{
  "context": "This evaluation assesses the engineer's ability to use Sharp's channel manipulation capabilities, specifically the joinChannel() method, to combine separate grayscale images into a multi-channel RGB or RGBA image. The focus is on proper usage of Sharp's API for channel operations.",
  "type": "weighted_checklist",
  "checklist": [
    {
      "name": "Uses joinChannel method",
      "description": "Solution uses Sharp's joinChannel() method to combine separate channel images into a multi-channel image",
      "max_score": 40
    },
    {
      "name": "Proper channel loading",
      "description": "Correctly loads each separate channel image (red, green, blue, and optionally alpha) using Sharp instances before joining",
      "max_score": 20
    },
    {
      "name": "Dimension validation",
      "description": "Uses Sharp's metadata() method to extract and validate that all input images have matching dimensions before combining",
      "max_score": 15
    },
    {
      "name": "Handles optional alpha",
      "description": "Correctly handles the optional alpha channel case, joining 3 channels for RGB or 4 channels for RGBA based on input",
      "max_score": 15
    },
    {
      "name": "Output formatting",
      "description": "Uses appropriate Sharp output methods (toFile(), toBuffer(), etc.) to save the combined multi-channel image",
      "max_score": 10
    }
  ]
}