Embedded dashboards: load dashboards that are outside the visible area of the host page, without waiting for the user to scroll to them

What is the problem or goal you're trying to solve or accomplish?

The customer embeds several Preset dashboards stacked vertically on one page of their application. Only the dashboard in view loads at page load. Dashboards below the fold start loading their charts only when the user scrolls to them, so users wait for each one in turn. Goal: every embedded dashboard on the page loads (or at least runs its chart queries) in the background at page load, so it is ready when the user scrolls to it.

Support reproduction (Staging-Environment, Preset 6.0.0.44, Chrome headless and headed, @preset-sdk/embedded 0.3.2, one dashboard embedded 3 times):

• Offscreen embeds load their document, guest-token auth, dashboard metadata and native-filter options at page load, but mount 0 charts and send 0 chart-data queries until scrolled into view (4/4 runs).

• Inside the offscreen iframe, Chrome delivers no requestAnimationFrame or ResizeObserver callbacks (0 in 2 s vs 120 rAF when visible); window.innerWidth is still known (1280).

• In upstream Superset 6.0.0 the grid sits inside @visx/responsive <ParentSize> and DashboardGrid renders null while width < 100, so the grid stays empty until the frame becomes visible. (Correlated suspicion: upstream source, Preset's build not inspected.)

• Not caused by DASHBOARD_VIRTUALIZATION: it persists when virtualization is bypassed via Superset's bot check (navigator.webdriver = true; the workspace flag itself was not changed). The bypass took effect: 9/9 charts drawn after scrolling vs 5/9 with virtualization active.

• The same dashboard opened directly in Preset (not embedded) loads without the delay.

How are you solving it currently?

No workaround in place: users scroll to each dashboard and wait for it to load. Whether the customer has tried any layout changes on their side is not established.

What is your recommended solution?

The customer has not proposed a specific implementation. Their request is that embedded dashboards outside the visible area load without needing to be scrolled into view. Possible directions for Product (Support suggestions, not the customer's): fall back to the iframe's own width (window.innerWidth) when no ResizeObserver measurement has arrived, so the grid can mount and queries can start; start chart-data queries independently of layout; or expose an opt-in embedded option (e.g. in dashboardUiConfig) to preload offscreen dashboards.