src/checkout.js has a 60-line submit() function with validation inline. Extract the validation (lines 5-25) into a new exported function `validateAmount(value)` in src/checkout.js. submit() should call validateAmount and re-throw its errors. The existing test.js must still pass.
| # | Model | Status | Duration | Tokens | Patch | Failure |
|---|---|---|---|---|---|---|
| 1 | agyexternal | pass | 1m 1s | - | yes | - |
| 2 | agy+MiniMax-M3+deepseek-v4-proconsensus | pass | 1m 1s | 138.0k | - | - |
| 3 | deepseek-v4-prodeepseek | done | 1m 1s | 78.9k | yes | - |
| 4 | MiniMax-M3minimax | done | 1m 1s | 59.1k | yes | - |