The snapshot does real Postgres work, so the first load left a blank board that
read as broken. Added a full-screen overlay (on-brand spinner + "connecting to
the control room…" + what it's fetching) that:
- shows on first paint, dismissed the instant real data renders (SSE, poll, or
historical fetch);
- after 5s of waiting, softens the sub-text to "taking a moment — still
fetching…" so a slow snapshot reads as working, not frozen;
- on a failed first fetch, flips to a red "couldn't reach the control room —
retrying…" state (stops the spinner) instead of hanging silently.
Verified headless: overlay visible at first paint, display:none once pnl/feed
populate (no JS errors); 500 path shows the error state.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
