Same bug class as the Slack/Feishu picks: buzz, dingtalk, email, google_chat,
line, ntfy, photon, sms, teams, wecom and whatsapp already had the platform
message id on the MessageEvent but built the SessionSource without it, so
source.message_id consumers (reply anchor in run.py, /sethome synthetic-thread
check, relay _event_ids fallback, shutdown notice anchor) saw None. Only sites
where the id variable was already in scope are widened.
719cb67bdb