Native extensions

Rust applications extend AGL by depending on the agl crate and registering handlers at startup:

let mut registry = agl::Registry::default();
registry.register("uppercase", |args, _agent| {
    let text = args["text"].as_str().unwrap_or_default();
    Ok(serde_json::json!({"text": text.to_uppercase()}))
});

Run the complete embedding example with:

cargo run --example native_embed

Register tasks on Registry and model-callable tools on ToolRegistry. Pass custom tools to registry_for_with_tools before running pipelines with a native provider adapter. Contextual task handlers receive an Invocation and return TaskOutput or HandlerFailure.

The versioned traits in agl::extension cover task handlers, tools, model adapters, hosts, policies, and graders. Validate extension descriptors against EXTENSION_API_VERSION before registration.

Custom handlers are compiled into the host application. AGL does not load Rust dynamic libraries or external handler modules. Native extensions share the host process and permissions.

For removed host APIs and migration steps, see the Rust-only migration notes.