Hello, dev here. I see what bug this mod uses in 2.0 to bypass the transport belt collision requirement: there was an issue with collision mask equals compare which was only checking if two collision masks have the same layers but not if they have the same flags. When transport belt prototypes were checked, checker first sees belts with collision mask that collides with itself, check passes and it remembers that collision mask as being already checked, and later when it sees linked belt that does not collide with belts, when checking if that mask was already checked it uses faulty equals compare and decides that this mask was already checked and check is skipped.

Unfortunately in 2.1 i was rewriting CollisionMask class due to modding interface requests to increase amount of layers which i did increasing the limit to 256 and during that rewrite i spotted the faulty collision mask equals compare so this issue was internally fixed since january 2026 and was released with the initial 2.1 experimental.

Just letting you know why it works.

Thanks for the heads up boskid!

I tested on 2.1.14 and you're right -- it breaks. I've opened this thread to request a formal API to opt out of the collision check.

If the API doesn't make it into 2.1.x, I'll probably rework the mod to allow no more than one connection to each balancer part. A breaking change I'd like to avoid (would also break BB2/3 shape compatibility), but it should preserve the core functionality.

Based on this feedback I've implemented the one-connection-per-balancer-part limit (optional in the 2.0 version of the mod, mandatory for 2.1).

So the mod is good to go for 2.1 at this point.

If/when the requested CollisionMask API gets implemented, I will relax this constraint back to the way it was.