BIP 54 implementation progresses without a mainnet activation plan
September updates to Bitcoin Core pull request #35793 advanced implementation of BIP 54’s consensus cleanup. The work explicitly excluded mainnet activation, keeping coding progress separate from deployment and adoption.
Bitcoin Core pull request #35793, “Implement BIP 54 without mainnet activation,” recorded September development activity, including code updates on September 25, 2026. The implementation followed the consensus-cleanup proposal authored by Antoine Poinsot and Matt Corallo.
BIP 54 addresses narrow consensus risks rather than introducing a new general-purpose transaction language. Its proposed changes cover block-time manipulation, expensive legacy signature-operation validation, 64-byte transactions that can confuse Merkle-proof interpretation, and coinbase uniqueness issues associated with duplicate transactions. Those mechanisms affect how Bitcoin data is validated or proved.
Changing consensus rules requires more than publishing code. The pull request’s explicit exclusion of mainnet activation meant that implementation progress did not establish a deployment schedule, miner agreement or active new rules on Bitcoin. September’s work made a concrete security proposal closer to testable software while leaving the social and technical process for any future activation unresolved.