Grammatically, comma or period after "no problem", "sure", "okay" and the like

Solution 1:

Consider the following sentences:

"OK, we're all going to the store today," mom informed us.

"OK: we're all going to the store today," mom informed us.

"OK. We're all going to the store today," mom informed us.

"OK; we're all going to the store today," mom informed us.

"OK – we're all going to the store today," mom informed us.

"OK! We're all going to the store today!" mom informed us."

"We're going to the store today, OK?"

Did you read the first 5 sentences the same way? This is why they're called style guides rather than grammar textbooks, but it doesn't take away the importance of having it read the way you want it to read.

Solution 2:

In this case, "okay" is being used as an interjection, and should therefore be separated from the rest of the sentence by a comma for a short pause and a period for a longer one. For interjections, one can choose among a comma, period, and exclamation point. "Don't worry" and "no problem" are also being used, in this case, as interjections, so commas can work.

Personally, I'd use a comma for a very short pause, a semicolon for a longer one, and a period for a significant pause.

Solution 3:

I often use the word "sure" at the beginning of a dialog, not as an affirmation, but as an emphatic. For instance, a character says, "Sure is hot out here." In this case, a comma would make the reading a bit awkward, so I do not use one. However, if I am using the word "sure" to affirm something, I would use a comma. For instance, if my character says, "Sure, I'll go along with that," then I use the comma. Word editors like Microsoft editor and Grammarly call for a comma following "sure" regardless of the circumstances under which I use the word, so I must still make the call myself.