High quality Landsat mosaic image production with an UI in JavaScript in GEE code editor. Go to https://code.earthengine.google.com/ and copy the code of HQComposite.js in the code editor and Run.

HQComposite.js

/*
 * High-Quality Landsat Mosaic Generation Tool
 * ==========================================
 * 
 * Author: Dr. Huan Li
 * Contact: huan.li@pku.edu.cn
 * Affiliation: Peking University (2018-2022)
 * 
 * Description:
 * This Google Earth Engine (GEE) application efficiently generates high-quality, 
 * user-ready Landsat mosaic images for any region globally. The tool integrates 
 * Landsat 4-9 data with advanced cloud masking and quality assessment algorithms.
 * 
 * 🚀 Quick Access:
 * - Web App (No GEE account needed): https://lihuan.projects.earthengine.app/view/user-ready-mosaic
 * - Source Code (GEE users): https://code.earthengine.google.com/?accept_repo=users/lihuan/LandsatMosaic
 * 
 * 📚 Citation:
 * If you use this tool in your research, please cite:
 * Li, H., Wan, W., Fang, Y., Zhu, S., Chen, X., Liu, B. and Hong, Y. (2019) 
 * "A Google Earth Engine-enabled software for efficiently generating high-quality 
 * user-ready Landsat mosaic images." Environmental Modelling & Software 112, 16-22.
 * DOI: https://doi.org/10.1016/j.envsoft.2018.10.004
 * 
 * 🔧 Features:
 * - Multi-sensor Landsat integration (Landsat 4, 5, 7, 8, 9)
 * - Advanced cloud and shadow masking
 * - Customizable time periods and quality filters
 * - Interactive visualization and export options
 * - Global coverage with WRS-2 path/row system
 * 
 * 🤝 Acknowledgments:
 * Special thanks to the Google Earth Engine community for their invaluable 
 * code sharing and collaborative spirit that made this tool possible.
 * 
 * 📧 Support:
 * For questions, bug reports, or collaboration opportunities:
 * Email: huan.li@pku.edu.cn
 * 
 * 
 * License: Open source - feel free to use, modify, and share!
 */