The charts weren't broken — the data pipe was empty. dashboard_api opened the
research connection ONCE at boot; if the DB was unreachable then (container
started before Postgres, or a blip) it stayed None forever, so /api/chart and
/api/bars returned 'no research db attached' and every candlestick + sparkline
rendered blank. Live-verified: GET /api/chart returned bars:[] reason:'no
research db attached' on the deployed dashboard. Now DashboardState._research()
opens the connection LAZILY and reopens if None — same self-heal as the
event-store emit fix. 2 tests; chart/backtest endpoint tests still green.
No library change: Lightweight Charts v5.2 is fine, it just had nothing to draw.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
