79bf0be53b
scope_id_for_chat only consulted the channel→team map, which is empty right after boot (and after a reconnect) until an inbound event from that channel arrives. A /handoff into a Slack home without a stored scope_id (SLACK_HOME_CHANNEL env homes, or config homes never re-set via /sethome) therefore built a key without the team while every thread reply carries it — the handed-off thread was still orphaned across a restart (#111896). When the map has no entry and the channel is not known to be shared across workspaces, fall back to the single authenticated workspace (filled by auth.test at connect); multi-workspace installs keep returning None.