Calling Another Agent (Scala)

Overview

Native definition-derived SDK clients extend AgentCompanionBase. CLI-generated internal bridge clients do not. The examples below use native SDK clients; no manually defined companion is required.

Setup

Define the agent trait. The SDK auto-generates a CounterAgentClient companion object at build time:

import golem.BaseAgent
import golem.runtime.annotations.agentDefinition
 
import scala.concurrent.Future
 
@agentDefinition()
trait CounterAgent extends BaseAgent {
  class Id(val name: String)
  def increment(): Future[Int]
  def getCount(): Future[Int]
}

Getting a Client

Use CounterAgentClient.get(...) with the target agent’s constructor parameters:

val counter = CounterAgentClient.get("my-counter")

This returns a CounterAgentRemote with per-method wrapper fields. It does not create the agent — the agent is created implicitly on its first invocation. If it already exists, you get a handle to the existing instance.

Awaited Call

Call a method and wait for the result:

val result: Future[Int] = counter.increment()
val count: Future[Int] = counter.getCount()

The call uses async-invoke-and-await under the hood — the calling agent suspends (yields the WASM event loop) until the target agent returns. The returned Future is genuinely async, enabling concurrent RPC calls to multiple agents.

Cancelable Call

The signatures here describe native SDK durable targets with stream-free methods. Native ephemeral clients expose newPhantom / getPhantom; CLI-generated ephemeral guest bridges expose only newPhantom. Their awaited calls return Future[InvocationResult[T]], cancelable calls return Future[CancelableAsyncInvocation[T]], trigger/schedule return Future[InvocationReceipt], and cancelable scheduling returns Future[CancelableInvocationReceipt] (types in golem.runtime.rpc).

Get a (Future[Out], CancellationToken) pair to cancel a pending call:

val (result, token) = counter.increment.cancelable()
// Later: token.cancel() — best-effort cancellation

Other Call Modes

Each method also supports fire-and-forget and scheduling:

counter.increment.trigger()                          // fire-and-forget
counter.increment.scheduleAt(Datetime.afterSeconds(60)) // scheduled
counter.increment.scheduleCancelableAt(Datetime.afterSeconds(60)) // cancelable scheduled

See the golem-fire-and-forget-scala and golem-schedule-future-call-scala skills.

Phantom Agents

To create multiple distinct instances with the same constructor parameters, use phantom agents. See the golem-multi-instance-agent-scala guide.

Cross-Component RPC

When calling agents defined in a different component, the generated client type is available after running golem build — the build step generates bridge SDK code for inter-component dependencies declared in golem.yaml.

Avoiding Deadlocks

Never create RPC cycles where A awaits B and B awaits A — this deadlocks both agents. Use .trigger() (fire-and-forget) to break cycles. See the golem-fire-and-forget-scala guide.