Few pointers:

Dont try and handle the entire project in context.

Use a well structured filesystem layout for your code with a few lines in an AGENTS.md describing the layout and core architectural requirements (no more than that, as per the article!).

Then work on small-medium tasks at a time with a fresh context.

At the end of your task, ask the agent if there are any key points about the project layout or architecture it would want to add to memory - audit those manually and amend your AGENTS.md accordingly.

If your code is well structured and you keep your tasks localised, you can get away with seemingly minuscule context windows.

It's also worth noting that high effort models love to slurp up whatever context they can. You almost never need/want high effort for non cross-cutting tasks.