Subscriptions for a dog grooming SaaS, review my webhook and plan gating

checkout.session.completed tells you someone started a subscription, not that they still have one. That is why your customer kept Pro.

Stop deriving the plan from individual events. On every customer.subscription.created, .updated and .deleted, write the whole state you care about:

await db.from('profiles').update({
  plan: sub.status === 'active' || sub.status === 'trialing' ? priceToPlan[sub.items.data[0].price.id] : 'free',
  current_period_end: new Date(sub.current_period_end * 1000)
}).eq('stripe_customer_id', sub.customer)

Stripe sends the full object every time, so the last event wins and out-of-order delivery stops mattering. Also store stripe_customer_id on the profile, not the session id.

Separate finding in the same file: your webhook route reads the body with await req.json() and then calls stripe.webhooks.constructEvent on a re-stringified copy. Signature verification needs the exact raw bytes, so this passes locally with the CLI and fails against live traffic the moment Stripe formats anything differently.

In an App Router route handler use await req.text() and pass that string straight to constructEvent. Parse afterwards.