Shopify app developer

Overview: I have a Shopify embedded app (Remix, Node 20, deployed on Fly.io, Postgres via Neon) that is ready for its first App Store submission except for one blocker: parts of the app still use the REST Admin API and a hardcoded, soon-to-be-deprecated API version. Shopify requires new public apps to use the GraphQL Admin API on a current, supported version. I need someone with direct experience doing REST → GraphQL Admin API migrations to migrate the remaining REST usage to GraphQL, remove the hardcoded API version, confirm nothing broke, and give me a pre-submission code review. Scope of work: 1. REST → GraphQL Admin API migration: Replace REST Admin API usage with GraphQL Admin API equivalents in these files: (app/shopify.server.ts) (app/services/orders-create-webhook.server.ts) (app/services/order-reconciliation.server.ts) 2. Remove the hardcoded API version: (app/services/customer-tax-exempt.server.ts) uses a hardcoded 2025-07 GraphQL endpoint in several places. Move to the app's configured/current supported API version so it doesn't fall inside the deprecation window. 3. Verify nothing regressed: mainly in order processing and tax-exempt sync 4. Pre-submission code review: A written review of the code and configuration against: 1. Security: auth/session handling,, input handling, webhook verification, any obvious vulnerabilities. 2. Shopify App Store submission criteria: evaluate compliance. 3. Data protection requirements: whether the code correctly handles Shopify protected customer data. To be clear: I am writing all the legal/policy documents myself. I do not need you to write or assess those. This review is about whether the code is secure and submission-ready and whether the implementation supports the data-protection requirements. What I will provide: - GitHub repo access - My audit document with exact findings and file locations What I'm NOT asking for: No new features or UI redesign No legal/policy documents (I'm writing those) No dependency/framework major-version upgrade (separately planned for post-launch) To apply: Please include an estimate of cost and hours for the scope above, and confirm you've done REST → GraphQL Admin API migrations before. I value clear feedback, clean code and a plain explanation of what changed.