Quit, restarted, and it's working again. Turns out... opening the preferences page breaks it. Go figure.
That may come across a bit non-sequitur, but people've been telling me Atom is tired and <x> is wired for a while now, and this always seems to happen JUST as I've gotten a new editor working how I want it and adapted to its quirks. I stuck with TextMate LONG after it had turned to crap, and only switched when it finally stopped working at all.
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