Method box

scripts/grid.cjs:63–94

(x, y, w, h, label, style = 'single')

  }

  box(x, y, w, h, label, style = 'single') {
    const s = STYLES[style] || STYLES.single;

    // Corners
    this.put(x, y, s.tl);
    this.put(x + w - 1, y, s.tr);
    this.put(x, y + h - 1, s.bl);
    this.put(x + w - 1, y + h - 1, s.br);

    // Top and bottom borders
    for (let i = 1; i < w - 1; i++) {
      this.put(x + i, y, s.h);
      this.put(x + i, y + h - 1, s.h);
    }

    // Side borders
    for (let j = 1; j < h - 1; j++) {
      this.put(x, y + j, s.v);
      this.put(x + w - 1, y + j, s.v);
    }

    // Label (centered, supports multiline)
    const lines = label.split('\n');
    const startY = y + Math.floor((h - lines.length) / 2);
    for (let li = 0; li < lines.length; li++) {
      const line = lines[li];
      const startX = x + Math.floor((w - line.length) / 2);
      this.text(startX, startY + li, line);
    }

    return { x, y, w, h };
  }

  hArrow(x1, x2, y, label, labelY) {
    const dir = x2 > x1 ? 1 : -1;