Traffic Policy

TrafficPolicy lets different request classes use different network behavior.

It is one of the main engineering abstractions in steam-go.

Traffic Classes

Class	Meaning
TrafficClassOfficialAPI	Normal typed Steam Web API traffic
TrafficClassPublicStorePage	Storefront web JSON or browser-like Store traffic
TrafficClassCommunityWeb	Steam Community inventory-style web JSON traffic
TrafficClassMarketWeb	Steam Community Market web JSON traffic

Why It Exists

Official API requests and public Store page requests should not always share the same strategy.

Official API traffic usually cares about:

• API key
• retry
• rate limit
• response decoding
• typed responses

Public Store page traffic may care about:

• browser-like headers
• cookies
• Referer
• block detection
• short cache
• lower concurrency
• proxy routing

Community or Market web JSON traffic may also care about:

• separate throttling from official API calls
• cookie jar reuse
• short cache for repeated reads
• block detection on 403, 429, or challenge HTML

Basic Example

client, err := steam.NewClient(
    steam.WithTrafficPolicy(
        steam.TrafficClassPublicStorePage,
        steam.TrafficPolicy{
            RateLimiter: &steam.TrafficRateLimiterPolicy{
                Limit: 10,
                Burst: 10,
            },
        },
    ),
)

Store-Page-Oriented Example

profile := steam.DefaultPublicStoreHeaderProfileEN()

client, err := steam.NewClient(
    steam.WithTrafficPolicy(
        steam.TrafficClassPublicStorePage,
        steam.TrafficPolicy{
            HeaderProfile: &profile,
            Cache: &steam.TrafficCachePolicy{
                TTL: time.Minute,
            },
            BlockPolicy: &steam.TrafficBlockPolicy{
                HTMLSniffBytes: 4096,
            },
        },
    ),
)

Request-Level Class Selection

ctx := steam.WithTrafficClass(
    context.Background(),
    steam.TrafficClassPublicStorePage,
)

In normal usage, the built-in client.Web.* methods already choose their default traffic class automatically:

• client.Web.Storefront.* -> TrafficClassPublicStorePage
• client.Web.Community.* -> TrafficClassCommunityWeb
• client.Web.Market.* -> TrafficClassMarketWeb

Policy Surface

TrafficPolicy can override:

• proxy selector
• cookie jar
• rate limiter
• retry policy
• host control
• session control
• short cache
• block detection
• header profile
• Referer selector
• transport hook

Request Observer

Use WithRequestObserver(...) when you need lightweight request metadata for logs or metrics without adding an OpenTelemetry dependency:

client, err := steam.NewClient(
    steam.WithRequestObserver(steam.RequestObserverFunc(func(event steam.RequestEvent) {
        _ = event.TrafficClass
        _ = event.Path
        _ = event.StatusCode
        _ = event.Duration
    })),
)

Observer events are emitted after SDK requests complete. They include the traffic class, method, host, path without raw query, status code, error kind, retry attempts, cache hit, block detection, and duration. They do not include raw query strings, headers, bodies, API keys, tokens, cookies, or proxy passwords.

Design Rule

Keep traffic behavior close to the SDK boundary.

Avoid pushing rate limits, cookies, proxy decisions, and browser-like headers into business code.