Function persistToolResult

src/utils/toolResultStorage.ts:137–184

(
  content: NonNullable<ToolResultBlockParam['content']>,
  toolUseId: string,
)

 * @returns Information about the persisted file including filepath and preview
 */
export async function persistToolResult(
  content: NonNullable<ToolResultBlockParam['content']>,
  toolUseId: string,
): Promise<PersistedToolResult | PersistToolResultError> {
  const isJson = Array.isArray(content)

  // Check for non-text content - we can only persist text blocks
  if (isJson) {
    const hasNonTextContent = content.some(block => block.type !== 'text')
    if (hasNonTextContent) {
      return {
        error: 'Cannot persist tool results containing non-text content',
      }
    }
  }

  await ensureToolResultsDir()
  const filepath = getToolResultPath(toolUseId, isJson)
  const contentStr = isJson ? jsonStringify(content, null, 2) : content

  // tool_use_id is unique per invocation and content is deterministic for a
  // given id, so skip if the file already exists. This prevents re-writing
  // the same content on every API turn when microcompact replays the
  // original messages. Use 'wx' instead of a stat-then-write race.
  try {
    await writeFile(filepath, contentStr, { encoding: 'utf-8', flag: 'wx' })
    logForDebugging(
      `Persisted tool result to ${filepath} (${formatFileSize(contentStr.length)})`,
    )
  } catch (error) {
    if (getErrnoCode(error) !== 'EEXIST') {
      logError(toError(error))
      return { error: getFileSystemErrorMessage(toError(error)) }
    }
    // EEXIST: already persisted on a prior turn, fall through to preview
  }

  // Generate a preview
  const { preview, hasMore } = generatePreview(contentStr, PREVIEW_SIZE_BYTES)

  return {
    filepath,
    originalSize: contentStr.length,
    isJson,
    preview,
    hasMore,
  }
}

/**
 * Build a message for large tool results with preview