LayerTree Bitcoin Scaling Targets Shared UTXOs

LayerTree is an early Bitcoin scaling design that would let thousands or potentially millions of users share one on-chain UTXO while tracking individual balances in an off-chain Merkle Sum Tree. Users could make routine payments through Lightning channels or signed vouchers, and use a proof of ownership to exit without an operator’s cooperation. Vouchers are not risk-free before settlement: conflicting claims could compete for limited funds. New estimates suggest a solo exit from a 65,536-slot LayerTree could take about 1,020 virtual bytes, compared with roughly 2,511 vB for a comparable transaction-tree design. A specialized, unactivated opcode could reduce the exit to about 540 vB, while group joins may cost less than 1 vB per member. However, 65,536 individual exits could take around 2,622 blocks—nearly 18 days—if processed sequentially, underscoring Bitcoin’s capacity limits and the need to distribute users across trees. LayerTree cannot run on Bitcoin today. It depends on proposed, unactivated script opcodes, and its most efficient version requires an additional opcode that has not been proposed. Its rules have 72 machine-checked Lean 4 theorems, but the off-chain timing and coordination model remains in development. Operators must approve new members, and long chains of unconfirmed updates could delay exits. For traders, LayerTree is a technical development, not an immediate market catalyst; its longer-term relevance depends on protocol upgrades and practical implementation.