ActivityPub 'Announce' sometimes not displayed correctly as 'Boost'

[vitalyster]

I'm sending something like this:

{"type":"Announce","id":"https://domain.tld/n/2944171-0#top","actor":"https://domain.tld/u/announcer","object":{"id":"https://domain.tld/n/2944171-0","published":"2019-06-04T07:51:33.779855Z","url":"https://domain.tld/m/2944171","to":["https://www.w3.org/ns/activitystreams#Public"],"content":"<p>text</p>","attributedTo":"https://domain.tld/u/poster","cc":["https://domain.tld/u/poster/followers/toc"],"type":"Note"},"type":"Announce","@context":["https://www.w3.org/ns/activitystreams","https://w3id.org/security/v1",{"Hashtag":"as:Hashtag"}]}

Expected behaviour

It should be displayed as "@announcer boosted message (@poster@domain.tld: Text)"

Actual behaviour

Sometimes it displayed correctly (I think its when @poster is already known to mastodon instance), sometimes it displayed as @announcer's(!) post, sometimes it displayed as "@announcer boosted @announcer's(!) post"

Specifications

I'm discovering my @announcer on mastodon.social instance, both poster and announcer are from another ActivityPub service.

[ClearlyClaire]

What is this other ActivityPub service? It seems like this could happen if the announced object is inlined and lacks an attributedTo attribute, which is not the case of the AP snippet you posted.

I'm not sure whether we should assume a boosted status is from the booster when no attributedTo attribute is present… but when that's the case, we can't attribute it at all.