How does Kaspa's lane commitment scheme reduce ZK prover costs?

Kaspa's KIP-0021 makes zero-knowledge proving costs scale with a single application's own activity rather than the entire network's traffic. Zero-knowledge (ZK) proofs are cryptographic tools that let software prove a computation was done correctly without exposing all underlying data. In a standard linear blockchain, generating such a proof requires processing global block activity for every block — even when the prover only cares about one application. KIP-0021 changes this by committing to "lane tips" and lane-local activity digests: compact summaries scoped to each individual application lane. A prover working on one lane only needs that lane's data, so its cost tracks only what that lane does. For developers building ZK-powered applications on Kaspa, this means proving costs won't balloon as overall network usage grows — they stay tied to your application's own footprint.