Senior Node.js Developer — take over, deploy and document an existing learning platform

We run corporate learning platforms in Mexico. The platform works well, but the engineer who built it operated it single-handedly and left no documentation: an admin panel was built but never deployed, content uploads were done manually, and known defects were patched with scripts only one person knew how to run. This is NOT a rewrite. The architecture is sound. We need someone to take it over, make it operable by our team, and document it end to end. SCOPE, BY MILESTONE: 1) Content uploads (urgent, ~4 days) — validate and complete the pending course uploads for our term, working side by side with our two in-house developers, and write the upload runbook while doing it. 2) Admin panel (~5 days) — deploy the existing panel to our environment, set up admin users, and write an operations manual so non-technical staff can replace course content without developer help. 3) Documentation (~8 days) — architecture map, data model, end-to-end content flow, tracking-integration spec, deployment procedures, known-issues register, and operational runbooks. All versioned in our repository. 4) Handover (~3 days) — two recorded working sessions with our team. ACCEPTANCE CRITERION (non-negotiable): at the end, two of our in-house developers must load a course, deploy a change, and diagnose a tracking issue using ONLY your documentation, with no help from you. That is when the project is done. STACK: Node.js/Express, MariaDB, React (student portal and admin panel), AWS (Elastic Beanstalk, RDS, S3), SCORM/xAPI content packages authored in Articulate Rise. We will provide a technical baseline document with verified findings so you don't start from zero. WHAT WE'RE LOOKING FOR: a senior developer who has taken over undocumented production systems before and left them operable by someone else's team. Please share examples of documentation you've written for that purpose — this matters more to us than years of experience. IMPORTANT: this is an application-layer role. Our in-house team handles all infrastructure, AWS administration and credentials. You work on the code with access we provide. LANGUAGE: the project runs in English. Spanish is welcome but not required. Budget is indicative. For the right fit we have flexibility on the total and on the milestone split. Please propose your own milestone breakdown with your bid.