PulseQueue — Live Digital Queue Manager for Neighbourhood Clinics

India's neighbourhood clinics run on paper tokens and shouting. Patients wait 2–3 hours with zero visibility. Receptionists manage queues from memory. Hospital management systems cost ₹50K–2L/year — overkill for a 1-doctor clinic. WhatsApp has no queue logic. Google Sheets need manual refresh. The gap: a free, real-time, two-screen system that works on any phone browser — no app install. Process Mapped 3 personas (receptionist, patient, doctor) to define constraints: <10s per action, works on any browser, no app install. Evaluated 4 real-time strategies. Chose Socket.IO for <50ms sync with auto-reconnection. Built receptionist-first: auto-focused input → Enter to submit → 3s token assignment. Then patient view — large type for wall-mounted readability, pulsing orb, sound chime on turn. What didn't work: started with HTTP polling at 2s intervals. Server load spiked with 15+ clients. Switched to event-driven Socket.IO — load dropped to near-zero. Results Token assignment time: 3 seconds (receptionist types name → presses Enter → done) Real-time sync latency: <50ms between receptionist action and patient screen update Page refreshes needed: 0 — Socket.IO pushes every mutation instantly Wait time accuracy: improves throughout the day as real consultation data accumulates (rolling average replaces 5-min default) Edge cases tested: skip/recall ordering, race conditions on concurrent "Call Next", sub-1-minute consultations, browser refresh recovery (localStorage + Socket.IO reconnect), empty queue handling, MongoDB failure graceful degradation. Reflection 1. Real clinic validation: I designed for a receptionist persona but never tested with one. A 30-min observation would've revealed friction I can't simulate — interruptions, multitasking, handwriting-to-typing flow. 2. SMS fallback: Not every patient has a smartphone. Twilio SMS ("Your turn in 5 min") would cover the 20% who don't. 3. Multi-doctor routing: Current system assumes 1 doctor. I'd add room-based queue separation for 2–3 doctor clinics. 4. Offline resilience: Service Worker so patient view degrades gracefully on network drops instead of showing stale data.