I ran a controlled test to check model isolation between GPT-5 and GPT-4o. Here's what happened:1. I typed a unique phrase into GPT-5 and then deleted the chat. 2. I opened a clean GPT-4o chat and asked a vague follow-up. 3. GPT-4o quoted the exact phrase from the deleted GPT-5 session. 4. Later, it also referenced content from a different GPT-5 session entirely—never typed or hinted at in the 4o chat.There was no memory crossover, no user error, and no paste. Just clear leakage across session b...