Spine-Branch cuts computer-use agent costs 34% to 70%

Spine-Branch, a multi-agent architecture, cuts computer-use costs 34% to 70% by never merging virtual machine states, per a new paper on arXiv.

Cost has limited how much parallel exploration long-horizon agent tasks can afford. A cut this steep changes that math.

Every prior system faced the same constraint. Two virtual machines' states can't be merged, and earlier approaches handled that ad hoc.

The architecture breaks a task into a graph instead. A single VM, the spine, carries state that must persist across the whole task. Branch VMs run in parallel solely to gather information, then get discarded, with nothing merging back except what they found.

Researchers tested Spine-Branch on 200 long-horizon tasks in the Odysseys benchmark, across three separate computer-use backbones. Success rose 6.0 to 16.5 points over baseline while per-task cost fell 34% to 70%.

If discard-and-never-merge holds up outside this benchmark, most multi-agent computer-use frameworks have been overpaying to reconcile machine states that were never reconcilable.