- Updated session handling to replace `Session_id` and `Conversation_id` headers with new logic ensuring consistent use of `Cache.ID` and prompt keys. - Restored `Session_id` as a priority extraction source for `ExtractSessionID`. - Added tests to validate case-sensitive and case-insensitive headers, canonical account header usage, and session key preservation. - Removed legacy support for deprecated `Conversation_id` header to clean up API.