
            }),
            order: None,
        };

        let expected = json!({
            "id": "1234",
            "event_seq": 1,
            "msg": {
                "type": "session_configured",
                "session_id": "67e55044-10b1-426f-9247-bb680e5fe0c8",
                "model": "codex-mini-latest",
                "reasoning_effort": "medium",
                "history_log_id": 0,
                "history_entry_count": 0,
                "rollout_path": format!("{}", rollout_file.path().display()),
            }
        });
        assert_eq!(expected, serde_json::to_value(&event)?);
        Ok(())
    }

    #[test]
    fn vec_u8_as_base64_serialization_and_deserialization() -> Result<()> {
        let event = ExecCommandOutputDeltaEvent {
            call_id: "call21".to_string(),
            stream: ExecOutputStream::Stdout,
            chunk: vec![1, 2, 3, 4, 5],
        };
        let serialized = serde_json::to_string(&event)?;
        assert_eq!(
            r#"{"call_id":"call21","stream":"stdout","chunk":"AQIDBAU="}"#,
            serialized,
        );

        let deserialized: ExecCommandOutputDeltaEvent = serde_json::from_str(&serialized)?;
        assert_eq!(deserialized, event);
        Ok(())
    }

    #[test]
    fn compaction_checkpoint_warning_round_trips() -> Result<()> {
        let event = EventMsg::CompactionCheckpointWarning(CompactionCheckpointWarningEvent {
            message: "History checkpoint: earlier conversation compacted.".to_string(),
        });

        let serialized = serde_json::to_string(&event)?;
        let restored: EventMsg = serde_json::from_str(&serialized)?;

        match restored {
            EventMsg::CompactionCheckpointWarning(payload) => {
                assert!(payload.message.contains("checkpoint"));
            }
            other => panic!("unexpected variant: {other:?}"),
        }

        Ok(())
    }
}