StoreKit 2: How do I reliably detect when a subscription has expired or renewed?

I find StoreKit 2 confusing, specifically around detecting subscription expiry and renewal.

My goal is simple: maintain a Boolean that reflects whether the user currently has an active subscription entitlement.

/// Indicates whether the user has an active subscription entitlement. var isSubscribed = false

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Expected Behaviour

The user downloads the app from the App Store.

The user performs actions that require a subscription.

The user is prompted to subscribe and completes the purchase.

isSubscribed = true

For testing purposes, the subscription duration is very short (e.g. five minutes).

The user cancels auto-renewal immediately.

When the subscription expires, the user should no longer be able to perform paid actions.

isSubscribed = false

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Test Setup

I am testing using StoreKit Transactions Manager in Xcode:

Scheme > Options > StoreKit Configuration → AppName.storekit

Editor > Subscription Renewal Rate → Any Renewal Every 30 seconds

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What I Did

1. Launch the app.

2. Attempt a paid action.

3. Subscribe when prompted.

4. Open StoreKit Transactions Manager.

5. Select Subscription Options → Cancel Subscription (expecting no further renewal).

6. Wait one to two minutes.

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What I Expected

I expected Transaction.updates to notify me that the subscription had expired, at which point I would set:

isSubscribed = false

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What Actually Happens

The subscription is cancelled and does not auto-renew.

The renewal period expires.

However, the app still allows paid actions indefinitely.

Transaction.updates does not appear to emit an update indicating expiration.

From the app’s point of view, the subscription seems to remain valid.

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My Question

How am I supposed to detect when a subscription has actually expired using StoreKit 2?

More specifically:

Is Transaction.updates expected to emit an event on expiration?

Should I be querying Product.SubscriptionInfo.Status instead of relying on transactions?

Am I misunderstanding how cancellation vs expiration works in StoreKit 2?

What is the recommended way to keep isSubscribed in sync with the current entitlement state?

At the moment, it appears that a user can cancel auto-renewal, let the subscription expire and still continue using paid features indefinitely.

What is the correct pattern for handling this?