Hi,

This is a follow up to #281, I'd like to start the discussion on how aggregate ARA could work with FLEDGE.

In terms of priorities, note that for RTB House the general ability to perform aggregate reporting from generateBid (on win/loss/imp/click events, as proposed in pull194@416) is critical before third party cookies go away (see also #93, #177). The FLEDGE-agg ARA compatibility discussed in this issue would be below that in terms of priorities, but still important.

The high level question I'd like to ask is:

• Could we make it possible to register aggregatable sources using all bidding signals that are available in generateBid?

The motivation behind this would be to unlock analysis and optimization of conversions based on bidding signals. (Note that "conversions" are used quite broadly here, and may actually mean any objectives that are measured on the advertiser's side.)

The solution discussed in #281, while satisfactory for the event-level case, would not work here - the bidding signals are not accessible in the Fenced Frame.

I anticipate there will be some technical details to work out (e.g. how to manage the privacy budget across win/loss/imp/click and conversion reporting), but I think it's best to start with a high level discussion on the general idea.

Best regards,
Jonasz