Struct ToolParkingLot 

pub struct ToolParkingLot { /* private fields */ }

A parking lot for custom tool calls awaiting client-delivered results.

The session loop calls park when agent.custom_tool_use is emitted, blocking until either:

1. The client sends user.custom_tool_result and the runtime calls deliver
2. The configured timeout elapses, returning RuntimeError::ToolTimeout

Thread-safe: the internal map is protected by a Mutex.

Implementations

impl ToolParkingLot

pub fn new(timeout: Duration) -> Self

Create a new parking lot with the specified timeout.

Arguments

• timeout - Maximum duration to wait for a tool result before returning RuntimeError::ToolTimeout.

pub fn with_default_timeout() -> Self

Create a new parking lot with the default timeout (5 minutes).

pub async fn park( &self, tool_use_id: &str, ) -> Result<Vec<ContentBlock>, RuntimeError>

Park the session loop, waiting for a custom tool result.

Creates a oneshot channel, stores the sender under tool_use_id, and awaits the receiver. Returns the content blocks when delivered, or RuntimeError::ToolTimeout if the timeout elapses.

Errors

• RuntimeError::ToolTimeout if no result is delivered within the timeout.
• RuntimeError::Internal if the sender is dropped unexpectedly.

pub async fn deliver( &self, tool_use_id: &str, content: Vec<ContentBlock>, ) -> Result<(), RuntimeError>

Deliver a result to a parked tool call.

Looks up the sender by tool_use_id and sends the content. Returns an error if no pending call with this ID exists (e.g., it already timed out or was never parked).

Errors

• RuntimeError::NotFound if no pending call exists for the given ID.