Support PRESCRIBED mode for sources that affect multiple profiles

[theo-brown]

This mirrors internal issue b/395854896.
See

torax/torax/sources/source.py

Lines 172 to 175 in 3ea75f5

	case runtime_params_lib.Mode.PRESCRIBED.value:
	# TODO(b/395854896) add support for sources that affect multiple core
	# profiles.
	return (dynamic_source_runtime_params.prescribed_values,)

[jcitrin]

Thanks for reminding that we should prioritize this. @Nush395 , would you like to take a look?

[theo-brown]

I suppose as @Nush395 has done the majority of the recent sources work he might be well placed, but if he's busy I can easily have a crack at it. Just wanted to check how it meshed with other plans, and whether someone's looking into it already.

[Nush395]

This will be much simpler to do once we have moved our configs to pydantic (this should be completed start of next week :) ). I believe @tamaranorman is planning to tackle this once this is done.

[tamaranorman]

I started looking at this but indeed pre and post pydantic it was going to look very different. If you want to contribute this go for it if not it is on the roadmap for the next couple of weeks

[theo-brown]

If you want to contribute this go for it

Given that the Pydantic changes mean it's a bit of a moving target I might give it a miss! Happy to have flagged that this is a bug that a user is interested in being fixed :)

(Very excited to see the switch to Pydantic generally though, I can see it being a big improvement)