detectFacets types facets with app.bsky.richtext.facet on mentions and leaves the field off entirely on links, but a place.stream record must carry place.stream.richtext.facet: a validator holding it to that lexicon rejects the whole message ("Expected place.stream.richtext.facet (got app.bsky.richtext.facet)"), which is how chat pings were being dropped. Add detectChatFacets() to @streamplace/core and use it from both chat send paths, so the facets and the allowed feature types are decided in one place.