Native handlers

AGL applications extend the runtime through Rust registries. Task declarations specify types in the DSL; a host supplies their implementations before execution.

Register a task

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()}))
});

Pass the registry to agl::execute_pipeline or agl::run_tests. Use Registry::register_contextual when a handler needs invocation identity, cancellation, usage reporting, or structured failures.

The executable example includes parsing, checking, registration, and execution:

cargo run --example native_embed

Register a tool

Model-callable tools use agl::adapters::tools::ToolRegistry. Register their handlers before passing the tool registry to agl::stdlib::registry_for_with_tools. Declare tool signatures in the DSL so arguments and results can be validated.

Execution boundary

Custom handlers are compiled into a Rust host application. The stock CLI uses built-in handlers and native provider adapters. It does not load external handler modules. Native handlers share the host process and its permissions.

See native extensions for extension contracts and testing for in-language test blocks.