By replenishment I don't mean a violent
series of deliberate cometary impacts
but by using "other" methods [hitherto
technologically unknown] to gradually replenish the Mars air lost by sputtering away. How many millibars worth of Mars air is lost to "sputtering" every century?
Every millenia?

And no Mars terraforming enthusiast
is saying that Mars would be a 'permanent' colony for human settlers.

And heavy gases like CO2, Ar, etc.,
don't sputter away that easily from
Mars. Even sputtering away of massive quantities of O2 from Mars takes time, many millenia and even megayears
perhaps.

Jacob