Resource guarding – what to do immediately after aggressive behavior

I have a 10-month-old female Golden Retriever who is very food motivated. A few months ago, she started showing signs of resource guarding with bones or other really high-value treats. We worked on this by doing the trade game and giving her space when she has those items. We also have an older German Shepherd, and we keep them separated when feeding or when highvalue treats are involved to avoid any conflict.

This has been working really well. We hadn’t had any incidents with the puppy for a while. She’s still wild when food is involved, but the growling/snapping/teeth-bearing we were seeing before had stopped.

Today I was getting their breakfast bowls ready. The puppy was being her usual overly excited self (which we’re actively working on before feedings). Our older dog was standing behind me in the kitchen. When I turned around with the bowls, the puppy went after the older dog. Luckily, I don’t think the older dog really knew what was happening and didn’t react.

I immediately put the food down and calmly but quickly grabbed the puppy and guided her into her crate. She’s crate trained and understands that it’s a safe space and that going in there means it’s time to calm down.

When things like this happen, what’s the best way to handle it? The trade game doesn’t really apply here. I feel like I de-escalated as best as I could — I didn’t yell, just said “hey, no,” and moved her into the crate right away (luckily it was right next to where it happened).

I wasn’t necessarily scared she was going to bite me in the moment, but I do understand that you’re not supposed to get between two dogs because the risk of injury is high.

Also to note we feed them in their separate rooms. I do make the puppy sit and wait while I go in the other room to place the older dogs food. Until I give her the release word she doesn't touch the food. Not sure if that is the best approach but the wait is something she is really good at and it helps me have a little more control when placing the bowls.

TLDR;

My 10-month-old puppy has food aggression and went after my older dog today. What’s the best way to handle it in the moment, and how can I work on preventing or fixing this long-term?