Solana agents are stateless. We're the memory layer.

The agent owner computes a Merkle root over their current ARMS memory state and posts it on-chain. The AgentMemory PDA's version increments. Subsequent retrievals reference this version.

{`// programs/locus/src/lib.rs
pub fn commit_memory(ctx: Context, root: [u8; 32]) -> Result<()> {
  let agent = &mut ctx.accounts.agent_memory;
  agent.memory_root = root;
  agent.version += 1;
  agent.last_updated = Clock::get()?.unix_timestamp;
  emit!(MemoryCommitted { agent: agent.key(), version, root, timestamp });
  Ok(())
}`}

A requester pays read_fee_lamports in SOL to the agent owner. A RetrievalAttestation PDA is created on-chain with the query hash, result hash, memory root snapshot, and version.

{`// programs/locus/src/lib.rs
pub fn attest_retrieval(
  ctx: Context,
  query_hash: [u8; 32],
  result_hash: [u8; 32],
  nonce: u64,
) -> Result<()> {
  // fee transfer: requester -> owner
  system_program::transfer(..., agent.read_fee_lamports)?;
  // new attestation PDA, immutable
  attestation.query_hash = query_hash;
  attestation.result_hash = result_hash;
  attestation.memory_root = agent.memory_root;
  Ok(())
}`}