Struct Handlers 

pub struct Handlers { /* private fields */ }

Available on crate feature async-client only.

The callbacks a Client uses to answer the harness.

Implementations

impl Handlers

pub fn new() -> Self

No handlers. Fine for a session with no client-side tools or hooks.

pub fn tool<F, Fut>(self, name: impl Into<String>, f: F) -> Self

where F: Fn(ToolCall) -> Fut + Send + Sync + 'static, Fut: Future<Output = ToolResponse> + Send + 'static,

Registers the implementation of a client-side tool.

name must match the Tool declared on HarnessOptions::tool; the harness dispatches by name.

use antigravity_codes::handlers::Handlers;
use antigravity_codes::protocol::ToolResponse;

let handlers = Handlers::new().tool("clock", |call| async move {
    ToolResponse::ok(call.id.unwrap_or_default(), r#"{"now":"2026-08-08T00:00:00Z"}"#)
});
assert!(handlers.handles_tool("clock"));

pub fn on_hook<F, Fut>(self, f: F) -> Self

where F: Fn(CallHookRequest) -> Fut + Send + Sync + 'static, Fut: Future<Output = CallHookResponse> + Send + 'static,

Handles every lifecycle hook the session subscribed to.

pub fn on_policy<F, Fut>(self, f: F) -> Self

where F: Fn(PolicyDecisionRequest) -> Fut + Send + Sync + 'static, Fut: Future<Output = PolicyDecisionResponse> + Send + 'static,

Adjudicates dynamic policy rules.

pub fn on_questions<F, Fut>(self, f: F) -> Self

where F: Fn(UserQuestionsRequest) -> Fut + Send + Sync + 'static, Fut: Future<Output = UserQuestionsResponse> + Send + 'static,

Answers questions the agent puts to the user.

pub fn on_tool_confirmation<F, Fut>(self, f: F) -> Self

where F: Fn(StepUpdate) -> Fut + Send + Sync + 'static, Fut: Future<Output = bool> + Send + 'static,

Approves or refuses a tool the harness wants confirmed before running.

The handler receives the whole StepUpdate, because the action being confirmed — the command line, the file path, the diff — is on the step, not on the (empty) request itself.

pub fn handles_tool(&self, name: &str) -> bool

Whether a tool of this name has an implementation registered.

Trait Implementations

impl Debug for Handlers

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

Formats the value using the given formatter.

impl Default for Handlers

fn default() -> Handlers

Returns the “default value” for a type.