Hook call order must be stable — cursor-based tracking

What does this output?

// Simulates React's hook tracking by call order
const hooks = [];
let cursor = 0;

function useState(init) {
  const i = cursor++;
  if (hooks[i] === undefined) hooks[i] = init;
  const setState = v => { hooks[i] = v; };
  return [hooks[i], setState];
}

function resetCursor() { cursor = 0; }

// Render 1
resetCursor();
const [a, setA] = useState('first');
const [b, setB] = useState('second');
console.log(a, b);

// State update
setA('FIRST');

// Render 2
resetCursor();
const [a2, setA2] = useState('first');
const [b2, setB2] = useState('second');
console.log(a2, b2);

Correct Output

first second
FIRST second

Why this output?