I used to use em dashes with spaces. I started using them without when I was more into reading style guides and it was—if I recall correctly—the Chicago Manual of Style which doesn’t use spaces. This was way before LLMs came onto the scene as a consumer technology.

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maratc 3 days ago | parent [-]

The Chicago Manual indeed advises against spaces, but it’s written for books. AP Stylebook — that recommends spaces — is for papers. Comments are an even shorter form, so they’re closer to AP than to Chicago.

When I go to print, I use hairspace, but it’s not worth the trouble in comments.

	▲	latexr 3 days ago \| parent [-]
		> Comments are an even shorter form, so they’re closer to AP than to Chicago. I’m not sure I agree with using length as the metric to decide which style guide is more appropriate for comments. I’d rather follow one consistent style in general than change it depending on the type of content I’m writing. Still, good point on the style guides targeting specific usages.