The engine switch moves out of main.js into src/standalone/engineSwitch.js: every
engine change in the page hands the session off (layers, Director, Contacts,
directions and satellite cameras), whether it came from the picker or from
history. Each attempt has a generation; a failure rolls back to the last engine
that started, requests made during a switch or recovery are reconciled once it
settles, and a picked engine adds its history entry only after it starts. The
first-frame wait only lifts the cover and never fails a started engine; a
hidden tab does not wait. Nothing starts after pagehide, and a failed recovery
leaves the picker usable.
Preserve the camera, map source and layer selection across engine sessions. Restore the previous engine if startup fails and retain local history navigation.
Remember the chosen engine and restore the current view after navigation. Keep the standalone JavaScript UI and retire the Dioxus migration and Cesium removal milestones.
German Khokhlov