Hi Erik, > Most nodes could operate on a rolling history validated by occasional, high-value commitments, while archival nodes remain free to preserve the full chain.
This is an old big-blocker idea, and still a terrible one. It effectively reduces what we now call validation to majority hash power control. IOW functionally equivalent to SPV. A few actual full nodes (maybe) validating does not have the implied effect. For a node's validation to matter, the node has to be accepting coin in trade. SPV entirely relies on the presumption that a very large portion of economic activity is actually validated. Very large means enough that majority hash power has a true disincentive to intentionally mine invalid blocks, despite the reward for doing so (e.g. unlimited inflation). What you are calling "archival nodes" don't actually "preserve the full chain" for everyone else, because their effect is limited to their own transactions. Otherwise we are talking about fraud proofs, which is a conversation that doesn't end well. > Because computing the full UTXO root is costly... It is not, it's getting cheaper every year. e On Monday, September 29, 2025 at 8:11:51 PM UTC-4 Erik Aronesty wrote: A soft fork could introduce a new opcode, `OP_CHECKUTXOSETHASH`, allowing miners to optionally commit a deterministic hash of the current UTXO set into a block. If present, all nodes must verify its correctness or reject the block; if absent, the block is still valid. Old nodes treat the opcode as unspendable, so backward compatibility is preserved. Because computing the full UTXO root is costly, this makes each checkpoint intentionally expensive to produce, ensuring that miners will only include them when compensated with sufficient fees. Additionally, it could be limited to one per block. The result is a voluntary, self-limiting, incentive-aligned, fee-driven system where checkpoints are cheaply consensus-enforced when included but never mandatory. Most nodes could operate on a rolling history validated by occasional, high-value commitments, while archival nodes remain free to preserve the full chain. This reduces the burden of initial sync and resource use without sacrificing Bitcoin’s security model, since any invalid checkpoint would invalidate its block. In practice, the chain becomes more efficient for everyday use while the historical record remains intact for those willing to bear the expense of maintaining it. -- You received this message because you are subscribed to the Google Groups "Bitcoin Development Mailing List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/bitcoindev/76c1b5a1-5b78-4576-981f-4df69aefc9a6n%40googlegroups.com.
