Mushroom Sync

Shared server-authoritative sync for the Mushroom mods. The host decides, clients follow, and nobody's local .cfg gets rewritten.

It has no gameplay of its own. It exists so the mods that need server-authoritative settings share one implementation instead of four copies of the same 300 lines.

Required by

Mod	Uses
Combat Adjustments	Config sync
Craftable Spawners	Config sync
Haldor Expansion	Config sync
Random Yggdrasil	Raw channel (world rotations)

MushroomSync.dll must be installed wherever those are — on every client and on the dedicated server. The release zip ships it alongside them, so extracting MushroomMods-plugins.zip into BepInEx/ is enough.

Using it

Config sync, in a plugin's Awake, before binding settings:

[BepInPlugin(PluginGuid, PluginName, PluginVersion)]
[BepInDependency(MushroomSyncPlugin.PluginGuid)]
public class MyPlugin : BaseUnityPlugin
{
    internal static ConfigSync Sync;

    private void Awake()
    {
        Sync = ConfigSync.Create(PluginGuid, PluginVersion, Logger)
            .Protecting(Config)
            .OnApplied(ReapplyRuntimeState);

        EnableThing = Config.Bind("General", "EnableThing", true, "...");
        Sync.Register(EnableThing);

        Sync.WatchForChanges(Config).Start();
    }
}

After that EnableThing.Value returns the host's value on a synced client and the local one everywhere else — no call site needs changing. Where you need to know which you got, or want the local value alongside, use Sync.TryGetSyncedValue(entry, out var v).

OnApplied matters for any mod that bakes settings into game objects: the config changing is not enough, the values have to be pushed back in. It fires both when host values arrive and when they are dropped.

Settings that must stay local

Sync.Exclude(SyncConfigInMultiplayer);   // the opt-out itself
Sync.Exclude(GrantTableVersion);         // server-only bookkeeping

An excluded entry is never sent and never overlaid.

Opting out

Two gates, deliberately separate:

Sync.GatedBy(() => LockConfiguration.Value);      // host: publish, or stay quiet
Sync.AcceptedWhen(() => SyncEnabled.Value);       // client: follow a host, or not

GatedBy is a host-side switch — it decides whether this machine publishes when it is the server. Haldor Expansion uses only this: a client with LockConfiguration off still follows a host that has it on.

AcceptedWhen is a client-side opt-out. Combat Adjustments passes the same predicate to both, because its SyncConfigInMultiplayer means "do not sync at all".

Conflating the two is a bug worth naming: a host-side switch that also refused incoming values would stop a client following a server merely because that client would not have shared its own settings when hosting.

Pushing your own data

For anything that is not a config entry, use the channel directly — this is what Random Yggdrasil does for world rotations:

var channel = SyncChannel.Create("MyMod.Thing", PluginVersion, Logger);
channel.WritePayload = pkg => { /* server writes */ };
channel.ReadPayload  = pkg => { /* client reads */ };
channel.Cleared      = reason => { /* fall back to local */ };
channel.Start();

channel.Broadcast();   // after the server changes something

SyncChannel.ReadCount(pkg) reads a length prefix with a sanity bound, so a corrupt packet cannot make you allocate without limit.

Design

See docs/DESIGN.md for why it is built this way — the layering, why it does not wrap login sockets the way ServerSync did, and why the value overlay is read-only.