Function moveSelection

src/setup/prompt.ts:55–64

(current: number, keyName: string | undefined, len: number)

/** Compute the next highlighted index for a keypress. Returns the same index for no-op keys. Pure → testable. */
export function moveSelection(current: number, keyName: string | undefined, len: number): number {
  if (len <= 0) return 0;
  if (keyName === 'up' || keyName === 'k') return (current - 1 + len) % len;
  if (keyName === 'down' || keyName === 'j') return (current + 1) % len;
  if (keyName && /^[1-9]$/.test(keyName)) {
    const n = parseInt(keyName, 10);
    if (n >= 1 && n <= len) return n - 1;
  }
  return current;
}

/**
 * Single-choice from a list. Returns the chosen value (not index).