Something pasted into the chat log by the user gets treated far differently from something that the agents discover and process on their own from disk.

During early stage dev Claude will happily gobble up API keys and DB passwords from .env files. Perhaps not such a big deal for early stage dev, but getting Claude to cough up precisely memorized tokens in the future by asking it to produce a "random" key of a certain sort will probably be an entertaining pastime for people in the future.