Putting a little TL;DR up here on top, because I'd really like to see folks' answers to this: What's the simple-language equivalent of, "You're so smart," or "That was so smart," but for intellectual effort?

Now, regularly scheduled thoughts :) :

What is a good, short method/word for praising effort?

with my 8.5-month old, "Good Job," specific variants on it ("Good Job climbing that staircase, tiny!") and such have worked wonderfully, but I seek something more-

It's so easy to praise a child's intelligence - "You're so smart!" "That's so clever!" - but much harder to praise effort, in my experience so far, because "I can tell you worked so hard to do that, that's so great!" just doesn't roll off the tongue very well! And this is important- "Good job!" is at the nexus of how I praise my little boy partially because he totally understand it. He's got that, even if he may not know the individual words exactly, he absolutely knows what Daddy means when, "Good job, baby!" comes out of daddy's mouth. I have VERY LOW FAITH that I could get, "I can tell you worked so hard to do that, that's so great!" to work the same!

(Incidentally, I also now feel I know more about why, in America at least, we often say, "I'm doing good," and variants thereof, instead of "I'm doing well." "Well" just isn't in the primal vocabulary quite as deeply, maybe because of its association with "Well, I was going to, but then I didn't," type of statements. "Good" is simple and meaningful, and I often find myself telling my son he's done something so "good," and then correcting myself a little, because, well, I want to teach him correct grammar, but more than that, I want to communicate with him meaningfully - and "good" gets a meaning across with which he's already familiar, while "well" does not, and has other common uses.)

So what's the simple-language equivalent of, "You're so smart," or "That was so smart," but for intellectual effort?

Maybe I need to invent a word for this and see if it catches on! :D