[vog]

> Relying on time stamps is a design decision that was good for its time, but it is no longer robust

I agree with the sentiment, but a small nitpick:

Relying on time stamps for older/newer comparisons is not robust.

Using time stamps (and perhaps file size) for equality checks is quite robust. And the combination with cryptographic hashes is even better (if a file is recreated but has the same contents afterwards, timestamp checks would trigger an unneeded rebuild, while a crypto hash check would recognize that there's nothing to rebuild).