Function validateImageSize

packages/ai-gemini/src/image/image-provider-options.ts:241–256

(
  model: string,
  size: string | undefined,
)

 * Throws an error if the size is invalid
 */
export function validateImageSize(
  model: string,
  size: string | undefined,
): void {
  if (!size) return

  const aspectRatio = sizeToAspectRatio(size)
  if (!aspectRatio) {
    const validSizes = Object.keys(GEMINI_SIZE_TO_ASPECT_RATIO)
    throw new Error(
      `Invalid size "${size}" for model "${model}". ` +
        `Gemini Imagen uses aspect ratios. Valid sizes that map to aspect ratios: ${validSizes.join(', ')}. ` +
        `Alternatively, use providerOptions.aspectRatio directly with values: 1:1, 3:4, 4:3, 9:16, 16:9, 9:21, 21:9`,
    )
  }
}

/**
 * Per-model caps on images per request.