{
  "analysis": "Still over budget at 302K bytes. The issue is that I'm using absolute positioning (ESC[r;cH) which is expensive. I need to use relative movements (CR, \\n, CUF, CUB) which are cheaper for navigating within a frame.",
  "plan": "Rewrite the encoder to use relative cursor movements: CR (1 byte) to go to column 1, \\n (1 byte) to move down, and CUF/CUB for horizontal moves.",
  "commands": [
    {
      "keystrokes": "cat > /app/termzip_ansi.py << 'EOF'\nimport struct\nimport sys\n\ndef find_runs(changes):\n    \"\"\"Find contiguous runs of changed columns.\"\"\"\n    runs = []\n    if not changes:\n        return runs\n    run_start = changes[0]\n    run_end = changes[0]\n    for c in changes[1:]:\n        if c == run_end + 1:\n            run_end = c\n        else:\n            runs.append((run_start, run_end))\n            run_start = run_end = c\n    runs.append((run_start, run_end))\n    return runs\n\ndef main():\n    if len(sys.argv) != 2:\n        sys.exit(1)\n    \n    with open(sys.argv[1], 'rb') as f:\n        magic = f.read(4)\n        if magic != b'TZA1':\n            sys.exit(1)\n        w, h = struct.unpack('<HH', f.read(4))\n        n_frames, max_bytes = struct.unpack('<II', f.read(8))\n        \n        # Read all frames\n        frames = [f.read(w * h) for _ in range(n_frames)]\n    \n    out = []\n    cursor_r, cursor_c = 1, 1\n    \n    # Frame 0: write non-space characters\n    for r in range(h):\n        row = frames[0][r*w:(r+1)*w]\n        non_space = [c for c in range(w) if row[c] != 32]\n        runs = find_runs(non_space)\n        for start, end in runs:\n            # Move to (r+1, start+1)\n            if cursor_r != r+1:\n                out.append('\\r')\n                dr = (r+1) - cursor_r\n                if dr > 0:\n                    out.append('\\n' * dr)\n                else:\n                    out.append(f'\\x1b[{-dr}A')\n                cursor_r = r+1\n                cursor_c = 1\n            if cursor_c != start+1:\n                dc = (start+1) - cursor_c\n                if dc > 0:\n                    out.append(f'\\x1b[{dc}C')\n                else:\n                    out.append(f'\\x1b[{-dc}D')\n                cursor_c = start+1\n            out.append(row[start:end+1].decode('latin1'))\n            cursor_c = end+2\n    out.append('\\x1e')\n    \n    # Subsequent frames\n    for i in range(1, n_frames):\n        # Find changed rows and their changes\n        row_changes = {}\n        for r in range(h):\n            prev_row = frames[i-1][r*w:(r+1)*w]\n            curr_row = frames[i][r*w:(r+1)*w]\n            if prev_row != curr_row:\n                changes = [c for c in range(w) if prev_row[c] != curr_row[c]]\n                row_changes[r] = (changes, curr_row)\n        \n        if not row_changes:\n            out.append('\\x1e')\n            continue\n        \n        for r, (changes, curr_row) in sorted(row_changes.items()):\n            runs = find_runs(changes)\n            \n            # Calculate costs\n            # EL+rewrite: CR + \\n*dr + ESC[2K + row\n            cost_erase = 1  # CR\n            dr = r - (cursor_r - 1)\n            if dr > 0:\n                cost_erase += dr  # \\n\n            elif dr < 0:\n                cost_erase += 4 + len(str(-dr))  # ESC[nA\n            cost_erase += 4 + w  # ESC[2K + row\n            \n            # Partial: movement + content for each run\n            cost_partial = 0\n            temp_r, temp_c = cursor_r, cursor_c\n            for start, end in runs:\n                if temp_r != r+1:\n                    cost_partial += 1  # CR\n                    dr = r - (temp_r - 1)\n                    if dr > 0:\n                        cost_partial += dr  # \\n\n                    elif dr < 0:\n                        cost_partial += 4 + len(str(-dr))  # ESC[nA\n                    temp_c = 1\n                if temp_c != start+1:\n                    dc = (start+1) - temp_c\n                    if dc > 0:\n                        cost_partial += 4 + len(str(dc))\n                    else:\n                        cost_partial += 4 + len(str(-dc))\n                temp_r, temp_c = r+1, end+2\n            cost_partial += len(changes)\n            \n            if cost_erase <= cost_partial:\n                # EL+rewrite\n                if cursor_r != r+1:\n                    out.append('\\r')\n                    dr = r - (cursor_r - 1)\n                    if dr > 0:\n                        out.append('\\n' * dr)\n                    else:\n                        out.append(f'\\x1b[{-dr}A')\n                out.append('\\x1b[2K')\n                out.append(curr_row.decode('latin1'))\n                cursor_r, cursor_c = r+1, w+1\n            else:\n                # Partial updates\n                for start, end in runs:\n                    if cursor_r != r+1:\n                        out.append('\\r')\n                        dr = r - (cursor_r - 1)\n                        if dr > 0:\n                            out.append('\\n' * dr)\n                        else:\n                            out.append(f'\\x1b[{-dr}A')\n                        cursor_r = r+1\n                        cursor_c = 1\n                    if cursor_c != start+1:\n                        dc = (start+1) - cursor_c\n                        if dc > 0:\n                            out.append(f'\\x1b[{dc}C')\n                        else:\n                            out.append(f'\\x1b[{-dc}D')\n                        cursor_c = start+1\n                    out.append(curr_row[start:end+1].decode('latin1'))\n                    cursor_c = end+2\n        \n        out.append('\\x1e')\n    \n    sys.stdout.write(''.join(out))\n\nif __name__ == '__main__':\n    main()\nEOF\n",
      "duration": 0.5
    }
  ]
}