Can I vibe code SmarterClick?

Build a lightweight, production-ready exit-intent modal system for an ecommerce storefront using vanilla JavaScript for the client script and Node.js (Hono/Express) for the backend API.

1. CLIENT-SIDE SCRIPT (`exit-engine.js`):
- Detect exit intent on desktop via mouseleave on the body element, checking if `e.clientY < 10` with high upward Y-velocity.
- Detect exit intent on mobile using tab visibility changes (`visibilitychange`) and rapid scroll-up behavior.
- Support configurable triggers: delay timer (e.g., 10s), scroll depth percentage (e.g., 50%), and cart value conditions stored in localStorage.
- Ensure frequency capping: write to `localStorage` to prevent showing the popup more than once per user session or every 7 days.
- Inject an accessible, responsive HTML `<dialog>` element containing an email input, dynamic headline, offer code, and close button. Ensure focus trapping and ESC key handlers are functional.
- Block page render until the script initializes asynchronously without causing CLS.

2. BACKEND API & DATA MODEL:
- Endpoint POST `/api/leads`: Accepts email, current cart value, page URL, and campaign ID. Validates email format, prevents duplicate submissions, and dispatches a webhook to Klaviyo/Shopify.
- Endpoint POST `/api/events`: Logs `impression`, `dismiss`, and `conversion` events with metadata (timestamp, user-agent, campaign_id, session_id).

3. FAILURE MODES & SECURITY:
- Gracefully handle cases where localStorage is disabled (private browsing mode) using fallback memory flags.
- Implement rate limiting on lead submissions to prevent spam attacks.
- Ensure low footprint (<5KB compressed) and zero external dependencies.

4. OUT OF SCOPE:
- No drag-and-drop visual builder. Config must be passed as a simple JSON object parameter.

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