Fix RAG Application Errors

I have an existing AI-based application that requires debugging, UI improvements, and performance optimization.

The main issues that need to be addressed are:

Authentication: Users are being logged out whenever the page is refreshed. Session/authentication persistence needs to be fixed.
AI Conversation Memory: The AI sometimes forgets the previous message/conversation context and does not properly maintain the chat history.
UI/UX Issues: Several visual issues need to be fixed, including overly dark text, inconsistent styling, spacing, and other minor UI problems.
Unknown Button Text: Some buttons are displaying incorrect, missing, or unexpected text and need to be identified and corrected.
AI Performance: AI responses are currently too slow. The request/response flow should be investigated and optimized where possible.
Document Upload: Uploaded documents are frequently showing a "failed" status. The complete upload flow needs to be debugged and fixed.

Expected Outcome
The goal is to make the application stable and production-ready by fixing the above issues without breaking the existing functionality. The developer should investigate the root causes rather than applying temporary workarounds.

Experience with AI applications, frontend development, authentication/session management, APIs, document/file uploads, and performance optimization would be preferred.