Function createPostCompactFileAttachments

src/services/compact/compact.ts:1415–1464

(
  readFileState: Record<string, { content: string; timestamp: number }>,
  toolUseContext: ToolUseContext,
  maxFiles: number,
  preservedMessages: Message[] = [],
)

 * @returns Array of attachment messages for the most recently accessed files that fit within token budget
 */
export async function createPostCompactFileAttachments(
  readFileState: Record<string, { content: string; timestamp: number }>,
  toolUseContext: ToolUseContext,
  maxFiles: number,
  preservedMessages: Message[] = [],
): Promise<AttachmentMessage[]> {
  const preservedReadPaths = collectReadToolFilePaths(preservedMessages)
  const recentFiles = Object.entries(readFileState)
    .map(([filename, state]) => ({ filename, ...state }))
    .filter(
      file =>
        !shouldExcludeFromPostCompactRestore(
          file.filename,
          toolUseContext.agentId,
        ) && !preservedReadPaths.has(expandPath(file.filename)),
    )
    .sort((a, b) => b.timestamp - a.timestamp)
    .slice(0, maxFiles)

  const results = await Promise.all(
    recentFiles.map(async file => {
      const attachment = await generateFileAttachment(
        file.filename,
        {
          ...toolUseContext,
          fileReadingLimits: {
            maxTokens: POST_COMPACT_MAX_TOKENS_PER_FILE,
          },
        },
        'tengu_post_compact_file_restore_success',
        'tengu_post_compact_file_restore_error',
        'compact',
      )
      return attachment ? createAttachmentMessage(attachment) : null
    }),
  )

  let usedTokens = 0
  return results.filter((result): result is AttachmentMessage => {
    if (result === null) {
      return false
    }
    const attachmentTokens = roughTokenCountEstimation(jsonStringify(result))
    if (usedTokens + attachmentTokens <= POST_COMPACT_TOKEN_BUDGET) {
      usedTokens += attachmentTokens
      return true
    }
    return false
  })
}

/**
 * Creates a plan file attachment if a plan file exists for the current session.