Accounts and PDAs

pub struct Pool {
    pub bin_step: u16,
    pub fee_rate: u32,                     // native units, FEE_PRECISION = 1e9
    pub protocol_share: u16,               // bps, protocol's cut of the swap fee
    pub bump: [u8; 1],
    pub active_bin_id: i32,
    pub dynamic_fee_state: DynamicFeeState,
    pub token_mint_x: Pubkey,
    pub token_mint_y: Pubkey,
    pub token_vault_x: Pubkey,
    pub token_vault_y: Pubkey,
    pub protocol_fee_x: u64,
    pub protocol_fee_y: u64,
}

pub struct BinArray {
    pub index: i32,
    pub pool: Pubkey,
    pub payer: Pubkey,          // rent payer — refunded on delete_bin_array
    pub bins: [Bin; 100],
}

pub struct Bin {
    pub amount_x: u64,
    pub amount_y: u64,
    pub price: u128,            // Q64.64, pre-computed at array creation
    pub total_shares: u128,
    pub fee_per_share_x: u128,  // Q64.64, monotonic swap-fee accumulator
    pub fee_per_share_y: u128,
}

pub struct Position {
    pub pool: Pubkey,
    pub position_mint: Pubkey,
    pub lower_bin_id: i32,
    pub upper_bin_id: i32,
    pub fee_states: [FeeState; 100],
}

pub struct FeeState {
    shares: u128,                       // this position's shares in this bin
    fee_per_share_checkpoint_x: u128,   // last-seen accumulator, for delta accrual
    fee_per_share_checkpoint_y: u128,
    fee_owed_x: u64,                    // materialized, claimable
    fee_owed_y: u64,
}

pub struct AdminConfig {
    pub authority: Pubkey,
    pub pending_authority: Pubkey,
    pub metadata_update_authority: Pubkey,
}