Enum Event 

#[non_exhaustive]
pub enum Event {
    PreToolUse,
    PostToolUse,
    Notification,
    UserPromptSubmit,
    Stop,
    SubagentStop,
    PreCompact,
    SessionStart,
    SessionEnd,
    PermissionRequest,
    PermissionDenied,
    ConfigChange,
    FileChanged,
    InstructionsLoaded,
    Custom(String),
}

Lifecycle event to attach to. Each integration maps this to its harness’s own event name (e.g., PreToolUse on Claude Code, BeforeTool on Gemini, tool.execute.before on OpenCode).

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

PreToolUse

Fire before a tool call is executed (the most common case; lets the hook modify or block the call).

PostToolUse

Fire after a tool call completes.

Notification

Hook fires when a notification event is dispatched.

UserPromptSubmit

Hook fires when user submits a prompt.

Stop

Hook fires when the agent stops.

SubagentStop

Hook fires when a subagent stops.

PreCompact

Hook fires before message compaction.

SessionStart

Hook fires when a session starts.

SessionEnd

Hook fires when a session ends.

PermissionRequest

Hook fires when a permission request is initiated.

PermissionDenied

Hook fires when a permission is denied.

ConfigChange

Hook fires when configuration changes.

FileChanged

Hook fires when a file is changed.

InstructionsLoaded

Hook fires when instructions are loaded.

Custom(String)

Pass through a custom event name verbatim.

Implementations

impl Event

pub fn as_str(&self) -> &str

Return the canonical string representation of the event.

Trait Implementations

impl Clone for Event

fn clone(&self) -> Event

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Event

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for Event

impl PartialEq for Event

fn eq(&self, other: &Event) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for Event