Function processImageURLPart

pkg/chat/attach.go:163–188

processImageURLPart handles MessagePartTypeImageURL. Only data: URIs are supported; remote http(s):// URLs are rejected. Callers with a remote URL should download the file locally first and pass it as a MessagePartTypeFile instead.

(part MessagePart)

// Callers with a remote URL should download the file locally first and
// pass it as a MessagePartTypeFile instead.
func processImageURLPart(part MessagePart) (Document, *ImageResizeResult, error) {
	if part.ImageURL == nil {
		return Document{}, nil, errors.New("ProcessAttachment: image-url part has nil ImageURL field")
	}
	rawURL := part.ImageURL.URL

	switch {
	case strings.HasPrefix(rawURL, "data:"):
		mimeType, data, err := parseDataURI(rawURL)
		if err != nil {
			return Document{}, nil, fmt.Errorf("ProcessAttachment: parse data URI: %w", err)
		}
		// When content detection returns an image type, prefer it over the
		// declared MIME. (Only image types are trusted from the sniffer.)
		if detected := DetectMimeTypeByContent(data); IsImageMimeType(detected) {
			mimeType = detected
		}
		return transcodeImageWithMeta("image", data, mimeType)

	case strings.HasPrefix(rawURL, "http://") || strings.HasPrefix(rawURL, "https://"):
		return Document{}, nil, errors.New("attachment: remote URLs are not supported; download the file locally first")

	default:
		return Document{}, nil, fmt.Errorf("attachment: unsupported image URL scheme: %q", rawURL)
	}
}

// processDocumentPart handles MessagePartTypeDocument.
// Images with InlineData are transcoded; other already-resolved documents pass through.