Solana Mainnet Upgrade Raises Max Transaction Size to 4,096 Bytes

The headline number understates the change: quadrupling transaction capacity is really about what can be composed atomically, since zero-knowledge proofs, multisig flows and new signature schemes were previously constrained by block space per transaction. Backward compatibility matters as much as the size bump, because wallets and apps face no forced migration and the upgrade's practical effect will show up unevenly across the ecosystem. Whether developers actually build toward the new ceiling, rather than defaulting to the familiar format, is the open question.