Function truncateContentBlocks

src/utils/mcpValidation.ts:94–149

(
  blocks: ContentBlockParam[],
  maxChars: number,
)

}

async function truncateContentBlocks(
  blocks: ContentBlockParam[],
  maxChars: number,
): Promise<ContentBlockParam[]> {
  const result: ContentBlockParam[] = []
  let currentChars = 0

  for (const block of blocks) {
    if (isTextBlock(block)) {
      const remainingChars = maxChars - currentChars
      if (remainingChars <= 0) break

      if (block.text.length <= remainingChars) {
        result.push(block)
        currentChars += block.text.length
      } else {
        result.push({ type: 'text', text: block.text.slice(0, remainingChars) })
        break
      }
    } else if (isImageBlock(block)) {
      // Include images but count their estimated size
      const imageChars = IMAGE_TOKEN_ESTIMATE * 4
      if (currentChars + imageChars <= maxChars) {
        result.push(block)
        currentChars += imageChars
      } else {
        // Image exceeds budget - try to compress it to fit remaining space
        const remainingChars = maxChars - currentChars
        if (remainingChars > 0) {
          // Convert remaining chars to bytes for compression
          // base64 uses ~4/3 the original size, so we calculate max bytes
          const remainingBytes = Math.floor(remainingChars * 0.75)
          try {
            const compressedBlock = await compressImageBlock(
              block,
              remainingBytes,
            )
            result.push(compressedBlock)
            // Update currentChars based on compressed image size
            if (compressedBlock.source.type === 'base64') {
              currentChars += compressedBlock.source.data.length
            } else {
              currentChars += imageChars
            }
          } catch {
            // If compression fails, skip the image
          }
        }
      }
    } else {
      result.push(block)
    }
  }

  return result
}

export async function mcpContentNeedsTruncation(