Reviewed my ChatGPT memories after OpenAI updated dreaming today:

In contrast to saved memories, dreaming leverages a background process that allows ChatGPT to learn from many conversations and synthesize ChatGPT’s memory state in order to always provide the freshest, most relevant context to your conversations. Dreaming also makes it easier for memory to include context that occurs naturally in conversation, without relying on explicit requests to remember something.

Claude has dreams too. Codex and OpenClaw use lots of Markdown files to update memory, which makes it fairly transparent.