Class Buffer

lib/buffer.ts:96–210

 * A terminal buffer (normal or alternate screen)
 */
export class Buffer implements IBuffer {
  private terminal: Terminal;
  private bufferType: 'normal' | 'alternate';
  private nullCell: BufferCell;

  constructor(terminal: Terminal, type: 'normal' | 'alternate') {
    this.terminal = terminal;
    this.bufferType = type;

    // Create a null cell (codepoint=0, default colors, no flags)
    const nullCellData: GhosttyCell = {
      codepoint: 0,
      fg_r: 204,
      fg_g: 204,
      fg_b: 204,
      bg_r: 0,
      bg_g: 0,
      bg_b: 0,
      flags: 0,
      width: 1,
      hyperlink_id: 0,
      grapheme_len: 0,
    };
    this.nullCell = new BufferCell(nullCellData, 0);
  }

  get type(): 'normal' | 'alternate' {
    return this.bufferType;
  }

  get cursorX(): number {
    const wasmTerm = this.getWasmTerm();
    if (!wasmTerm) return 0;
    return wasmTerm.getCursor().x;
  }

  get cursorY(): number {
    const wasmTerm = this.getWasmTerm();
    if (!wasmTerm) return 0;
    return wasmTerm.getCursor().y;
  }

  get viewportY(): number {
    // Get viewport offset from Terminal
    // For now, return 0 (no scrollback navigation implemented yet)
    return 0;
  }

  get baseY(): number {
    // For normal buffer: 0
    // For alternate buffer: 0 (alternate has no scrollback)
    return 0;
  }

  get length(): number {
    const wasmTerm = this.getWasmTerm();
    if (!wasmTerm) return 0;