DatasetSelectField fetches options live from /dataset-options (filter_options-aware),
refetches when its dependency (State) changes, clears stale selection. Wired through
schema/types/client/forms for option_source=dataset; AssignBody made dataset-aware so
shared city field stays a real select.
SQL artifacts: cascade filter rule + rebuild City/State datasets from tbl_branches
(every captured city is branch-backed, so Assign region→agent cascade always resolves).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>