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refactor(PERC-8463): extract charge_fee_to_insurance helper #81

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Merged
dcccrypto merged 1 commit into from
Apr 5, 2026
Merged

refactor(PERC-8463): extract charge_fee_to_insurance helper #81

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46 changes: 22 additions & 24 deletions src/percolator.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2537,23 +2537,7 @@ impl RiskEngine {
.saturating_sub(due as i128);

// If fee_credits is negative, pay from capital using set_capital helper (spec §4.1)
let mut paid_from_capital = 0u128;
if self.accounts[idx as usize].fee_credits.is_negative() {
let owed = neg_i128_to_u128(self.accounts[idx as usize].fee_credits.get());
let current_cap = self.accounts[idx as usize].capital.get();
let pay = core::cmp::min(owed, current_cap);

// Use set_capital helper to maintain c_tot aggregate (spec §4.1)
self.set_capital(idx as usize, current_cap.saturating_sub(pay));
self.insurance_fund.balance += pay;
self.insurance_fund.fee_revenue += pay;

// Credit back what was paid
self.accounts[idx as usize].fee_credits = self.accounts[idx as usize]
.fee_credits
.saturating_add(u128_to_i128_clamped(pay));
paid_from_capital = pay;
}
let paid_from_capital = self.charge_fee_to_insurance(idx as usize);

// Check maintenance margin if account has a position (MTM check)
if !self.accounts[idx as usize].position_size.is_zero() {
Expand Down Expand Up @@ -2601,24 +2585,38 @@ impl RiskEngine {
.saturating_sub(due as i128);

// If negative, pay what we can from capital using set_capital helper (spec §4.1)
let paid_from_capital = self.charge_fee_to_insurance(idx as usize);

Ok(paid_from_capital) // Return actual amount paid into insurance
}

/// Shared helper: if account has negative `fee_credits`, pay down as much as
/// possible from `capital` and route into `insurance_fund` (balance + fee_revenue),
/// crediting back `fee_credits` by the amount paid. Returns amount paid into insurance.
///
/// Invariants preserved (spec §4.1):
/// - Uses `set_capital` to maintain `c_tot` aggregate
/// - Only touches capital when `fee_credits` is already negative
/// - Pay = min(owed, current_cap); never underflows capital
fn charge_fee_to_insurance(&mut self, idx: usize) -> u128 {
let mut paid_from_capital = 0u128;
if self.accounts[idx as usize].fee_credits.is_negative() {
let owed = neg_i128_to_u128(self.accounts[idx as usize].fee_credits.get());
let current_cap = self.accounts[idx as usize].capital.get();
if self.accounts[idx].fee_credits.is_negative() {
let owed = neg_i128_to_u128(self.accounts[idx].fee_credits.get());
let current_cap = self.accounts[idx].capital.get();
let pay = core::cmp::min(owed, current_cap);

// Use set_capital helper to maintain c_tot aggregate (spec §4.1)
self.set_capital(idx as usize, current_cap.saturating_sub(pay));
self.set_capital(idx, current_cap.saturating_sub(pay));
self.insurance_fund.balance += pay;
self.insurance_fund.fee_revenue += pay;

self.accounts[idx as usize].fee_credits = self.accounts[idx as usize]
// Credit back what was paid
self.accounts[idx].fee_credits = self.accounts[idx]
.fee_credits
.saturating_add(u128_to_i128_clamped(pay));
paid_from_capital = pay;
}

Ok(paid_from_capital) // Return actual amount paid into insurance
paid_from_capital
}

/// Best-effort warmup settlement for crank: settles any warmed positive PnL to capital.
Expand Down
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