Claude's random GIF generator, without seeing the parser code

gengif_nocode.py

from typing import BinaryIO
import random
import struct

def generate_random_input(out: BinaryIO):
    # Generate a random width and height (between 1 and 1000)
    width = random.randint(1, 1000)
    height = random.randint(1, 1000)

    # Write GIF header
    out.write(b'GIF89a')

    # Write logical screen descriptor
    out.write(struct.pack('<HH', width, height))
    out.write(struct.pack('<B', random.randint(0, 255)))  # Global color table flag and color resolution
    out.write(struct.pack('<B', random.randint(0, 255)))  # Background color index
    out.write(struct.pack('<B', 0))  # Pixel aspect ratio

    # Generate a random number of frames (between 1 and 10)
    num_frames = random.randint(1, 10)

    for _ in range(num_frames):
        # Write graphics control extension (optional)
        if random.random() < 0.5:
            out.write(b'\x21\xF9\x04')
            out.write(struct.pack('<B', random.randint(0, 255)))  # Packed fields
            out.write(struct.pack('<H', random.randint(0, 65535)))  # Delay time
            out.write(struct.pack('<B', random.randint(0, 255)))  # Transparent color index
            out.write(b'\x00')

        # Write image descriptor
        out.write(b'\x2C')
        out.write(struct.pack('<HH', random.randint(0, width), random.randint(0, height)))  # Image left and top
        out.write(struct.pack('<HH', random.randint(1, width), random.randint(1, height)))  # Image width and height
        out.write(struct.pack('<B', random.randint(0, 255)))  # Local color table flag and interlace flag

        # Write random image data
        out.write(struct.pack('<B', random.randint(2, 8)))  # LZW minimum code size
        image_data_size = random.randint(1, 1000)
        for _ in range(image_data_size):
            out.write(struct.pack('<B', random.randint(0, 255)))
        out.write(b'\x00')  # Block terminator

    # Write trailer
    out.write(b'\x3B')

import sys
for f in sys.argv[1:]:
    with open(f,'wb') as of:
        generate_random_input(of)
    print(f)