Can I vibe code FunnelKit?

Build a lightweight WordPress plugin named 'Custom WooCommerce Funnel Engine' that implements checkout customization, pre-purchase order bumps, and post-purchase upsells.

1. DATA MODEL & STRUCTURE:
- Register a Custom Post Type `fk_funnel` with meta for step order: Checkout Page -> Post-Purchase Offer -> Thank You Page.
- Store offer products, discounted prices, and condition rules (e.g., cart total > $50) in post meta.

2. PRE-PURCHASE ORDER BUMP:
- Inject an HTML/JS order bump box into `woocommerce_review_order_before_submit` action hook.
- When checked, fire an AJAX call to add the bump product ID to `WC()->cart` at a custom discounted price using `woocommerce_before_calculate_totals` filter.
- If unchecked, remove the item from cart seamlessly without full page reload.

3. POST-PURCHASE ONE-CLICK UPSELL:
- Intercept the post-payment order completion hook (`woocommerce_payment_complete`).
- Check if the gateway used (e.g., Stripe) saved a customer payment token (`WC_Payment_Token`).
- If token exists and active funnel has a post-purchase offer, redirect user to a custom post-purchase page (`/funnel-upsell/?order_id=X&hash=Y`) instead of the standard thank-you page.
- On the offer page, present 'Add to Order' and 'Skip' buttons.
- If clicked 'Add to Order', trigger a background API request to charge the saved gateway payment token for the upsell product price, add line item to the existing WooCommerce order, recalculate order totals, and log the transaction.
- Redirect to standard order received page upon acceptance or decline.

4. ERROR HANDLING & SECURITY:
- Nonce verification on all AJAX requests and offer page URLs.
- Verify `hash` signature matching `order_id` + secret salt on post-purchase pages to prevent unauthorized access.
- If tokenized payment fails during post-purchase upsell, log the error, do not modify order status, and gracefully redirect to Thank You page with standard confirmation.

5. OUT OF SCOPE:
- Visual drag-and-drop template editor (use standard WordPress theme templates or shortcodes).
- A/B testing analytics engine.
- External CRM/Webhook automation engine.

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