split-engine

split-engine takes any yield-bearing vault share and mints two tradable SPL tokens: PT (redeems 1:1 at maturity) and YT (receives all yield accrued before maturity).

Accounts

Market

["market", vault, maturity].

Field	Type	Notes
`vault`	`Pubkey`	Underlying vault (e.g. delta-vault)
`vault_share_mint`	`Pubkey`	Vault share SPL mint
`pt_mint`	`Pubkey`	Principal token mint (authority = market PDA)
`yt_mint`	`Pubkey`	Yield token mint (authority = market PDA)
`vault_share_escrow`	`Pubkey`	Holds deposited shares
`maturity`	`i64`	unix timestamp
`total_deposits`	`u64`	PT supply
`total_yt_supply`	`u64`	should equal total_deposits
`reward_per_share`	`u128`	MasterChef accumulator (9-decimal)
`last_vault_share_price`	`u64`	for delta computation
`accumulated_yield`	`u64`	total yield held in escrow

UserPosition

["position", market, owner].

Field	Type	Notes
`owner`	`Pubkey`
`market`	`Pubkey`
`yt_balance`	`u64`
`reward_debt`	`u128`	`yt_balance × reward_per_share` at last interaction

Instructions

Instruction	Who	Purpose
`initialize_market`	admin	Create market with maturity and mints
`deposit`	user	Auto-claim pending → escrow shares → mint PT+YT 1:1
`claim_yield`	user	Transfer pending yield (vault shares) from escrow
`redeem_pt`	user	At maturity: burn PT → receive vault shares 1:1
`early_exit`	user	Burn matched PT+YT → shares minus 0.3% fee
`update_rewards`	anyone	Sync `reward_per_share` with current vault share price

MasterChef flow

// On any join/leave:
pending        = user.yt_balance × market.reward_per_share - user.reward_debt
auto_claim(user, pending)
user.yt_balance = new_balance
user.reward_debt = user.yt_balance × market.reward_per_share

This guarantees every YT holder earns exactly the yield accrued while they held, regardless of when others join or leave.

update_rewards

Anyone can crank:

Read vault.share_price().
delta = share_price - last_vault_share_price.
If delta > 0: reward_per_share += delta × PRECISION / total_yt_supply (clamped at 1 if supply=0).
last_vault_share_price = share_price.

Negative share-price movement does not decrement reward_per_share, losses are already absorbed at the vault layer (insurance fund + NAV).

Errors

NotMatured, AlreadyMatured, SupplyInvariantViolated, NoYieldToClaim, MathOverflow.

PT / YT concept

Why split, worked example.

yield-amm

Where PT and underlying trade.

Start

Concepts

Programs

Accounts

Market

UserPosition

Instructions

MasterChef flow

update_rewards

Errors

Read next

PT / YT concept

yield-amm

​Accounts

​Market

​UserPosition

​Instructions

​MasterChef flow

​update_rewards

​Errors

​Read next

PT / YT concept

yield-amm

Accounts

Market

UserPosition

Instructions

MasterChef flow

update_rewards

Errors

Read next