Reorganize project into folder structure

Prefabs/combinable_item.gd

@@ -0,0 +1,24 @@
+class_name CombinableItem
+extends Node
+
+## Identity of this item, referenced by other items' recipes.
+@export var id: StringName
+
+## Recipes describing what the item holding this component turns into when
+## another item is combined into it while snapped. Recipes are directional:
+## only the snapped (base) item's recipes are consulted.
+@export var recipes: Array[CombineRecipe] = []
+
+
+func _ready() -> void:
+	if id.is_empty():
+		push_error("CombinableItem on ", get_parent().name, " has no 'id' set.")
+
+
+## Returns the scene this item becomes when combined with [param other_id],
+## or null if there is no matching recipe.
+func get_result_for(other_id: StringName) -> PackedScene:
+	for recipe in recipes:
+		if recipe and recipe.ingredient_id == other_id:
+			return recipe.result
+	return null