Shopify-Savvy Senior Developer - Maintenance of Custom Photo Editor App

We're a DTC photo book brand replacing a costly third-party SaaS photo editor with our own custom app, deeply connected to Shopify. We need a senior developer comfortable with e-commerce integrations to take over long-term maintenance and evolutions of this editor once it's built. Right now our editor runs on a third-party SaaS: costly, and we have zero control over it — no way to adapt it to our needs. So we're building our own in-house editor to get off it. The developer building it is handling initial development only — he won't be taking on maintenance afterward. We're looking for a senior developer to take over ongoing maintenance and continuous improvement of this editor, on a maintenance retainer (not full-time — volume varies based on needs). Stack: Bun backend, React frontend (fully responsive, mobile-heavy traffic), Shopify (theme dev, Storefront/Admin API). What you'll do: Pick up a codebase you didn't write and get up to speed fast Respond quickly when something's reported (bug, blocker, outage) — same-day fixes Solve problems autonomously, without technical supervision Implement requested features/improvements over time Manage and maintain the connections with our Shopify back office You're a fit if you have: Senior-level experience with production web apps Proven experience with e-commerce/Shopify integrations A track record of taking over and maintaining legacy/existing code A reputation for being responsive, reliable, and autonomous Solid written English (we work async, in writing) Contract type: Ongoing maintenance retainer — not full-time. You're called on when something breaks or an evolution is requested.