A 1M context window isn't free

So agent harnesses like Claude and Antigravity recently introduced 1M-token context windows, which was great, until I realized that I was torching my token budget. Why? It turned out that the whole context window for the conversation is re-sent on every turn, so a near-full window burns through your usage limit fast. There’s a fix though — Claude has a setting to cap the context window back to the standard 200k. That significantly improved my token consumption. So today I learned that more context isn’t free — sometimes you want less of it.