Crafting

SPI the game implements to supply its recipe book — the piece is inert (every craft returns UnknownRecipe) until a non-default catalog is registered. Register your implementation BEFORE AddCrossplayCrafting (a TryAdd seam) so it wins over the empty default. The framework calls TryGet once per craft request to resolve the recipe; keep it allocation-free and fast (it runs on the poll thread) — typically a lookup in a prebuilt dictionary of your game's recipes.

sealed class GameRecipes : ICraftingCatalog
{
    readonly Dictionary<ushort, CraftingRecipe> _byId = Build();
    public bool TryGet(ushort recipeId, out CraftingRecipe recipe) => _byId.TryGetValue(recipeId, out recipe!);
}
// services.AddSingleton<ICraftingCatalog, GameRecipes>(); // BEFORE AddCrossplayCrafting()

• bool TryGet(ushort recipeId, out CraftingRecipe recipe)

  Resolves a recipe by its game-defined id.

Optional SPI the game implements to gate crafts beyond "holds the ingredients" — skill/level checks, a required crafting station in range, per-recipe cooldowns, quest prerequisites, and the rest of the game's vocabulary. Default: allow every craft whose ingredients are present. Register your own BEFORE AddCrossplayCrafting (a TryAdd seam). Called AFTER the recipe resolved and BEFORE any ingredient is touched, on the poll thread.

sealed class StationRules : ICraftingRules
{
    public bool CanCraft(ISession session, long characterId, CraftingRecipe recipe)
        => _stations.IsNearForge(characterId); // false => CraftRefused
}

• bool CanCraft(ISession session, long characterId, CraftingRecipe recipe)

  Decide whether this character may craft this recipe right now.