Feat/65 stripe webhook handler

[hajunk05]

Description

Adds a stripe webhook handler that reconciles payment state onto registrations. Handles completed payments, expired payments, failed payments, and refunded payments.

Closes #65

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

• Manual testing (requires screenshots or videos)

5 Test cases: 5/5

Setup:

• Created a Stripe test account, then added the API key and secret key to .env
• Triggered events via the stripe CLI against the local endpoint
• Also initiated a Stripe CLI listener

There was already an existing social session, so I used this, with a new User I created using my email, to create registrations for that social session.

Test 1: Successful payment checkout

Created a new registration for a social session

Then ran:

stripe trigger checkout.session.completed \
    --override checkout_session:metadata.registrationId=6a1a24abb771e5d0ad258c9a

Payment Status: Pending -> Paid, with amount paid populated from nothing to 30.

Confirmed via Stripe CLI listener output:

Test 2: Idempotency

On the paid registration from Test 1, re-ran the same command

stripe trigger checkout.session.completed \
    --override `checkout_session:metadata.registrationId=6a1a24abb771e5d0ad258c9a`

Temporarily added a console.log to check it’s skipped here if paymentStatus is already paid.

Then confirmed it skips:

Test 3: Checkout Expired

New social session registration

Then ran:

stripe trigger checkout.session.expired \
    --override checkout_session:metadata.registrationId=6a1a269ab771e5d0ad258d0d

Registration status: Pending -> Cancelled:

Confirmed via Stripe CLI listener output:

Test 4: Payment Failed

Another new social session registration

Then ran:

stripe trigger payment_intent.payment_failed \
    --override payment_intent:metadata.registrationId=6a1a27feb771e5d0ad258dd1

Registration Status: Pending -> Cancelled

Confirmed via Stripe CLI listener output:

Test 5: Refund

Last new social session registration:

Then ran these two commands in series:

# 1. Create + confirm PaymentIntent (NZD 20.00)
stripe payment_intents create \
    --amount=2000 --currency=nzd \
    -d "metadata[registrationId]=6a1a2992b771e5d0ad258e1f" \
    -d "payment_method=pm_card_visa" -d "confirm=true" \
    -d "return_url=http://localhost:3000"
# → pi_3TcaYmRQexddMwff1Hqna327 (amount_received 2000)

# 2. Refund it
stripe refunds create -d "payment_intent=pi_3TcaYmRQexddMwff1Hqna327"

Registration Status: Registered -> Cancelled
Payment Status: Paid (After first command) -> Refunded (After second command)

Checklist before requesting a review

• My code follows the style guidelines of this project
• [ ] I have commented my code in hard-to-understand areas
• I have made corresponding changes to the documentation if needed
• I've requested a review from another team member