Picture a birthday dinner. There are 20 people at the table, and the waitress isn't writing anything down. Every time she comes back, another person sits down and orders. After a while she starts mixing things up.
That's a context window. Every message you send is another person at the table, and after a while the memory gets foggy.
Why does a long chat with Claude get worse?
The tank is filling up. Each chat has a fixed amount of room measured in tokens, and when it's full Claude starts compacting: summarizing the conversation and keeping only what it thinks matters. Sometimes that's not what you think matters.
How do I fix it?
Give the waitress a notepad. I built a skill called /compact that summarizes a long chat into one handoff brief. I start a new chat, drop in the brief and keep going without losing anything important.
Better still, put the things Claude must always know in a Claude Project or a skill. Then it reads them fresh every time instead of trying to remember them.