Dev shares key lessons from building a Redis queue system for a Shopify app

A developer building SyncFlow, a Shopify embedded app, implemented a Redis-backed background queue system (US-002) to handle inventory sync jobs outside the main request flow. During code review, several critical issues surfaced despite the feature appearing complete, including a TypeScript syntax error that prevented the app from building. Dependency management problems also emerged, as an untracked pnpm lockfile conflicted with the project's npm setup, risking inconsistent environments across developers. The health check endpoint was found to be fragile, potentially crashing instead of returning a clean error response when Redis configuration was missing. Additionally, a retry queue was created without a dedicated worker, meaning failed jobs could stall indefinitely — highlighting that every queue in a system must have a defined read, write, and failure flow.