Table of Contents

Server mods implement IServerMod or inherit ServerModBase / ServerMelonModBase. Use S1DS.Server for access to server systems.

Lifecycle Hooks

  • OnServerInitialize()
  • OnServerStarted()
  • OnServerShutdown()
  • OnPlayerConnected(string playerId)
  • OnPlayerDisconnected(string playerId)
  • OnBeforeSave()
  • OnAfterSave()
  • OnBeforeLoad()
  • OnAfterLoad()
  • OnCustomMessage(string messageType, byte[] data, string senderId)

Keep connect/disconnect hooks light and move heavy work elsewhere when possible.

Server Systems

Available in SERVER builds via S1DS.Server:

  • Players
  • Network
  • GameSystems
  • Persistence
  • IsRunning
  • PlayerCount

Example:

public override void OnServerStarted()
{
    int total = S1DS.Server.PlayerCount;
}

Registration

Auto-discovery

Any MelonMod that implements IServerMod is discovered automatically. This includes:

  • SideAwareMelonModBase
  • ServerMelonModBase
  • direct IServerMod implementations

Manual registration

internal sealed class MyServerHandler : ServerModBase
{
    public override void OnServerInitialize()
    {
    }
}

public sealed class MyMod : MelonMod
{
    public override void OnInitializeMelon()
    {
#if SERVER
        ModManager.RegisterServerMod(new MyServerHandler());
#endif
    }
}

If registration happens after the server is already live, OnServerInitialize() is invoked immediately.

Do not manually register a MelonMod that already implements IServerMod or inherits ServerMelonModBase / SideAwareMelonModBase.

Declaring A Client Companion

If your server mod expects or supports a client companion, declare it at the assembly level:

using DedicatedServerMod.API;

[assembly: S1DSClientCompanion(
    modId: "ghost.marketterminal",
    displayName: "Market Terminal",
    Required = true,
    MinVersion = "2.0.0")]

Use this when:

  • the server mod requires client UI or client-side behavior
  • the client companion is optional but should still be validated when present

Guidance:

  • keep modId stable across releases
  • prefer MinVersion for normal compatibility
  • only populate PinnedSha256 when you intentionally support strict-mode operators

See Companion Mods and Verification Metadata for the complete workflow.

Messaging On Server

Prefer the shared messaging API for client-to-server communication. See Custom Messaging.

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