Dev Model preservation restores a Model into a runtime started at another URL or in another tab #1635

Summary

In dev, Model preservation can restore a Model into a runtime that started at a different URL, or in a different tab, than the one that preserved it. The page then shows the previous screen while the address bar shows the new URL. A manual refresh fixes it, because the restore is served only once.

Observed with [email protected] and vite-plugin-foldkit on a routed makeApplication.

Reproduction

1. Run a routed app with the Vite dev server. Open /a in tab 1 and interact so the runtime preserves its Model (the debounced foldkit:preserve-model).
2. Edit any module in the app's graph. handleHotUpdate fires HotUpdateFired, which marks every preserved entry isReloadFlush: true.
3. Navigate a tab to /b. It can be a new tab, or the same tab navigated from another site, e.g. a link opened by an embedding host.
4. The runtime at /b sends foldkit:request-model with its container id. It receives the Model preserved by /a, decodes it successfully, and skips init.

Result: URL /b, screen and route from /a. DevTools' init entry shows the stale route in maybeModel.

In our case, an OAuth consent screen in its "redirecting" state reappeared when the user opened /connect-whatsapp/<id> from an MCP App card, after a file had been saved while they were testing.

Cause

• The preservation key is the container id (runtime.ts: runtimeId = hydration.runtimeId || container.id). It is the same for every tab and every URL of the application.
• handleRequestModelReceived serves any entry flagged isReloadFlush, whatever page or tab requests it.
• runtime.ts restores whenever decodePreservedModel succeeds, without comparing the preserved Model's URL with window.location.href (currentUrl).

The restore is meant for the reload boundary of the page that preserved it. Neither a navigation to another URL nor a fresh tab is that boundary.

Suggested fix

• Store the URL with the entry. Add the href to PreserveModelMessage and PreservedEntry. Restore only when it equals the starting window.location.href; otherwise run init.
  • This alone covers same-tab navigations to another URL.
  • Vite's full reload keeps the URL, so the intended case is unchanged.
• Optionally, scope the entry to the tab. Key it by runtimeId plus a per-tab id kept in sessionStorage, as scrollPreservation.ts already does. A second tab on the same URL then never picks up the first tab's Model.

Happy to open a PR for the URL check if this direction sounds right.