A lifecycle autosave persists the placeholder state behind the menu

Fact

Menus commonly render over a live but inert instance of the thing they launch — a demo world behind a title card, a blank document behind a template picker. That instance is indistinguishable from a real one at the persistence layer.

So an autosave wired to a lifecycle event fires for it:

window.addEventListener('beforeunload', save);   // runs even if nothing started

Merely opening the page and leaving writes a save. On the next visit the menu offers "Continue" for a session the user never began, restoring a placeholder as if it were their progress.

Why it matters

It only appears on a clean profile, which is the one state the developer never has. Local storage from testing hides it completely, and by the time the entry point is reviewed the save has existed for weeks.

The failure is also self-confirming: the offer looks correct, because a save genuinely exists.

How to apply

• Guard persistence on an explicit session-started flag, set where the user actually commits, and check it inside the save function rather than at each call site — lifecycle handlers are easy to forget.
• Do not guard on "state exists". Placeholder state exists too.
• Verify on a clean profile: load the entry point, navigate away, come back, and assert the resume affordance is absent.