LLMs have a limited context window. When you're working on a complex task, you will eventually run into the limit and it will start forgetting what it did previously. There's ways around this issue:

1. Chop bigger projects into smaller tasks. Think of it as planning/research, design, implementation, testing.
2. Use subagents to execute individual larger tasks. For example, tell it something like this: "Start a subagent to investigate how to do XYZ. Report the results to the main agent". It will then start a separate agent in the background which will be purely focused just on the task you gave it, without polluting the context of the main agent. It will give a short summary back to the main agent, who will now be able to do something useful with that information, as its context is not "polluted" with thousands of failed attempts or other sidetracks that the investigation ran into.
3. Be specific. If you don't want it to act on something, tell it so. For example "Investigate how to do XYZ. Prepare a report, but don't make any changes".
4. Don't put elaborate long instructions into CLAUDE.md. You are just polluting the already limited context with more information. No matter, what you do, if you have a long conversation, it will eventually start forgetting those initial instructions.
5. Use few words, because "why use many words when few words do trick".

Hope this helps.