I see the problem - my cursor tracking is wrong. When I skip unchanged cells, the cursor doesn't actually move. Let me fix this:

```json
{
  "analysis": "The cursor tracking is incorrect. When I skip unchanged cells, I'm incrementing cur_col but the actual cursor stays at the position of the last written character. I need to only update cur_col when the cursor actually moves.",
  "plan": "Fix cursor tracking to only update when we output characters or control sequences. Use EL to clear trailing spaces when appropriate.",
  "commands": [
    {
      "keystrokes": "cat > /app/termzip_ansi.py << 'ENDOFFILE'\n#!/usr/bin/env python3\nimport struct\nimport sys\n\ndef read_tza(filename):\n    with open(filename, 'rb') as f:\n        magic = f.read(4)\n        if magic != b'TZA1':\n            raise ValueError(f'Invalid magic: {magic}')\n        width, height = struct.unpack('<HH', f.read(4))\n        n_frames, max_bytes = struct.unpack('<II', f.read(8))\n        frames = []\n        for _ in range(n_frames):\n            frame_data = f.read(width * height)\n            frames.append(frame_data)\n        return width, height, n_frames, max_bytes, frames\n\ndef main():\n    if len(sys.argv) != 2:\n        sys.stderr.write(f'Usage: {sys.argv[0]} <frames.tza>\\n')\n        sys.exit(1)\n    \n    filename = sys.argv[1]\n    width, height, n_frames, max_bytes, frames = read_tza(filename)\n    \n    prev_frame = b' ' * (width * height)\n    output = bytearray()\n    \n    cur_row, cur_col = 0, 0\n    \n    def move_to(row, col):\n        nonlocal cur_row, cur_col, output\n        if row == cur_row and col == cur_col:\n            return\n        \n        if row > cur_row:\n            output.extend(b'\\n' * (row - cur_row))\n            cur_row = row\n            cur_col = 0\n        elif row < cur_row:\n            output.extend(f'\\x1b[{cur_row - row}A'.encode())\n            cur_row = row\n        \n        if col != cur_col:\n            if col == 0:\n                output.extend(b'\\r')\n            elif col < cur_col:\n                output.extend(b'\\b' * (cur_col - col))\n            else:\n                dist = col - cur_col\n                cost_cuf = len(f'\\x1b[{dist}C')\n                cost_cr_cuf = 1 + len(f'\\x1b[{col}C')\n                if cost_cr_cuf < cost_cuf:\n                    output.extend(b'\\r')\n                    output.extend(f'\\x1b[{col}C'.encode())\n                else:\n                    output.extend(f'\\x1b[{dist}C'.encode())\n            cur_col = col\n    \n    for frame in frames:\n        for r in range(height):\n            row_start = r * width\n            c = 0\n            while c < width:\n                if prev_frame[row_start + c] != frame[row_start + c]:\n                    move_to(r, c)\n                    while c < width and prev_frame[row_start + c] != frame[row_start + c]:\n                        output.append(frame[row_start + c])\n                        c += 1\n                        cur_col += 1\n                        if cur_col >= width:\n                            cur_col = 0\n                            cur_row += 1\n                else:\n                    c += 1\n            # After processing row, check if rest should be cleared\n            if cur_col < width and cur_row == r:\n                all_spaces = True\n                for cc in range(cur_col, width):\n                    if frame[row_start + cc] != ord(' '):\n                        all_spaces = False\n                        break\n                if all_spaces:\n                    output.extend(b'\\x1b[0K')\n                    cur_col = width\n        \n        output.append(0x1e)\n        prev_frame = frame\n    \n    sys.stdout.buffer.write(output)\n\nif __name__ == '__main__':\n    main()\nENDOFFILE\n",
      "duration": 0.5
    },
    {
      "keystrokes": "python3 /app/termzip_ansi.py /app/frames.tza | wc -c\n",
      "duration": 2.0
    }
  ]
}
```