Update FLEDGE_Key_Value_Server_API.md

[thegreatfatzby]

Looking for clarity disguised as commit, main page indicates interest group names being concatenated and added to the KV call for commong kv URLs, and table below mentions multiple IG names, want to make sure I'm understanding.

[peiwenhu]

This doc is written by Protected Audience's TEE K/V server implementation (which will replace the BYOS servers in the future) and the APIs are what it'll support.
V1 is aligned to the BYOS API described in the main doc. However, some advanced features like concatenated IG names are not supported in TEE K/V server.
V2 which is probably what you saw that has multiple IG names, is specific to the TEE implementation that has more privacy protections. BYOS k/v servers are not expected or supported to use it.

Because we don't intend to support IG names in V1, the commit probably won't be necessary but we can continue with the clarification here if necessary.

[thegreatfatzby]

Hey @peiwenhu , so for the "v1" of BYOS server, the auction code will concatenate the IG names for any identical KV server URLs if the appropriate parameter is included?

[brusshamilton]

Yes, for the BYOS method the bidding signal fetch URL will contain both the keys and the interest group names. As with the keys, the interest group names will be URL escaped and then joined into a comma separated list.
See the Chrome implementation here: https://source.chromium.org/chromium/chromium/src/+/main:content/services/auction_worklet/trusted_signals.cc;l=370

Note that the list of interest groups is only intended to be used to fetch the corresponding priority vectors in the response. The list of interest groups specifically should not control the return value for other keys or implement any operations based on the set of interest groups a user is a member of (or not a member of).

[thegreatfatzby]

@brusshamilton will there be some Terms of Service for an Ad Tech using these APIs to enforce that and other BYOS restrictions?