diff --git a/src/main/kotlin/ru/dbotthepony/mc/otm/block/entity/storage/ItemMonitorBlockEntity.kt b/src/main/kotlin/ru/dbotthepony/mc/otm/block/entity/storage/ItemMonitorBlockEntity.kt
index 3a6a0d860..5d9f7e8b7 100644
--- a/src/main/kotlin/ru/dbotthepony/mc/otm/block/entity/storage/ItemMonitorBlockEntity.kt
+++ b/src/main/kotlin/ru/dbotthepony/mc/otm/block/entity/storage/ItemMonitorBlockEntity.kt
@@ -240,7 +240,7 @@ class ItemMonitorBlockEntity(p_155229_: BlockPos, p_155230_: BlockState) :
 					val item = craftingGrid[i]
 
 					if (!item.isEmpty) {
-						poweredView[ItemStackWrapper(item).key()].let(craftingGridTuples[i]::addAll)
+						poweredView[ItemStackWrapper(item).key()]?.let(craftingGridTuples[i]::add)
 					}
 				}
 			}
@@ -248,7 +248,6 @@ class ItemMonitorBlockEntity(p_155229_: BlockPos, p_155230_: BlockState) :
 	}
 
 	private val craftingGridTuples = Array(3 * 3) { HashSet<UUID>() }
-	private val craftingGridTuplesFuzzy = Array(3 * 3) { HashSet<UUID>() }
 
 	private val craftingMenu = object : AbstractContainerMenu(null, Int.MIN_VALUE) {
 		override fun stillValid(p_38874_: Player): Boolean {
diff --git a/src/main/kotlin/ru/dbotthepony/mc/otm/storage/API.kt b/src/main/kotlin/ru/dbotthepony/mc/otm/storage/API.kt
index 8b6558614..44380ac09 100644
--- a/src/main/kotlin/ru/dbotthepony/mc/otm/storage/API.kt
+++ b/src/main/kotlin/ru/dbotthepony/mc/otm/storage/API.kt
@@ -101,6 +101,9 @@ interface IStorageEventConsumer<T : IStorageStack> : IStorage<T> {
 	fun removeStack(stack: T, id: UUID)
 }
 
+/**
+ * Storage acceptor, accepts (insert only) stacks provided via [insertStack] method.
+ */
 interface IStorageAcceptor<T : IStorageStack> : IStorage<T> {
 	/**
 	 * Inserts an item into system.
@@ -109,14 +112,40 @@ interface IStorageAcceptor<T : IStorageStack> : IStorage<T> {
 	fun insertStack(stack: T, simulate: Boolean): T
 }
 
+/**
+ * Storage provider, provides (extract only) stacks to whoever needs them (the "warehouse").
+ *
+ * [get] methods work as in bidirectional map.
+ *
+ * It is **required** for storage having **exactly one or none** of mappings of one stack [T]
+ * to one [UUID] (exactly one *UUID -> stack* and exactly one *stack -> UUID*).
+ *
+ * What this means is that [get] with [T] as an argument shall never experience a situation where
+ * two stacks match provided key.
+ *
+ * Technical decision of using [UUID]s for primary key for locating stacks is performance.
+ * This allows us to avoid burden of constantly constructing keys out of stacks (e.g. [net.minecraft.world.item.ItemStack]s)
+ * which may or may not produce performance hit; [UUID]s are lightweight, semantically not bound to anything and are
+ * very good for distributed ID generation (so nothing in game has to be bound to one sequential number generator).
+ */
 interface IStorageProvider<T : IStorageStack> : IStorageEventProducer<T> {
 	/**
+	 * Attempts to retrieve stored stack by its [id].
+	 *
+	 * Returns stored stack as-is. If no stack with [id] exists, then
+	 * "empty stack" is returned.
+	 *
 	 * @param id identifier of stack
 	 * @return stored object (not a copy). Do not edit it.
 	 */
 	operator fun get(id: UUID): T
 
 	/**
+	 * Attempts to map given [key] to [UUID] inside this storage provider.
+	 *
+	 * Implementation requirement: There should **never** be a situation where one [key]
+	 * matches two or more stacks. **Exactly one or none**.
+	 *
 	 * @param key stack we want to find UUID of
 	 * @return UUID of stack if present
 	 */
@@ -169,6 +198,9 @@ fun <T : IStorageStack> IStorageProvider<T>.addListenerAuto(listener: IStorageEv
 	return false
 }
 
+/**
+ * Storage component, which basically implement Input and Output
+ */
 interface IStorageComponent<T : IStorageStack> : IStorageProvider<T>, IStorageAcceptor<T>
 
 fun <T : IStorageStack> IStorageEventConsumer<T>.changeStack(tuple: IStorageTuple<T>, oldCount: BigInteger) {