256k seems sweet spot. Even large codebase can be handled you just has to map out areas for agent. Anything past 256k usually exception than norm to be.

At least this my discovery when I did evals on my reviewers skills. 10k LOC is high end for high effort or around 150k context using opus. You can push towards 15k but that’s on max effort with about 400-500k ctx.

Fast models like haiku do not even need 1M ctx in my view

Is there a straightforward way to check the current context window usage in the web chat interfaces, btw?