[BIP Proposal] Limit ScriptPubkey Size >= 520 Bytes Consensus.

The conversation within the Bitcoin Development Mailing List, featuring inputs from Andrew Poelstra among others, delves into technical considerations surrounding Bitcoin's scriptpubkey size limits. Poelstra, a notable figure from Blockstream Research, articulates a preference for constraining the maximum size of scriptpubkeys to below the current 520-byte threshold. This perspective is rooted in the anticipation of a "post-covenant" scenario in Bitcoin's evolution, suggesting a forward-looking approach to blockchain protocol adjustments.

Highlighting the practical implications of such a policy, Poelstra addresses potential concerns related to the risk of coin confiscation due to pre-signed but unpublished transactions that designate new outputs with oversized scriptPubKeys. Given the enduring standardness rules and the historical adoption of P2SH (Pay to Script Hash) and P2WSH (Pay to Witness Script Hash), he expresses skepticism towards the existence of such transactions that would be adversely affected. Nevertheless, he acknowledges the possibility of exceptions, particularly for transactions involving UTXOs (Unspent Transaction Outputs) predating any new size regulations. In such cases, exemptions could be made to allow the creation of new UTXOs with larger script sizes than newly established limits would typically permit.

Poelstra’s commentary encapsulates a nuanced stance on managing Bitcoin’s technical constraints, balancing innovation with the safeguarding of existing assets. His insights contribute to the broader dialogue on how best to evolve Bitcoin's protocol in ways that address both future opportunities and present challenges. For more information about Andrew Poelstra and his work, one can visit Blockstream Research.