Why ProxySelector

ProxySelector exists because a single proxy URL is not enough for real-world Steam integrations.

The Simple Approach

A basic client might support only:

http.ProxyURL(proxyURL)

This works for small cases, but it cannot express:

• rotating proxies
• health checks
• cooldown after failures
• session affinity
• routing by host and path
• direct connection fallback
• per-traffic-class proxy policy

The steam-go Approach

steam-go uses:

type ProxySelector interface {
    Next(req *http.Request) (*url.URL, error)
}

The selector receives the request, so it can make decisions based on:

• request host
• request path
• request context
• session key
• traffic class
• proxy health state

What This Enables

Feature	Why It Needs a Selector
Round-robin	Needs internal state
Health check	Needs failure memory
Sticky proxy	Needs session key
Routing proxy	Needs request host/path
Direct fallback	Needs route-level decision
Metrics	Needs selection and result tracking

Example

base, _ := steam.NewRoundRobinProxySelector(
    "http://127.0.0.1:7897",
    "http://127.0.0.1:7898",
)

selector := steam.NewStickyProxySelector(base)

client, err := steam.NewClient(
    steam.WithProxySelector(selector),
)

Design Principle

Proxy behavior is request policy, not just static configuration.