Time vs Slippage

Every exchange mechanism makes a tradeoff. The DollarStore protocol's tradeoff is explicit: perfect price, variable time.

The traditional tradeoff

AMMs and order books guarantee execution but not price:

Mechanism	Users get	Users give up
AMM (Uniswap)	Instant execution	Price (slippage + fees)
Order book	Price discovery	Instant execution (may not fill)
DollarStore	Exact 1:1 price	Instant execution (may queue)

When users get instant execution

Swaps execute instantly when the desired stablecoin is available in supply:

USDT in supply: 50,000
User swap: 10,000 USDC → USDT
Result: Instant, 10,000 USDT received

When users wait

If the desired stablecoin isn't available, users have a choice:

USDT in supply: 5,000
User swap: 10,000 USDC → USDT

Option 1: Partial fill + queue
  → Receive 5,000 USDT instantly
  → Get in line for remaining 5,000

Option 2: Partial fill + take back remaining USDC
  → Receive 5,000 USDT instantly
  → Take back remaining 5,000 USDC instantly

Option 3: Revert (aggregator mode)
  → Transaction fails
  → Route through different venue

Predictable behavior for integrators

The swapExactInput function (for aggregators) never queues. It either executes fully or reverts.

// This either gives exactly amountIn of USDT, or reverts
// Never partial fills, never queues
uint256 out = dollarStore.swapExactInput(
    USDC, USDT, amountIn, amountIn, recipient, deadline
);

Aggregators check getSwapQuote first. If it returns the full amount, the protocol will execute the swap. If it returns 0, route elsewhere.