Aion

Who it is for

Use Aion when a job has several steps and must keep its state across failures or long waits. Approval flows, scheduled jobs and agent workflows can all use the same engine.

A workflow records decisions and activity results. On recovery, Aion replays that record. Your activity code still needs to handle a request that arrives more than once.

Start with one workflow

The first guide uses a small AWL file. It needs no activity worker, agent account or external Gleam compiler.

What runs where

The Rust server owns storage and the workflow engine. AWL compiles directly to BEAM bytecode. Gleam also targets BEAM bytecode. Aion executes both through beamr.

Workers run external activities in separate processes. The console and public APIs share the server’s HTTP listener. The assistant opens an ACP conversation with a selected agent harness on the server host.

Read durability and replay before using Aion for side effects. Read auth and Lys before exposing the server to other machines.

Versions

Main

Workspace 0.31.0; Rust edition 2024; minimum Rust 1.89; AGPL-3.0-only. The source revision is shown in this page’s version badge.

Public release

crates.io aion-cli 0.31.0, published 18 September 2026. Its source commit is ebd8ebcd83ac49da4ed04b77e308708cfe6cf0cc.

Main additions

Main code commit 969e23048495fefe650d2f6283097476e1063901 is 5,736 commits beyond the public crate’s source. Venues, worker connected, store migrate-package-rows and server.grpc_addresses require this newer main code.

CLI

The main command tree has 55 help surfaces. Use your installed command’s help to select its supported options.

AWL

The main language guide has 112 entries: 72 reserved and 40 positional words.

MCP

14 public workflow tools and 3 assistant conversation tools. Their schemas are in the MCP reference.