You can tell if you input something or not, based on the blinking cursor, in which case it is not "frozen".

semanticc 2 days ago | parent | next [-]

Unless you disable cursor blinking because you find it annoying (like I do).

	▲	setopt 2 days ago \| parent [-]
		Yeah, disabling cursor blinking is the first configuration I do in any terminal.

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written-beyond a day ago | parent | prev [-]

I mean a trivial solution to all of these work around a could have been each keystroke registers a single asterisk that goes away after a delay. You wouldn't reveal the length and you'd had a standard way of informing the user that their keystroke was registered.

	▲	layer8 19 hours ago \| parent [-]
		It doesn’t tell you if backspace works, however.