Function validateImagesForAPI

src/utils/imageValidation.ts:65–104

(messages: unknown[])

 * @throws ImageSizeError if any image exceeds the API limit
 */
export function validateImagesForAPI(messages: unknown[]): void {
  const oversizedImages: OversizedImage[] = []
  let imageIndex = 0

  for (const msg of messages) {
    if (typeof msg !== 'object' || msg === null) continue

    const m = msg as Record<string, unknown>

    // Handle wrapped message format { type: 'user', message: { role, content } }
    // Only check user messages
    if (m.type !== 'user') continue

    const innerMessage = m.message as Record<string, unknown> | undefined
    if (!innerMessage) continue

    const content = innerMessage.content
    if (typeof content === 'string' || !Array.isArray(content)) continue

    for (const block of content) {
      if (isBase64ImageBlock(block)) {
        imageIndex++
        // Check the base64-encoded string length directly (not decoded bytes)
        // The API limit applies to the base64 payload size
        const base64Size = block.source.data.length
        if (base64Size > API_IMAGE_MAX_BASE64_SIZE) {
          logEvent('tengu_image_api_validation_failed', {
            base64_size_bytes: base64Size,
            max_bytes: API_IMAGE_MAX_BASE64_SIZE,
          })
          oversizedImages.push({ index: imageIndex, size: base64Size })
        }
      }
    }
  }

  if (oversizedImages.length > 0) {
    throw new ImageSizeError(oversizedImages, API_IMAGE_MAX_BASE64_SIZE)
  }
}