Steamworks

SwiftlyS2 ships generated server-side Steamworks bindings under SwiftlyS2.Shared.SteamAPI (using SwiftlyS2.Shared.SteamAPI;), covering identity, authorization, server metadata, license/Workshop checks, and Steam's async callback patterns, as static classes mirroring the native ISteamGameServer* interfaces - see APISteamGameServer, APISteamGameServerUtils, APISteamGameServerUGC and APISteamGameServerStats for the full member lists (or the Quick Reference table at the end for the class overview).

Waiting for the Steam API

Steam callbacks aren't usable until the Steam API finishes activating - subscribe to Core.Event.OnSteamAPIActivated before touching any class above:

public override void Load(bool hotReload)
{
    Core.Event.OnSteamAPIActivated += OnSteamApiActivated;
}
 
private void OnSteamApiActivated()
{
    var appId = SteamGameServerUtils.GetAppID();
    Core.Logger.LogInformation("Steam API ready, AppId={AppId}", appId.m_AppId);
}

Converting Player IDs to Steam IDs

IPlayer.SteamID is a plain ulong - wrap it in APICSteamID before passing it to a Steam API call:

IPlayer? player = Core.PlayerManager.GetPlayer(playerId);
if (player == null) return;
 
var steamId = new CSteamID(player.SteamID);
if (!steamId.IsValid() || !steamId.BIndividualAccount())
{
    Core.Logger.LogWarning("Invalid SteamID for slot {PlayerId}", playerId);
    return;
}

Authorization Signals

Core.Event.OnClientSteamAuthorize/OnClientSteamAuthorizeFail fire once Steam confirms or rejects a connecting client:

Core.Event.OnClientSteamAuthorize += @event =>
    Core.Logger.LogInformation("Steam auth OK for slot {PlayerId}", @event.PlayerId);
 
Core.Event.OnClientSteamAuthorizeFail += @event =>
    Core.Logger.LogWarning("Steam auth failed for slot {PlayerId}", @event.PlayerId);

Server Metadata

SteamGameServer.SetServerName("My Swiftly Server");
SteamGameServer.SetMapName("de_dust2");
SteamGameServer.SetMaxPlayerCount(32);
SteamGameServer.SetPasswordProtected(false);
 
bool loggedOn = SteamGameServer.BLoggedOn();
bool secure = SteamGameServer.BSecure();
CSteamID serverSteamId = SteamGameServer.GetSteamID();

License / Ownership Checks

var appId = new AppId_t(730); // see ApiRef: AppId_t
var result = SteamGameServer.UserHasLicenseForApp(steamId, appId);
 
if (result == EUserHasLicenseForAppResult.k_EUserHasLicenseResultHasLicense)
{
    Core.Logger.LogInformation("Player owns app {AppId}", appId.m_AppId);
}

Workshop Items

Use SteamGameServerUGC - not the client-side SteamUGC - for server-side Workshop queries:

var fileId = new PublishedFileId_t(3070212801);
var state = (EItemState)SteamGameServerUGC.GetItemState(fileId);
 
if ((state & EItemState.k_EItemStateInstalled) == 0)
{
    SteamGameServerUGC.DownloadItem(fileId, bHighPriority: true);
}

Downloads complete asynchronously through a Steam callback struct - see below.

Steam Callbacks and Call Results

Steam surfaces two async patterns: APICallback`1 fires whenever a matching struct is posted; APICallResult`1 is a one-shot result tied to a SteamAPICall_t from a request method. Both are IDisposable - dispose them, typically in Unload.

private Callback<DownloadItemResult_t>? _downloadResult;
 
public override void Load(bool hotReload)
{
    _downloadResult = Callback<DownloadItemResult_t>.Create(OnDownloadItemResult);
}
 
public override void Unload()
{
    _downloadResult?.Dispose();
}
 
private void OnDownloadItemResult(DownloadItemResult_t result)
{
    if (result.m_eResult != EResult.k_EResultOK) return;
 
    SteamGameServerUGC.GetItemInstallInfo(
        result.m_nPublishedFileId, out ulong size, out string folder, 1024, out uint timestamp);
}

Auth Sessions

To validate a client-provided auth ticket manually, use BeginAuthSession/EndAuthSession rather than the deprecated connect/disconnect variants:

var authResult = SteamGameServer.BeginAuthSession(ticket, ticket.Length, steamId);
if (authResult != EBeginAuthSessionResult.k_EBeginAuthSessionResultOK)
{
    return;
}
 
// ... later, once the session ends ...
SteamGameServer.EndAuthSession(steamId);

Quick Reference

Class	Namespace	Purpose
`SteamGameServer`	`SwiftlyS2.Shared.SteamAPI`	Identity, auth sessions, metadata, license checks
`SteamGameServerUtils`	`SwiftlyS2.Shared.SteamAPI`	Misc utility queries (app ID, etc.)
`SteamGameServerUGC`	`SwiftlyS2.Shared.SteamAPI`	Workshop item state and download
`SteamGameServerStats`	`SwiftlyS2.Shared.SteamAPI`	Server-managed user stats
`CSteamID`, `AppId_t`, `PublishedFileId_t`	`SwiftlyS2.Shared.SteamAPI`	Core Steam identifier value types
`Callback<T>` / `CallResult<T>`	`SwiftlyS2.Shared.SteamAPI`	Async callback / call-result handling