checkout-implementation

Checkout Implementation

Builds Stripe payment flows matched to the project stack.

Choose the approach

Need	Use
Fastest, hosted	Stripe Checkout (checkout.sessions.create)
Embedded, custom UI	Payment Element + PaymentIntent/SetupIntent
Recurring	subscription mode

Checkout Session essentials

• mode: subscription
• line_items: price + quantity
• customer OR customer_email (reuse existing customer to avoid dupes)
• success_url / cancel_url
• allow_promotion_codes: true
• subscription_data metadata: user_id
• automatic_tax enabled (if using Stripe Tax)

Critical rules

• Reuse customer: check for existing stripe_customer_id; for plan changes use subscriptions.update (proration), never a 2nd subscription
• Pass user_id in metadata for webhook provisioning
• Server-side price validation (whitelist price IDs)

Verify

stripe_implementation_planner (MCP) for architecture; test with test cards; confirm via webhook-implementation.