The image passes every check, so I accepted it with a score of 10/10. The verdict is in artifacts/review.json, which I left untracked as required.

Checked directly:

• Hash: the downloaded file (saved outside the repo, in /tmp) has the expected sha256, 4f572c3a…de302.
• Format: it is a 512×512 PNG, 8-bit colour, not interlaced.
• No text: the file has no text metadata. Since the decoded image contains only two colours, there can't be any drawn text in it either.
• Colours: Pillow isn't installed, so I decoded the pixels with a short Python script of my own. Every pixel is one of two colours:
  • near-black #0E0E12 (14,14,18): 167,280 pixels
  • purple #8C52D6 (140,82,214): 94,864 pixels
• Shape: the purple pixels all fall between x=102–409 and y=102–409. That box is 308×308 = 94,864 pixels, exactly the purple count, so it is one completely filled square.
• Centring: the square's centre is at (255.5, 255.5), which is the exact centre of the image. The margin is 102 px on every side.

Judgement calls:

• With only two colours, there can be no gradient, anti-aliasing or other shape.
• I took #8C52D6 as "purple" and #0E0E12 as "near black" by eye. The task gives no exact colour values to check against.

Not covered: the task didn't say what size the square should be, so I didn't judge that.