recipes.md

Recipes

Copy-paste solutions to common Rust SDK tasks. Complete runnable versions live in examples/.

In-process runtime for tests

use arcp::auth::NoneAuthenticator;
use arcp::messages::Capabilities;
use arcp::runtime::ARCPRuntime;
use arcp::transport::paired;

# async fn make_pair() -> Result<(), Box<dyn std::error::Error>> {
let caps = Capabilities {
    anonymous: Some(true),
    ..Default::default()
};
let runtime = ARCPRuntime::builder()
    .with_authenticator(Box::new(NoneAuthenticator::new()))
    .with_capabilities(caps)
    .build()
    .await?;

let (client_transport, runtime_transport) = paired();
let _server = runtime.serve_connection(runtime_transport);
# let _ = client_transport;
# Ok(())
# }

Run a local WebSocket runtime

cargo run -- serve --bind 127.0.0.1:7777 --bearer tok --principal me

Pair it with a client or one of the WebSocket examples.

Enforce a budget in tool code

# use arcp::runtime::context::ToolContext;
# async fn call(ctx: &ToolContext) -> Result<(), arcp::ARCPError> {
ctx.charge("cost.llm", 0.03, "USD").await?;
# Ok(())
# }

When the matching cost.budget counter is exhausted, the helper returns BUDGET_EXHAUSTED and the runtime can surface a terminal job failure.

Enforce model use

# use arcp::runtime::context::ToolContext;
# async fn call(ctx: &ToolContext) -> Result<(), arcp::ARCPError> {
ctx.enforce_model_use("tier-fast/small").await?;
# Ok(())
# }

Use this before calling an LLM gateway when the job lease includes model.use.

Issue lease-bound credentials

Implement CredentialProvisioner when an upstream service needs a short-lived credential derived from the accepted lease. The runtime redacts credential values from debug output, subscriptions, and job inventory responses, then revokes outstanding ids on job termination.

See examples/provisioned_credentials/.

Recover after reconnect

Use a file-backed EventLog and persist (session_id, resume_token, last_event_seq) in your application state. On reconnect, pass that tuple in the resume handshake and replay events after last_event_seq.

See examples/resumability/.