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emanuele-em
The clock injection for testing temporal nodes is a really nice touch. Most BT libraries force you to actually wait or mock everything yourself. This would work well for orchestrating retries and fallback logic in microservices, not just game AI. Any plans for parallel composite nodes?
[dead] redoh
[flagged]
dgb23
Not a Go veteran, but I implememted a behavior tree in a little simulation game prototype. Looked very similar structurally but your version is nicer.

As an aside:

I don’t particularly like behavior trees. Not sure why, but they feel brute-force-y to me, and I find them much harder to reason about than state machines. Once you express state machines as data, they can become just as powerful and feel less fiddly.

A different thought I have that I couldn’t get around exploring is to implement behavior trees with channels (no go routines). But that’s just a vague notion.

There was a article from Russ Cox „Storing Data in Control Flow“. Maybe there‘s something there?

sh0gg0the
> A different thought I have that I couldn’t get around exploring is to implement behavior trees with channels (no go routines).

I don't think "channels without go routines" are possible. One thread can't send and simultaneously receive on a channel. I remember libraries that used go channels for control flow because the code looked better this way. They had to start a second thread to make it work which is very inefficient.

Better approaches are "functions" with internal state (generators) or the relatively new stdlib iter package.

Edit: the iter package internally uses compiler quirks to implement coroutines to be able to send and receive values on the same thread.

reducirimagen
I really like the approach to time-travel testing here. Injecting the clock directly into the BTContext is a very clean way to avoid flaky CI tests without having to mock global time interfaces.

Quick technical question: When a node returns 0 (Running), does the Supervisor strictly adhere to the fixed tick interval (like the 100ms in the example), or is there any built-in exponential backoff? I'm wondering how it handles CPU load if you have hundreds of trees just waiting on I/O. Really clean architecture, great work!