In a Nutshell

High-level System Overview

1. State is stored as call data in Solana's ledger, resulting in very low rent cost

2. Transactions specify the state they access (read/write) and include it in the transaction payload

3. State Validation:

   1. Solana Programs invoke the Light Protocol System Program to update compressed state

      1. The protocol validates the state (validity of existing state, sum checks, ownership checks)

      2. The protocol enforces a schema: Classic Accounts → Compressed Accounts. Compressed accounts have a layout similar to classic accounts

4. State Updates: At the end of an instruction, the new state is recorded as a log on the Solana ledger

5. Photon RPC Nodes: These nodes index the state changes, making the compressed account state available to clients via the ZK Compression RPC API

6. Forester Nodes (Keeper Nodes): Interact with the Account Compression Program to empty queues and rollover state trees.