Seed

Deterministic RNG for the run: a single seed int on Ephemeral is advanced after each draw (System.Random + feedback into store).

State (Ephemeral)

How it looks in save / template JSON

In the Gnosis Engine’s default template (Assets/Resources/Data/ephemeral.json), run data lives under Ephemeral. For this service you only need to think about one field — at path Ephemeral.seed:

{
  "seed": 0
}

(That object is the Ephemeral JSON object: the file wraps it as "Ephemeral": { ... }; the snippet above is just the Seed-owned part.)

• 0 — “pick a fresh run seed” on first real GetSeed() in play.
• After RNG calls, seed becomes a non-zero integer until something resets it.

Events

None.

Functions

Usage examples (real call sites)

GetSeed — stable basis for a run

Game code often reads GetSeed once (or when the run starts) so deterministic choices—encounter rotation, loot tables, procedural steps—stay stable for that run. Example pattern:

        private int TryReadSeedFromSeedService()
        {
            if (Context?.Store == null || Context.CallService == null)
                return 0;
 
            var empty = GnosisNode.CreateObject(Context.Store);
            var result = CallService("Seed", "GetSeed", empty);
            if (!result.Success || !result.Data.IsValid || result.Data.Type != GnosisValueType.Object)
                return 0;
 
            var n = result.Data["seed"];
            if (!n.IsValid)
                return 0;
            if (n.Type == GnosisValueType.Int)
                return (int)n;
            if (n.Type == GnosisValueType.Long)
                return (int)(long)n;
            return 0;
        }

(Excerpt from lines 44–62 in a sample game project; any service with CallService can do the same.)

RangeInt — pick index for currency SFX

GnosisCurrencyService asks Seed for an index in [0, count) when choosing which configured clip to play from a currency row’s increaseSfx / decreaseSfx list (see GetSeededRandomIndex in the engine package):

        private int GetSeededRandomIndex(int count)
        {
            if (count <= 1 || Context?.Store == null || Context.CallService == null)
                return 0;
 
            var args = GnosisNode.CreateObject(Context.Store);
            args.Set("min", 0);
            args.Set("max", count);
            var result = CallService("Seed", "RangeInt", args);
            if (!result.Success || !result.Data.IsValid || result.Data.Type != GnosisValueType.Object)
                return 0;
 
            var valueNode = result.Data["value"];
            // ... normalizes int / long / float into index ...
            return value;
        }

JSON invocation (from rules / data)

Same calls are often expressed as invocations with service / function / parameters. Example for a random roll:

{
  "service": "Seed",
  "function": "RangeInt",
  "parameters": { "min": 0, "max": 10 }
}

(Return value is in the function result’s Data object, e.g. value, same as C#.)

Statistics

None.