Finality Gadget
A consensus mechanism layered on top of a base block-production process specifically to formally finalize blocks, making them irreversible.
A finality gadget is a consensus mechanism layered on top of a network's base block-production process, specifically responsible for formally finalizing a batch of blocks — after which reversing them would require an extraordinarily costly and detectable attack, rather than simply being statistically unlikely.
This separates the two concerns of producing new blocks quickly and finalizing them with strong irreversibility guarantees, letting a network optimize each independently rather than requiring a single mechanism to do both well simultaneously. See Kaavon's "Consensus Finality" glossary definition for the broader finality concept this formalizes.
Examples
- A finality gadget can formally finalize a batch of already-produced blocks, providing a stronger irreversibility guarantee than simply waiting for more confirmations.
- Separating block production from finalization lets a network optimize each process independently, rather than requiring one mechanism to handle both.