"[vite] hot updated" fires but React component state resets on every edit — Fast Refresh boundary issue?

I'm seeing a consistent behavior in a Vite dev server setup where HMR appears to work — the console logs the hot update event and no full page reload occurs — yet the edited React component loses all of its local state on every save. My understanding is that Fast Refresh should preserve component state across edits when the module is structured correctly.

From the documentation, Fast Refresh relies on a file exporting only React components (or components plus hooks) for state preservation to work. My component file also exports a couple of plain utility constants and a non-component helper function, and I suspect this mixed export pattern is what forces a fallback that remounts the component instead of refreshing it.

Relevant constraints: this is on Vite 5.x with the official React plugin, and I know HMR behavior around CSS and side-effectful modules changed between major versions, so I want to be sure I'm reasoning about the current semantics. The module does not call import.meta.hot.accept() manually.

My questions:

1. Does mixing non-component exports with component exports in one file definitively disable state-preserving Fast Refresh for that module in Vite 5.x?
2. Is there a documented way to confirm at runtime whether a given module qualified for Fast Refresh versus falling back to a remount?
3. Would adding an explicit import.meta.hot.accept() handler change this behavior, or does the React plugin override it?