Cross-tab communication via events

[elimenko]

So recently our team got hit by the Storage Partitioning flag rollout in the latest Chrome versions, which broke our mechanism of cross tab communication via Local Storage events.
We have a setup where site a.example.com embeds an iframe from site b.example.com. We have a mechanism where user action on site a.example.com opens a new browser tab in the b.example.com domain. Previously we were relying on Local Storage events for communication between those two tabs, but now, due to storage partitioning, it's no longer possible.
It seems that Shared Storage is designed to have secured cross-site unpartitioned storage, but searching through documentation I haven't found if we are able to use some like Storage Events with Shared Storage. Does it sound like Shared Storage is capable of helping in my case? Thanks in advance!

[xyaoinum]

Shared storage has carefully constructed output gates. The "Window: storage event" API as is can leak arbitrary amount of information, which doesn't seem to be something Shared Storage can support.

[elimenko]

@xyaoinum Thank you for the answer. May be you could suggest, which approach can be used for cross-tab cross-domain communication in the Privacy Sandbox? It seems that for Cookies we can rely on First Party Sets. Is there anything similar to this, but for other storage types?

[menonasha]

@elimenko I believe this thread is the most relevant to your ask and it may be worth posting more about your use case there