Worked on security hardening for the exported session HTML feature in the badlogic/pi-mono repository, focusing on mitigating XSS vulnerabilities in shared content. Addressed this by implementing custom link and image renderers that sanitize markdown-rendered links and images, blocking dangerous URL protocols such as javascript:, vbscript:, and data:. Escaped relevant attributes including href, title, and alt to prevent attribute breakout, and ensured image MIME types were properly handled in session JSONL. Utilized JavaScript and TypeScript for front end development and testing, resulting in safer content sharing and improved user trust in the export functionality without introducing new features.