Currently, the model:set JS hook is only triggered if a model is changed by something on the client-side - e.g. a user types into an input or the user has a <button data-model="foo" data-value="bar" data-action="live#update">.

But, if the user triggers a LiveAction, and in that code, we change the value of a prop in PHP, the model:set hook is NOT called. This was done originally... only slightly on purpose: it was more code to add this feature, so I waited until it came up. Now it has, via a user on Slack.

I think it makes sense to trigger this whenever a prop changes for any reason. We DO have a spot where the props from the server are used to update the client-side props - https://github.com/symfony/ux/blob/2.x/src/LiveComponent/assets/src/Component/ValueStore.ts#L107 - it might require some sort of diff to detect any changes, then trigger the hook.