Shopify Expert for E-commerce Store

Project Overview We are an established e-commerce business operating an industrial/horticultural supply store on Shopify. We fulfill out of a centralized distribution hub in Melbourne, Australia. We have completely outgrown off-the-shelf procurement and inventory apps. They are too rigid, feature arbitrary historical data limits, and lack the advanced cross-vendor validation logic required for our supply chain. We are seeking an expert, senior-level full-stack developer to build a Custom Private Shopify Application. This app will act as our master procurement middleware database—extracting unfulfilled store orders, aggregating line items cleanly by vendor parameters, handling complex purchase order (PO) lifecycle logic (Draft, Append, Soft-Merge), managing supplier Minimum Order Value (MOV) triggers, and updating storefront product pages dynamically via GraphQL Metafield mutations. Core Technical Stack Requirements Backend: Node.js (Express) or Python (FastAPI / Django). Database: PostgreSQL (to handle relational custom PO states, line-item overrides, and historic audit logs). Frontend: React, Tailwind CSS, and Shopify Polaris component library to match native Shopify admin styling. APIs: Comprehensive proficiency with the Shopify Admin API (GraphQL) and Shopify Admin UI Extensions (Admin Blocks). Key Modules & Scope of Work to Deliver 1. Infinite Order Ingestion & Aggregation Engine Extract all unfulfilled and partially fulfilled customer orders via Shopify GraphQL Admin API. Implement server-side pagination with unrestricted historical lookup (bypassing standard 2-week app limitations). Build a multi-select grid allowing operators to manually combine any collection of orders across weeks or months for vendor allocation. 2. Advanced PO Lifecycle Operations (Draft, Append, Soft-Merge) New Draft POs: Create clean procurement documents with custom sequential string numbering. Append Engine: Append selected lines into an active open draft. If an item variant already exists inside the targeted draft, the backend must automatically sum and increment the quantity needed. Non-Destructive Soft Merge: Allow merging multiple Draft POs. Source records must not be deleted; their status must shift to MERGED, and they must retain a relational pointer (merged_into_po_number) to the new consolidated Master PO to preserve an unbroken historical audit trail. 3. Cross-Vendor Validation Gate & Exception Modals Implement a strict backend block preventing line items from being allocated to a mismatching vendor PO. If a validation error triggers, a frontend Intercept Exception Modal must launch, forcing the operator into safe resolution pathways (e.g., automatically routing the item to the correct vendor draft, launching a pristine PO run for that specific vendor, or cancelling the action). 4. Financial Canvas Overrides For every item row, pull the live Shopify inventoryItem.unitCost (Buying Price). Provide interactive input fields for the operator to manually override "Ordered Quantity" (for box-multipliers/buffer stock) and "Buying Price" (for vendor bulk discount adjustments), recalculating totals instantly on screen. 5. Supplier Profiles & Move-to-Review Triggers Build a centralized supplier registry supporting 3 automation behaviors: Pure Dropship Bypass (instant PO output), MOV Thresholds (holds drafts until cumulative row totals cross an explicit AUD dollar value), and Scheduled Delivery Cycles (holds lines until a fixed weekly day/time window closes). Automatically trigger an email notification to our admin team the exact second a Draft PO satisfies its vendor profile constraints and shifts to a READY_FOR_REVIEW state. Build a "Smart Scan" tool inside the PO view that checks for any open, unlinked customer lines matching that vendor and suggests them for one-click mass appending. 6. Order Aging Alerts (Business Days) Build a tracking loop calculating elapsed time between customer purchase and PO placement. This must calculate Business Days only (excluding weekends and public Victorian/Australian holidays). Expose a grace-period variable input in Settings (defaulted to 5 business days). Exceeding this threshold must visually escalate the line row to an highlighted alert state and float it to the top of a "Critical Pending" widget. 7. Native Shopify Admin UI Extensions (Admin Blocks) Deploy a custom Shopify Admin Block UI Extension straight onto the native Shopify Order Details page (/admin/orders/XXXX). This block must run a live relational lookup against the app's database using the active order ID to display real-time procurement statuses, deep hyperlinks opening the associated PO files directly inside the app, and breakdown details if the customer order was split across multiple supplier runs. Seamlessly inject corresponding tracking tags (PO: Draft, PO: Sent, PO: Received) back to the core Shopify Order module. 8. Front-End Metafield Sync Layer Provide a "Trigger Front-End Delay Warning" action button next to any incomplete or backordered PO line item. This must fire a GraphQL mutation setting a custom product metafield (procurement.availability_status) to "stock limited", which our front-end theme will use to display a shipping delay banner to customers. Clicking the standard warehouse check-in button upon item delivery must instantly nullify/clear this metafield value, returning the web page layout back to normal. Project Type & Budget Structure This is a Fixed-Price Contract split across three distinct milestones. We have an isolated staging repository ready to go. Code must be developed via distinct Git feature branches and thoroughly tested before final deployment. Milestone 1: Extraction Engine & Database Architecture — Successful GraphQL Admin API connection, infinite historical extraction table, and relational database schema lock. Milestone 2: Advanced PO Logic & Validation Loops— Implementation of Append rules, the Non-Destructive Soft Merge traceability engine, and the Cross-Vendor Intercept validation modal blocks. Milestone 3: UI Completion, Ingestions, & Shopify Admin Blocks — Deployment of the responsive Polaris dashboard, supplier trigger alarms, Smart-Scanner asset, Omni-channel webhook parser, native Shopify Admin UI Extensions, and the automated front-end Metafield mutation toggles. Budget is open to reasonable negotiation based on your depth of engineering experience and portfolio proof.