interest.systems

Non-custodial, transparent, liquid yield from Solana validator rewards, paid in USDC.

• Non-custodial: Funds live in a program-derived account (PDA); users hold redeemable vault shares.
• Transparent: Price-per-share (PPS) and boost accounting are on-chain; Merkle roots are posted per epoch.
• Liquid: USDC stays in-vault; deposit and withdraw at any time.

How it works

1. Deposit USDC → receive vault shares
   • Users deposit USDC to the vault and receive fungible vault shares. PPS starts at 1e12 (RAY) and increases as rewards are donated.
2. Validator rewards → USDC → donate
   • The operator swaps SOL rewards to USDC off-chain, then calls DonateReward(amount, epoch, boost_bps).
   • Base portion increases PPS for all share holders; boost portion is set aside for delegators of that validator.
3. Delegator boost
   • Operator posts a Merkle root of delegator weights via PostRoot(epoch, total_weight, root).
   • Delegators claim USDC boost with Claim(epoch, index, weight, proof).
4. Withdraw anytime
   • Burn vault shares and receive USDC equal to shares * PPS / RAY.

Monorepo

interest.systems/
├─ programs/interest_vault    # Pinocchio on-chain program
├─ sdk/js                     # Gill TypeScript SDK (PDAs, ix data, helpers)
├─ tests/litesvm              # Fast Rust LiteSVM smoke tests
├─ surfpool                   # Runbooks for deploy/E2E
├─ scripts                    # Build/dev scripts
└─ site                       # Placeholder site

On-chain program

• Pinocchio entrypoint + zero-copy parsing.
• SPL Token checked CPIs (TransferChecked, MintToChecked, BurnChecked).
• Merkle proofs via Solana keccak256 syscall.

State

• VaultState: admin, operator, usdc_mint, share_mint, vault_pda, total_shares (u128), pps (u128, RAY=1e12), buffered_base.
• BoostDistributor (per epoch): epoch, root[32], total_weight (u128), boost_total (u64).
• ClaimBitmap256: 256-bit claim bitmap (MVP).

PDAs (seeds)

• Vault: [b"vault", usdc_mint, admin]
• Boost: [b"boost", vault_pda, epoch_le]
• Claims bitmap: [b"claims", vault_pda, epoch_le]

Instructions

• InitializeVault(decimals)
• Deposit(amount, usdc_decimals)
• Withdraw(shares, usdc_decimals)
• DonateReward(amount, epoch, boost_bps, usdc_decimals)
• PostRoot(epoch, total_weight, root)
• Claim(epoch, index, weight, proof[])

SDK (Gill)

• PDA helpers via getProgramDerivedAddress.
• Instruction data builders for all ops.
• Transaction helpers using createSolanaClient and signTransactionMessageWithSigners.

Build & test

• Build SBF program

  ./scripts/build-program.sh

• LiteSVM smoke tests (build .so first)

  cargo test -p interest_litesvm_tests

• SDK (Node)

  cd sdk/js
  npm i && npm run build

• Surfpool (local)

  surfpool start
  # UI: run "Deploy Local" (provide program .so/keypair), then "E2E Local"

Trust & risks

• Non-custodial: USDC held by PDA; withdraw via PPS at any time.
• Operator: can donate rewards and post Merkle roots; cannot seize user funds.
• Risks: SOL→USDC swap execution; correctness of posted roots/weights; SPL Token/USDC mint assumptions.

Roadmap

• IDL export for auto-encoding in Surfpool.
• Harvester CLI (swap, donate, post root).
• Sharded/extended claim bitmaps.

License

Apache-2.0