Bitcoin Developers Converge on Two Key Proposals for Next Soft Fork

Bitcoin's developer community is showing signs of converging on two Bitcoin Improvement Proposals (BIPs) for the next soft fork: BIP 119, also known as OP_CHECKTEMPLATEVERIFY (CTV), and BIP 348, known as OP_CHECKSIGFROMSTACK (CSFS). These proposals are part of the formal process for discussing and implementing changes to Bitcoin, and if they gain sufficient support, they will be added to Bitcoin through a soft fork or a routine update to Bitcoin Core.

The process of reaching consensus on these BIPs involves extensive debate among Bitcoin's technical community. The Taproot Wizards, a Bitcoin development firm, have provided a graphic explaining the complex and iterative nature of these discussions. The Bitcoin soft fork process requires an estimate of support from various stakeholders, including developers, custodians, investors, and miners. Miners play a crucial role in signaling support for changes by including signals in their mined blocks. Typically, Bitcoin Core seeks 95% of blocks over a period to signal for the change before locking in the update for activation.

However, defining "widespread support" is challenging due to Bitcoin's decentralized structure. Over the past few months, there has been a noticeable shift as numerous developers have explicitly expressed their support for CTV and CSFS. These proposals introduce new ways of writing Bitcoin script, which is the lower-level programming language used for creating and sending transactions. CTV, proposed by former Bitcoin core contributor Jeremy Rubin, has been around for over five years, while CSFS was formalized in November 2024 by Rubin and Brandon Black.

Both BIPs enable "covenants" on Bitcoin, which restrict how a wallet can spend bitcoin in future transactions. Covenants are expected to enhance Bitcoin self-custody, fee management, and existing technologies like Lightning, Ark, and contract-based applications. Developers consider these proposals to be "narrowly defined," meaning there is a low probability of users exploiting them for unexpected purposes. The Bitcoin developer community is known for its cautious approach to changes, and even though BIP 119 has remained unchanged for nearly half a decade, it was once considered too aggressive for activation.

Rubin's previous campaign for CTV faced significant pushback from prominent figures in the Bitcoin community, including Adam Back and Jimmy Song. However, recent advocacy for the OP_CAT opcode (BIP 347) has widened the acceptance of Bitcoin proposals, framing CTV and CSFS as more conservative options. Most supporters of OP_CAT also favor BIPs 119 and 348, indicating a growing consensus among developers.

As the conversation continues, developers are expected to gather at technical conferences such as OPNEXT in April, BTC++ in July, and TABConf in October. Once a rough consensus is formed, the actual activation of the soft fork will move to the miners, community, and investors. However, there is no formalized process for soft forking Bitcoin, leaving many open questions. For instance, it is unclear whether the potential soft fork will include just CTV and CSFS, or if OP_CAT will also be part of the conversation. The activation process and the involvement of other stakeholders, such as Bitcoin miners, remain uncertain.

Despite the uncertainties, one thing is clear: the path to the next Bitcoin soft fork will involve a lot of technical discussions and the use of numerous abbreviations. The developer community's focus on CTV and CSFS signals a potential shift in Bitcoin's technical landscape, with implications for self-custody, fee management, and existing technologies. As the conversation continues, the community will need to navigate the complexities of reaching consensus in a decentralized network.