Worked on enhancing the qiancai/docs-cn repository by documenting the behavior of the tidb_enable_window_function system variable, focusing on how it governs the recognition of window function keywords within the TiDB syntax tree. The update, written in Markdown and leveraging strong documentation skills, clarified the relationship between configuration and code semantics, reducing ambiguity for users. By aligning the documentation with actual code behavior, the work improved onboarding and usability for developers implementing window-function features. No bugs were addressed during this period, as the primary focus was on delivering clear, traceable guidance to support smoother adoption of window function capabilities in TiDB.