2.4 compatibility in Nexa 3.0

This page describes the retained 2.4 language/runtime path. Sources without a version declaration use this path. Start new Open Programs with Nexa 3.0; compare contracts in the migration guide.

Actor syntax and usage

Actors use spawn, pass, and await to express concurrent workers and mailboxes. See Actor lifecycle for ownership, concurrency limits, and accounting.

Syntax	Meaning
worker = spawn Agent("task");	Create an isolated Agent session owned by this flow
pass "next" to worker;	Queue another input in the Actor's sequential mailbox
result = await worker;	Close the mailbox, wait, and return the final result

Successive messages suit staged analysis of one task. Create multiple Actors for independent work, and await each before returning from the flow. On failure, the runtime cancels remaining tasks and waits for their threads.

Standalone receive() from older designs requires a custom message handler; model Actors consume their mailboxes automatically. Use durable runs across processes.

---

Source and validation · actors