Borrow Fixed Rate

Supply collateral and borrow at a fixed rate in a single transaction, receiving USDC via the BT→FW→token path.

Also available: borrowSingleToken — same flow but skips the collateral supply step (assumes collateral already supplied).

Key references: src/fira_bonding/router/ActionBorrow.sol::supplyAndBorrowSingleToken, borrowSingleToken.

Details

• Goal: Supply collateral and receive a target token in one transaction (via BT→FW→token path).
• Preconditions:

  • User approved collateralToken to the router.
  • tokensToBorrow > 0, collateralAmount > 0, receiver != 0x0.
  • Market is initialized; firaMarket and lendingMarket set.
  • User must have authorized the router on the LendingMarket (setAuthorization(router, true)).
• Parameters (high level):

  • marketParams (Fira Lending), collateralAmount, tokensToBorrow (BT),
  • output (TokenOutput: tokenOut, tokenRedeemFw, minTokenOut, firaSwap, swapData),
  • limitOrderData (kept for interface compatibility, orderbook not used in current version).

Views and events

Views

• Lending: getUserPosition(marketParams, user) → supplyAssets, supplyShares, borrowAssets, borrowShares, collateralAssets.
• Lending: position(id, user), market(id).
• Market (fixed-rate): readTokens(), isExpired().

Events

• Lending: EventsLib.SupplyCollateral, EventsLib.Borrow.
• Market: Swap (BT→FW), UpdateImpliedRate.
• FW: Deposit (tokenIn→FW), Redeem (FW→tokenOut).

Reward share (fixed-rate borrow)

• Suggested formula: userBorrowBT / totalBorrowBT over the epoch (TWAP).
• Functions to call:

  • LendingMarket.getUserPosition(marketParamsBT, user) → borrowAssets (userBorrowBT)
  • LendingMarket.market(idBT).totalBorrowAssets → totalBorrowBT (consider accrueInterest(marketParamsBT) before reading)
  • FiraMarket.readTokens() → BT address; FiraMarket.isExpired()
• Events to index: EventsLib.Borrow, FiraMarket.Swap (BT→FW), IFiraWrappedStandardized.Redeem