Property Mapping - Define a 'source of truth' source that wins when multiple sources are used.

Is your feature request related to a problem?

I've run into a headache where if I use property mappings and then a user write stage, if i don't an expression to strip extraneous data, it overwrites fields that i didn't want updated. Side-note. Property Mappings seem to handle group updates on login without the write stage, but attributes only sync the first time and never again unless I set up a write stage.

Example where I only want discord updating attributes, but not key properties like Username or Name. I'm sure there's a better way to do this, but this was a quick and dirty solution.

from authentik.sources.oauth.models import OAuthSource

if not isinstance(context['source'], OAuthSource) or context['source'].provider_type != "discord":
    return True

DOMAIN_TO_SKIP = 'example.org'

if request.context["pending_user"].email.split('@')[-1] == DOMAIN_TO_SKIP:
    non_attribute_keys = [ key for key in request.context['prompt_data'] if key != 'attributes' ]
    for key in non_attribute_keys:
        removed_key = request.context["prompt_data"].pop(key, None)

return True

Describe the solution you'd like

A priority list to define which sources are primary, or an option to define what to sync from sources if a value exists alread.

Describe alternatives that you've considered

A hacky shim that just strips out data before doing the write in the auth flow. Seems a little heavy

Additional context

No response