Struct AgentBuilder 

pub struct AgentBuilder<B: LlmBackend> { /* private fields */ }

Fluent builder for Agent.

Example

use agnt_core::AgentBuilder;
use my_backend::Backend;

let agent = AgentBuilder::new(Backend::ollama("gemma4:e4b"))
    .system("You are a helpful assistant.")
    .max_steps(5)
    .max_window(20)
    .max_tool_result_bytes(32 * 1024)
    .on_token(Box::new(|tok| print!("{}", tok)))
    .build();

Implementations

impl<B: LlmBackend> AgentBuilder<B>

pub fn new(backend: B) -> Self

Start a new builder with the given backend. The system prompt defaults to the empty string and can be set with AgentBuilder::system.

pub fn system(self, system: impl Into<String>) -> Self

Set the system prompt.

pub fn tool(self, tool: Box<dyn Tool>) -> Self

Register a single tool.

pub fn tools(self, tools: Vec<Box<dyn Tool>>) -> Self

Register many tools at once.

pub fn max_steps(self, n: usize) -> Self

Maximum inference turns per Agent::step call. Default: 10.

pub fn max_window(self, n: usize) -> Self

Maximum messages sent to the backend per turn. Default: 40.

pub fn max_tool_result_bytes(self, n: usize) -> Self

Cap on raw bytes per tool result before envelope framing. Default: 64KB.

pub fn store( self, store: Arc<dyn MessageStore>, session: impl Into<String>, ) -> Self

Attach a persistent message store and session id.

pub fn observer(self, observer: Arc<dyn Observer>) -> Self

Attach a lifecycle observer.

pub fn on_token(self, sink: Box<dyn FnMut(&str) + Send>) -> Self

Install a token callback. Each streamed delta from the backend is passed to this closure during inference.

pub fn build(self) -> Result<Agent<B>, String>

Finalize the builder and produce an Agent.

If a store was provided, this calls Agent::attach_store. Any error from attaching the store is returned.