chat-hook: watch-ack successfully for store subscripttion kills
^- (quip card _state)
?~ saw [~ state]
?+ wir [~ state]
+ [%store @ *]
+ [~ state(synced (~(del by synced) t.wir))]
+ ::
[%backlog @ @ @ *]
=/ pax `path`(oust [(dec (lent t.wir)) 1] `(list @ta)`t.wir)
=. synced (~(del by synced) pax)
