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opencode/packages/app/src/addons/serialize.test.ts

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+import { describe, test, expect, beforeAll, afterEach } from "bun:test"
+import { Terminal, Ghostty } from "ghostty-web"
+import { SerializeAddon } from "./serialize"
+
+let ghostty: Ghostty
+beforeAll(async () => {
+  ghostty = await Ghostty.load()
+})
+
+const terminals: Terminal[] = []
+
+afterEach(() => {
+  for (const term of terminals) {
+    term.dispose()
+  }
+  terminals.length = 0
+  document.body.innerHTML = ""
+})
+
+function createTerminal(cols = 80, rows = 24): { term: Terminal; addon: SerializeAddon; container: HTMLElement } {
+  const container = document.createElement("div")
+  document.body.appendChild(container)
+
+  const term = new Terminal({ cols, rows, ghostty })
+  const addon = new SerializeAddon()
+  term.loadAddon(addon)
+  term.open(container)
+  terminals.push(term)
+
+  return { term, addon, container }
+}
+
+function writeAndWait(term: Terminal, data: string): Promise<void> {
+  return new Promise((resolve) => {
+    term.write(data, resolve)
+  })
+}
+
+describe("SerializeAddon", () => {
+  describe("ANSI color preservation", () => {
+    test("should preserve text attributes (bold, italic, underline)", async () => {
+      const { term, addon } = createTerminal()
+
+      const input = "\x1b[1mBOLD\x1b[0m \x1b[3mITALIC\x1b[0m \x1b[4mUNDER\x1b[0m"
+      await writeAndWait(term, input)
+
+      const origLine = term.buffer.active.getLine(0)
+      expect(origLine!.getCell(0)!.isBold()).toBe(1)
+      expect(origLine!.getCell(5)!.isItalic()).toBe(1)
+      expect(origLine!.getCell(12)!.isUnderline()).toBe(1)
+
+      const serialized = addon.serialize({ range: { start: 0, end: 0 } })
+
+      const { term: term2 } = createTerminal()
+      terminals.push(term2)
+      await writeAndWait(term2, serialized)
+
+      const line = term2.buffer.active.getLine(0)
+
+      const boldCell = line!.getCell(0)
+      expect(boldCell!.getChars()).toBe("B")
+      expect(boldCell!.isBold()).toBe(1)
+
+      const italicCell = line!.getCell(5)
+      expect(italicCell!.getChars()).toBe("I")
+      expect(italicCell!.isItalic()).toBe(1)
+
+      const underCell = line!.getCell(12)
+      expect(underCell!.getChars()).toBe("U")
+      expect(underCell!.isUnderline()).toBe(1)
+    })
+
+    test("should preserve basic 16-color foreground colors", async () => {
+      const { term, addon } = createTerminal()
+
+      const input = "\x1b[31mRED\x1b[32mGREEN\x1b[34mBLUE\x1b[0mNORMAL"
+      await writeAndWait(term, input)
+
+      const origLine = term.buffer.active.getLine(0)
+      const origRedFg = origLine!.getCell(0)!.getFgColor()
+      const origGreenFg = origLine!.getCell(3)!.getFgColor()
+      const origBlueFg = origLine!.getCell(8)!.getFgColor()
+
+      const serialized = addon.serialize({ range: { start: 0, end: 0 } })
+
+      const { term: term2 } = createTerminal()
+      terminals.push(term2)
+      await writeAndWait(term2, serialized)
+
+      const line = term2.buffer.active.getLine(0)
+      expect(line).toBeDefined()
+
+      const redCell = line!.getCell(0)
+      expect(redCell!.getChars()).toBe("R")
+      expect(redCell!.getFgColor()).toBe(origRedFg)
+
+      const greenCell = line!.getCell(3)
+      expect(greenCell!.getChars()).toBe("G")
+      expect(greenCell!.getFgColor()).toBe(origGreenFg)
+
+      const blueCell = line!.getCell(8)
+      expect(blueCell!.getChars()).toBe("B")
+      expect(blueCell!.getFgColor()).toBe(origBlueFg)
+    })
+
+    test("should preserve 256-color palette colors", async () => {
+      const { term, addon } = createTerminal()
+
+      const input = "\x1b[38;5;196mRED256\x1b[0mNORMAL"
+      await writeAndWait(term, input)
+
+      const origLine = term.buffer.active.getLine(0)
+      const origRedFg = origLine!.getCell(0)!.getFgColor()
+
+      const serialized = addon.serialize({ range: { start: 0, end: 0 } })
+
+      const { term: term2 } = createTerminal()
+      terminals.push(term2)
+      await writeAndWait(term2, serialized)
+
+      const line = term2.buffer.active.getLine(0)
+      const redCell = line!.getCell(0)
+      expect(redCell!.getChars()).toBe("R")
+      expect(redCell!.getFgColor()).toBe(origRedFg)
+    })
+
+    test("should preserve RGB/truecolor colors", async () => {
+      const { term, addon } = createTerminal()
+
+      const input = "\x1b[38;2;255;128;64mRGB_TEXT\x1b[0mNORMAL"
+      await writeAndWait(term, input)
+
+      const origLine = term.buffer.active.getLine(0)
+      const origRgbFg = origLine!.getCell(0)!.getFgColor()
+
+      const serialized = addon.serialize({ range: { start: 0, end: 0 } })
+
+      const { term: term2 } = createTerminal()
+      terminals.push(term2)
+      await writeAndWait(term2, serialized)
+
+      const line = term2.buffer.active.getLine(0)
+      const rgbCell = line!.getCell(0)
+      expect(rgbCell!.getChars()).toBe("R")
+      expect(rgbCell!.getFgColor()).toBe(origRgbFg)
+    })
+
+    test("should preserve background colors", async () => {
+      const { term, addon } = createTerminal()
+
+      const input = "\x1b[48;2;255;0;0mRED_BG\x1b[48;2;0;255;0mGREEN_BG\x1b[0mNORMAL"
+      await writeAndWait(term, input)
+
+      const origLine = term.buffer.active.getLine(0)
+      const origRedBg = origLine!.getCell(0)!.getBgColor()
+      const origGreenBg = origLine!.getCell(6)!.getBgColor()
+
+      const serialized = addon.serialize({ range: { start: 0, end: 0 } })
+
+      const { term: term2 } = createTerminal()
+      terminals.push(term2)
+      await writeAndWait(term2, serialized)
+
+      const line = term2.buffer.active.getLine(0)
+
+      const redBgCell = line!.getCell(0)
+      expect(redBgCell!.getChars()).toBe("R")
+      expect(redBgCell!.getBgColor()).toBe(origRedBg)
+
+      const greenBgCell = line!.getCell(6)
+      expect(greenBgCell!.getChars()).toBe("G")
+      expect(greenBgCell!.getBgColor()).toBe(origGreenBg)
+    })
+
+    test("should handle combined colors and attributes", async () => {
+      const { term, addon } = createTerminal()
+
+      const input =
+        "\x1b[1;38;2;255;0;0;48;2;255;255;0mCOMBO\x1b[0mNORMAL                                                                    "
+      await writeAndWait(term, input)
+
+      const origLine = term.buffer.active.getLine(0)
+      const origFg = origLine!.getCell(0)!.getFgColor()
+      const origBg = origLine!.getCell(0)!.getBgColor()
+      expect(origLine!.getCell(0)!.isBold()).toBe(1)
+
+      const serialized = addon.serialize({ range: { start: 0, end: 0 } })
+      const cleanSerialized = serialized.replace(/\x1b\[\d+X/g, "")
+
+      expect(cleanSerialized.startsWith("\x1b[1;")).toBe(true)
+
+      const { term: term2 } = createTerminal()
+      terminals.push(term2)
+      await writeAndWait(term2, cleanSerialized)
+
+      const line = term2.buffer.active.getLine(0)
+      const comboCell = line!.getCell(0)
+
+      expect(comboCell!.getChars()).toBe("C")
+      expect(cleanSerialized).toContain("\x1b[1;38;2;255;0;0;48;2;255;255;0m")
+    })
+  })
+
+  describe("round-trip serialization", () => {
+    test("should not produce ECH sequences", async () => {
+      const { term, addon } = createTerminal()
+
+      await writeAndWait(term, "\x1b[31mHello\x1b[0m World")
+
+      const serialized = addon.serialize()
+
+      const hasECH = /\x1b\[\d+X/.test(serialized)
+      expect(hasECH).toBe(false)
+    })
+
+    test("multi-line content should not have garbage characters", async () => {
+      const { term, addon } = createTerminal()
+
+      const content = [
+        "\x1b[1;32m❯\x1b[0m \x1b[34mcd\x1b[0m /some/path",
+        "\x1b[1;32m❯\x1b[0m \x1b[34mls\x1b[0m -la",
+        "total 42",
+      ].join("\r\n")
+
+      await writeAndWait(term, content)
+
+      const serialized = addon.serialize()
+
+      expect(/\x1b\[\d+X/.test(serialized)).toBe(false)
+
+      const { term: term2 } = createTerminal()
+      terminals.push(term2)
+      await writeAndWait(term2, serialized)
+
+      for (let row = 0; row < 3; row++) {
+        const line = term2.buffer.active.getLine(row)?.translateToString(true)
+        expect(line?.includes("𑼝")).toBe(false)
+      }
+
+      expect(term2.buffer.active.getLine(0)?.translateToString(true)).toContain("cd /some/path")
+      expect(term2.buffer.active.getLine(1)?.translateToString(true)).toContain("ls -la")
+      expect(term2.buffer.active.getLine(2)?.translateToString(true)).toBe("total 42")
+    })
+
+    test("serialized output should restore after Terminal.reset()", async () => {
+      const { term, addon } = createTerminal()
+
+      const content = [
+        "\x1b[1;32m❯\x1b[0m \x1b[34mcd\x1b[0m /some/path",
+        "\x1b[1;32m❯\x1b[0m \x1b[34mls\x1b[0m -la",
+        "total 42",
+      ].join("\r\n")
+
+      await writeAndWait(term, content)
+
+      const serialized = addon.serialize()
+
+      const { term: term2 } = createTerminal()
+      terminals.push(term2)
+      term2.reset()
+      await writeAndWait(term2, serialized)
+
+      expect(term2.buffer.active.getLine(0)?.translateToString(true)).toContain("cd /some/path")
+      expect(term2.buffer.active.getLine(1)?.translateToString(true)).toContain("ls -la")
+      expect(term2.buffer.active.getLine(2)?.translateToString(true)).toBe("total 42")
+    })
+
+    test("alternate buffer should round-trip without garbage", async () => {
+      const { term, addon } = createTerminal(20, 5)
+
+      await writeAndWait(term, "normal\r\n")
+      await writeAndWait(term, "\x1b[?1049h\x1b[HALT")
+
+      expect(term.buffer.active.type).toBe("alternate")
+
+      const serialized = addon.serialize()
+
+      const { term: term2 } = createTerminal(20, 5)
+      terminals.push(term2)
+      await writeAndWait(term2, serialized)
+
+      expect(term2.buffer.active.type).toBe("alternate")
+
+      const line = term2.buffer.active.getLine(0)
+      expect(line?.translateToString(true)).toBe("ALT")
+
+      // Ensure a cell beyond content isn't garbage
+      const cellCode = line?.getCell(10)?.getCode()
+      expect(cellCode === 0 || cellCode === 32).toBe(true)
+    })
+
+    test("serialized output written to new terminal should match original colors", async () => {
+      const { term, addon } = createTerminal(40, 5)
+
+      const input = "\x1b[38;2;255;0;0mHello\x1b[0m \x1b[38;2;0;255;0mWorld\x1b[0m!                            "
+      await writeAndWait(term, input)
+
+      const origLine = term.buffer.active.getLine(0)
+      const origHelloFg = origLine!.getCell(0)!.getFgColor()
+      const origWorldFg = origLine!.getCell(6)!.getFgColor()
+
+      const serialized = addon.serialize({ range: { start: 0, end: 0 } })
+
+      const { term: term2 } = createTerminal(40, 5)
+      terminals.push(term2)
+      await writeAndWait(term2, serialized)
+
+      const newLine = term2.buffer.active.getLine(0)
+
+      expect(newLine!.getCell(0)!.getChars()).toBe("H")
+      expect(newLine!.getCell(0)!.getFgColor()).toBe(origHelloFg)
+
+      expect(newLine!.getCell(6)!.getChars()).toBe("W")
+      expect(newLine!.getCell(6)!.getFgColor()).toBe(origWorldFg)
+
+      expect(newLine!.getCell(11)!.getChars()).toBe("!")
+    })
+  })
+})

opencode/packages/app/src/addons/serialize.ts

@@ -0,0 +1,634 @@
+/**
+ * SerializeAddon - Serialize terminal buffer contents
+ *
+ * Port of xterm.js addon-serialize for ghostty-web.
+ * Enables serialization of terminal contents to a string that can
+ * be written back to restore terminal state.
+ *
+ * Usage:
+ * ```typescript
+ * const serializeAddon = new SerializeAddon();
+ * term.loadAddon(serializeAddon);
+ * const content = serializeAddon.serialize();
+ * ```
+ */
+
+import type { ITerminalAddon, ITerminalCore, IBufferRange } from "ghostty-web"
+
+// ============================================================================
+// Buffer Types (matching ghostty-web internal interfaces)
+// ============================================================================
+
+interface IBuffer {
+  readonly type: "normal" | "alternate"
+  readonly cursorX: number
+  readonly cursorY: number
+  readonly viewportY: number
+  readonly baseY: number
+  readonly length: number
+  getLine(y: number): IBufferLine | undefined
+  getNullCell(): IBufferCell
+}
+
+interface IBufferLine {
+  readonly length: number
+  readonly isWrapped: boolean
+  getCell(x: number): IBufferCell | undefined
+  translateToString(trimRight?: boolean, startColumn?: number, endColumn?: number): string
+}
+
+interface IBufferCell {
+  getChars(): string
+  getCode(): number
+  getWidth(): number
+  getFgColorMode(): number
+  getBgColorMode(): number
+  getFgColor(): number
+  getBgColor(): number
+  isBold(): number
+  isItalic(): number
+  isUnderline(): number
+  isStrikethrough(): number
+  isBlink(): number
+  isInverse(): number
+  isInvisible(): number
+  isFaint(): number
+  isDim(): boolean
+}
+
+type TerminalBuffers = {
+  active?: IBuffer
+  normal?: IBuffer
+  alternate?: IBuffer
+}
+
+const isRecord = (value: unknown): value is Record<string, unknown> => {
+  return typeof value === "object" && value !== null
+}
+
+const isBuffer = (value: unknown): value is IBuffer => {
+  if (!isRecord(value)) return false
+  if (typeof value.length !== "number") return false
+  if (typeof value.cursorX !== "number") return false
+  if (typeof value.cursorY !== "number") return false
+  if (typeof value.baseY !== "number") return false
+  if (typeof value.viewportY !== "number") return false
+  if (typeof value.getLine !== "function") return false
+  if (typeof value.getNullCell !== "function") return false
+  return true
+}
+
+const getTerminalBuffers = (value: ITerminalCore): TerminalBuffers | undefined => {
+  if (!isRecord(value)) return
+  const raw = value.buffer
+  if (!isRecord(raw)) return
+  const active = isBuffer(raw.active) ? raw.active : undefined
+  const normal = isBuffer(raw.normal) ? raw.normal : undefined
+  const alternate = isBuffer(raw.alternate) ? raw.alternate : undefined
+  if (!active && !normal) return
+  return { active, normal, alternate }
+}
+
+// ============================================================================
+// Types
+// ============================================================================
+
+export interface ISerializeOptions {
+  /**
+   * The row range to serialize. When an explicit range is specified, the cursor
+   * will get its final repositioning.
+   */
+  range?: ISerializeRange
+  /**
+   * The number of rows in the scrollback buffer to serialize, starting from
+   * the bottom of the scrollback buffer. When not specified, all available
+   * rows in the scrollback buffer will be serialized.
+   */
+  scrollback?: number
+  /**
+   * Whether to exclude the terminal modes from the serialization.
+   * Default: false
+   */
+  excludeModes?: boolean
+  /**
+   * Whether to exclude the alt buffer from the serialization.
+   * Default: false
+   */
+  excludeAltBuffer?: boolean
+}
+
+export interface ISerializeRange {
+  /**
+   * The line to start serializing (inclusive).
+   */
+  start: number
+  /**
+   * The line to end serializing (inclusive).
+   */
+  end: number
+}
+
+export interface IHTMLSerializeOptions {
+  /**
+   * The number of rows in the scrollback buffer to serialize, starting from
+   * the bottom of the scrollback buffer.
+   */
+  scrollback?: number
+  /**
+   * Whether to only serialize the selection.
+   * Default: false
+   */
+  onlySelection?: boolean
+  /**
+   * Whether to include the global background of the terminal.
+   * Default: false
+   */
+  includeGlobalBackground?: boolean
+  /**
+   * The range to serialize. This is prioritized over onlySelection.
+   */
+  range?: {
+    startLine: number
+    endLine: number
+    startCol: number
+  }
+}
+
+// ============================================================================
+// Helper Functions
+// ============================================================================
+
+function constrain(value: number, low: number, high: number): number {
+  return Math.max(low, Math.min(value, high))
+}
+
+function equalFg(cell1: IBufferCell, cell2: IBufferCell): boolean {
+  return cell1.getFgColorMode() === cell2.getFgColorMode() && cell1.getFgColor() === cell2.getFgColor()
+}
+
+function equalBg(cell1: IBufferCell, cell2: IBufferCell): boolean {
+  return cell1.getBgColorMode() === cell2.getBgColorMode() && cell1.getBgColor() === cell2.getBgColor()
+}
+
+function equalFlags(cell1: IBufferCell, cell2: IBufferCell): boolean {
+  return (
+    !!cell1.isInverse() === !!cell2.isInverse() &&
+    !!cell1.isBold() === !!cell2.isBold() &&
+    !!cell1.isUnderline() === !!cell2.isUnderline() &&
+    !!cell1.isBlink() === !!cell2.isBlink() &&
+    !!cell1.isInvisible() === !!cell2.isInvisible() &&
+    !!cell1.isItalic() === !!cell2.isItalic() &&
+    !!cell1.isDim() === !!cell2.isDim() &&
+    !!cell1.isStrikethrough() === !!cell2.isStrikethrough()
+  )
+}
+
+// ============================================================================
+// Base Serialize Handler
+// ============================================================================
+
+abstract class BaseSerializeHandler {
+  constructor(protected readonly _buffer: IBuffer) {}
+
+  public serialize(range: IBufferRange, excludeFinalCursorPosition?: boolean): string {
+    let oldCell = this._buffer.getNullCell()
+
+    const startRow = range.start.y
+    const endRow = range.end.y
+    const startColumn = range.start.x
+    const endColumn = range.end.x
+
+    this._beforeSerialize(endRow - startRow + 1, startRow, endRow)
+
+    for (let row = startRow; row <= endRow; row++) {
+      const line = this._buffer.getLine(row)
+      if (line) {
+        const startLineColumn = row === range.start.y ? startColumn : 0
+        const endLineColumn = Math.min(endColumn, line.length)
+
+        for (let col = startLineColumn; col < endLineColumn; col++) {
+          const c = line.getCell(col)
+          if (!c) {
+            continue
+          }
+          this._nextCell(c, oldCell, row, col)
+          oldCell = c
+        }
+      }
+      this._rowEnd(row, row === endRow)
+    }
+
+    this._afterSerialize()
+
+    return this._serializeString(excludeFinalCursorPosition)
+  }
+
+  protected _nextCell(_cell: IBufferCell, _oldCell: IBufferCell, _row: number, _col: number): void {}
+  protected _rowEnd(_row: number, _isLastRow: boolean): void {}
+  protected _beforeSerialize(_rows: number, _startRow: number, _endRow: number): void {}
+  protected _afterSerialize(): void {}
+  protected _serializeString(_excludeFinalCursorPosition?: boolean): string {
+    return ""
+  }
+}
+
+// ============================================================================
+// String Serialize Handler
+// ============================================================================
+
+class StringSerializeHandler extends BaseSerializeHandler {
+  private _rowIndex: number = 0
+  private _allRows: string[] = []
+  private _allRowSeparators: string[] = []
+  private _currentRow: string = ""
+  private _nullCellCount: number = 0
+  private _cursorStyle: IBufferCell
+  private _firstRow: number = 0
+  private _lastCursorRow: number = 0
+  private _lastCursorCol: number = 0
+  private _lastContentCursorRow: number = 0
+  private _lastContentCursorCol: number = 0
+
+  constructor(
+    buffer: IBuffer,
+    private readonly _terminal: ITerminalCore,
+  ) {
+    super(buffer)
+    this._cursorStyle = this._buffer.getNullCell()
+  }
+
+  protected _beforeSerialize(rows: number, start: number, _end: number): void {
+    this._allRows = new Array<string>(rows)
+    this._allRowSeparators = new Array<string>(rows)
+    this._rowIndex = 0
+
+    this._currentRow = ""
+    this._nullCellCount = 0
+    this._cursorStyle = this._buffer.getNullCell()
+
+    this._lastContentCursorRow = start
+    this._lastCursorRow = start
+    this._firstRow = start
+  }
+
+  protected _rowEnd(row: number, isLastRow: boolean): void {
+    let rowSeparator = ""
+
+    const nextLine = isLastRow ? undefined : this._buffer.getLine(row + 1)
+    const wrapped = !!nextLine?.isWrapped
+
+    if (this._nullCellCount > 0 && wrapped) {
+      this._currentRow += " ".repeat(this._nullCellCount)
+    }
+
+    this._nullCellCount = 0
+
+    if (!isLastRow && !wrapped) {
+      rowSeparator = "\r\n"
+      this._lastCursorRow = row + 1
+      this._lastCursorCol = 0
+    }
+
+    this._allRows[this._rowIndex] = this._currentRow
+    this._allRowSeparators[this._rowIndex++] = rowSeparator
+    this._currentRow = ""
+    this._nullCellCount = 0
+  }
+
+  private _diffStyle(cell: IBufferCell, oldCell: IBufferCell): number[] {
+    const sgrSeq: number[] = []
+    const fgChanged = !equalFg(cell, oldCell)
+    const bgChanged = !equalBg(cell, oldCell)
+    const flagsChanged = !equalFlags(cell, oldCell)
+
+    if (fgChanged || bgChanged || flagsChanged) {
+      if (this._isAttributeDefault(cell)) {
+        if (!this._isAttributeDefault(oldCell)) {
+          sgrSeq.push(0)
+        }
+      } else {
+        if (flagsChanged) {
+          if (!!cell.isInverse() !== !!oldCell.isInverse()) {
+            sgrSeq.push(cell.isInverse() ? 7 : 27)
+          }
+          if (!!cell.isBold() !== !!oldCell.isBold()) {
+            sgrSeq.push(cell.isBold() ? 1 : 22)
+          }
+          if (!!cell.isUnderline() !== !!oldCell.isUnderline()) {
+            sgrSeq.push(cell.isUnderline() ? 4 : 24)
+          }
+          if (!!cell.isBlink() !== !!oldCell.isBlink()) {
+            sgrSeq.push(cell.isBlink() ? 5 : 25)
+          }
+          if (!!cell.isInvisible() !== !!oldCell.isInvisible()) {
+            sgrSeq.push(cell.isInvisible() ? 8 : 28)
+          }
+          if (!!cell.isItalic() !== !!oldCell.isItalic()) {
+            sgrSeq.push(cell.isItalic() ? 3 : 23)
+          }
+          if (!!cell.isDim() !== !!oldCell.isDim()) {
+            sgrSeq.push(cell.isDim() ? 2 : 22)
+          }
+          if (!!cell.isStrikethrough() !== !!oldCell.isStrikethrough()) {
+            sgrSeq.push(cell.isStrikethrough() ? 9 : 29)
+          }
+        }
+        if (fgChanged) {
+          const color = cell.getFgColor()
+          const mode = cell.getFgColorMode()
+          if (mode === 2 || mode === 3 || mode === -1) {
+            sgrSeq.push(38, 2, (color >>> 16) & 0xff, (color >>> 8) & 0xff, color & 0xff)
+          } else if (mode === 1) {
+            // Palette
+            if (color >= 16) {
+              sgrSeq.push(38, 5, color)
+            } else {
+              sgrSeq.push(color & 8 ? 90 + (color & 7) : 30 + (color & 7))
+            }
+          } else {
+            sgrSeq.push(39)
+          }
+        }
+        if (bgChanged) {
+          const color = cell.getBgColor()
+          const mode = cell.getBgColorMode()
+          if (mode === 2 || mode === 3 || mode === -1) {
+            sgrSeq.push(48, 2, (color >>> 16) & 0xff, (color >>> 8) & 0xff, color & 0xff)
+          } else if (mode === 1) {
+            // Palette
+            if (color >= 16) {
+              sgrSeq.push(48, 5, color)
+            } else {
+              sgrSeq.push(color & 8 ? 100 + (color & 7) : 40 + (color & 7))
+            }
+          } else {
+            sgrSeq.push(49)
+          }
+        }
+      }
+    }
+
+    return sgrSeq
+  }
+
+  private _isAttributeDefault(cell: IBufferCell): boolean {
+    const mode = cell.getFgColorMode()
+    const bgMode = cell.getBgColorMode()
+
+    if (mode === 0 && bgMode === 0) {
+      return (
+        !cell.isBold() &&
+        !cell.isItalic() &&
+        !cell.isUnderline() &&
+        !cell.isBlink() &&
+        !cell.isInverse() &&
+        !cell.isInvisible() &&
+        !cell.isDim() &&
+        !cell.isStrikethrough()
+      )
+    }
+
+    const fgColor = cell.getFgColor()
+    const bgColor = cell.getBgColor()
+    const nullCell = this._buffer.getNullCell()
+    const nullFg = nullCell.getFgColor()
+    const nullBg = nullCell.getBgColor()
+
+    return (
+      fgColor === nullFg &&
+      bgColor === nullBg &&
+      !cell.isBold() &&
+      !cell.isItalic() &&
+      !cell.isUnderline() &&
+      !cell.isBlink() &&
+      !cell.isInverse() &&
+      !cell.isInvisible() &&
+      !cell.isDim() &&
+      !cell.isStrikethrough()
+    )
+  }
+
+  protected _nextCell(cell: IBufferCell, _oldCell: IBufferCell, row: number, col: number): void {
+    const isPlaceHolderCell = cell.getWidth() === 0
+
+    if (isPlaceHolderCell) {
+      return
+    }
+
+    const codepoint = cell.getCode()
+    const isInvalidCodepoint = codepoint > 0x10ffff || (codepoint >= 0xd800 && codepoint <= 0xdfff)
+    const isGarbage = isInvalidCodepoint || (codepoint >= 0xf000 && cell.getWidth() === 1)
+    const isEmptyCell = codepoint === 0 || cell.getChars() === "" || isGarbage
+
+    const sgrSeq = this._diffStyle(cell, this._cursorStyle)
+
+    const styleChanged = sgrSeq.length > 0
+
+    if (styleChanged) {
+      if (this._nullCellCount > 0) {
+        this._currentRow += " ".repeat(this._nullCellCount)
+        this._nullCellCount = 0
+      }
+
+      this._lastContentCursorRow = this._lastCursorRow = row
+      this._lastContentCursorCol = this._lastCursorCol = col
+
+      this._currentRow += `\u001b[${sgrSeq.join(";")}m`
+
+      const line = this._buffer.getLine(row)
+      const cellFromLine = line?.getCell(col)
+      if (cellFromLine) {
+        this._cursorStyle = cellFromLine
+      }
+    }
+
+    if (isEmptyCell) {
+      this._nullCellCount += cell.getWidth()
+    } else {
+      if (this._nullCellCount > 0) {
+        this._currentRow += " ".repeat(this._nullCellCount)
+        this._nullCellCount = 0
+      }
+
+      this._currentRow += cell.getChars()
+
+      this._lastContentCursorRow = this._lastCursorRow = row
+      this._lastContentCursorCol = this._lastCursorCol = col + cell.getWidth()
+    }
+  }
+
+  protected _serializeString(excludeFinalCursorPosition?: boolean): string {
+    let rowEnd = this._allRows.length
+
+    if (this._buffer.length - this._firstRow <= this._terminal.rows) {
+      rowEnd = this._lastContentCursorRow + 1 - this._firstRow
+      this._lastCursorCol = this._lastContentCursorCol
+      this._lastCursorRow = this._lastContentCursorRow
+    }
+
+    let content = ""
+
+    for (let i = 0; i < rowEnd; i++) {
+      content += this._allRows[i]
+      if (i + 1 < rowEnd) {
+        content += this._allRowSeparators[i]
+      }
+    }
+
+    if (excludeFinalCursorPosition) return content
+
+    const absoluteCursorRow = (this._buffer.baseY ?? 0) + this._buffer.cursorY
+    const cursorRow = constrain(absoluteCursorRow - this._firstRow + 1, 1, Number.MAX_SAFE_INTEGER)
+    const cursorCol = this._buffer.cursorX + 1
+    content += `\u001b[${cursorRow};${cursorCol}H`
+
+    const line = this._buffer.getLine(absoluteCursorRow)
+    const cell = line?.getCell(this._buffer.cursorX)
+    const style = (() => {
+      if (!cell) return this._buffer.getNullCell()
+      if (cell.getWidth() !== 0) return cell
+      if (this._buffer.cursorX > 0) return line?.getCell(this._buffer.cursorX - 1) ?? cell
+      return cell
+    })()
+
+    const sgrSeq = this._diffStyle(style, this._cursorStyle)
+    if (sgrSeq.length) content += `\u001b[${sgrSeq.join(";")}m`
+
+    return content
+  }
+}
+
+// ============================================================================
+// SerializeAddon Class
+// ============================================================================
+
+export class SerializeAddon implements ITerminalAddon {
+  private _terminal?: ITerminalCore
+
+  /**
+   * Activate the addon (called by Terminal.loadAddon)
+   */
+  public activate(terminal: ITerminalCore): void {
+    this._terminal = terminal
+  }
+
+  /**
+   * Dispose the addon and clean up resources
+   */
+  public dispose(): void {
+    this._terminal = undefined
+  }
+
+  /**
+   * Serializes terminal rows into a string that can be written back to the
+   * terminal to restore the state. The cursor will also be positioned to the
+   * correct cell.
+   *
+   * @param options Custom options to allow control over what gets serialized.
+   */
+  public serialize(options?: ISerializeOptions): string {
+    if (!this._terminal) {
+      throw new Error("Cannot use addon until it has been loaded")
+    }
+
+    const buffer = getTerminalBuffers(this._terminal)
+
+    if (!buffer) {
+      return ""
+    }
+
+    const normalBuffer = buffer.normal ?? buffer.active
+    const altBuffer = buffer.alternate
+
+    if (!normalBuffer) {
+      return ""
+    }
+
+    let content = options?.range
+      ? this._serializeBufferByRange(normalBuffer, options.range, true)
+      : this._serializeBufferByScrollback(normalBuffer, options?.scrollback)
+
+    if (!options?.excludeAltBuffer && buffer.active?.type === "alternate" && altBuffer) {
+      const alternateContent = this._serializeBufferByScrollback(altBuffer, undefined)
+      content += `\u001b[?1049h\u001b[H${alternateContent}`
+    }
+
+    return content
+  }
+
+  /**
+   * Serializes terminal content as plain text (no escape sequences)
+   * @param options Custom options to allow control over what gets serialized.
+   */
+  public serializeAsText(options?: { scrollback?: number; trimWhitespace?: boolean }): string {
+    if (!this._terminal) {
+      throw new Error("Cannot use addon until it has been loaded")
+    }
+
+    const buffer = getTerminalBuffers(this._terminal)
+
+    if (!buffer) {
+      return ""
+    }
+
+    const activeBuffer = buffer.active ?? buffer.normal
+    if (!activeBuffer) {
+      return ""
+    }
+
+    const maxRows = activeBuffer.length
+    const scrollback = options?.scrollback
+    const correctRows = scrollback === undefined ? maxRows : constrain(scrollback + this._terminal.rows, 0, maxRows)
+
+    const startRow = maxRows - correctRows
+    const endRow = maxRows - 1
+    const lines: string[] = []
+
+    for (let row = startRow; row <= endRow; row++) {
+      const line = activeBuffer.getLine(row)
+      if (line) {
+        const text = line.translateToString(options?.trimWhitespace ?? true)
+        lines.push(text)
+      }
+    }
+
+    // Trim trailing empty lines if requested
+    if (options?.trimWhitespace) {
+      while (lines.length > 0 && lines[lines.length - 1] === "") {
+        lines.pop()
+      }
+    }
+
+    return lines.join("\n")
+  }
+
+  private _serializeBufferByScrollback(buffer: IBuffer, scrollback?: number): string {
+    const maxRows = buffer.length
+    const rows = this._terminal?.rows ?? 24
+    const correctRows = scrollback === undefined ? maxRows : constrain(scrollback + rows, 0, maxRows)
+    return this._serializeBufferByRange(
+      buffer,
+      {
+        start: maxRows - correctRows,
+        end: maxRows - 1,
+      },
+      false,
+    )
+  }
+
+  private _serializeBufferByRange(
+    buffer: IBuffer,
+    range: ISerializeRange,
+    excludeFinalCursorPosition: boolean,
+  ): string {
+    const handler = new StringSerializeHandler(buffer, this._terminal!)
+    const cols = this._terminal?.cols ?? 80
+    return handler.serialize(
+      {
+        start: { x: 0, y: range.start },
+        end: { x: cols, y: range.end },
+      },
+      excludeFinalCursorPosition,
+    )
+  }
+}