Struct Engine 

pub struct Engine { /* private fields */ }

The core ReAct agent loop.

Drives an LLM through iterative reasoning and tool execution until the model produces a final text answer or the iteration limit is reached.

Starting a turn

Every agent turn goes through Engine::run, which returns a RunBuilder. Chain axis setters (.ops, .cancel, .chunked) in any order, then call one of the three terminators (.result, .callback, .stream) to execute the turn:

use std::sync::Arc;
use motosan_agent_loop::{Engine, Message};

let agent = Arc::new(Engine::builder().build());

// Simplest: just the final result.
let result = Arc::clone(&agent)
    .run(llm.clone(), vec![Message::user("Hi!")])
    .result()
    .await?;

// Live token-by-token UI with AskUser support:
Arc::clone(&agent)
    .run(llm, vec![Message::user("Ask me a question")])
    .chunked()
    .ops(ops_rx)
    .callback(|event| println!("{event:?}"))
    .await?;

See RunBuilder for the full axis/terminator matrix and Engine::run for the entry point.

The loop does not own the LLM client; instead, RunBuilder takes Arc<dyn LlmClient> so the same loop can be reused with different backends.

Implementations

impl Engine

pub fn builder() -> EngineBuilder

Create a builder with default settings.

pub fn channel_config(&self) -> &ChannelConfig

Returns the channel configuration for this agent loop.

Used by AgentSession to create bounded channels with the configured capacities and policies.

impl Engine

pub fn run( self: Arc<Self>, llm: Arc<dyn LlmClient>, messages: Vec<Message>, ) -> RunBuilder

Build a run configuration for this agent.

Chain axis setters (.ops(rx), .cancel(token), .chunked()) in any order, then call one of the terminators (.result(), .callback(cb), .stream()) to execute the turn.

Example

use std::sync::Arc;
use motosan_agent_loop::{Engine, Message};

let agent = Arc::new(Engine::builder().build());

// Simplest: just the final result.
let result = Arc::clone(&agent)
    .run(llm.clone(), vec![Message::user("Hi!")])
    .result()
    .await?;

See the RunBuilder struct documentation for the full set of axis setters and terminators.