Building a (Restrained) Software Factory

bb is probably best known for extending itself, but extensibility was a much later addition to the app. bb started as an agent orchestrator whose pitch was: If you can do it in the editor, an agent in bb can do it too. A big thing that spun out of this is that agents can orchestrate other agents, and it turns out this becomes a powerful primitive for making bb the command center for all of your agents. Some might even call it a software factory.

I know how that sounds. I'm not going to tell you how to tokenmaxx and endlessly fire off your slop cannon. You don't have to have psychosis to automate the repetitive parts of your work: look for what you keep doing by hand, and use the tools at your disposal to make that less painful. The key is observability. bb lets you automate that work while still seeing what every agent is doing, and taking over when you need to.

Here's how I've used bb to build my (restrained) software factory, one thread at a time.

Level 1: Cross-Provider Sub-Threads

Any agent inside bb can spawn other agents as child threads and talk to them. Those children don't have to use the same provider as the parent.

A basic example: let's say you're using Fable through Claude Code to implement something. You can ask that agent to spawn a GPT-6 Astra worker to review the code. When a thread is spawned as a child of another, the parent gets notified when the child stops working. In our reviewer case then the parent thread can implement the feedback the child has for it.

You aren't limited to spawning a single thread at a time! For example you can have a Fable / Astra worker interview you and create the plan for a feature and then have a series of cheaper models (like Meta Muse or GPT Luna) do the implementation for you..

I personally use large fan-out spawning like this sparingly. For most implementation work, a single agent does better than a swarm. Where it can pay off though is when there are a lot of decisions and deep thinking to be made up front, but the implementation itself is pretty straightforward and can use a cheaper model.

Level 2: Long-Lived Managers

A few months ago I was really excited by the idea of manager agents: you talk to one agent and it does all of the orchestration across other agents for you. I wrote an article about having a middle manager, and the middleman project was a precursor to bb.