I’m building a browser-based application where three distinct roles—Admin, Teacher, and SENCO—can exchange PDF documents and keep every action traceable and timely. Core workflow • Any user uploads a PDF, assigns it to one or more colleagues, and sets an open/close review window. • While the window is active, assignees can add threaded comments directly on the document. • When the window closes, the document locks for further edits and all comments become read-only. • Time-based email or in-app alerts remind each participant of approaching deadlines, overdue reviews, or new activity. Key features to build 1. Secure account system supporting the three roles, each with its own permissions dashboard. 2. Drag-and-drop PDF upload, server-side storage, and version control. 3. Inline commenting, @mentions, and change history. 4. Scheduler that triggers notifications at configurable intervals (e.g., 48-hour reminder, window-closing alert). 5. Search and filter by document status, owner, or review deadline. 6. Responsive UI so the whole flow works smoothly on desktop, tablet, and phone. Tech preferences I’m flexible on the stack as long as it’s built with widely adopted tools (React + Node, Vue + Laravel, Django, or similar), uses a relational database, and stores files either locally or in S3-compatible object storage. Please outline your proposed architecture and any third-party libraries you plan to leverage for PDF rendering and real-time notifications. Acceptance criteria • Role-based permissions tested and proven. • PDFs upload, download, and render without quality loss. • Commenting and notification rules function exactly to the timing windows we set during onboarding. • Code pushed to a private Git repo with setup instructions for a fresh server deploy. If you’ve delivered something similar—especially in education or document compliance—share a quick demo or repo link. I’m ready to start as soon as we align on the stack and milestones.