feat: generate readme markdown with ai

Author: Sepehr Bazyar

README.md

@@ -1,2 +1,50 @@
-# NYSE
-Real-time Trading Notifier
+# Real-Time Trading Notification System
+
+Scalable real-time system that sends new deal updates to users who follow one or more company tags/symbols.
+
+### What it does
+
+- Merchants post new deals via API
+- Users receive only deals for the tags they follow
+- Updates arrive via WebSocket in < 1 second (usually 100–300 ms)
+
+### Core design choices
+
+- **One Redis Pub/Sub channel** ("new_deals")
+  → every app server subscribes only once
+  → avoids thousands of connections per user
+
+- **Server-side fan-out**
+  → app servers receive every deal → filter locally → send only to relevant connected users
+  → no per-tag channels, no client-side filtering
+
+- **Per-user batching** (default 100 ms)
+  → messages are collected briefly → sent as JSON array
+  → fewer packets, better mobile experience, less server overhead
+
+- **In-memory tracking** per app instance
+  tag → connected WebSockets
+  WebSocket → subscribed tags
+  → very fast, scales horizontally by adding more app servers
+
+### Tech stack (2025–2026 style)
+
+- FastAPI                (REST + WebSocket)
+- SQLModel               (database models)
+- PostgreSQL / SQLite    (persistent data)
+- Redis Pub/Sub          (lightweight broadcast)
+- asyncio + in-memory dicts   (fan-out & batching)
+
+### Why these choices?
+
+- **Redis single channel** → constant low connection count
+- **No Kafka / RabbitMQ** → overkill, higher latency & ops cost
+- **In-memory fan-out** → fastest possible delivery (no extra network hops)
+- **Batching** → huge win for throughput and battery/network efficiency
+- **FastAPI + SQLModel** → modern, async, type-safe, easy to maintain
+
+### Quick start
+
+```bash
+poetry install
+uvicorn src.main:app --reload