Four follow-up issues found in the combined-stack live verification:
(1) handle_kanban_get had no exception handler; ImportError (webui-only deploy
without hermes_cli), ValueError, LookupError, RuntimeError would bubble
as 500. Wrapped in same exception cascade as POST/PATCH/DELETE.
(2) ImportError on any verb now returns 503 "kanban unavailable: <reason>"
instead of 500. Frontend's existing try/catch surfaces a clean toast.
(3) The 'Read-only view' banner (legacy of read-only PR #1645) was always
visible regardless of actual board state. Default-hidden in HTML;
loadKanban() toggles based on _kanbanBoard.read_only.
(4) .btn / .btn.secondary class names were referenced in 4 places (Bulk
action / Nudge dispatcher / New task / Back to board) but no matching
CSS shipped — buttons rendered as browser-default beveled controls
that clashed with the dark theme. Added scoped CSS rules under the
kanban-* parent containers.
+4 behavioral + static UI tests covering the contracts.
Co-authored-by: ai-ag2026 <ai-ag2026@users.noreply.github.com>
7e48a2fd85
