As someone not involved in AI development, it seems really surprising that memories are another text-format issue. Seems like (in a human analogy) something more equivalent to your notebook or scratchpad.

Memories are lossy things that live in our brains, I’d expect they to be stored in some native LLM encoded representation (which would make the lack of standardization understandable).

This probably seems like a dumb distinction, but I think some of the problems in the article come from calling these things memories. Like, the prompt injection/provenience issue. The model has received some notes from someone about a topic, if it they were treated as “notes from <whoever sent them> about <topic>” instead of “my memories about <topic>” that should put things on the right footing to start at least, right?

The issue with storing the memories in some encoded representation (e.g. in embedding space) is that this would turn that representation into something that has to be supported "forever". I have projects that I have worked on with Opus 4.6, 4.7, 4.8, 5, 5.5, as well as Fable 5 and 5.1, and obvious some Sonnet subagents along the way. And I expect to keep working on the same codebase when Opus 6 and Opus 7 release. Text is trivially compatible with all of those, but their embeddings all differ. And whatever other representation you come up with right now in Opus 5.5 might no longer make sense in the model architecture of Opus 7

Imho the interesting challenges with memory are about "what does this memory belong to" (attaching it to lines of code or similar), "what does it relate to" (webs of memories), "is this even still true" ("sleeping", "reconciliation", etc). But there's no real consensus what is even useful to handle, never mind how to handle it