I propose a theme song for this comment section.

One of my fond memories of high school is being a little snot and posing a math problem to a "dumb kid". I proceeded to think up the wrong answer, and he got the right one (order of operations :D ). This memory is a big roadblock to me modeling other people as different "types" - differences are mostly of degree, not kind. A smart person can do math? Well, a dumb person has math that they can do well. A smart person plans their life? Dumb people make plans too. A dumb person uses bad reasoning? Smart people use bad reasoning.

I consistently, predictably get mad at her for things like saying she'll do the dishes and then not doing them

This doesn't sound like a lack of agentiness. This sounds like a communication problem. Do you think that you're more likely to think of someone as "agenty" if their planning processes are (seemingly) transparent to you (e.g. "this person said they wanted a cookie, then they took actions to get a cookie") vs. non-transparent (e.g. "that person said they wanted a salad, then they took actions to get a cookie")?