Custom Shopify Search Integration

I already have a fast, fully-featured product search engine running on my own servers; now I need a small Shopify app that plugs it into my storefront.

Here’s what has to happen:
• Every customer search—whether it comes from the header bar or search results page must be intercepted and routed to my search engine.
• The app should call my search service which will return (liquid if appropriate, or JSON if appropriate) then display those results inside the existing theme so shoppers think they’re seeing Shopify’s native results page. It needs to look and behave like a normal collection/search view.

A straightforward custom Shopify app (using theme app blocks, a proxy route, JavaScript Fetch/Ajax API, Liquid overrides, etc.) seems the most practical route, but I’m open to your approach as long as it satisfies the flow above.

I’ll supply:
• Full API docs and sample payloads for the search engine
• A staging copy of the store for development/testing
• Design guidelines so styling lines up with the current theme

Deliverable:
An installable private Shopify app (or equivalent theme extension) that:
1. Redirects all storefront searches to my engine
2. Parses the returned data
3. Renders products and pagination in the theme’s standard layout
4. Handles errors gracefully and falls back if the API is unreachable

If you’ve built something similar—or have deep experience with Shopify’s proxy routes, Shopify search, and Liquid—let’s talk details and timelines.