# Mission: Server-Sent Events (SSE)

## Why
As a frontend engineer, you want durable judgment about realtime delivery — not a one-off tutorial. When a feature needs live updates, you should pick the right transport with confidence and defend that choice in design reviews.

## Success looks like
- Given a product requirement, choose among short polling, long polling, SSE, and WebSockets (and say why)
- Know what the browser gives you for free with `EventSource` — and what it does not
- Spot deal-breakers early (bidirectional chat, binary media, custom auth headers, proxy buffering, connection limits)
## Status
**Core mission complete** (lessons 1–5 + references). Decision fluency is the bar; no implementation lab in this workspace.

## Constraints
- Frontend-first: system design decisions and browser APIs, not deep server frameworks
- No urgent product deadline — optimize for retention and decision quality over speed
- Prefer short, interactive lessons over long theory dumps

## Out of scope
- Building a production event bus / message broker architecture
- WebRTC, gRPC streaming, and GraphQL subscriptions (except as brief comparison labels)
- Full backend implementation courses (Node/Go/etc. only as needed to understand the wire format)