A throwaway page to prove two things on your iPhone before we build them into the estate: that an installed app opens offline, and that a push reaches the lock screen with the app closed.
Environment
Running asStandalone means you opened it from the home-screen icon
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Service worker
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Cached for offline
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Network
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iOS version
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Step 1 · Install & offline
On iPhone: tap the Share button in Safari, then Add to Home Screen. Open the app from its icon, then come back and this will flip to “Standalone”.