Forwardable Peerswap Incentives, And Closing Surreptitious Communications Tunnels

A robust hash-exchange protocol requires that “commitment” refers to an enforceable, on-chain action rather than a mere exchange of signatures or mutual intent to proceed. It is important for the protocol to explicitly define which signatures or blockchain transactions bind the parties such that aborting after the hash disclosure either becomes impossible or incurs a significant penalty. Furthermore, clear procedural guidelines must address scenarios where a participant withholds subsequent messages or actions.

Forwarders exercise strict control over the transaction flow by withholding any relay activity, including the hash itself, until they have verified that the Spilman channel—used as a preliminary payment channel—has been confirmed on-chain for at least the correct negotiated amount. This ensures that Forwarders do not provide their services unless there is a verifiable commitment from the Initiator, evidenced by expenditure of on-chain fees and confirmation wait times. If the Initiator aborts after this stage, the cost has already been incurred in terms of lost opportunity and blockchain fees.

The Spilman channel presents semantic limitations for flexible Lightning routing, a fact that motivates Forwarders to insist on enforceable commitments. Their objective is to guarantee that they play an essential role in indirectly connecting the Initiator with the Acceptor, thereby establishing a future routing path through themselves. To complete the process, both the Initiator and Acceptor must jointly sign a transaction to close the Spilman channel into a standard Lightning channel, which entails another round of on-chain fees.

A critical consideration arises when comparing the prospective in-Lightning fees charged by Forwarders against the immediate on-chain fees required to transfer funds directly from the Spilman channel to a Lightning channel between Initiator and Acceptor. While one could argue that this mirrors the scenario of opening a channel directly with the Acceptor, the unique value provided by Forwarders lies in facilitating the discovery and connection between nodes requiring inbound capacity (the Acceptor) and those seeking outbound capacity (the Initiator). The cost associated with accessing this network intelligence and connectivity is the upfront on-chain commitment made by the Initiator.