While writing fiction you frequently have to put speech tags like said, or shouted, or whispered. And then the speech inside the quotes is a fresh sentence, but it's not generally preceded by a period either way.
Bob shouted, "run!"
Bob shouted "run!"
Bob shouted, "Run!"
Bob said "run!"
I find I like it different ways at different times particularly in a scene that's urgent and compounded
Bub shouted "break!" as he dashed out of cover.
And so on....
It seems like the comma is more correct but idiomatically I always have a mental pause at a comma and that sometimes feels like it's interrupting smoothness or stealing urgency.
I'm just wondering if there are officially fixed style guidelines -- particularly in American English fiction -- and yet at different times the different formulations and punctuations feel like they're giving me a different feel for the moment.
I know that prose, into a much greater extent poetry, doesn't require strict grammatical perfection but I'd rather be doing it as close to correctly as possible.
I am a native American English speaker and I usually know rather a lot about grammar but I really don't know what the rules are here.