I Spent 6 Hours Fixing LangChain's ConversationBufferMemory — Here's the Automated Test You Need

At 4:59 PM on a Friday, I was about to close my laptop and sneak out when the QA colleague's icon flashed on DingTalk: "Come check this out. The support bot remembers I'm Zhang San, but when I ask for my order number, it insists it belongs to Li Si." I pulled up the logs and saw LangChain's ConversationBufferMemory behaving like it had severe amnesia — Session A was mixing up chat history from Session B. In that moment, I knew that unless I built an automated test suite to lock down the accuracy