What is the name of this filter? I am having this simple function which acts on two state variable $s_t$ (states being $\{0,1\}$, boolean in sense), and I am evaluating it in discrete time steps. The function is $f_t=1$ if $s_t$ has been $1$ for last $W$ samples (some fixed window size), and $f_t=0$ otherwise. So basically this will set the output to active if the input signal has been active for certain amount of time/samples. Is there some name or category for this? I thought it is latching but according to definitions on web it seems latching is more about delaying the signal, instead of asking "was the signal delayed on input".
There's no known name for this kind of filter in the signal processing world, as far as I know – and what good would such a name be, anyway?

So, I'd describe it in a signal processing context as "discrete state moving window sum with threshold", since it's a non-linear filter (and not much of a signal filter, if you ask me!). Simply because that's how I'd implement it: Sum up the last $W$ states, and output a 1 iff the result is $W$.

If you leave the realm of signal processing and think more of the basic electronic circuits that implement that, or by the purpose: You could call it a watchdog, or a digital anti-ringing, or a self-resetting cycle counter with a threshold, for example.

Your approach with the latch is from the latter category of names; "latch" is not anything that I'd call a filter in a signal processing context. Especially, the functionality you describe is not a latch (alone).