What a Direct inbox answer teaches the session: the inbox sequence number the
server last issued (seq_id on the inbox page). It is server-decided,
session-scoped state — the profile's Message button reaches the lookup after a
search, not an inbox visit, yet still sends the number an earlier inbox answer
issued. The one live writer is the inbox feed's request
(directInboxFeed): it decodes the page's seq_id and adopts it, so the
launch burst, the Direct tab and every later page all record it, and the
Direct requests that send seq_id read one source (the screens never carry a
copy). A scenario driver declaring the fact it starts from calls
this too, with the number its session already holds.
What a Direct inbox answer teaches the session: the inbox sequence number the server last issued (
seq_idon the inbox page). It is server-decided, session-scoped state — the profile's Message button reaches the lookup after a search, not an inbox visit, yet still sends the number an earlier inbox answer issued. The one live writer is the inbox feed'srequest(directInboxFeed): it decodes the page'sseq_idand adopts it, so the launch burst, the Direct tab and every later page all record it, and the Direct requests that sendseq_idread one source (the screens never carry a copy). A scenario driver declaring the fact it starts from calls this too, with the number its session already holds.