Forester

Forester is the permissionless keeper service in Light Protocol's architecture responsible for performing routine Merkle tree maintenance operations that must be triggered by an external party rather than automatically on-chain, including nullifier queue processing (finalizing spent compressed account hashes to prevent double-spends), address queue processing (registering new compressed account addresses), and rolling epoch-based tree updates. Without an active Forester, nullifier queues can fill up and block new state transitions in a compressed tree, so Light Protocol incentivizes Forester operators through protocol fees collected during these maintenance operations. Forester nodes are run permissionlessly by anyone against a Solana RPC and monitor on-chain queue accounts, submitting crank transactions when queues require processing.