Will chickens flatten a raised bed?

I had this fantasy that i was going to paddock the entire garden so that I could plant self-havestable chicken food and the chickens could deal with the pests (I would train them to eat slugs since those are a big problem in the PNW). Then today I learned that chickens will flatten raised beds. On our heavy clay soil, raised beds are required to grow any kind of vegetables and most of anything else.

question 1: will chickens flatten a raised bed? Is there a breed of chicken that is less inclined to flatten the bed in search of worms but still inclined to forage the self-harvestables? (two mutually exclusive traits im 99% sure, but it doesn't hurt to ask).

Question 2: What poultry, aside from ducks can: keep pests down, self forage, and wont flatten a raised bed? I'm allergic to duck eggs but if there aren't any other qualified poultry, I could raise them for meat. Guinea fowl sound great but I haven't quite convinced my father to allow noisy birds on the property.

Yes chickens will flatten a raised bed. I think you can mitigate this by having formal sides to the bed, either with inexpensive lumber (not treated, of course) or logs or maybe even rocks. They will still get in there and scratch but if you're adding mulch anyway it shouldn't matter too much.

Also, you could try to put mesh or wire over the bed so they can't scratch below a certain depth.

If you have raised beds with sides made out of wood/stone/etc, chickens probably won't hurt the soil structure much unless you keep them on it constantly. Though if it's bare soil they're likely to dust bathe in it and that can be a bit damaging! If it's a raised bed made of just mounded earth, they may scratch it up to the point of flattening.

I have observed that my soil had definitely improved since I've had my six chickens rotating through, but I also don't let chickens into my vegetable patch until winter, as they are pretty destructive with their scratching, pecking, and dust bathing (though established perennials and lawn can manage a once-a-week rotation just fine).

More than a few chickens in a garden for more than a short amount of time will destroy it. If your plants are already well established and pretty big, you'll have better luck, but the chickens will still scratch and dig and dust bathe.

Ducks won't be able to jump up anything much higher than 12 inches, if that helps.